Characterization and in Vitro Bioactivity of Green Extract from Fermented Soybean Waste

Extracts were extricated from raw okara and okara fermented with Rhizopus oligosporus using a clean, green protocol; water was used as the extraction solvent and coupled with ultrasound assistance for enhanced extraction. In vitro anti-oxidant analyses for antioxidant potential and capacity, superoxide scavenging activity, and nitric oxide scavenging activity validated that fermented okara yielded superior bioactive performance compared to raw okara. Fermented okara extracts showed no toxicity to erythrocytes and successfully prevented induced haemolysis. After 48 h incubation at the highest tested concentration (100 mg/mL), fermented okara extracts could inhibit HepG2 cells by 48.47 ± 5.28%, which was significantly different from their effects on NIH 3T3 cells. Gas chromatography-mass spectrometry characterization of extracts validated amino acids to be the chief fraction responsible for the detected bioactivity of the fermented okara extract. The results derived in this study open up the possibility that biofermented okara extract may be a potential novel sustainable nutraceutical.