PURIFICATION AND CHARACTERIZATION OF ANTI-HYPERGLYCEMIC BIOACTIVE MOLECULE FROM COSTUS PICTUS D. DON

Costus pictus D. Don., commonly known as the ‘Insulin plant’ is being used as a natural remedy to treat diabetes mellitus. The present study is focused to identify the chemical constituent responsible for the anti-diabetic activity of Costus pictus. The methanol extract was prepared from the fresh leaves of Costus pictus and washed with water to remove excess oxalic acid content present to get the non-toxic water-insoluble extract (CWI). The CWI was fractionated into low polar (CWI-LP), medium polar (CWI-MP) and high polar (CWI-HP) fractions by silica gel column chromatography. CWI and CWI-HP fraction showed prominent dose-dependent glucose tolerance effects in rats by GTT whereas the other fractions did not show any effect. Phytochemical analysis of CWI-HP resulted in isolation and characterization of the active compound present, namely β-Sitosterol-3-O-β-D-glucoside (daucosterol). The compound was purified by silica gel column chromatography and identified using various spectroscopic techniques, mainly through 1D and 2D NMR, HRMS. Since daucosterol is unstable in acidic pH, the enteric coating was performed on the molecule and CWI-HP fraction. Daucosterol and CWI-HP fraction were evaluated in rats after enteric coating at different doses and found to have significant hypoglycemic activity at a very low dose compared to uncoated compound and fraction. HPTLC estimation revealed that the CWI extract of Costus pictus is a rich source of daucosterol. This is the first effort to identify the active principle from Costus pictus.