Priti Tiwari

Identification of pongamol and karanjin as lead compounds with antihyperglycemic activity from Pongamia pinnata fruits

AIM OF THE STUDY To identify pongamol and karanjin as lead compounds with antihyperglycemic activity from Pongamia pinnata fruits. MATERIAL AND METHODS Streptozotocin-induced diabetic rats and hyperglycemic, hyperlipidemic and hyperinsulinemic db/db mice were used to investigate the antihyperglycemic activity of pongamol and karangin isolated from the fruits of Pongamia pinnata. RESULTS In streptozotocin-induced diabetic rats, single dose treatment of pongamol and karanjin lowered the blood glucose level by 12.8% (p<0.05) and 11.7% (p<0.05) at 50mg /kg dose and 22.0% (p<0.01) and 20.7% (p<0.01) at 100mg/kg dose, respectively after 6h post-oral administration. The compounds also significantly lowered blood glucose level in db/db mice with percent activity of 35.7 (p<0.01) and 30.6 (p<0.01), respectively at 100mg/kg dose after consecutive treatment for 10 days. The compounds were observed to exert a significant inhibitory effect on enzyme protein tyrosine phosphatase-1B (EC 3.1.3.48). CONCLUSION The results showed that pongamol and karangin isolated from the fruits of Pongamia pinnata possesses significant antihyperglycemic activity in Streptozotocin-induced diabetic rats and type 2 diabetic db/db mice and protein tyrosine phosphatase-1B may be the possible target for their activity.

Flavone-Based Novel Antidiabetic and Antidyslipidemic Agents

The hybrid congeners 62-90 of 6- and 7-hydroxyflavones with aminopropanol have been synthesized and evaluated for their antidiabetic activity in sucrose-challenged low-dosed streptozotocin (STZ)-induced diabetic rats and db/db mice. The optical enantiomers 70a, 70b, 90a, and 90b of two congeners 70 and 90 exhibiting consistent antidiabetic and antidyslipidemic activities were also prepared, and their antidiabetic activity results indicate its association mainly with S isomers. These compounds also lower cholesterol and TG profiles while improving high-density lipoprotein cholesterol to CHOL ratio in db/db mice. The bioavailability of compound 70 and its isomer varies between 27 and 29% whereas that of the more polar compound 90a is poor as determined in rat by oral and intraperitoneal administrations.

Structure and activities of a steroidal saponin from Chlorophytum nimonii (Grah) Dalz.

A new steroidal saponin, chloragin (1), was isolated and characterised from the aerial part of Chlorophytum nimonii. The structure of chloragin (1) was established as tigogenin-3-O-α-L-rhamnopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 4)-β-D-xyloopyranoside on the basis of detailed chemical and spectral evidence. The saponin showed potent antihyperglycaemic and antidyslipidaemic activities in albino rats.

Antihyperglycemic activity of Rhizophora apiculata Bl. in rats

The article reveals the antihyperglycemic activity of the ethanolic extract of the roots of the Rhizophora apiculata in rats (GLM and STZ models). On further fractionation of the ethanolic extract into four fractions, the activity was localized in the chloroform and aqueous fractions. These on purification led to the isolation of 7 pure compounds – lupeol (1), oleanolic acid (2), β-sitosterol (3), palmitic acid (4), β-sitosterol-β-D-glucoside (5), inositol (6), and pinitol (7). The inositol and pinitol, two of the pure compounds, showed promising activity in STZ model at 100 mg kg−1 dose level.