A series of quassinoids was tested for antifeedant activity against the aphidMyzus persicae (Hemiptera, Aphididae). Isobrucein B, brucein B and C, glaucarubinone, and quassin decreased feeding at concentrations down to 0.05% and isobrucein A was effective at 0.01%. Only quassin showed no phytotoxic effects and is therefore the most promising compound for further development.

Biologically inactive but easily available chaparrin 2a has been converted into potent antileukemic C-15 esters of glaucarubolone 2b and quassinoid analogs in which the C-15 ester side chain has been replaced by an alkyl or alkenyl group.The synthetic methodology developed has been applied to the preparation of C-15 ester derivatives 15, 16, 17 and quassinoid analogs 12, 13 and 14.

The structure of 15-O-benzoyl-brucein D, a new quassinoid isolated from Soulamea amara Lam., has been established from spectral data and by single-crystal X-ray analysis ; the previously known picrasin B, isobrucein A and B were also isolated.

The structure of 15-O-benzoyl-brucein D, a new quassinoid isolated from Soulamea amara Lam., has been established from spectral data and by single-crystal X-ray analysis ; the previously known picrasin B, isobrucein A and B were also isolated.

The antifeedant activity of 13 quassinoids of different structural types has been studied against the Mexican bean beetle (Epilachna varivestis Mulsant) 4th instar larvae and the southern armyworm (Spodoptera eridania Crawer) 5th instar larvae. All quassinoids tested displayed significant activity against the Mexican bean beetle and, thus, do not reveal a simple structure-activity relationship. Five quassinoids were active against the southern armyworm. Interestingly, four of these-bruceantin (I), glaucarubinone (VI), isobruceine A (VIII), and simalikalactone D (XI)-possess the required structural features for antineoplastic activity. The noncytotoxic quassin (X) is an exception; it is active against both pests.

Two new toxic quassinoid glucosides, 15-O-β-D-glucopyranosyl glaucarubolone 3 and 15-O-β-D-glucopyranosyl glaucarubol 4, have been isolated from Simarouba glauca seeds. Their structures were deduced from spectral data and that of 3 established by single-crystal X-ray analysis.

Laurycolactone A 2 and B 3 are new quassinoids with a C18 basic skeleton isolated from the Vietnamese Simaroubaceae, Eurycoma longifolia Jack. The structure of Eurycomalactone, a C19 quassinoid isolated previously from the same plant, has been revised and shown to be 4. The structures have been established by spectral means and those of 2 and 4 confirmed by X-ray diffraction analysis.