As part of an ongoing investigation of new bioactive metabolites from rainforest flora, extracts from five different plants were determined to have interesting compounds that were new and/or cytotoxic. These phytochemicals were isolated by various separation techniques and then characterized by common spectroscopic methods.

A bark extract of a Tambourissa species yielded a new hydroxybutanolide with moderate cytotoxicity. The long hydrocarbon chain in this molecule is unique, and its structure was determined by various NMR techniques.

A fruit extract from Macaranga alnifolia yielded four new prenylated stilbenes, one new geranylated dihydroflavanol, and five known compounds. The stilbenoids are highly cytotoxic, and the National Cancer Institute (NCI) further evaluated one of the new compounds.

Bark and leaf extracts from Cerbera manghas yielded a known iridoid and a known cardiac glycoside, both of which showed good bioactivity. The cytotoxicity associated with the iridoid is unprecedented, and it also was further evaluated by the NCI.

An extract of a Cordia species yielded two known compounds - a naphthoquinone dimer and a triterpene. Both of these structures are new to the Cordia genus of plants and showed moderate bioactivity.

An extract of a Monoporus species yielded a known triterpene saponin. The compound has been previously located in the same plant family, but it is new to this genus and has no prior record of cytotoxicity.