Phytochemical Investigation of Cassia spectablis Seeds Isolation and Structural Studies of Two New Flavone Glycosides

From the ethanolic extract of the seeds of Cassia spectablis two flavone glycosides C2iH2o08 (1) m.p. 185 °C (d) and C ^ H ^ O N (2) m .p . 280 °C (d) have been isolated. Homogeneity and purity of these compounds were established by chromatography. C 2 I H 2 0 O 8 (1) was found to be a glycoside. On acid hydrolysis it gave arabinose and an aglycone C I 6 H 1 2 0 4 , m.p. 245 ° C which showed colour reactions characteristic of flavone. The aglycone analysed for one hydroxyl group (mono acetate) and one methoxyl group (IR 2915 and 1185 cm 1 [2]; NMR (3 3.75, 3H, -OCH3). UV spectral studies of the aglycone 240, 345 nm) indicated the absence of hydroxyl group at positions 5,7 and 4' (No shift with A 1 C 1 3 , NaOAc, NaOMe). The aglycone gave anisic acid on oxidation with neutral potassium permanganate, which confirmed the position of methoxyl group at position-4' in ring B. NMR spectrum of the aglycone showed doublets at (3 7.28 ppm (2H, H-2' , H-6') and 7.00 ppm (2H, H-3' , H-5') representing A2B2 system in ring C. NMR spectrum of the aglycone also showed signals of three protons for ring A,