Isolation and characterization of novel flavonoid from methanolic extract of Pongamia pinnata pods

Pongamia pinnata (Linn) Pierre (family Papiolanaceae) is an important medicinal plant found in tidal forests of India and has been largely used in the traditional Indian system of medicine for bronchitis, whooping cough, rheumatic arthritis and diabetes. Significant hypoglycemic activity has already been reported in flowers of the plant. But due to the short flowering period of the plant, the pods of the plants were studied as a potential alternative of flowers for getting some novel compounds with potential of the similar activity. In the present study, methanolic extract of P. pinnata pods were fractionated with column chromatography from its methanolic extract. Elution of the column with petroleum ether: chloroform (1:3) in fractions 51-79 yielded a novel flavonoid as yellow crystalline powder that was recrystallized from methanol. It showed R_f value: 0.90 (Petroleum ether: chloroform:: 1:3) and mp as 131°C The isolated novel compound was characterized with UV-Vis., Infrared (IR), Mass, ^lH and ¹³C-NMR (Nuclear Magnetic Resonance) spectroscopy. The isolated novel compound was found to be 13'-(3'-hydroxy-4'-methoxychalconyl-13-3, 4-dimethoxychalcone and hence named as Pongamiachalcone). Being a novel flavonoid isolated from the plant there are very good chances that this can also be another novel hypoglycemic agent from P. pinnata. Therefore, in vivo hypoglycemic activity of the novel compound may be carried out for its probable hypoglycemic activity like that of other flavonoids obtained from P. pinnata pods.