In vitro antioxidant and apoptotic activity of Lablab purpureus (L.) Sweet isolate and hydrolysates

Cancer is a disease that invades the lives of millions of people each year. Chemotherapy is currently the most effective treatment however resulting in many adverse effects to the human body. Alternative treatments are being explored to overcome this obstacle. Peptides that possess radical scavenging activity and bioactive properties can be advantageous in prevention and treatment of chronic diseases. In this study, Lablab purpureus isolate and its hydrolysates (trypsin, pepsin and alcalase) were analysed for radical scavenging potential (DPPH, ABTS, superoxide radical scavenging and FRAP) and antiproliferative activity. Antiproliferative activity was confirmed with the peptides ability to induce apoptosis (Caspase 3/7 activity and Annexin V-PI). The lowest inhibitory concentrations (IC50) for DPPH, ABTS and Superoxide radical scavenging ranged between 1.81-4.47, 1.73-2.42 and 1.36-4.41 mg/mL, respectively. FRAP ranged from 19.20 to 21.94 mg/mL. Generally, it is considered that a good antioxidant encompasses antiproliferative potential. Cell lines, A549, MCF-7 and HEK293, treated with pepsin hydrolysate showed (IC50 values of 119.6, 9.80 and 13.86 mu g/mL). The isolate and pepsin were chosen for apoptotic studies. The pepsin hydrolysate showed the highest inhibition in the cancerous cell lines (A549 and MCF-7) without greatly effecting normal cells (HEK293), and the isolate was selected for comparative analysis. Annexin V-PI staining showed cells in different stages of apoptosis (cells during early apoptosis; A549, 42%; MCF-7, 17%; HEK, 34%). Caspase 3/7 assay demonstrated that the peptide causes an increase in caspase activity Peptides have the potential to act as chemo-preventative agents due to their antioxidant and apoptotic abilities.