SUMMARY OF THE PHYTOCHEMICAL RESEARCH PERFORMED TO DATE ON SIDERITIS SPECIES
From a botanical perspective, the large number of species of the genus Sideritis coupled with the tendency to hybridise between the different species has prompted an accurate study designed to clarify all the controversial points in the botanical classification of this genus. The past phytochemical studies of the Sideritis species have been performed with different extracts from the aerial parts, essential oils and isolated compounds such as diterpenoids, flavonoids or phenylpropanoid glycosides. These investigations have justified the traditional uses for these plants and provided direction for new pharmacological research. In recent years, other compounds such as iridoids, coumarins, lignans and phenylpropanoid glycosides have also been isolated and identified. The results have shown that essential oils act as good antimicrobial agents against both Gram-positive and Gram-negative bacteria and against the Candida albicans fungus. Diterpenoids have shown antimicrobial, anti-inflammatory and antifeedant activity, and flavonoids are active as anti-ulcerous, anti-inflammatory and antioxidant agents. Future research should focus on the pharmacological activity of these isolated compounds to find new active principles and identify their mechanisms of action. In addition, it would be interesting to investigate new pharmacological activities apart from those used in traditional medicine; recent studies have shown that diterpenes and some diterpene derivatives act as effective anti-HIV and antiproliferative agents.