Bioassay-directed fractionation of the methanolic extract of the leaves and flowers of Viburnum odoratissimum resulted in the isolation of two new diterpenes, vibsanol A (1) and vibsanol B (2), together with two new triterpenoids, 6beta-hydroxylup-20(29)-en-3-oxo-27,28-dioic acid (3) and 6alpha-hydroxylup-20(29)-en-3-oxo-27,28-dioic acid (4). In addition, the known terpenoids vibsanins B and E, and 6alpha-hydroxylup-20(29)-en-3-oxo-28-oic acid, were also isolated. The structures of the new compounds were established by chemical and spectroscopic means. Vibsanol A (1) and compound 3 exhibited significant cytotoxicity against human gastric (NUGC) tumor cells.

A new 2(3-->20) abeotaxane, taxumairone A (1), and a new cis-p-coumaroyl myo-inositol have been isolated from the seeds of Taxus mairei in addition to taxin B (2), taxinine A, taxuspine X, decinnamoyltaxinine E, 5alpha-cinnamoyloxy-9alpha,10beta,13alpha- triacetoxy-taxa-4(20)11-diene and 5alpha-cinnamoyloxy-2alpha,9alpha,10beta,+ ++13alpha-tetraacetoxy-taxa-4(20)11-diene. The structure of 1 was determined by 2D-NMR spectral analysis and chemical correlation with taxin B (2). Compound 1 exhibited potent cytotoxicity against human colon carcinoma cells with an ED50 of 0.1 microg/ml.

Fractionation of the ethanolic extract of the seeds of Calophyllum inophyllum L. has resulted in the isolation of four novel pyranocoumarin derivatives, designated as inocalophyllins A (1), B (2) and their methyl esters (3, 4) in addition to the known calophyllolide. The structures of these compounds have been determined on the basis of spectroscopic analysis including MS, heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and two dimensional incredible natural abundance double quantum transfer experiment (2D-INADEQUATE). Two new methylated products, 5 and 6 were also prepared by methylation of compounds 1 and 2, respectively.

α‐Amyrin margarate (1), moretenyl margarate (2) and moretenyl palmitate (3), three triterpenoid fatty acid esters, have been isolated from the acetone extract of the small twigs of Viburnum odoratissimum in addition to the three known compounds, α‐amyrin palmitate (4), ursolic acid (7) and vibsanin‐K (8). The structures of compounds 1–3 were elucidated based on extensive spectroscopic analysis and alkaline hydrolysis. Preliminary pharmacological studies revealed that vibsanin‐K and ursolic acid exhibited significant cytotoxicity against human gastric (NUGC) and oral epidermoid (HONE‐1) tumor cells at a concentration of 50 μg/mL while compounds 1–3 were inactive.