Plant Resources, Chemical Constituents and Bioactivities of Tea Plants from the Genus Camellia Section Thea.

Tea, as one of the most popular beverages with various bioactivities, is commonly produced from the fresh leaves of two widely cultivated tea plants, C. sinensis and C. sinensis var. assamica. Both plants belong to the genus Camellia section Thea, which was considered to have 12 species and 6 varieties according to Min's taxonomic system. Most species except the cultivated ones are known as wild tea plants and have been exploited and utilized to producing teas by the local people of its growing areas. So far, six species and varieties have been phytochemically studied, leading to the identification of 398 compounds, including hydrolyzable tannins, flavan-3-ols, flavonoids, terpenoids, alkaloids and other phenolics and related compounds. Various health beneficial effects were reported for tea and its components, involving antioxidant, anti-tumor and antimutagenic, anti-diabetic, hypolipidemic, anti-inflammatory, anti-microbial, antiviral, antifungal, neuro-protective, hepatoprotective and so on. In this review, the geographical distribution of tea plants and the chemical constituents (1-398) reported from the genus Camellia section Thea and some tea products (green, black, oolong and Pu-er teas) ever been studied between 1970 and 2018 have been summarized, taking species as the main hint, and the main biological activities are also discussed.