Purification and characterisation of a hypoglycemic peptide from Momordica Charantia L. Var. abbreviata Ser.

A water-soluble peptide MC2-1-5 from Momordica charantia L. Var. Abbreviata Ser., with hypoglycemic effect, was purified by ultrafiltration, gel filtration chromatography and reverse-phase high performance liquid chromatography (RP-HPLC). The infrared (IR) spectra showed characteristic absorption peaks and the molecular mass of MC2-1-5 was found to be 3405.5174 Da by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The sequence of its first 10 N-terminal amino acids was GHPYYSIKKS as determined by a protein sequencer. MC2-1-5 reduced the blood glucose level in alloxan-induced diabetic mice by 61.70% and 69.18% at 2 and 4 h, respectively, after oral administration at a dose of 2 mg/kg. The oral glucose tolerance test (OGTT) showed MC2-1-5 produced a reduction of 25.50%, 39.62% and 41.74% in blood glucose level after 1, 2 and 3 h, respectively, of oral administration compared with a diabetic control.