Githiori John B, Athanasiadou Spiridoula, Thamsborg Stig M
International Livestock Research Institute (ILRI), Nairobi, Kenya.
Vet Parasitol. 2006 Jul 31;139(4):308-20. doi: 10.1016/j.vetpar.2006.04.021. Epub 2006 May 24.
Helminth infections are a major cause for reduced productivity in livestock, particularly those owned by the poor worldwide. Phytomedicine has been used for eons by farmers and traditional healers to treat parasitism and improve performance of livestock, and many modern commercial medicines are derived from plants. However, scientific evidence on the anti-parasitic efficacy of most plant products is limited, regardless of their wide ethnoveterinary usage. Scientific validation of the anti-parasitic effects and possible side-effects of plant products in ruminants is necessary prior to their adoption as a novel method for parasite control. A variety of methods has been explored to validate the anthelmintic properties of such plant remedies, both in vivo and in vitro. In vitro assays are useful as pre-screens of activity and are mainly performed with the free-living rather than parasitic stages of nematodes. Concentrations of potentially active substances used in vitro do not always correspond to in vivo bioavailability. Therefore, in vitro assays should always be accompanied by in vivo studies when used to validate the anthelmintic properties of plant remedies. In vivo controlled studies have shown that plant remedies have in most instances resulted in reductions in the level of parasitism much lower than those observed with anthelmintic drugs. Whether it is necessary or not to achieve very high efficacy in order for plant remedies to have a role in the control of parasitism depends on the determination of biologically important levels of reduction of parasitism and it will be required prior to the wide-scale use of plant products for parasite control. Similarly, standardisation of validation studies in reference to the numbers of animals required for in vivo studies to measure direct anthelmintic effects of a plant needs to be established. Although in many cases the active compounds in the herbal remedies have not been fully identified, plant enzymes, such as cysteine proteinases, or secondary metabolites, such as alkaloids, glycosides and tannins have shown dose-dependent anti-parasitic properties. However, as some of the active compounds may also have anti-nutritional effects, such as reduced food intake and performance, it is essential to validate the anti-parasitic effects of plant products in relation to their potential anti-nutritional and other side effects. A concerted effort on isolation, development, and validation of the effects of these herbal remedies will have to be undertaken before their wider acceptance.
蠕虫感染是导致牲畜生产力下降的主要原因，对于全球贫困人群所拥有的牲畜而言尤其如此。长期以来，农民和传统治疗师一直使用植物药来治疗寄生虫病并提高牲畜的生产性能，而且许多现代商业药物都源自植物。然而，尽管大多数植物产品在民族兽医学中被广泛使用，但其抗寄生虫功效的科学证据却很有限。在将植物产品用作控制寄生虫的新方法之前，有必要对其在反刍动物中的抗寄生虫效果及可能的副作用进行科学验证。人们已经探索了多种方法来在体内和体外验证此类植物疗法的驱虫特性。体外试验作为活性预筛选很有用，主要针对线虫的自由生活阶段而非寄生阶段进行。体外使用的潜在活性物质浓度并不总是与体内生物利用度相对应。因此，在用于验证植物疗法的驱虫特性时，体外试验应始终辅以体内研究。体内对照研究表明，在大多数情况下，植物疗法导致的寄生虫感染水平降低幅度远低于驱虫药物所观察到的水平。植物疗法要在寄生虫控制中发挥作用，是否需要达到非常高的疗效，这取决于确定具有生物学重要意义的寄生虫感染降低水平，并且在广泛使用植物产品进行寄生虫控制之前就需要这样做。同样，需要确立体内研究测量植物直接驱虫效果所需动物数量方面的验证研究标准化。尽管在许多情况下草药中的活性化合物尚未完全鉴定出来，但植物酶（如半胱氨酸蛋白酶）或次生代谢产物（如生物碱、糖苷和单宁）已显示出剂量依赖性的抗寄生虫特性。然而，由于一些活性化合物也可能具有抗营养作用，如减少食物摄入量和生产性能，因此有必要结合其潜在的抗营养作用和其他副作用来验证植物产品的抗寄生虫效果。在这些草药疗法被更广泛接受之前，必须齐心协力对其进行分离、开发和效果验证。
