Three new quinic acid derivatives and a new shikimic acid derivative from the leaves of Castanopsis orthacantha

Three new quinic acids derivatives, 3-O-trans-caffeoyl-5-O-galloylquinic acid (1), 3-O-trans-caffeoly-5-O-galloylquinic acid methyl ester (2), 3-O-trans-caffeoyl-4-O-galloylquinic acid methyl ester (3), and a new shikimic acid derivative as orthacanthain A (4), along with three known compounds, 3-O-caffeoylquinic acid (5), methyl-3-O-galloylquinic acid (6), and emblifatmin (7), were isolated from the 70% methanol extract of the leaves of Castanopsis orthacantha France. The structures of all compounds were identified by optical rotation, MS, UV, IR, 1D and 2D NMR spectral data and comparison with literature. The IC₅₀ value of compound 3 was (0.024±0.009) mmol/L, which had strong inhibitory activity on α-glucosidase.