psammaplin-a and allosamidin

Topics: Acetylglucosamine; Biological Factors; Chitinases; Dipeptides; Disulfides; Enzyme Inhibitors; Molecular Structure; Peptides, Cyclic; Proline; Trisaccharides; Tyrosine; Xanthines

Hydrolytic enzymes involved in chitin degradation are important to allow moulting during insect development. Chitinases are interesting targets to disturb growth and develop alternative strategies to control insect pests. In this work, a chitinase from the aphid Myzus persicae was purified with a 36-fold purification rate in a three step procedure by ammonium sulphate fractionation, anion-exchange chromatography on a DEAE column and on an affinity Concanavalin A column. The purified chitinase purity assessed by 1D and 2D SDS-PAGE revealed a single band and three spots at 31 kDa, respectively. Chitinases were found to have high homologies with Concanavalins A and B, two chitinase-related proteins, a fungal endochitinase and an aphid acetylhydrolase by peptide identification by Maldi-Tof-Tof. The efficiency of two potent chitinase inhibitors, namely allosamidin and psammaplin A, was tested and showed significant rate of enzymatic inhibition.

Topics: Acetylglucosamine; Animals; Aphids; Chitinases; Disulfides; Enzyme Inhibitors; Molecular Weight; Pest Control, Biological; Trisaccharides; Tyrosine

Four chitinase inhibitors, cyclo-(Proline-Tyrosine), cyclo-(Histidine-Proline), allosamidin and psammaplin A, were selected for in vitro feeding experiments with the peach-potato aphid, Myzus persicae (Sulzer), under controlled photoperiod and temperature conditions. Artificial diets were used to provide chitinase inhibitors at 10, 50 and 100 microg mL(-1) to M. persicae. Except for cyclo-(Proline-Tyrosine), which did not modify aphid demographic parameters, chitinase inhibitors induced differential aphicidal effects on M. persicae. At all doses, cyclo-(Histidine-Proline) induced significant effects affecting daily fecundity, intrinsic rate of natural increase (r(m)) and doubling time of population. When compared with the control diet, allosamidin decreased nymph survival and daily fecundity, increasing the doubling time of population from 1 to 1.5 days. Psammaplin A was the most toxic inhibitor when delivered via artificial diet, as it induced the death of all aphids reared at 50 and 100 microg mL(-1). The results demonstrate the potential use of chitinase inhibitors as aphid management tools.

Topics: Acetylglucosamine; Animals; Aphids; Chitinases; Disulfides; Female; Insecticides; Trisaccharides; Tyrosine