Isolation and Characterization of Bioenhancing Catechins from Thea sinensis Leaves

Abstract

Thea sinensis syn. Camellia sinensis (Theaceae) is an evergreen shrub indigenous to India. The leaves of this tea plant have been used both as a social and medicinal beverage since 3000 BC [1]. Traditionally green tea is recommended for headaches, body aches and pains, digestion, enhancement of immune defenses, detoxification, as an energizer and to prolong life [2]. The leaves have more than 700 chemical constituents, among which flavanoids, amino acids, vitamins, caffeine and polysaccharides are important to human health. In general, fresh tea leaves contain polyphenols, among which catechins prevail [3]. In the present study, phytochemical and biological screening of leaves of T. sinensis was undertaken. Column chromatography of methanolic extract with chloroform-methanol mixture in the increasing order of polarity yielded six catechins characterized as eremphilanyl gallate, epigallocatechin galactosidic tridecadiene, dimethoxycatechin gallate diglucosidic decane, protocatechinic acid triglycosidic undecane, protocatechinic acid tetraglycosidic decane and protocatechinic acid tetraglycosidic octane on the basis of NMR, ESI-MS, FTIR and UV data. The methanolic extract of tea leaves, at concentrations (3% and 6% w/v), were evaluated as permeation enhancers for amoxicillin using everted rat sac model. amoxicillin is a class III drug with low permeability. The amount of Amoxicillin that traversed the gut was followed spectrophotometrically at 254nm. The extract showed significant increase in its availability at both the concentrations (P<0.05). It has recently been reported that some catechins of green tea enhanced the effect of β-lactams [4]. Here it is postulated that catechins may be responsible for enhanced activity of β-lactams by increasing its availability.