RHA™ anti-Avermectin monoclonal antibody, clone AVM

Due to the widespread occurrence and spread of anthelmintic resistance, there is a need to develop new drugs against resistant parasitic nematodes of livestock animals. The Nobel Prize-winning discovery and development of the anti-parasitic drugs avermectin and artemisinin has renewed the interest in exploring natural products as anthelmintics. In the present study, we screened 7500 plant extracts for in vitro-activity against the barber's pole worm, Haemonchus contortus, a highly significant pathogen of ruminants. The anthelmintic extracts from two plants, Cryptocarya novoguineensis and Piper methysticum, were fractionated by high-performance liquid chromatography (HPLC). Subsequently, compounds were purified from fractions with significant biological activity. Four alpha-pyrones, namely goniothalamin (GNT), dihydrokavain (DHK), desmethoxyyangonin (DMY) and yangonin (YGN), were purified from fractions from the two plants, GNT from C. novoguineensis, and DHK, DMY and YGN (= kavalactones) from P. methysticum. The three kavalactones induced a lethal, eviscerated (Evi) phenotype in treated exsheathed third-stage larvae (xL3s), and DMY and YGN had moderate potencies (IC50 values of 31.7 +/- 0.23 mu M and 23.7 +/- 2.05 mu M, respectively) at inhibiting the development of xL3s to fourth-stage larvae (L4s). Although GNT had limited potency (IC50 of 200-300 mu M) at inhibiting L4 development, it was the only compound that reduced L4 motility (IC50 of 6.25-12.50 mu M). The compounds purified from each plant affected H. contortus in an irreversible manner. These findings suggest that structure-activity relationship studies of alpha-pyrones should be pursued to assess their potential as anthelmintics.

The relatively poor sensitivity is the main bottleneck restricting the application of microbial fuel cell biosensor (MFC-biosensor) for toxicity monitoring. Previous studies have shown that external resistance (R-ext) had an obvious effect on sensor sensitivity. However, these studies reported different results and the reason of this discrepancy was not clear. The objective of this research was to observe the effect of R-ext on sensor sensitivity when detecting different types of pollutants and reveal its microbiological mechanism. Results demonstrated that the optimal R-ext of MFC-biosensor varied with the type of pollutants. The optimal values for detecting avermectins, tetracyclines and heavy metals were 100 Omega, 330 Omega and 680 Omega, respectively. This discrepancy was mainly due to the visible differences in anodic microbial communities at different R-ext settings. Both Azospirillum and Acinetobacter were susceptible to Cd and Pb, occuping 19.20% of the anodic microbial population in 680 Omega MFC-biosensor. Pseudomonas accounted for 10.73% in 330 Omega MFC-biosensor and possessed the sensitivity to tetracyclines. As for 100 Omega MFC-biosensor, the avermectin-intolerant Ocillibacter made up 2.55% of the anodic microbial community. This study indicated that the R-ext of MFC-biosensor should be optimized according to the potential pollutants. (C) 2018 Elsevier B.V. All rights reserved.