Analysis of labdane-type diterpenes from Cistus creticus (subsp creticus and subsp eriocephalus), by GC and GC-MS

The qualitative and quantitative analysis of labdane-type diterpenes of the hexane extracts and of the essential oils of the leaves, fruits and resin "Ladano", of Cistus creticus subsp. creticus and Cistus creticus subsp. eri ocephalus, have been carried out by CC and CC-MS analysis using two capilla ry chromatographic columns, i.e., HP-5MS and CP-Wax. The methanolic extract of the fruits of C. creticus subsp. creticus was examined and seven labdan e diterpenes were isolated and identified by spectroscopic methods. Data on the investigation of labdane diterpenes by GC and CC-MS is limited and mos t of them have never been analysed by this method. The results obtained by this analysis could be useful for identifying them in crude plant extracts. Manoyl oxides were studied further for the percentage content of their iso mers. The hexane extracts of the two subspecies as well as the manoyl oxide isomers isolated from the methanolic extract of the fruits of C. creticus subsp. creticus, were tested for their antimicrobial activity against Gram- positive and Cram-negative bacteria. Global numerical differences of these C. creticus subspecies, based on labdane diterpenes content in the hexane e xtracts as well as in the essential oils, were established by statistical m ethods. Phenotypic differences are discussed.