Effect of conventional and novel techniques on extraction yield, chemical characterisation and biological activities of proteins from bitter gourd (Momordica charantia)

The study investigates the effect of conventional and novel extraction techniques on the protein extraction yield from bitter gourd seeds (Momordica charantia). Ultrasound assisted-extraction (UAE) treatment for 30 min at 4 °C using a 20 kHz ultrasound probe resulted in the highest extraction yield of crude proteins. After purification, 9.08 ± 0.23 g of protein with 82.69 ± 0.78% purity was obtained from 100 g of M. charantia seeds on a dry basis. Mass spectrometry identified proteins with reported antidiabetic activity. Antidiabetic assays showed significantly higher antidiabetic activity for the purified protein (81.10 ± 2.64%) compared to the crude protein (32.59 ± 2.76%). In vitro cytotoxicity analysis showed minimal cytotoxicity levels at concentrations <200 μg.mL−1. Overall, UAE was effective to obtain crude protein from M. charantia seeds and a subsequent purification step enhanced antidiabetic activity. However, further research is required to demonstrate in-vivo antidiabetic activity.