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Three novel compounds, as well as a bitter-tasting flavonoid glycoside of known structure, kaempferol-3-O-β- d -glucopyranoside-7-O-α- l -rhamnopyranoside, were isolated from the rhizomes of Selliguea feei. The structures of the new compounds were determined as (−)-4β-carboxymethyl epiafzelechin (3′-deoxydryopteric acid), epiafzelechin-(4β→8, 2β→O→7)-epiafzelechin-(4β→8)-3′-deoxydryopteric acid methyl ester (selligueain B), and (+)-afzelechin-O-β- 4′- d -glucopyranoside.

Three protoberberine alkaloids, berberine chloride, berberrubine chloride and thalifendine chloride were isolated from the roots of Fibraurea chloroleuca Miers, and found to show significant cytotoxic activity with one or more human cancer cell-lines and cultured P-388 cells. A phytoecdysteroid, 20-hydroxyecdysone, was also isolated as a noncytotoxic compound. Based on comparison with previous investigations, different collections of F. chloroleuca roots appear to exhibit considerable variation in their alkaloidal profiles.

Three new compounds, 2-hydroxy-5-butoxyphenylacetic acid, 2-β- d -glucopyranosyloxy-5-butoxyphenylacetic acid, and entadamide A-β- d -glucopyranoside, in addition to the new natural product 2,5-dihydroxyphenylacetic acid methyl ester, have been isolated and characterized from seeds ofEntada phaseoloides collected in Indonesia. None of these compounds was found to demonstrate significant cytotoxicity for cultured human cancer cells, but 2-hydroxy-5-butoxyphenylacetic acid and 2,5-dihydroxyphenylacetic acid methyl ester gave ED50 values of 1.0 and 1.7 μg ml−1, respectively, with cultured P-388 cells.

A novel flavan-3-ol glycoside, plumerubroside, was isolated from a water-soluble extract of the stem bark of Plumeria rubra and its structure and conformation elucidated by spectroscopic means as (2R,3S)-3,4′-dihydroxy-7,3′,5′-trimethoxyflavan-5-O-β- d -glucopyranoside.

Selligueain A, a novel sweet trimeric proanthocyanidin with a doubly linked A unit, has been isolated from the rhizomes of Selliguea feei collected in Indonesia. The structure of this substance was established as epiafzelechin-(4 beta-->8, 2 beta-->O-->7)-epiafzelechin-(4 beta-->8)-afzelechin [1], on the basis of a combination of spectral and chemical methods. The compound was not acutely toxic for mice and not mutagenic in a forward mutation assay utilizing Salmonella typhimurium strain TM677. Selligueain A [1] was rated by a taste panel as exhibiting about 35 times the sweetness intensity of a 2% w/v aqueous sucrose solution, and at a concentration of 0.5% w/v in H2O was perceived as pleasant-tasting rather than astringent.

By bioactivity-directed fractionation, six cytotoxic constituents have been characterized from the bark of Plumeria rubra collected in Indonesia. Three iridoids, fulvoplumierin [1], allamcin [2], and allamandin [3], as well as 2,5-dimethoxy-p-benzoquinone [4], were found to be active constituents of the P. rubra petroleum-ether- and CHCl3-soluble extracts. Cytotoxic compounds isolated from the H2O-soluble extract of the bark were the iridoid plumericin [5], and the lignan liriodendrin [6]. Each of these substances was found to demonstrate general cytotoxic activity when evaluated with a panel of cell lines composed of murine lymphocytic leukemia (P-388) and a number of human cancer cell-types (breast, colon, fibrosarcoma, lung, melanoma, KB). Five additional iridoids, 15-demethylplumieride [7], plumieride [8], alpha-allamcidin [9], beta-allamcidin [10], and 13-O-trans-p-coumaroylplumieride [11], were obtained as inactive constituents. Compound 7 was found to be a novel natural product, and its structure was determined by spectroscopic methods and by conversion to plumieride [8]. The configuration of the C-4 stereocenter was unambiguously assigned for compounds 9 and 10, and certain nmr reassignments have been provided for compound 1.

By bioactivity-directed fractionation, five cytotoxic constituents have been characterized from the roots of Eurycoma longifolia collected in Kalimantan, Indonesia. Four canthin-6-one alkaloids, namely, 9-methoxycanthin-6-one, 9-methoxycanthin-6-one-N-oxide, 9-hydroxycanthin-6-one, and 9-hydroxycanthin-6-one-N-oxide, and one quassinoid, eurycomanone, were found to be cytotoxic principles. Each of these compounds was evaluated against a panel of cell lines comprising a number of human cancer cell types [breast, colon, fibrosarcoma, lung, melanoma, KB, and KB-V1 (a multi-drug resistant cell line derived from KB)] and murine lymphocytic leukemia (P-388). The canthin-6-ones 1-4 were found to be active with all cell lines tested except for the KB-V1 cell line. Eurycomanone was inactive against murine lymphocytic leukemia (P-388) but was significantly active against the human cell lines tested. Two additional isolates, the beta-carboline alkaloids beta-carboline-1-propionic acid and 7-methoxy-beta-carboline-1-propionic acid, were not significantly active with these cultured cells. However, compounds 5 and 7 were found to demonstrate significant antimalarial activity as judged by studies conducted with cultured Plasmodium falciparum strains. The structures of the novel compounds 2-4 and 7 were established by spectral and chemical methods.