Cladocalol, a pentacyclic 28-nor-triterpene from Eucalyptus cladocalyx with cytotoxic activity.

A formylated triterpene named cladocalol has been isolated from the leaves of Eucalyptus cladocalyx, together with ursulolactone acetate, ursolic acid, 3 beta-acetate-12,20(29)-lupadien-28-oic acid, beta-sitosterol and the known flavonoid eucalyptine. Their structures were mainly established by extensive NMR studies (1H NMR, 13C NMR, DEPT, 1H-1H COSY, HSQC, HMBC) and mass spectroscopy as well as by X-ray crystallographic analysis. In this paper, we report on the cytotoxic effect induced by cladocalol and its derivatives on the myeloid leukemia cell line HL-60.