Benzyl isothiocyanate is the chief or sole anthelmintic in papaya seed extracts

Papaya (Carica papaya) seeds were extracted in an aqueous buffer or in orga nic solvents. fractionated by chromatography on silica and aliquots tested for anthelmintic activity by viability assays using Caenorhabditis elegans. For all preparations and fractions tested, anthelmintic activity and benzy l isothiocyanate content correlated positively. Aqueous extracts prepared f rom heat-treated seeds had no anthelmintic activity or benzyl isothiocyanat e content although both appeared when these extracts were incubated with a myrosinase-containing fraction prepared fi om papaya seeds. A 10 h incubati on of crude seed extracts at room temperature led to a decrease in anthelmi ntic activity and fractionated samples showed a lower benzyl isothiocyanate content relative to non-incubated controls. Benzyl thiocyanate, benzyl cya nide, and benzonitrile were not detected in any preparations and cyanogenic glucosides, which were present, could not account for the anthelmintic act ivity detected. Thus, our results are best explained if benzyl isothiocyana te is the predominant ol sole anthelmintic agent in papaya seed extracts re gardless of how seeds are extracted. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.