Essential oils and hexane extracts from leaves and fruits of Cistus monspeliensis. Cytotoxic activity of ent-13-epi-manoyl oxide and its isomers.

Essential oils and hexane extracts from Cistus monspeliensis L. leaves and fruits were analysed by GC-MS. Manoyl oxide and its isomers, 3 beta-hydroxy-manoyl oxide, 3 beta-hydroxy-13-epi-manoyl oxide, as well as 3 beta-acetoxy-13-epi-manoyl oxide were detected for the first time in C. monspeliensis L. Ent-13-epimanoyl oxide was isolated from the hexane extract of leaves and its structure was determined using spectroscopic methods. In vitro cytotoxic activity of ent-13-epi-manoyl oxide and mixtures of manoyl oxide isomers at 10(-4) M concentrations ranged from 11.1 to 32.2% of the activity for a vinblastine control evaluated against nine leukemic cell lines. The results showed that the manoyl oxide isomer mixtures as well as ent-13-epi-manoyl oxide exhibited a slight growth inhibiting activity.