Hydrolysable tannins and coumarin from ceratonia siliqua

A new hydrolysable tannin: 1-methyl-2,3-di-O-galloyl-alpha-[4]C[1]- glucopyranose [1] was isolated from the fruits of Ceratonia siliqua, together with six known phenolic compounds [2-7]. The structures of the isolated compounds were elucidated by chemical and spectroscopic analyses. The known compounds were 2,3,4-tri-O-galloyl-[alpha/beta-[4]C[1] -glucopyranose [2], 1,2,36-tetra-O-galloyl-beta[4]C[1]-glucopyranose [3], 1,2,6-tri-O-galloyl- beta-[4]C[1] -glucopyranose [4], gallic acid methyl ester[5], gallic acid [6] and 7,8-dihydroxycoumarin [7]. The alcoholic extract [70%] and gallic acid [isolated from the same extract] exhibited an antioxidant activity by Paramagnetic Spin Resonance method