Title:The Antidiabetic Effects of The Bioactive Flavonoid (Kaempferol-3-O-β-D-6{P- Coumaroyl} Glucopyranoside) Isolated From Allium cepa
Volume: 11
Issue: 1
Author(s): Ogbonna J. Ikechukwu and Ofoefule S. Ifeanyi
Affiliation:
Keywords:
Allium cepa, diabetes mellitus, hypoglycaemic effects, chromatography, spectroscopic methods,
glibenclamide, kaempferol.
Abstract: Background: Allium cepa has been in use in traditional medicine in the treatment
of diabetes mellitus. The aqueous and ethanolic extracts have been found effective in
lowering blood glucose levels in experimental diabetic rats and guinea pigs.
Methods: The study was carried out to isolate the active principle responsible for the observed
hypoglycaemic effect in experimental animals. Freeze-dried aqueous extract of Allium
cepa was separated into various fractions using column chromatography with silica gel
as a stationary phase. The column was eluted with various ratios of mixtures of hexane, chloroform, ethyl acetate
and methanol. These column fractions obtained were tested for hypoglycaemic effects in alloxan-induced
diabetic male rats. The identified active fraction was further separated by means of preparative thin layer
chromatography (P-TLC) using silica gel as stationary phase and mixture of solvents chloroform, ethyl acetate,
and methanol in the ratio of 10: 4: 1 respectively as the mobile phase. Pre-coated P-TLC plates were used
and the fraction bands were identified under u.v. lamp and by spraying with concentrated sulphuric acidvanillin
reagent. The isolated bands (Rf 0.438) were scrapped off from the P-TLC plates, redissolved in absolute
methanol, filtered and concentrated to dryness.
Results: The isolated compound’s structure was determined be means of one and two dimensional nuclear
magnetic resonance spectroscopy as well as comparison with literature data. The isolated compound given at
25 mg/kg dose reduced blood glucose in diabetic rats in manner which was comparable to the effect obtained
with 2 mg/kg of glibenclamide (p < 0.05). The structure of the compound was found to be that of kaempferol-
3-O- - D 6{P-coumaroyl} glucopyranoside.
Conclusion: The research findings have supported the claims that extracts of Allium cepa possess glucose
lowering properties in experimental diabetic animals.
