A new microplate assay for cytotoxicity testing using A. salina has been developed and shown to give results comparable to a previously published test-tube method. The assay reliably detected all of the compounds toxic to KB cells in a series of 21 pharmacologically active agents, except for two which require metabolic activation in man. Four quassinoids with cyto-toxic and antiplasmodial activity were also toxic to the brine shrimp while quassin itself was inactive in all three systems. It is proposed that this assay provides a convenient means by which the presence of cytotoxic quassinoids may be detected during the fractionation of plant extracts.

Reinvestigation of the polar fractions from the stem bark of Stemmadenia minima A. Gentry (Apocynaceae) afforded two known and four new lignan glucosides. Their structures were deduced by spectroscopic and chemical methods.