Anti-diabetic Activity of Convallatoxin Isolated from the Root Bark of Parquetina nigrescens (Afzel.) Bullock (Asclepiadaceae)
Date
2018-11
Journal Title
Journal ISSN
Volume Title
Publisher
Science Domain International
Abstract
This study investigated the anti-diabetic activity of the root bark extract of Parquetina nigrescens and the isolated compound, convallatoxin, from the root bark. A powdered sample of the plant was extracted with methanol, and the extract (A) was tested in glucose-loaded normal rats at 100, 200 and 400 mg/kg for the determination of the most active dose. The anti-diabetic activity of A at 200 mg/kg was carried out on streptozotocin-induced diabetic rats. A was further partitioned to obtain its n-hexane (B1), dichloromethane (B2), ethyl acetate (B3) and mother liquor (B4) fractions that were tested for blood glucose lowering activity using glucose-loaded normal rats model. The anti-diabetic activity of the isolated compound from B3 was carried out on streptozotocin-induced diabetic rats. The results were subjected to one way ANOVA followed by Bonferroni post hoc tests and p< 0.05 was considered significant. A showed dose-independent and time dependent blood glucose level reduction activity at 200 mg/kg with the highest percentage of 30% at 4 h that was comparable to the standard, glibenclamide at 5 mg/kg. A at 200 mg/kg showed a blood glucose level reduction of 49, 68 and 70% by Day 4, 7 and 10 respectively as against glibenclamide at 5 mg/kg of 18, 33 and 39% by Day 4, 7 and 10 respectively on streptozotocin-induced diabetic rats. B3 showed a time-dependent blood glucose level reduction activity up to the fourth hour similar to glibenclamide with 35% as against 38% of glibenclamide. B1, B2 and B4 were devoid of blood glucose level reduction activity. Convallatoxin isolated from B3 gave 83 % blood glucose levels reduction at day 10 as against 38% of glibenclamide. The anti-diabetic activity of convallatoxin was significantly (p<0.05) more than glibenclamide at all-time point. The structure of convallatoxin was determined using IR, 1D and 2D NMR spectroscopy and the spectroscopic data compared well with published data in the literature.
Description
Keywords
Parquetina nigrescens, root bark, anti-diabetes, chromatography, convallatoxin
Citation
Faloye Kolade Olatubosun, Ayoola Marcus Durojaye, Amos-Tautua Bamidele Martin, Famuyiwa Samson Oluwaseyi. Anti-diabetic Activity of Convallatoxin Isolated from the Root Bark of Parquetina nigrescens (Afzel.) Bullock (Asclepiadaceae). European Journal of Medicinal Plants. 2018 Nov; 25(4): 1-9