2005 Volume 53 Issue 3 Pages 296-300
Six new ent-kaurane-type diterpenoids were isolated from the leaves of the endemic Vietnamese medicinal plant Croton tonkinensis GAGNEP. (Euphorbiaceae) together with three known ent-11α-acetoxy-7β,14α-dihydroxykaur-16-en-15-one (1), ent-kaur-16-en-15-one 18-oic acid (5) and ent-18-hydroxykaur-16-ene (7). Their structures were determined by spectroscopic analyses to be ent-7β-acetoxy-11α-hydroxykaur-16-en-15-one (2), ent-18-acetoxy-11α-hydroxykaur-16-en-15-one (3), ent-11α-acetoxykaur-16-en-18-oic acid (4), ent-15α,18-dihydroxykaur-16-ene (6), ent-11α,18-diacetoxy-7β-hydroxykaur-16-en-15-one (8), and ent-(16S)-1α,14α-diacetoxy-7β-hydroxy-17-methoxykauran-15-one (14). ent-Kaurane-type diterpenoids from Croton tonkinensis 2—4, 6, and 9—13, were tested for toxicity in the brine shrimp lethality assay. Compounds 9, 10, and 12 demonstrated significant activity, compounds 2, 3, 6, and 11 showed weak activity, and compounds 4 and 13 were inactive.
