Birch buds (Gemmae Betulae) are widely used in Russian and
Chinese traditional medicine mainly as a
diuretic and diaphoretic agent but also as an
antiseptic, anti-inflammatory and
analgesic. Despite the long history of
therapeutic use of birch buds in
folk medicine, the existing information on their chemical composition and pharmacological effects is insufficient. This circumstance warrants further study of the chemistry and pharmacology of birch buds. The present study was designed to investigate (a) the chemical composition of buds from two species of white birch and (b) the in vitro cytotoxic effect of extracts from these sources on selected tumour cells. Extracts from Betula pubescens Ehrh. and Betula pendula Roth. buds were obtained using three different methods:
carbon dioxide supercritical fluid extraction (SFE), washing of exudate covering whole buds, and extraction of milled buds with
diethyl ether. The chemical composition of extracts was investigated by GC-MS. Cytotoxicity was determined by MTT assay, and cell proliferation was determined by [3H]
thymidine uptake in
cancer cells and normal skin fibroblasts. The GC-MS investigation identified a total of 150 substances of different classes. The chemical composition of B. pubescens and B. pendula buds differed, with bud extracts from the former containing a relatively high quantity of
sesquiterpenoids and
flavonoids, while the main components of extracts from the latter were
triterpenoids. The results of the
biological assay indicated that birch bud extracts demonstrated time- and concentration-dependent and differential cytotoxicity. The highest cytotoxic activity demonstrated bud exudates and SFE extracts obtained from both Betula species. The rich chemical composition of birch buds suggests the possibility of a wider spectrum of
biological activity than previously thought. Birch bud extracts could be a promising source of compounds with cytotoxic activity against various
cancers.