Molecules

892 KiB

Open AccessReview

Structural and Pharmacological Effects of Ring-Closing Metathesis in Peptides

by Øyvind Jacobsen, Jo Klaveness and Pål Rongved

Molecules 2010, 15(9), 6638-6677; https://doi.org/10.3390/molecules15096638 - 21 Sep 2010

Cited by 37 | Viewed by 9943

Applications of ring-closing alkene metathesis (RCM) in acyclic α- and β-peptides and closely related systems are reviewed, with a special emphasis on the structural and pharmacological effects of cyclization by RCM. Full article

(This article belongs to the Special Issue Ring-Closing Metathesis)

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179 KiB

Open AccessArticle

The Antigerminative Activity of Twenty-Seven Monoterpenes

by Laura De Martino, Emilia Mancini, Luiz Fernando Rolim de Almeida and Vincenzo De Feo

Molecules 2010, 15(9), 6630-6637; https://doi.org/10.3390/molecules15096630 - 21 Sep 2010

Cited by 172 | Viewed by 14285

Abstract

Monoterpenes, the main constituents of essential oils, are known for their many biological activities. The present work studied the potential biological activity of twenty-seven monoterpenes, including monoterpene hydrocarbons and oxygenated ones, against seed germination and subsequent primary radicle growth of Raphanus sativus L. [...] Read more.

Monoterpenes, the main constituents of essential oils, are known for their many biological activities. The present work studied the potential biological activity of twenty-seven monoterpenes, including monoterpene hydrocarbons and oxygenated ones, against seed germination and subsequent primary radicle growth of Raphanus sativus L. (radish) and Lepidium sativum L. (garden cress), under laboratory conditions. The compounds, belonging to different chemical classes, showed different potency in affecting both parameters evaluated. The assayed compounds demonstrated a good inhibitory activity in a dose-dependent way. In general, radish seed is more sensitive than garden cress and its germination appeares more inhibited by alcohols; at the highest concentration tested, the more active substances were geraniol, borneol, (±)-β-citronellol and α-terpineol. Geraniol and carvone inhibited, in a significant way, the germination of garden cress, at the highest concentration tested. Radicle elongation of two test species was inhibited mainly by alcohols and ketones. Carvone inhibited the radicle elongation of both seeds, at almost all concentrations assayed, while 1,8-cineole inhibited their radicle elongation at the lowest concentrations (10⁻⁵ M, 10⁻⁶ M). Full article

(This article belongs to the Section Natural Products Chemistry)

151 KiB

Open AccessArticle

Green One Pot Solvent-Free Synthesis of Pyrano[2,3-c]-Pyrazoles and Pyrazolo[1,5-a]Pyrimidines

by Hamad M. Al-Matar, Khaled D. Khalil, Aisha Y. Adam and Mohamed H. Elnagdi

Molecules 2010, 15(9), 6619-6629; https://doi.org/10.3390/molecules15096619 - 20 Sep 2010

Cited by 93 | Viewed by 14124

Abstract

Pyrano[2,3-c]pyrazoles are obtained via mixing ethyl acetoacetate, hydrazine hydrate, aldehydes or ketones and malononitrile in the absence of solvent. These same products were also obtained by reacting arylidenemalononitriles 3 with 3-methyl-2-pyrazolin-5-ones. NOE difference experiments confirmed that these products exist solely in [...] Read more.

Pyrano[2,3-c]pyrazoles are obtained via mixing ethyl acetoacetate, hydrazine hydrate, aldehydes or ketones and malononitrile in the absence of solvent. These same products were also obtained by reacting arylidenemalononitriles 3 with 3-methyl-2-pyrazolin-5-ones. NOE difference experiments confirmed that these products exist solely in the 2H form. Similar treatments of 3-amino-2-pyrazolin-5-one with arylidene-malononitrile afforded adduct 6. Similarly mixing ethyl cyanoacetate, hydrazine hydrate, aldehydes, with malononitrile gave the same product 6. A novel synthesis of 4-oxo-4H-pyrano[2,3-c]pyrazole (8) could be achieved via reacting 3-methyl-2-pyrazolin-5-one with a mixture of cyanoacetic acid and acetic anhydride. Similar treatment of 3-aminopyrazole 11 with the benzylidene-malononitrile produced the pyrazolo[2,3-a]pyrimidines 12a,b. Full article

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198 KiB

Open AccessReview

Kinin Receptor Antagonists as Potential Neuroprotective Agents in Central Nervous System Injury

by Emma Thornton, Jenna M Ziebell, Anna V Leonard and Robert Vink

Molecules 2010, 15(9), 6598-6618; https://doi.org/10.3390/molecules15096598 - 20 Sep 2010

Cited by 37 | Viewed by 11069

Abstract

Injury to the central nervous system initiates complex physiological, cellular and molecular processes that can result in neuronal cell death. Of interest to this review is the activation of the kinin family of neuropeptides, in particular bradykinin and substance P. These neuropeptides are [...] Read more.

Injury to the central nervous system initiates complex physiological, cellular and molecular processes that can result in neuronal cell death. Of interest to this review is the activation of the kinin family of neuropeptides, in particular bradykinin and substance P. These neuropeptides are known to have a potent pro-inflammatory role and can initiate neurogenic inflammation resulting in vasodilation, plasma extravasation and the subsequent development of edema. As inflammation and edema play an integral role in the progressive secondary injury that causes neurological deficits, this review critically examines kinin receptor antagonists as a potential neuroprotective intervention for acute brain injury, and more specifically, traumatic brain and spinal cord injury and stroke. Full article

(This article belongs to the Special Issue Neuroprotective Strategies)

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188 KiB

Open AccessArticle

Synthesis of Chiral Macrocyclic or Linear Pyridine Carboxamides from Pyridine-2,6-dicarbonyl Dichloride as Antimicrobial Agents

by Rashad A. Al-Salahi, Mohamed A Al-Omar and Abd El-Galil E Amr

Molecules 2010, 15(9), 6588-6597; https://doi.org/10.3390/molecules15096588 - 20 Sep 2010

Cited by 56 | Viewed by 10689

Abstract

A series of chiral linear and macrocyclic bridged pyridines has been prepared starting from pyridine-2,6-dicarbonyl dichloride (2). The coupling of 1 with D-alanyl methyl ester gave 2,6-bis-D-alanyl pyridine methyl ester (3). Hydrazinolysis of 3 with hydrazine hydrate afforded bis-hydrazide 4. The latter was [...] Read more.

A series of chiral linear and macrocyclic bridged pyridines has been prepared starting from pyridine-2,6-dicarbonyl dichloride (2). The coupling of 1 with D-alanyl methyl ester gave 2,6-bis-D-alanyl pyridine methyl ester (3). Hydrazinolysis of 3 with hydrazine hydrate afforded bis-hydrazide 4. The latter was reacted with thiophene-2-carbaldehyde, phthalic anhydride or cyclohexanone to afford bis-carboxamide pyridine derivatives 5-7, respectively. Compound 4 was coupled with p-methoxy- or p-nitroaceto-phenone to yield compounds 8 and 9. In addition, 4 was reacted with 1,2,4,5-benzenetetra-carboxylic acid dianhydride or 1,4,5,8-naphthalenetetracarboxylic acid dianhydride to afford the macrocyclic octacarboxaamide pyridines 10 and 11. The detailed synthesis, spectroscopic data and antimicrobial screening for the synthesized compounds are reported. Full article

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223 KiB

Open AccessCommunication

Variation of Oleanolic and Ursolic Acid in the Flesh of Persimmon Fruit among Different Cultivars

by Chunhua Zhou, Yanle Sheng, Daqiu Zhao, Zhiqin Wang and Jun Tao

Molecules 2010, 15(9), 6580-6587; https://doi.org/10.3390/molecules15096580 - 20 Sep 2010

Cited by 35 | Viewed by 9142

Abstract

Oleanolic acid (OA) and ursolic acid (UA) are important bioactive components in many plants, including persimmon (Diospyros kaki L.). The present work was carried out to determine OA and UA contents in the flesh of persimmon fruit from 32 cultivars, including 23 astringent [...] Read more.

Oleanolic acid (OA) and ursolic acid (UA) are important bioactive components in many plants, including persimmon (Diospyros kaki L.). The present work was carried out to determine OA and UA contents in the flesh of persimmon fruit from 32 cultivars, including 23 astringent and 9 non-astringent ones, by applying high performance liquid chromatography (HPLC) with UV detection. Both OA and UA were present in all of the investigated cultivars, except for three, ‘Hiratanenashi’, ‘Ribenhongshi’ and ‘Matsumotowase’. The OA content ranged from traces to 88.57 μg/g FW, and that of UA were between traces and 27.64 μg/g FW. Full article

(This article belongs to the Section Natural Products Chemistry)

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228 KiB

Open AccessArticle

Determination of Quercetin and Resveratrol in Whole Blood—Implications for Bioavailability Studies

by Lucia Biasutto, Ester Marotta, Spiridione Garbisa, Mario Zoratti and Cristina Paradisi

Molecules 2010, 15(9), 6570-6579; https://doi.org/10.3390/molecules15096570 - 20 Sep 2010

Cited by 70 | Viewed by 13133

Abstract

Resveratrol (trans-3,4',5-trihydroxystilbene) and quercetin (3,3’,4’,5,7-pentahydroxyflavone) are two naturally occurring polyphenols with the potential to exert beneficial health effects. Since their low bioavailability is a major obstacle to biomedical applications, efforts are being made to improve their absorption and slow down phase [...] Read more.

Resveratrol (trans-3,4',5-trihydroxystilbene) and quercetin (3,3’,4’,5,7-pentahydroxyflavone) are two naturally occurring polyphenols with the potential to exert beneficial health effects. Since their low bioavailability is a major obstacle to biomedical applications, efforts are being made to improve their absorption and slow down phase II metabolism. An accurate evaluation of the corresponding levels in the bloodstream is important to assess delivery strategies, as well as to verify claims of efficacy based on in vitro results. In the present work we have optimized a simple method ensuring complete stabilization and extraction of resveratrol and quercetin from whole blood. The suitability of different protocols was evaluated by measuring the recovery of polyphenol and internal standard from spiked blood samples via HPLC/UV analysis. The optimized procedure ensured a satisfactory recovery of both internal standards and compounds. Comparing plasma and whole blood, up to 76% of the analyte, being associated with the cellular fraction, was unaccounted for when examining only plasma. This indicates the importance of analysing whole blood rather than plasma to avoid underestimating polyphenol absorption in bioavailability studies. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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2862 KiB

Open AccessArticle

Correlation between Cytotoxic Activities and Reduction Potentials of Heterocyclic Quinones

by Junko Koyama, Izumi Morita and Takao Yamori

Molecules 2010, 15(9), 6559-6569; https://doi.org/10.3390/molecules15096559 - 20 Sep 2010

Cited by 18 | Viewed by 7904

Abstract

To search for possible anti-tumor agents or anti-tumor promoters among natural or synthetic products, we used cyclic voltammetry to determine the reduction-oxidation potentials of heterocyclic quinones in phosphate buffer at pH 7.2. We determined the growth inhibitory- and cytotoxic activities of 12 heterocyclic [...] Read more.

To search for possible anti-tumor agents or anti-tumor promoters among natural or synthetic products, we used cyclic voltammetry to determine the reduction-oxidation potentials of heterocyclic quinones in phosphate buffer at pH 7.2. We determined the growth inhibitory- and cytotoxic activities of 12 heterocyclic quinone anti-tumor agent candidates against a panel of 39 human cancer cell lines (JFCR39). The average concentrations of the heterocyclic quinones required for 50% growth inhibition (GI₅₀) against JFCR39 ranged from 0.045 to 13.2 µM, and the 50% lethal concentration (LC₅₀) against JFCR39 ranged from 0.398 to 77.7 µM. The average values of GI₅₀ or LC₅₀ of the heterocyclic quinones correlated significantly with their reduction potentials. These results suggested that reduction-oxidation potentials could be a useful method for the discovery of novel antitumor agents. Full article

(This article belongs to the Collection Bioactive Compounds)

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276 KiB

Open AccessArticle

New 2-Arylbenzofurans from the Root Bark of Artocarpus lakoocha

by Boonchoo Sritularak, Kullasap Tantrakarnsakul, Kittisak Likhitwitayawuid and Vimolmas Lipipun

Molecules 2010, 15(9), 6548-6558; https://doi.org/10.3390/molecules15096548 - 17 Sep 2010

Cited by 17 | Viewed by 5997

Abstract

Three new prenylated 2-arylbenzofurans – artolakoochol, 4-hydroxy-artolakoochol and cycloartolakoochol – have been isolated from the root bark of Artocarpus lakoocha Roxb., Their structures were elucidated through analysis of their spectroscopic data, and their antiherpetic potential was evaluated by the plaque reduction assay. Full article

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Open AccessReview

The 9-Phenyl-9-fluorenyl Group for Nitrogen Protection in Enantiospecific Synthesis

by Essi J. Karppanen and Ari M. P. Koskinen

Molecules 2010, 15(9), 6512-6547; https://doi.org/10.3390/molecules15096512 - 17 Sep 2010

Cited by 13 | Viewed by 11189

Abstract

One of the biggest challenges in asymmetric synthesis is to prevent racemization of enantiopure starting materials. However, at least some of the enantiopurity is lost in most of the existing reactions used in synthetic organic chemistry. This translates into unnecessary material losses. Naturally [...] Read more.

One of the biggest challenges in asymmetric synthesis is to prevent racemization of enantiopure starting materials. However, at least some of the enantiopurity is lost in most of the existing reactions used in synthetic organic chemistry. This translates into unnecessary material losses. Naturally enantiopure proteinogenic amino acids that can be transformed into many useful intermediates in drug syntheses, for example, are especially vulnerable to this. The phenylfluoren-9-yl (Pf) group, a relatively rarely used protecting group, has proven to be able to prevent racemization in α-amino compounds. This review article showcases the use of Pf-protected amino acid derivatives in enantiospecific synthesis. Full article

(This article belongs to the Special Issue Protecting Group in Organic Synthesis)

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Graphical abstract

197 KiB

Open AccessArticle

Synthesis and Antitumor Activity of Diterpenylhydroquinone Derivatives of Natural Ent-Labdanes

by Luis Espinoza Catalán, Evelyn Baeza Maturana, Karen Catalán Marín, Mauricio Osorio Olivares, Héctor Carrasco Altamirano, Mauricio Cuellar Fritis and Joan Villena García

Molecules 2010, 15(9), 6502-6511; https://doi.org/10.3390/molecules15096502 - 17 Sep 2010

Cited by 12 | Viewed by 9021

Abstract

Two new compounds 2β-acetoxy-15-phenyl-(22,25-acetoxy)-ent-labda-8(17), 13(E)-diene (9) and 2β-hydroxy-15-phenyl-(22,24,26-trimethoxy)-ent-labda-8(17),13(E)-diene (10) have been prepared by an Electrophilic Aromatic Substitution (EAS) reaction between diterpenyl allylic alcohols and 1,4-hydroquinone or 1,3,5-trimethoxybenzene using BF [...] Read more.

Two new compounds 2β-acetoxy-15-phenyl-(22,25-acetoxy)-ent-labda-8(17), 13(E)-diene (9) and 2β-hydroxy-15-phenyl-(22,24,26-trimethoxy)-ent-labda-8(17),13(E)-diene (10) have been prepared by an Electrophilic Aromatic Substitution (EAS) reaction between diterpenyl allylic alcohols and 1,4-hydroquinone or 1,3,5-trimethoxybenzene using BF₃^.Et₂O as a catalyst. These compounds, along with a series of natural ent-labdanes 3-8, have been evaluated for their in vitro cytotoxic activities against cultured human cancer cells of PC-3 and DU-145 human prostate cancer, MCF-7 and MDA-MB-231 breast carcinoma and dermal human fibroblasts (DHF). Some compounds displayed inhibition at µM IC₅₀values. Full article

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184 KiB

Open AccessArticle

An Efficient and Chemoselective Procedure for Acylal Synthesis

by Da-He Fan, Hui Wang, Xing-Xing Mao and Yong-Miao Shen

Molecules 2010, 15(9), 6493-6501; https://doi.org/10.3390/molecules15096493 - 16 Sep 2010

Cited by 8 | Viewed by 10704

Abstract

A novel heterogeneous efficient procedure has been developed for the chemoselective synthesis of acylals (1,1-diacetates) under solvent-free conditions. A novel catalyst prepared by the sulfuric acid catalyzed copolymerization of p-toluenesulfonic acid and paraformaldehyde displays extremely high activities for the title reactions, affording [...] Read more.

A novel heterogeneous efficient procedure has been developed for the chemoselective synthesis of acylals (1,1-diacetates) under solvent-free conditions. A novel catalyst prepared by the sulfuric acid catalyzed copolymerization of p-toluenesulfonic acid and paraformaldehyde displays extremely high activities for the title reactions, affording average yields over 90% within several minutes. A comparative study showed that the novel catalyst has much higher activity than other catalysts used for this purpose. Besides, the novel catalyst displays chemoselectivity for the protection of aldehydes in the presence of ketones. In addition the high acidity (4.0 mmol/g), thermal stability (200 ºC) and easy reusability make the novel catalyst one of the best choices for the process. Full article

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269 KiB

Open AccessCommunication

Synthesis and Antifungal Activity of Carabrone Derivatives

by Jun-Tao Feng, Zhi-Qing Ma, Jiang-Hua Li, Jun He, Hui Xu and Xing Zhang

Molecules 2010, 15(9), 6485-6492; https://doi.org/10.3390/molecules15096485 - 16 Sep 2010

Cited by 22 | Viewed by 6909

Abstract

Nine derivatives 6-14 of carabrone (1) were synthesized and tested in vitro against Colletotrichum lagenarium Ell et Halst using the spore germination method. Among all of the derivatives, compounds 6-8 and 12 showed more potent antifungal activity than [...] Read more.

Nine derivatives 6-14 of carabrone (1) were synthesized and tested in vitro against Colletotrichum lagenarium Ell et Halst using the spore germination method. Among all of the derivatives, compounds 6-8 and 12 showed more potent antifungal activity than 1. Structure-activity relationships (SAR) demonstrated that the γ-lactone was necessary for the antifungal activity of 1, and the substituents on the C-4 position of 1 could significantly affect the antifungal activity. Full article

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Open AccessCommunication

Isoquinolines from the Roots of Thalictrum flavum L. and Their Evaluation as Antiparasitic Compounds

by Jacqueline Ropivia, Séverine Derbré, Caroline Rouger, Fabrice Pagniez, Patrice Le Pape and Pascal Richomme

Molecules 2010, 15(9), 6476-6484; https://doi.org/10.3390/molecules15096476 - 16 Sep 2010

Cited by 22 | Viewed by 16279

Abstract

Alkaloids from Thalictrum flavum L. (Ranuculaceae) growing in the Loire valley (France) were isolated and evaluated for their antiplasmodial and leishmanicidal activities. Berberine was identified as a major component but its analogue, pseudoberberine, was isolated for the first time from this plant. As [...] Read more.

Alkaloids from Thalictrum flavum L. (Ranuculaceae) growing in the Loire valley (France) were isolated and evaluated for their antiplasmodial and leishmanicidal activities. Berberine was identified as a major component but its analogue, pseudoberberine, was isolated for the first time from this plant. As far as bisbenzylisoquinolines are concerned, thalfoetidine was also isolated and, besides, its nor- derivative, northalfoetidine, was identified as a new compound. Previously isolated alkaloids from Thalictrum species such as northalidasine, northalrugosidine, thaligosidine, thalicberine, thaliglucinone, preocoteine, O-methylcassythine and armepavine were newly described in the roots of T. flavum. Tertiary isoquinolines, and particularly bisbenzylisoquinolines, were found to be leishmanicidal against L. major. Thalfoetidine appeared as the most potent but its new nor- derivative northalfoetidine, as well as northalidasine, were of particular interest due to the fact that their potential leishmanicidal activity was not associated to a strong cytotoxicity. Full article

(This article belongs to the Section Natural Products Chemistry)

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Open AccessArticle

Effects of Eupatilin and Jaceosidin on Cytochrome P450 Enzyme Activities in Human Liver Microsomes

by Hye Young Ji, Sung Yeon Kim, Dong Kyun Kim, Ji Hyun Jeong and Hye Suk Lee

Molecules 2010, 15(9), 6466-6475; https://doi.org/10.3390/molecules15096466 - 16 Sep 2010

Cited by 33 | Viewed by 11695

Abstract

Eupatilin and jaceosidin are bioactive flavones found in the medicinal herbs of the genus Artemisia. These bioactive flavones exhibit various antioxidant, antiinflammatory, antiallergic, and antitumor activities. The inhibitory potentials of eupatilin and jaceosidin on the activities of seven major human cytochrome P450 [...] Read more.

Eupatilin and jaceosidin are bioactive flavones found in the medicinal herbs of the genus Artemisia. These bioactive flavones exhibit various antioxidant, antiinflammatory, antiallergic, and antitumor activities. The inhibitory potentials of eupatilin and jaceosidin on the activities of seven major human cytochrome P450 enzymes in human liver microsomes were investigated using a cocktail probe assay. Eupatilin and jaceosidin potently inhibited CYP1A2-catalyzed phenacetin O-deethylation with 50% inhibitory concentration (IC₅₀) values of 9.4 mM and 5.3 mM, respectively, and CYP2C9-catalyzed diclofenac 4-hydroxylation with IC₅₀ values of 4.1 mM and 10.2 mM, respectively. Eupatilin and jaceosidin were also found to moderately inhibit CYP2C19-catalyzed [S]-mephenytoin 4¢-hydroxylation, CYP2D6-catalyzed bufuralol 1¢-hydroxylation, and CYP2C8-catalyzed amodiaquine N-deethylation. Kinetic analysis of human liver microsomes showed that eupatilin is a competitive inhibitor of CYP1A2 with a K_i value of 2.3 mM and a mixed-type inhibitor of CYP2C9 with a K_i value of 1.6 mM. Jaceosidin was shown to be a competitive inhibitor of CYP1A2 with a K_i value of 3.8 mM and a mixed-type inhibitor of CYP2C9 with K_i value of 6.4 mM in human liver microsomes. These in vitro results suggest that eupatilin and jaceosidin should be further examined for potential pharmacokinetic drug interactions in vivo due to inhibition of CYP1A2 and CYP2C9. Full article

(This article belongs to the Collection Bioactive Compounds)

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Figure 1
Representative Dixon plots for inhibitory effects of eupatilin on (a) CYP1A2-catalyzed phenacetin O-deethylation, (b) CYP2C8-catalyzed amodiaquine N-deethylation, (c) CYP2C9-catalyzed diclofenac 4-hydroxylation, (d) CYP2C19-catalyzed [S]-mephenytoin 4'-hydroxylation, and (e) CYP2D6-catalyzed bufuralol 1'-hydroxylation in pooled human liver microsomes. Each symbol represents the substrate concentration. (a) phenacetin: 10 μM (▽), 20 μM (○), 40 μM (△), and 80 μM (□); (b) amodiaquine:0.5 μM (▽), 1.0 μM (○), 2.0 μM (△), and 5.0 μM (□); (c) diclofenac: 1 μM (▽), 5 μM (○),10 μM (△), and 50 μM (□); (d) [S]-mephenytoin: 10 μM (▽), 20 μM (○), 50 μM (△), and 100 μM (□); (e) bufuralol: 0.5 μM (▽), 1.0 μM (○), 2.0 μM (△), and 5.0 μM (□). Each data point represents the mean of triplicate experiments. Full article ">Figure 2
Representative Dixon plots for inhibitory effects of jaceosidin on (a) CYP1A2-catalyzed phenacetin O-deethylation, (b) CYP2C8-catalyzed amodiaquine N-deethylation, (c) CYP2C9-catalyzed diclofenac 4-hydroxylation, (d) CYP2C19-catalyzed [S]-mephenytoin 4'-hydroxylation, and (e) CYP2D6-catalyzed bufuralol 1'-hydroxylation in pooled human liver microsomes. Each symbol represents the substrate concentration. (a) phenacetin: 10 μM (▽), 20 μM (○), 40 μM (△), and 80 μM (□); (b) amodiaquine:0.5 μM (▽), 1.0 μM (○), 2.0 μM (△), and 5.0 μM (□); (c) diclofenac: 1 μM (▽), 5 μM (○),10 μM (△), and 50 μM (□); (d) [S]-mephenytoin: 10 μM (▽), 20 μM (○), 50 μM (△), and 100 μM (□); (e) bufuralol: 0.5 μM (▽), 1.0 μM (○), 2.0 μM (△), and 5.0 μM (□). Each data point represents the mean of triplicate experiments. Full article ">

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Open AccessReview

Honokiol and Magnolol as Multifunctional Antioxidative Molecules for Dermatologic Disorders

by Jui-Lung Shen, Kee-Ming Man, Po-Hsun Huang, Wen-Chi Chen, Der-Cherng Chen, Ya-Wen Cheng, Po-Len Liu, Ming-Chih Chou and Yung-Hsiang Chen

Molecules 2010, 15(9), 6452-6465; https://doi.org/10.3390/molecules15096452 - 16 Sep 2010

Cited by 142 | Viewed by 21636

Abstract

Chinese herbs have been and still are widely used as important remedies in Oriental medicine. Over the recent years, a variety of biologically active constituents have been isolated from these sources and confirmed to have multifunctional activity in experimental studies. Honokiol is a [...] Read more.

Chinese herbs have been and still are widely used as important remedies in Oriental medicine. Over the recent years, a variety of biologically active constituents have been isolated from these sources and confirmed to have multifunctional activity in experimental studies. Honokiol is a small-molecule polyphenol isolated from the genus Magnolia. It is accompanied by other related polyphenols, including magnolol, with which it shares certain biological properties. Recently, honokiol and magnolol have been found to have anti-oxidative, anti-inflammatory, anti-tumor, and anti-microbial properties in preclinical models, without appreciable toxicity. These findings have increased interest in bringing honokiol and magnolol to the clinic as novel therapeutic agents in dermatology. In this review, the findings concerning the major mechanisms of action of honokiol and magnolol are described. Knowledge of the multiple activities of honokiol and magnolol can assist with the development of honokiol and magnolol derivatives and the design of clinical trials that will maximize the potential benefit of honokiol and magnolol in the patient setting for dermatologic disorders. Full article

(This article belongs to the Special Issue Antioxidants)

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Open AccessArticle

Anti-Inflammatory Activity of Chrysophanol through the Suppression of NF-kB/Caspase-1 Activation in Vitro and in Vivo

by Su-Jin Kim, Min-Cheol Kim, Byong-Joo Lee, Dae-Hee Park, Seung-Heon Hong and Jae-Young Um

Molecules 2010, 15(9), 6436-6451; https://doi.org/10.3390/molecules15096436 - 16 Sep 2010

Cited by 118 | Viewed by 13952

Abstract

Chrysophanol is a member of the anthraquinone family and has multiple pharmacological effects, but the exact mechanism of the anti-inflammatory effects of chrysophanol has yet to be thoroughly elucidated. In this study, we attempted to determine the effects of chrysophanol on dextran sulfate [...] Read more.

Chrysophanol is a member of the anthraquinone family and has multiple pharmacological effects, but the exact mechanism of the anti-inflammatory effects of chrysophanol has yet to be thoroughly elucidated. In this study, we attempted to determine the effects of chrysophanol on dextran sulfate sodium (DSS)-induced colitis and lipopolysaccharide (LPS)-induced inflammatory responses in mouse peritoneal macrophages. The findings of this study demonstrated that chrysophanol effectively attenuated overall clinical scores as well as various pathological markers of colitis. Additionally, chrysophanol inhibited the production of tumor necrosis factor (TNF)-a, interleukin (IL)-6 and the expression of cyclooxygenase (COX)-2 levels induced by LPS. We showed that this anti-inflammatory effect of chrysophanol is through suppression of the activation of NF-kB and caspase-1 in LPS-stimulated macrophages. These results provide novel insights into the pharmacological actions of chrysophanol as a potential molecule for use in the treatment of inflammatory diseases. Full article

(This article belongs to the Section Natural Products Chemistry)

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Effect of chrysophanol on clinical signs in DSS-induced colitis. Experimental colitis in mice was induced by a 5% DSS dissolved in the drinking water for 7 days. Chrysophanol was administered at doses of 5 mg/kg once a day for 7 days prior to 5% DSS supplement. (A) Body weight of mice was measured; (B) The colons were removed at day 7 after DSS treatment, and the colon lengths were measured; (C) Relative colon lengths were represented; (D) DAI was calculated as described in the Experimental. Sulfasalazine (150 mg/kg) was used as a positive control. (1) Control group; (2) DSS alone-treated group; (3) chrysophanol (5 mg/kg) + DSS treated group; (4) sulfasalazine (150 mg/kg) + DSS treated group. Values were represented in the mean ± S.E.M. (n = 5) of duplicate determinations from triplicate separate experiments(# p < 0.05 vs. control, * p < 0.05 vs. DSS alone). Full article ">Figure 2
Effects of chrysophanol on the level of IL-6 and COX-2 in DSS-treated colon tissue. Experimental colitis in mice was induced by a 5% DSS dissolved in the drinking water for 7 days. Chrysophanol was administered at doses of 5 mg/kg once a day for 7 days prior to 5% DSS supplement. At the end of experiment, the colon tissues were cut out and homogenized. (A) The levels of IL-6 in the indicated groups were measured by ELISA; (B) The levels of COX-2 were evaluated by Western blot analysis; (C) The relative expression level of COX-2 was measured using an image analyzer.1) Control group; 2) DSS alone-treated group; 3) chrysophanol (5 mg/kg) + DSS treated group; 4) sulfasalazine(150 mg/kg) + DSS treated group. Values were represented in the mean ± S.E.M. (n = 5) of duplicate determinations from triplicate separate experiments (#p < 0.05 vs. control, *p < 0.05 vs. DSS alone). Full article ">Figure 3
Effects of chrysophanol on the activation of NF-κB p65 and caspase-1 in DSS-treated colon tissue. At the end of experiment, the colon tissues were cut out and homogenized. (A) The levels of NF-κB p65 were evaluated by Western blot analysis; (B) The relative expression level of NF-κB was measured using an image analyzer; (C) Colon were removed and embedded in paraffin, and then 5 μm sections were prepared and stained with anti-NF-κB; (D) The enzymatic activity of caspase-1 was evaluated via a caspase colorimetric assay. 1) Control group; 2) DSS alone-treated group; 3) chrysophanol (5 mg/kg) + DSS treated group; 4) sulfasalazine (150 mg/kg) + DSS treated group.Values were represented in the mean ± S.E.M. (n = 5) of triplicate determinations from triplicate separate experiments (# p < 0.05 vs. control, * p < 0.05 vs. DSS alone). Full article ">Figure 4
Effect of chrysophanol on TNF-α, IL-6, PGE2 production and COX-2 expression in LPS-stimulated murine peritoneal macrophages. (A) Cells (3 × 105 cells/mL) were pretreated for 1 h with chrysophanol (2 and 20 μM), and then stimulated for 24 h with LPS (1 μg/mL). The levels of TNF-α and IL-6 in the supernatant were measured by ELISA; (B) Cells (5 × 106 cells/mL) were pretreated for 1 h with chrysophanol (2 and 20 μM), and then stimulated for 24 h with LPS (1 μg/mL). The protein extracts were assayed by Western blot analysis for COX-2; (C) The amount of PGE2 production was measured usingimmunoassay kits. 1) unstimulated cells; 2) LPS (1 μg/mL); 3) chrysophanol (2 μM) plus LPS (1 μg/mL); 4) chrysophanol (20 μM) plus LPS (1 μg/mL). All data were represented in the mean ± S.E.M. of triplicate determinations from triplicate separate experiments (# p < 0.05 vs. control, * p < 0.05 vs. LPS alone). Full article ">Figure 5
Effect of chrysophanol on degradation of IκB-α and activation of NF-κB and caspase-1 in LPS-stimulated murine peritoneal macrophages. (A) Cells (5 × 106) were pretreated for 1 h with chrysophanol (2 and 20 μM) and then treated for 1 h with LPS (1 μg/mL). The cytosolic extracts were prepared as described in the Experimental section and evaluated for IκB-αby Western blot analysis; (B) Nuclear extracts were prepared as described in the Experimental section and evaluated for RelA/p65 by Western blot analysis; (C)The relative expression levels of IκB-α/ RelA/p65were measured using an image analyzer; (D) The cells were pretreated with chrysophanol (2 and 20 µM) for 1 h prior to LPS stimulation for 12 h. The levels of pro-caspase-1 were assayed by Western blot analysis; (E) The relative expression levels of pro-caspase-1 wererepresented; (F) The enzymatic activity of caspase-1 was evaluated using a caspase colorimetric assay. (1) unstimulated cells; (2) LPS (1 μg/mL); (3) chrysophanol (2 μM) plus LPS (1 μg/mL); (4) chrysophanol (20 μM) plus LPS (1 μg/mL). All data were represented in the mean ± S.E.M. of triplicate determinations from triplicate separate experiments (# P < 0.05 vs. control, * P < 0.05 vs. LPS alone). Full article ">Figure 6
Proposed anti-inflammatory mechanism of chrysophanol in LPS-stimulated mouse peritoneal macrophage. Full article ">

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Open AccessArticle

Inhibitory Effect of Indigo Naturalis on Tumor Necrosis Factor-α-Induced Vascular Cell Adhesion Molecule-1 Expression in Human Umbilical Vein Endothelial Cells

by Hsin-Ning Chang, Jong-Hwei Su Pang, Sien-Hung Yang, Chi-Feng Hung, Chi-Hsin Chiang, Tung-Yi Lin and Yin-Ku Lin

Molecules 2010, 15(9), 6423-6435; https://doi.org/10.3390/molecules15096423 - 14 Sep 2010

Cited by 25 | Viewed by 10273

Abstract

The use of indigo naturalis to treat psoriasis has proved effective in our previous clinical studies. The present study was designed to examine the anti-inflammatory effect of indigo naturalis in primary cultured human umbilical vein endothelial cells (HUVECs). Pretreatment of cells with indigo [...] Read more.

The use of indigo naturalis to treat psoriasis has proved effective in our previous clinical studies. The present study was designed to examine the anti-inflammatory effect of indigo naturalis in primary cultured human umbilical vein endothelial cells (HUVECs). Pretreatment of cells with indigo naturalis extract attenuated TNF-α-induced increase in Jurkat T cell adhesion to HUVECs as well as decreased the protein and messenger (m)RNA expression levels of vascular cell adhesion molecule-1 (VCAM-1) on HUVECs. Indigo naturalis extract also inhibited the protein expression of activator protein-1 (AP-1)/c-Jun, a critical transcription factor for the activation of VCAM-1 gene expression. Since the reduction of lymphocyte adhesion to vascular cells by indigo naturalis extract could subsequently reduce the inflammatory reactions caused by lymphocyte infiltration in the epidermal layer and help to improve psoriasis, this study provides a potential mechanism for the anti-inflammatory therapeutic effect of indigo naturalis extract in psoriasis. Full article

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180 KiB

Open AccessArticle

Chemical Analysis and Biological Activity of the Essential Oils of Two Valerianaceous Species from China: Nardostachys chinensis and Valeriana officinalis

by Jihua Wang, Jianglin Zhao, Hao Liu, Ligang Zhou, Zhilong Liu, Jingguo Wang, Jianguo Han, Zhu Yu and Fuyu Yang

Molecules 2010, 15(9), 6411-6422; https://doi.org/10.3390/molecules15096411 - 14 Sep 2010

Cited by 95 | Viewed by 12364

Abstract

In order to investigate essential oils with biological activity from local wild plants, two valerianaceous species, Nardostachys chinensis and Valeriana officinalis, were screened for their antimicrobial and antioxidant activity. The essential oils were obtained from the roots and rhizomes of the two [...] Read more.

In order to investigate essential oils with biological activity from local wild plants, two valerianaceous species, Nardostachys chinensis and Valeriana officinalis, were screened for their antimicrobial and antioxidant activity. The essential oils were obtained from the roots and rhizomes of the two plants by hydro-distillation, and were analyzed for their chemical composition by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Calarene (25.31%), aristolone (13.35%), α-selinene (7.32%) and β-maaliene (6.70%) were the major compounds of the 23 identified components which accounted for 92.76% of the total oil of N. chinensis. Patchoulol (16.75%), α-pinene (14.81%), and β-humulene (8.19%) were the major compounds among the 20 identified components, which accounted for 88.11% of the total oil of V. officinalis. Both oils were rich in sesquiterpene hydrocarbons as well as their oxygenated derivatives. Essential oils were shown to have broad spectrum antibacterial activity with MIC values that ranged from 62.5 μg/mL to 400 μg/mL, and IC₅₀ values from 36.93 μg/mL to 374.72 μg/mL. The oils were also shown to have moderate antifungal activity to Candida albicans growth as well as inhibition of spore germination of Magnaporthe oryzae. Two essential oils were assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, β-carotene bleaching and ferrozine-ferrous ions assays, respectively, to show moderate antioxidant activity. Results suggest that the isolated essential oils could be used for future development of antimicrobial and antioxidant agents. Full article

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Open AccessArticle

Solid-Phase Synthesis and Evaluation of Glycopeptide Fragments from Rat Epididymal Cysteine-Rich Secretory Protein-1 (Crisp-1) ^‡

by Mian Liu, David W. Hamilton and George Barany

Molecules 2010, 15(9), 6399-6410; https://doi.org/10.3390/molecules15096399 - 14 Sep 2010

Cited by 2 | Viewed by 10407

Abstract

Three 18-residue peptides with the sequence Glp-Asp-Thr-Thr-Asp-Glu-Trp-Asp-Arg-Asp-Leu-Glu-Asn-Leu-Ser-Thr-Thr-Lys, taken from the N-terminus of the rat epididymal cysteine-rich secretory protein (Crisp-1) that is important in the fertilization process, were prepared by Fmoc solid-phase synthesis using a convergent strategy. These [...] Read more.

Three 18-residue peptides with the sequence Glp-Asp-Thr-Thr-Asp-Glu-Trp-Asp-Arg-Asp-Leu-Glu-Asn-Leu-Ser-Thr-Thr-Lys, taken from the N-terminus of the rat epididymal cysteine-rich secretory protein (Crisp-1) that is important in the fertilization process, were prepared by Fmoc solid-phase synthesis using a convergent strategy. These peptides were the parent sequence, plus two possible α-O-linked T_N antigen-containing glycopeptides with a Thr(α-D-GalNAc) residue in place of either Thr³ or Thr⁴. During chain assembly, two deletion peptides [des-Asp² and des-Thr(Ac₃-α-D-GalNAc)] and one terminated peptide [N-acetylated 14-mer] arose, as did several peptides in which aspartimide formation had occurred at each of the four possible positions in the sequence. These by-products totaled ~20% of the desired product; they were recognized by HPLC and ESI-MS and removed during the intermediate purifications. Final products, obtained in 15-21% overall yields, were characterized by HPLC purities and ESI-MS. Circular dichroism (CD) spectra for all three purified peptides, recorded in pure water and in trifluoroethanol-H₂O (1:1), revealed that the presence of a sugar moiety does not significantly impact the sampled conformations. Future biological evaluation could elucidate the nature and locus of sugar modification of Crisp-1, and provide insight as to why Crisp-1 protein E binds sperm irreversibly, in contrast to protein D that lacks a sugar near the N-terminus and only binds sperm loosely. Full article

(This article belongs to the Special Issue Solid Phase Synthesis)

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196 KiB

Open AccessArticle

Bio-guided Isolation of Antioxidant Compounds from Chrysophyllum perpulchrum, a Plant Used in the Ivory Coast Pharmacopeia

by Bidie Alain Philippe, Ndjoko Karine, Attioua Koffi Barthélemy, Zirihi Guédé Noél, N’guessan Jean David, Djaman Allico Joseph and Kurt Hosttetmann

Molecules 2010, 15(9), 6386-6398; https://doi.org/10.3390/molecules15096386 - 13 Sep 2010

Cited by 15 | Viewed by 9313

Abstract

Chrysophyllum perpulchrum (Sapotaceae) is used in the traditional Ivory Coast pharmacopeia to cure fevers. The extract of C. perpulchrum used for this study was the powdered form obtained from the maceration of the dried plant bark in 96% methanol, followed by evaporation to [...] Read more.

Chrysophyllum perpulchrum (Sapotaceae) is used in the traditional Ivory Coast pharmacopeia to cure fevers. The extract of C. perpulchrum used for this study was the powdered form obtained from the maceration of the dried plant bark in 96% methanol, followed by evaporation to dryness. In the present study, the antioxidative and radical-scavenging activities of the methanolic extract were studied with three standard biological tests: DPPH reduction, ferric thiocyanate (FTC) lipidic peroxidation inhibition and thiobarbituric acid reacting substances (TBARS). Gallic acid and quercetin were used as references. The total amount of phenolic compounds in the extract was determined by ultraviolet (UV) spectrometry and calculated as gallic acid equivalents. Catechin and two dimeric procyanidins were found to be the compounds responsible for the activities. They were chemically dereplicated in the extract by LC-MS. For quantitation purposes, they were isolated by successive chromatographic methods and characterized by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectrometry. The quantities of these compounds in C. perpulchrum were 5.4% for catechin (P1), and 5.6 and 9.2% for dimers (compounds 2 (P2) and 3 (P3)), respectively. They displayed antioxidant activity with IC₅₀ values of 2.50 ± 0.15 µg/mL (P1), 2.10 ± 0.2 µg/mL (P2) and 2.10 ± 0.1 µg/mL (P3). The total extract, the active fractions and the pure compounds inhibited the lipid peroxidation by the FTC method and the TBARS method in the range of 60%. These values were comparable to those seen for quercetin. Full article

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Open AccessArticle

Composition of Sulla (Hedysarum coronarium L.) Honey Solvent Extractives Determined by GC/MS: Norisoprenoids and Other Volatile Organic Compounds

by Igor Jerković, Carlo I.G. Tuberso, Mirko Gugić and Dragan Bubalo

Molecules 2010, 15(9), 6375-6385; https://doi.org/10.3390/molecules15096375 - 9 Sep 2010

Cited by 32 | Viewed by 12030 | Correction

Abstract

Samples of unifloral sulla (Hedysarum coronarum L.) honey from Sardinia (Italy) were analysed. To investigate the chemical composition of the honey volatiles two solvent systems were used for ultrasonic solvent extraction (USE): 1) a 1:2 (v/v) pentane and diethyl ether mixture and [...] Read more.

Samples of unifloral sulla (Hedysarum coronarum L.) honey from Sardinia (Italy) were analysed. To investigate the chemical composition of the honey volatiles two solvent systems were used for ultrasonic solvent extraction (USE): 1) a 1:2 (v/v) pentane and diethyl ether mixture and 2) dichloromethane. All the extracts were analysed by GC and GC/MS. These procedures have permitted the identification of 56 compounds that include norisoprenoids, benzene derivatives, aliphatic compounds and Maillard reaction products. Norisoprenoids were the major compounds in both extracts, dominated by vomifoliol (5.3-11.2%; 9.6-14.0%) followed by minor percentages of other norisoprenoids such as α-isophorone, 4-ketoisophorone, 3-oxo-α-ionol or 3-oxo-α-ionone. Other abundant single compounds in the extracts were 3-hydroxy-4-phenylbutan-2-one (0.8-5.4%; 0.6-5.7%) and methyl syringate (3.0-5.7%; 2.2-4.1%). The composition of the volatiles and semi-volatiles in the obtained extracts suggests that sulla honey is quite distinctive relative to the other honeys that have been chemically studied by GC/MS, but no specific markers of the honey botanical origin were found. Full article

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125 KiB

Open AccessArticle

Microwave Assisted Extraction of Phenolic Compounds from Four Different Spices

by Monica Gallo, Rosalia Ferracane, Giulia Graziani, Alberto Ritieni and Vincenzo Fogliano

Molecules 2010, 15(9), 6365-6374; https://doi.org/10.3390/molecules15096365 - 9 Sep 2010

Cited by 130 | Viewed by 14755

Abstract

Spices and herbs are known not only for their taste, aroma and flavour, but also for their medical properties and value. Both spices and herbs have been used for centuries in traditional medical systems to cure various kinds of illnesses such as common [...] Read more.

Spices and herbs are known not only for their taste, aroma and flavour, but also for their medical properties and value. Both spices and herbs have been used for centuries in traditional medical systems to cure various kinds of illnesses such as common cold, diabetes, cough and cancers. The aim of this work was the comparison between two different extractive techniques in order to get qualitative and quantitative data regarding bioactive compounds of four different spices (Cinnamomum zeylanicum, Coriandrum sativum, Cuminum cyminum, Crocus sativus). The plants were extracted employing ultrasonication and microwave-assisted extractions. The efficiency of extraction of bioactive compounds obtained with the microwave extraction process was in general about four times higher than that resulting from sonication extraction. The various extracts obtained were analyzed for their antioxidant activity using ABTS, DPPH and FRAP assays and for their total polyphenolic content. It can be concluded that microwave-assisted extractions provide significant advantages in terms of extraction efficiency and time savings. Full article

(This article belongs to the Special Issue Phytochemicals with Signaling, Medicinal and Therapeutic Properties)

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Open AccessArticle

Two New Flavones from Tridax procumbens Linn

by Runsheng Xu, Jing Zhang and Ke Yuan

Molecules 2010, 15(9), 6357-6364; https://doi.org/10.3390/molecules15096357 - 9 Sep 2010

Cited by 22 | Viewed by 10041

Abstract

Two new flavones, 8,3′-dihydroxy-3,7,4′-trimethoxy-6-O-β-D-glucopyranosyl flavone (1) and 6,8,3′-trihydroxy-3,7,4′-trimethoxyflavone (2) were isolated from Tridax procumbens Linn., together with the four known compounds puerarin (3), esculetin (4), oleanolic acid (5 [...] Read more.

Two new flavones, 8,3′-dihydroxy-3,7,4′-trimethoxy-6-O-β-D-glucopyranosyl flavone (1) and 6,8,3′-trihydroxy-3,7,4′-trimethoxyflavone (2) were isolated from Tridax procumbens Linn., together with the four known compounds puerarin (3), esculetin (4), oleanolic acid (5) and betulinic acid (6). The structures of the two new flavones were elucidated based on chemical analysis and spectral methods (IR, 1D and 2D NMR, ESI-MS, HR-ESI-MS). The antioxidant activity of the two new flavones were evaluated by two methods, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) assays, and the data showed that compounds 1 and 2 have certain antioxidant activity, with the antioxidant activity of compound 2 being stronger than that of compound 1. Full article

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Open AccessArticle

Isolation and Crystal Structure of Marcanine A from Polyalthia plagioneura

by Bingjing Liu, Lin Wang, Guangying Chen, Changri Han and Jing Wang

Molecules 2010, 15(9), 6349-6356; https://doi.org/10.3390/molecules15096349 - 9 Sep 2010

Cited by 10 | Viewed by 8381

Abstract

Marcanine A was isolated from the stems of Polyalthia plagioneura as light yellow crystals. The molecular and crystal structures have been determined by 1D,2D-NMR and X-ray diffraction analysis. It crystallizes in the triclinic system, space group P-1 with a = 5.2140(5)Å, b = [...] Read more.

Marcanine A was isolated from the stems of Polyalthia plagioneura as light yellow crystals. The molecular and crystal structures have been determined by 1D,2D-NMR and X-ray diffraction analysis. It crystallizes in the triclinic system, space group P-1 with a = 5.2140(5)Å, b = 10.1871(11)Å, c = 11.0709(13)Å, α = 110.452(2)º, β = 103.376(2)°, γ = 90.1870(10)°, V = 533.74(10)Å³, Z = 2. There are three intermolecular hydrogen bonds in a unit cell. It displays some inhibitory activities towards four kinds of human tumor cells, including BEL-7402, K562, SPCA-1and SGC-7409. Full article

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Open AccessReview

Transactivation of Genes Encoding for Phase II Enzymes and Phase III Transporters by Phytochemical Antioxidants

by Yoon Mee Yang, Kyoung Noh, Chang Yeob Han and Sang Geon Kim

Molecules 2010, 15(9), 6332-6348; https://doi.org/10.3390/molecules15096332 - 7 Sep 2010

Cited by 23 | Viewed by 10619

Abstract

The induction of phase II enzymes and phase III transporters contributes to the metabolism, detoxification of xenobiotics, antioxidant capacity, redox homeostasis and cell viability. Transactivation of the genes that encode for phase II enzymes and phase III transporters is coordinatively regulated by activating [...] Read more.

The induction of phase II enzymes and phase III transporters contributes to the metabolism, detoxification of xenobiotics, antioxidant capacity, redox homeostasis and cell viability. Transactivation of the genes that encode for phase II enzymes and phase III transporters is coordinatively regulated by activating transcription factors in response to external stimuli. Comprehensive studies indicate that antioxidant phytochemicals promote the induction of phase II enzymes and/or phase III transporters through various signaling pathways, including phosphoinositide 3-kinase, protein kinase C, and mitogen-activated protein kinases. This paper focuses on the molecular mechanisms and signaling pathways responsible for the transactivation of genes encoding for these proteins, as orchestrated by a series of transcription factors and related signaling components. Full article

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Open AccessReview

Recent Applications of Polymer Supported Organometallic Catalysts in Organic Synthesis

by Nina Kann

Molecules 2010, 15(9), 6306-6331; https://doi.org/10.3390/molecules15096306 - 7 Sep 2010

Cited by 80 | Viewed by 11764

Abstract

Recent developments concerning the application of polymer supported organometallic reagents in solid phase synthesis are reviewed, with a special focus on methodology for carbon-carbon formation. Examples of reactions that are covered include the classical Suzuki, Sonogashira and Heck coupings, but also aryl amination, [...] Read more.

Recent developments concerning the application of polymer supported organometallic reagents in solid phase synthesis are reviewed, with a special focus on methodology for carbon-carbon formation. Examples of reactions that are covered include the classical Suzuki, Sonogashira and Heck coupings, but also aryl amination, epoxide opening, rearrangements, metathesis and cyclopropanation. Applications in the field of asymmetric synthesis are also discussed. Full article

(This article belongs to the Special Issue Solid Phase Synthesis)

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Open AccessArticle

Content of Phenolic Compounds and Antioxidant Capacity in Fruits of Apricot Genotypes

by Jiri Sochor, Ondrej Zitka, Helena Skutkova, Dusan Pavlik, Petr Babula, Boris Krska, Ales Horna, Vojtech Adam, Ivo Provaznik and Rene Kizek

Molecules 2010, 15(9), 6285-6305; https://doi.org/10.3390/molecules15096285 - 7 Sep 2010

Cited by 106 | Viewed by 15120

Abstract

Research on natural compounds is increasingly focused on their effects on human health. In this study, we were interested in the evaluation of nutritional value expressed as content of total phenolic compounds and antioxidant capacity of new apricot (Prunus armeniaca L.) genotypes [...] Read more.

Research on natural compounds is increasingly focused on their effects on human health. In this study, we were interested in the evaluation of nutritional value expressed as content of total phenolic compounds and antioxidant capacity of new apricot (Prunus armeniaca L.) genotypes resistant against Plum pox virus (PPV) cultivated on Department of Fruit Growing of Mendel University in Brno. Fruits of twenty one apricot genotypes were collected at the onset of consumption ripeness. Antioxidant capacities of the genotypes were determined spectrometrically using DPPH• (1,1-diphenyl-2-picryl-hydrazyl free radicals) scavenging test, TEAC (Trolox Equivalent Antioxidant Capacity), and FRAP (Ferric Reducing Antioxidant Power)methods. The highest antioxidant capacities were determined in the genotypes LE-3228 and LE-2527, the lowest ones in the LE-985 and LE-994 genotypes. Moreover, close correlation (r = 0.964) was determined between the TEAC and DPPH assays. Based on the antioxidant capacity and total polyphenols content, a clump analysis dendrogram of the monitored apricot genotypes was constructed. In addition, we optimized high performance liquid chromatography coupled with tandem electrochemical and spectrometric detection and determined phenolic profile consisting of the following fifteen phenolic compounds: gallic acid, 4-aminobenzoic acid, chlorogenic acid, ferulic acid, caffeic acid, procatechin, salicylic acid, p-coumaric acid, the flavonols quercetin and quercitrin, the flavonol glycoside rutin, resveratrol, vanillin, and the isomers epicatechin, (–)- and (+)- catechin. Full article

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Open AccessReview

The Structural Diversity of Deoxyribozymes

by Simon A. McManus and Yingfu Li

Molecules 2010, 15(9), 6269-6284; https://doi.org/10.3390/molecules15096269 - 6 Sep 2010

Cited by 18 | Viewed by 11121

Abstract

When not constrained to long double-helical arrangements, DNA is capable of forming structural arrangements that enable specific sequences to perform functions such as binding and catalysis under defined conditions. Through a process called in vitro selection, numerous catalytic DNAs, known as deoxyribozymes or [...] Read more.

When not constrained to long double-helical arrangements, DNA is capable of forming structural arrangements that enable specific sequences to perform functions such as binding and catalysis under defined conditions. Through a process called in vitro selection, numerous catalytic DNAs, known as deoxyribozymes or DNAzymes, have been isolated. Many of these molecules have the potential to act as therapeutic agents and diagnostic tools. As such, a better understanding of the structural arrangements present in these functional DNAs will aid further efforts in the development and optimization of these useful molecules. Structural characterization of several deoxyribozymes through mutagenesis, in vitro re-selection, chemical probing and circular dichroism has revealed many distinct and elaborate structural classes. Deoxyribozymes have been found to contain diverse structural elements including helical junctions, pseudoknots, triplexes, and guanine quadruplexes. Some of these studies have further shown the repeated isolation of similar structural motifs in independent selection experiments for the same type of chemical reaction, suggesting that some structural motifs are well suited for catalyzing a specific chemical reaction. To investigate the extent of structural diversity possible in deoxyribozymes, a group of kinase deoxyribozymes have been extensively characterized. Such studies have discovered some interesting structural features of these DNAzymes while revealing some novel DNA structures. Full article

(This article belongs to the Special Issue Catalytic Nucleic Acids)

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Figure 1
RNA-cleaving deoxyribozymes using a two-binding arm motif. (a) A general structural framework for RNA-cleaving deoxyribozymes that use the two binding arm motif. The deoxyribozyme contains two regions called binding arms (shown in blue) that base-pair to the substrate (shown in red). The RNA cleavage site (indicated with an arrow) is between the two base-paired regions. The catalytic core (shown in green) is opposite the cleavage site. rN represents the ribonucleotide at the cleavage site. (B) Secondary structural model for the 8-17 deoxyribozyme. (C) Secondary structural model for the 10-23 deoxyribozyme. At the cleavage site, rY can be rU or rC, and R can be G or A. Full article ">Figure 2
Deoxyribozymes with different secondary structural arrangements. (A) Structural model of the E47 ligase deoxyribozyme. Substrates are shown in red. OH represents a 5′ hydroxyl and P-Im represents a 3′ phophorimidazolide. Solid lines represent Watson-Crick base-pair interactions. (B) Secondary structural model of the L78 DNA ligase deoxyribozyme. 5′,5′ pyrophosphate cap is represented by ppA. (C) Secondary structural model of the 10-28 N-glycosylase deoxyribozyme. Site of glycosylation is shown with a red G. Circles represent G-T wobble base-pairs. (D) Secondary structural model of 5J-A28, an RNA-cleaving, fluorescence-generating deoxyribozyme. F and Q represent a fluorescein- and a DABCYL-containing deoxythymidine, respectively. rA denotes adenine ribonucleotide. Full article ">Figure 3
Deoxyribozymes with tertiary interactions. (A) Structural model of a DNA-cleaving deoxyribozyme utilizing a triplex structure. The substrate is shown in red and the cleavage site indicated by an arrow. (B) Structural model of the class I self-capping deoxyribozyme containing a multi-tiered guanine quadruplex. Guanines involved in quadruplex interactions are shown in blue. Gp represents a 5′ phosphoryated guanine. (C) Structural model for the UV1C thymine dimer repair deoxyribozyme containing a two-tiered guanine quadruplex. Red parallel lines represent the thymine dimer (the thymines within the dimer are not connected by a phosphodiester bond). The quadruplex is thought to act as a light-harvesting antenna facilitating the repair of the T-T dimer. Full article ">Figure 4
Structure diversity of kinase (self-phosphorylating) deoxyribozymes. (A) Structural model of Dk1, an ATP-utilizing kinase deoxyribozyme. Dk1 contains a central stem flanked by two unstructured regions. The site of self-phosphorylation is shown in red. (B) Secondary structural model for GTP-utilizing kinase deoxyribozymes Dk2, Dk3, and Dk4. Red lines indicate base-pairs that are present in Dk3 and Dk4 but not Dk2. (C) Structural model of Dk5, an ATP and GTP utilizing kinase deoxyribozyme. The structure contains a two-tiered guanine quadruplex shown in blue. A three base-pair stem (shown in green) forms a pseudoknot interaction with the quadruplex. Full article ">Scheme 1
Deoxyribozymes isolated through in vitro selection have been shown to use many different arrangements in their active structures, such as Watson-Crick helices and higher-order structures containing guanine quadruplex and triple helix motifs. Full article ">

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Open AccessArticle

Microwave Irradiation-Assisted Synthesis of a Novel Crown Ether Crosslinked Chitosan as a Chelating Agent for Heavy Metal Ions (M⁺ⁿ)

by Awwad A. Radwan, Fars K. Alanazi and Ibrahim A. Alsarra

Molecules 2010, 15(9), 6257-6268; https://doi.org/10.3390/molecules15096257 - 6 Sep 2010

Cited by 35 | Viewed by 10209

Abstract

Microwave irradiation was used to obtain a di-Schiff base type crosslinked chitosan dibenzocrown ether (CCdBE) via the reaction between the –NH₂ and –CHO groups in chitosan and 4,4′-diformyldibenzo-18-c-6, respectively. The structure of the synthesized compound was characterized by elemental analysis, solid state [...] Read more.

Microwave irradiation was used to obtain a di-Schiff base type crosslinked chitosan dibenzocrown ether (CCdBE) via the reaction between the –NH₂ and –CHO groups in chitosan and 4,4′-diformyldibenzo-18-c-6, respectively. The structure of the synthesized compound was characterized by elemental analysis, solid state ¹³C-NMR and FT-IR spectra analysis. The results showed that the mass fraction of nitrogen in the CCdBE derivative was much lower than those of chitosan. The FT-IR spectra of CCdBE revealed the expected chitosan-crown ether structure, as evidenced by the presence of the characteristic C=N and Ar peaks. The adsorption properties of CCdBE for Pd²⁺ and Hg²⁺ were investigated and the results demonstrated that the adsorbent has both desirable adsorption properties with a high particular adsorption selectivity for Hg²⁺ when in the presence of Pb²⁺ as well as selectivity coefficients for metal ions of K_Hg²⁺ _/Pb²⁺= 8.00 and K_Hg ²⁺_/Pb²⁺= 10.62 at pH values of 4 and 6, respectively. The reusability tests for CCdBE for Pb²⁺ adsorption showed that complete recovery of the ion was possible with CCdBE after 10-multiple reuses while CTS had no reusability at acidic solution because of its higher dissolution. The studied features of CCdBE suggested that the material could be considered as a new adsorbent. It is envisaged that the crosslinking of CTS into CCdBE would enhance practicality and effectiveness of adsorption in ion separation and removal procedures. Full article

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Molecules, Volume 15, Issue 9 (September 2010) – 56 articles , Pages 5840-6677

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