Molan Abdul L, Duncan Adrian J, Barry Tom N, McNabb Warren C
AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand.
Parasitol Int. 2003 Sep;52(3):209-18. doi: 10.1016/s1383-5769(03)00011-4.
The objective of this study was to determine the effects of condensed tannins (CT) and an extract containing crude sesquiterpene lactones (CSL) from chicory (Cichorium intybus) on the motility of the first-(L1) and third-stage (L3) larvae of deer lungworm Dictyocaulus viviparus and the L3 larvae of gastrointestinal nematodes in vitro, using the larval migration inhibition (LMI) assay. The CT and CSL had a profound effect on the motility of the larvae displayed by their ability to inhibit larval passage through nylon mesh sieves. Incubation of lungworm L1 larvae in rumen fluid (collected from deer fed pasture) containing 100, 400 and 1000 microg CT/ml, inhibited 12, 28 and 41% of the larvae from passing through the sieves, respectively, while the incubation of L3 larvae with rumen fluid (pH 6.6) containing the same concentrations inhibited 26, 37 and 67% of L3 larvae from passing through the sieves, respectively. Gastrointestinal larvae seem more susceptible to CT than lungworm larvae especially at higher concentrations. CT inhibited 27, 56 and 73% of gastrointestinal larvae from passing through the sieves when used at a concentration of 100, 400 and 1000 microg/ml, respectively. CT were more effective (P<0.001) at reducing the motility of lungworm L1 and L3 larvae when added to the rumen fluid than when added to the abomasal fluid (pH 3.0). Addition of 2 microg polyethylene glycol/microg CT eliminated the inhibitory effect of CT against L1 and L3 larvae especially during incubation in rumen fluid, confirming the effect as due to CT. The CSL extract also showed similar inhibitory activity against L1 and L3 lungworm and L3 gastrointestinal larvae in both fluids, indicating that this extract was not affected by the pH of the fluid, and was more effective against L3 than L1 lungworm larvae. Condensed tannins appeared to be more effective than CSL at inactivating L1 and L3 lungworm and L3 gastrointestinal larvae in rumen fluid, but CSL were particularly effective against L3 lungworm larvae in abomasal fluid. Activity of these secondary compounds explains the reduced parasite problem of young deer grazing chicory.
本研究的目的是使用幼虫迁移抑制（LMI）试验，在体外确定缩合单宁（CT）和一种含有来自菊苣（菊苣属）的粗倍半萜内酯（CSL）的提取物对鹿肺线虫网尾线虫第一期（L1）和第三期（L3）幼虫以及胃肠道线虫L3幼虫运动性的影响。CT和CSL对幼虫的运动性有显著影响，表现为它们能够抑制幼虫穿过尼龙筛网。将肺线虫L1幼虫在含有100、400和1000微克CT/毫升的瘤胃液（从采食牧场的鹿收集）中孵育，分别抑制了12%、28%和41%的幼虫穿过筛网，而将L3幼虫与含有相同浓度的瘤胃液（pH 6.6）孵育，分别抑制了26%、37%和67%的L3幼虫穿过筛网。胃肠道幼虫似乎比肺线虫幼虫对CT更敏感，尤其是在较高浓度时。当CT分别以100、400和1000微克/毫升的浓度使用时，抑制了27%、56%和73%的胃肠道幼虫穿过筛网。当添加到瘤胃液中时，CT在降低肺线虫L1和L3幼虫的运动性方面比添加到皱胃液（pH 3.0）中更有效（P<0.001）。添加2微克聚乙二醇/微克CT消除了CT对L1和L3幼虫的抑制作用，尤其是在瘤胃液孵育期间，证实了这种作用是由CT引起的。CSL提取物在两种液体中对L1和L3肺线虫以及L3胃肠道幼虫也表现出类似的抑制活性，表明该提取物不受液体pH值的影响，并且对L3肺线虫幼虫的作用比对L1幼虫更有效。在使瘤胃液中的L1和L3肺线虫以及L3胃肠道幼虫失活方面，缩合单宁似乎比CSL更有效，但CSL对皱胃液中的L3肺线虫幼虫特别有效。这些次生化合物的活性解释了采食菊苣的幼鹿寄生虫问题减少的原因。
