EP1560492A1

EP1560492A1 - Treatment relating to leather

Info

Publication number: EP1560492A1
Application number: EP03756562A
Authority: EP
Inventors: B. The Ethiopian Agricultural Res. Organiz KASSA
Original assignee: Ethiopian Agricultural Research Organisation
Current assignee: Ethiopian Agricultural Research Organisation
Priority date: 2002-10-10
Filing date: 2003-10-10
Publication date: 2005-08-10
Also published as: WO2004032631A1; GB0223657D0; AU2003299784A1

Abstract

Leather-producing animals are treated by contacting their skin with an extract of Phytolacca in order to reduce lice or ked infestation that results in lesions in the resulting tanned leather.

Description

TREATMENT RELATING TO LEATHER

The present invention relates to a treatment that can be carried out, usually on a leather-producing animal, to avoid or to reduce. certain imperfections in the final leather grain that might otherwise result from the animal becoming infested with lice, eds or other ectoparasites or other organisms. Such organisms can cause skin damage which may lead to bacterial or other infection. The treatment can inhibit or prevent the growth or reproduction of such organisms, thus preventing or reducing skin damage or allowing earlier damage to heal. Often the damage is not apparent in the living animal, and only becomes apparent at some stage during tanning of the skin.

Various terms, such as skin, pelt, hide and leather, are used in the industry depending on the animal concerned and on the extent of tanning or other treatment that has been carried out. For simplicity, in the present specification the term "skin" will be used where no tanning treatment has yet been carried out, but the term "leather" is used broadly and does not imply that all tanning and other processing steps have been carried out. Also, the invention is particularly applicable to sheep, in particular, to Ethiopian hair sheep, but the term "leather" does not imply any particular animal. For example, the invention will be applicable to other sheep, to goats and to cattle.

Leather quality is important because it can affect the end use to which the leather can be put, and therefore affects its value. A particular problem arises in connection with faults that cannot readily be determined until the tanning process is complete, or at least is well-advanced. In this case skins will need to be purchased before their final quality can be fully assessed. There is therefore a great need for some means of reducing skin damage in general, and in particular of reducing the kind of damage that is not immediately apparent. Certain scars or lesions are of this latter type. I am particularly concerned with damage that occurs through infestations of the animals' skins by parasites such as keds or lice. The damage that results from such infestations, often small lesions of a diameter of 5- 10 mm, frequently allows bacterial infection to occur, which further impairs the quality of the final leather. These problems are known, and techniques have been proposed to overcome them. For example, long-haired animals; such as Ethiopian hair sheep may be shorn in order to reduce infestation by lice or keds. Unfortunately, however much care is taken, shearing itself can mechanically damage the skin resulting in imperfections in the final leather. Various pesticides, such as that known by the trade mark

"Diazinon", may be used. Such pesticides show some success, but they are often unavailable where they are needed, they can be expensive, and not all are environmentally acceptable.

I have now discovered that extracts from a certain genus of plants, , Phytolacca, are extremely useful in ensuring high leather quality. These extracts can ^■not only prevent infestation, but if used on an infested animal where skin damage has already occurred, can allow normal healing processes to remove the damage.

This plant, Phytolacca, is indigenous in Ethiopia and is also well known in other parts of Africa. Furthermore, it is known that extracts of Phytolacca can be used to treat human and animal diseases. In particular, such extracts have been disclosed as molluscicides (for example against mussels), insecticides (for example against mosquitoes) and as herbal medicines for treatment of, for example, diphtheria in calves and as cures for fungal and worm infestations. A common species of Phytolacca, Phytolacca dodecandra, is a perennial, large shrubby herb that is known in Africa by various names including Endod, L'Herit and Soapberry. It is easily cultivated over a wide range of environmental conditions, and is in fact regarded as a weed in many places. It is known to have low mammalian toxicity in general, although its seeds and leaves can be poisonous if taken orally. It is known to be poisonous to fish, although, being biodegradable, it does not exist long in the environment. For example fish return after a few weeks to rivers where Phytolacca extracts have been used. One interesting use of Phytolacca extracts was discovered by the Ethiopian scientist Aklilu Lemma in 1965. He discovered that fresh water snails which transmit schistosomiasis are killed by Phytolacca extracts. As a result, rivers in which these snails bread have been treated with the extract. Following that useful discovery, various techniques were devised for

-extracting the active compounds from various parts of the Phytolacca plant, in particular from the berries.

Reference may be made to an-article by A Regassa entitled "The use of herbal preparations for tick control in Western Ethiopia" (0038-2809 Tydskr.S.Afr.vet.Ner,(2000)71(4),240-243). In that article various preparations from various plants are disclosed for the control of ticks. One of these plants is

Phytolacca dodecandra, where the preparation is said to be produced from crushed fresh leaves. There is reference to the treatment of cattle, and tests were said to be carried out on the tick species A variegation and A cohaerens. Reference was made to an undesirable side effect, namely localised hair loss in cattle. There was no suggestion that such extracts could serve to avoid lesions that results in faults in - leather.

It should also be noted that Phytolacca extracts appear to be active against only certain organisms, and precisely where those extracts will be active cannot be predicted. For example, as mentioned above activity against fish, snails, mosquitos, ticks and mussels has been noted. However, other fauna, for example, insects, frogs and tadpoles are unaffected. Reference may be made to the following articles: Isharaza, W. K. Tropical Doctor Nol.27 (supplement 1), page 30, (1997); Monkiedje, A et al, Journal of Environmental Science and Health, part B, Pesticides, Food, Contaminants and Agricultural Wastes Vol. 30 (1), pages 73-94 (1995); Spielman, A et al, AM J Trap Med Hyg, 22 (6 Part 1), pages 802-804 (1973); Birrie, H et al, East African Medical Journal, 75 (5) pages 311 to 314 (1998); and Gebre-Amlak Assefa, International Journal of Pest Management, 45 (1) pages 9 to 13 (January to March 1999)^ It was surprising, in view of the particularity of the previously known uses of extracts of Phytolacca that it would provide such significant benefits in the leather industry.

Thus, the present invention provides use of an extract of Phytolacca in the manufacture of a medicament for the treatment or prevention of a skin infestation by an organism that impairs leather quality.

The invention also provides an extract of Phytolacca for use in the treatment or prevention of a skin infestation by an organism that impairs leather quality. The invention further provides a method of treating a leather-producing animal having or susceptible to a skin infestation by an organism that impairs leather quality, which methods comprises applying to skin of the animal an extract of Phytolacca.

The invention still further provides a method of preventing or inhibiting growth or reproduction of an organism that impairs leather quality by infesting the leather-producing animal, which method comprises applying to an environment infested or susceptible to infestation by said organism an extract of Phytolacca.

As mentioned above, the leather-producing animal is preferable a sheep, such as an Ethiopian hair sheep, although the invention will be applicable to other animals.

The Phytolacca extracts are particularly useful where the organism that causes the skin infestation is a lice or a ked, in particular a species of Bovicola or Melophagus. The species that infect sheep are, of course, Bovicola ovis and Melophagus ovis. In general, the invention is useful in connection with these or other species that cause the disease variously known as cockle or Ekek, or otherwise causes grain layer lesions or other imperfections in tanned leather.

The species of Phytolacca which we prefer is Phytolacca dodecandra, although other species may be used, for example P acinosa, americana, brachystachys, dioica, esc laenta, lioida, octandra, rivinoids and rugose. Various parts of the plant may be used to produce the extract, including the berries, leaves, stem bark and root bark.

As may be expected, various compounds are obtained from Phytolacca when an extraction technique is carried out, in particular saponins which may be obtained from berries, stem bark, root bark and leaves. The stem bark also produces steroids, alkaloids and flavonoids; the root bark also produces terpenoids; and the leaves also produce steroids, flavonoids, alkaloids and glycosides.

Reference may be made to GB 1277417 which discloses extraction of a mixture of triterpenoid saponins from berries of Phytolacca dodecandra. The extract is obtained as a molluscicidial agent for killing snails. The berries are preferably first dried and ground, and then extraction is carried out in an alcoholic solvent and the extract material subjected to alkaline hydrolysis. It was noted that the active agent is also present in the leaves and other parts of the plant, but the cost of extraction is greater. It should also be noted that if the active agent is to be harvested repeatedly, it is undesirable to remove too much of the plant in a way that will reduce the following year's crop.

The saponins extracted have the following formula:

In which R is a glycoside chain containing from 2 to 4 sugar units, and M is hydrogen or an alkali metal.

Alcohol extraction from the plant produces corresponding compounds where the group -COOM is present as a sugar ester. These compounds are inactive, at least against snails. It is for this reason that alkaline hydrolysis is carried out to produce active saponins which contain a free carboxyl group, or the alkali metal salt. It may be noted that the methyl ester is also inactive.

GB 1277417 also suggests that a fat removal step be carried out on the berries before the extraction. However, fat removal, if desired, may be carried out at a later stage in the overall extraction process. Detailed extraction techniques are also disclosed in US 3813383, US 5252330 and US 5334386. In each of these three specifications the extract is used to kill snails. These is no disclosure that the active material would be useful in connection with leather. Although I do not wish to be bound by any theory, I believe that the extract operates not only by toxicosis of the lice or keds or other parasites, but also by disinfecting, or by allowing natural disinfection, of the wound of bacteria. These two processes would appear to account for the observed avoidance of skin damage and cure of skin damage that would otherwise result in imperfections in the tanned leather. The way in which the extracts works on the parasite will depend on the precise nature of the parasite. For example, I believe that the extract kills both larvae and adults of lice and keds. In the case at least of keds, which, being larviparous, do not lay eggs the pupae are not affected. The eggs of lice take from 10 to 15 days to hatch, and therefore two treatments separated by at least such a period are desirable if all current infestation is to be dealt with. Analogously, the pupae of keds remain in that form for about three weeks, and therefore two treatments separated by at least that period is desirable. Any suitable formulation of the extract may be used, and any suitable treatment may be used. In general, a simple aqueous solution or suspension will be sufficient. However, other materials may be added for example to enhance penetration of the material through hair or wool. Suitable application techniques include washing, spraying, and dipping.

Experimental Results

One hundred and fifty male sheep of about one year old having lice and/or ked infestation were obtained from the Debre Birhan region of Ethiopia. They were then vaccinated against sheep pox, pasteurelosis and anthrax. They were allowed to graze in a field during the day and were kept in pens at night^' with bales of hay to feed on ad libitum. Twenty two of the sheep died due to various diseases which include fascioliasis, pneumonia and coenuriosis.

The sheep were examined for external and internal parasites and were treated with Triclabendazole and oxybendazole against the helminth parasites.

The lice and keds on each sheep were counted on both the left and the right side of the body at six different parts: the neck, shoulder, flank, back, belly and rump. On each part six partings were examined each of which was about 10 cm long. The surviving sheep were divided into four equal groups of 32 and were kept for about one month to adapt to the environment. The following was the treatment schedule.

In January eight sheep were slaughtered from each group before any treatment was started. Before slaughtering, however, the sheep were examined for external and internal parasites, their body weights were taken and their PCVs were determined. Post mortem examination was carried out and the skin was preserved with salt and sent to Walia Tannery for processing and grading.

Soon after slaughtering the rest of the sheep were treated accordingly to Table 1 below.

Table 1 - Treatment of Sheep against Cockle

The sheep of Group I were sheared with shearing scissors, each shearing taking about one hour. Great care was taken by the shearer to make sure there was not damage of any sort to the skin.

The sheep of Group II were washed first with a mixture of tobacco, soap and salt at a ratio of 1:1:6. This was repeated at three weeks interval. Then the sheep were washed with 7% Phytolacca suspension twice at three weeks intervals and this was repeated in January, April and July. The sheep from Group III were sprayed with 60% Diazinon by mixing it with water at the rate of 1 : 1600. Each sheep was sprayed thoroughly to the skin. This was carried out three times in January, April and July.

The sheep of Group IV were kept as control.

Before treatment all the sheep were positive for lice and keds. Each sheep had an average of 28 lice and 2.4 keds. The Kce were identified as Bovicola and the keds as Melophagus.

The sheep treated with Diazinon in January were free of lice and keds until the end of the trial period. The sheep that were sheared had lower numbers of lice and keds in April than those of the control group and than those treated with tobacco. This shows that the tobacco treatment carried out in January was not effective against the sheep lice and keds. Some ticks were found in the hooves and tail tips of all the sheep examined and were identified as Rhipicephalus simus.

Examination carried out in July for ectoparasites showed that the sheep of the treatment groups had an almost insignificant number office and keds, while those of the control had a significant number office and keds. In October sheep of the treatment groups had no lice and keds at all. The lice and keds on the sheep of control group had increased by 88.6% and 14.8% respectively.

Table 2 - Lice and Keds Count

Sheep of Group I had an average body weight gain of 28 grams per day. Those of Group II had 19, those. of Group UI 35 and those of Group IV 1 . This shows that those of Groups II and IV had much lower body weight gain than those of Groups I and HI. Sheep of Group II lbst.much body weight while they were treated with tobacco; but they regained as much as the other treatment groups after they were treated with Phytolacca.

Table 3 - Mean Body Weight Gain of the Trial Sheep

The skins of the sheep slaughtered in January were all graded as rejects because of cockle defects. In April the sheep of Groups I and III had better skin quality than those of Groups U and IV. The skins of the sheep of Group H were as bad as those of the control group because, during the treatment with tobacco, there was no reduction in the number office and keds. This was reflected on the quality of the skin. This can be proved by the fact that in July, after the treatment with Phytolacca, the skins produced from the sheep of Group II had better quality than that from those slaughtered in April.

Table 5 - Mean Skin Grade of the Trial Sheep

The PCV of the sheep of all the groups had values within the normal limits. Sheep with values above 25% were not considered to be anaemic. There was also no significant difference between the PCV of the treated groups and that of the control. Table 6 - PCN of the Trial Sheep Slaughtered Quarterly

It may be concluded, therefore, that the effect on lice and keds and the skin quality of the sheep treated with Phytolacca and Diazinon and those sheared are similar. The value of the resulting leather may therefore be similar. However, there are significant differences in body weight gain between Diazinon, shearing and Phytolacca treatment. This is because of the effect of the lice and keds during the previous three months when the tobacco extract treatment was carried out. However, this difference is not as great as the difference between the control and the treatment Groups. If the sheep of Group JJ were not treated with tobacco extract, they would have gained weight at least as much as the sheep of Group III.

Considering the potential environmental hazard of Diazinon and its unavailability where it is most needed (compared to the widely-available and biodegradeable Phytolacca extract) and considering the effect of cuts that will usually occur during shearing, the treatment provided by the invention is clearly superior to the other treatments considered.

Claims

1. Use of an extract of Phytolacca in the manufacture of the medicament for the treatment or prevention of skin infestation by an organism that impairs leather quality.

2. An extract of Phytolacca for use in the treatment or prevention of skin infestation by an organism that impairs leather quality.

3. A method of treating a leather-producing animal having or susceptible to skin infestation by an organism that impairs leather quality, which method comprises applying to skin of the animal an extract of Phytolacca.

4. A method of preserving or improving quality of leather to be obtained from a leather-producing animal infested or susceptible to infestation by an organism that impairs leather quality, which method comprises to applying to skin of the animal an extract of Phytolacca.

5. A use, extract, or method according to any preceding claim, in which the animal is a sheep.

6. A method of preventing or inhibiting growth or reproduction of an organism that impairs leather quality by infesting the leather-producing animal for which method comprises applying to an environment infested or susceptible to infestation by said organism an extract of Phytolacca.

I. A use, extract or method according to any preceding claim, in which the organism is a lice or a ked.

8. A use, extract or method according to claim 7, in which the organism is a species of Bovicola or. Melophagus, or a species that causes cockle or Ekek or grain layer lesions in tanned leather.

9. A use, extract or method according to any preceding claim, in which the extract is obtained at least in part from Phytolacca berries.

10. A use, extract or method, according to any preceding claim, in which the extract is applied at least twice to an environment infested or susceptible to infestation.

I I. A use, extract or method according to claim 10, in which the two applications are separated by at least ten days.