WILD THYME, THYMUS-CAPITATUS, ESSENTIAL OIL SEASONAL-CHANGES AND ANTIMYCOTIC ACTIVITY

Monthly quantitative and qualitative changes in the essential oils of Thymus capitatus, growing wild in Sardinia, were studied over the two years 1987-1988, and their antimycotic activity against Penicillium italicum and Alternaria alternata was examined. Maximum oil yield occurred in August, but depended upon whether leaves, flowers or residual infructescences were used. Of the eight constituents identified, the biogenetically related carvacrol, p-cymene and gamma-terpinene showed changes related to the different growth stages of the season, with carvacrol levels at a maximum (70-80%) before and until after flowering (April-September); the flowers and residual infructescence contained more than the leaves. The oil proved to be fungistatic to P. italicum and fungicidal at 400 ppm to A. alternata in August 1987 and 1988. Fungitoxic effects were mainly due to carvacrol, but not always in proportion to its content in the oil.