Thymus vulgaris L. (Thyme): In Vitro Culture and the Production of Secondary Metabolites

Abstract

Thymus is a perennial herb of the Labiatae family (Fig. 1A) and can grow to a height of some 30 cm. There are more than 100 varieties of Thymus distributed throughout Europe. It has dark green leaves and light mauve-pink flowers in early summer. Thyme is a good rock-garden plant, as it spreads easily. It originates on the coast of the Mediterranean Sea and in the region of Asia Minor. Now it is cultivated in numerous European countries, Russia, Canada, America, and some of the North African countries. Thyme is one of the great culinary and medicinal herbs, and is a classic constituent of a bouquet garni (Fleming 1990), but only a few species are used in the kitchen, e.g., common thyme (T. vulgaris) and lemon thyme (T. citriodorus.) The essential oil (Marhuenda et al. 1988; Blazquez and Zafra-Polo 1989) of thyme has also been reported to be effective in food preservatives, antioxidants (Farag et al. 1990), antimicrobials (Morris et al. 1979), breath-freshen- ing dentifrices (Ishikawa and Shibuya 1989), medical disinfectants, etc. In general, the dried leaves contain 0.7–2.5% dry wt. of the essential oil. The major components are thymol (15–62%), carvacrol (2–44%), p-cymene, and γ-terpinene. The typical chemical structure is shown in Fig. 2.