α glucosidase

Combiflash R_f 200i (Teledyne ISCO) fitted with glass column and silica gel 60 RP-18 (40–63 μm) were used for purification of fractions. Shimadzu HPLC, LC 20AD with PDA detector fitted with either an analytical column (Discovery RP Amide C-16 Supelco 5 μm 250 × 4.6 mm) or semi-preparative (Discovery Amide C-16 Supelco 5 μm 250 × 10 mm) were used for analysis and purification of compounds. Column chromatography was carried out with Merck silica gel (100–200 mesh size). Thin layer chromatography (TLC) was done on TLC plates pre-coated with silica gel 60F254 (0.25 mm normal phase Merck). α-Glucosidase (Maltase EC 3.2.1.20) and p-nitro phenyl-α-d-glucopyranoside were purchased from Sisco Research Laboratory (SRL). Streptozotocin was purchased from Sisco Research Laboratories, Mumbai and metformin from Sigma Aldrich USA. 6-NBDG was procured from Invitrogen. NMR spectra were recorded on a Bruker Avance 500 MHz instrument with TMS as internal standard. Chemical shifts are expressed in δ values. Agilent 6520 Accurate mass Q-TOF/LC-MS was used to determine molecular weight. Absorbance was measured by Thermo Scientific Multiskan spectrometer. All other chemicals and reagents were of analytical grade.