Chemistry and Antidiabetic Effects of Phlogacanthus thyrsiflorus Nees Flowers

Abstract

The present study was carried out to evaluate the chemical constituents and antidiabetic activity of flower extracts of Phlogacanthus thyrsiflorus Nees in streptozotocin induced diabetic Long-Evans rats by feeding for 28 days. The ethanolic extract (1.25 mg/kg bw) exhibited significant reduction of fasting serum glucose level in diabetic rats. The ethanolic extract also showed improvement in parameters of lipid profile. Five compounds namely, β- sitosterol (1), stigmasterol (2), 8(17),13-labdadien-15,16-olide-19-oic acid (3), 19-hydroxy-8(17),13- labdadien-15,16-olide (4) were isolated from the dichloromethane extract and 2-(3,4-dihydroxyphenyl)-5,7- dihydroxy-4-chromenone (Luteolin) (5) were isolated from the 1-butanol part of methanol extract of flowers. The structures of these compounds were elucidated by extensive spectroscopic studies. This is the first report of isolation of compounds (1-5) from flowers of this plant. The activities of the flower extract may be due to the presence of some of these compounds which demands further studies.