Diurnal and seasonal variation of the essential oil labdanes and clerodanes from Cistus monspeliensis L. leaves

The composition of the essential oil from the leaves of Cistus monspeliensis (Cistaceae) shows seasonal and diurnal variation. The essential oils were investigated by GC-FID and GC-MS. Labdanes which were identified for the first time in the essential oil of C. monspeliensis, are predominant in autumn and in winter and they were found in great amount with clerodanes in spring. Manoyl oxide, 3beta-hydroxy-13-epi-manoyl oxide, 3beta-acetoxy-13-epi-manoyl oxide and their isomers varied through the day and the year. The results obtained from GC-MS analysis of the oils were submitted to statistical analysis. (C) 2002 Elsevier Science Ltd. All rights reserved.