Arylated gymnemic acids from Gymnema sylvestre R.Br. as potential α-glucosidase inhibitors

Publication date: June 2018 Source:Phytochemistry Letters, Volume 25 Author(s): Naila Hassan Alkefai, Javed Ahamad, Saima Amin, Manju Sharma, Showkat R. Mir A mixture of gymnemic acids was precipitated from the water extract of leaves of Gymnema sylvestre (Retz.) R.Br. ex Sm. (Asclepiadaceae) by acidification with mineral acid. The chromatographic separation of gymnemic acids mixture afforded four new arylated gymnemic acids (1–4) along with a gymnemasaponin (5). The compounds were characterized on the basis of extensive spectral data analysis. The arylated compounds (1–4) showed dose dependent inhibition of α-glucosidase that was found to be comparable to acarbose (IC50 265 μg/ml). Maximum α-glucosidase inhibition was achieved with compound 2 (IC50 145 μg/ml) followed by 3 (IC50 220 μg/ml), 1 (IC50 230 μg/ml) and 4 (IC50 310 μg/ml). The results revealed that the overall pattern of acyl/aryl substitution and glycosylation of compounds affected their inhibitory activity. The bidesmosidic glycosides (2 and 3) showed improved potency than the monodesmosidic glycosides (1 and 4) possibly because the additional glucose unit in the former facilitated stronger hydrogen bonding at the catalytic site. The current study provides relatively direct evidence of effectiveness of G. sylvestre against hyperglycemia. Graphical abstract

Source: Phytochemistry Letters - May 18, 2018 Category: Chemistry Source Type: research