Synergism between the potato glycoalkaloids alpha-chaconine and alpha-solanine in inhibition of snail feeding

Snails (Helix aspersa L.) were fed filter paper treated with the potato gly coalkaloids, alpha -solanine and alpha -chaconine, singly or together. In p ure form, both glycoalkaloids deterred feeding, with chaconine being the mo re active compound. In combination, authentic solanine and chaconine intera cted synergistically in their inhibition of feeding. The antifeedant activi ties of methanolic extracts of tuber peel of the potato varieties Majestic and Sharpe's Express presented via filter paper discs did not differ signif icantly from those of authentic glycoalkaloid solutions of comparable conce ntration and ratio. In contrast, feeding inhibition by diluted tuber peel e xtracts of the variety Homeguard was greater than that elicited by comparab le authentic glycoalkaloid solutions suggesting additional inhibitory compo und(s) in the peel of this variety. Comparison of data from peel extracts o f all three potato varieties and authentic glycoalkaloids indicated that th e level of feeding inhibition by the extracts was: at least in part, a cons equence of a synergism between solanine and chaconine. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.