Isolation, Purification and Characterization of Proteins in “Señorita” Banana (Musa acuminata (AAA) ‘Señorita’) Pulp with Bioactive Peptides Exhibiting Antihypertensive and Antioxidant Activities

Abstract

Banana is one of the most important crops, providing multiple benefits. Although it has been widely studied for its health benefits, little information can be found about its proteins. This study determined the antihypertensive and antioxidant activities of the crude, purified, and hydrolyzed protein extracts from ‘Señorita’ banana pulp. Crude proteins were extracted using Tris-HCl buffer and purified through ammonium sulfate precipitation, dialysis, and gel filtration chromatography. The protein content of the crude, partially purified, and purified extracts were found to be 167.32, 120.45, and 28.51 μg·mL⁻¹, respectively, with major protein having an approximate molecular weight of 15 kDa. These extracts were then subjected to enzymatic hydrolysis for release of bioactive peptides prior to ACE inhibitory and antioxidant activities determination. Among these samples, the undigested crude extract had the highest ACE inhibitory activity (85.20%). There was also an observable increase in ACE inhibition of the digested samples with increased digestion time. Meanwhile, the 3-h and 4-h crude digests had the highest DPPH radical scavenging activity with 30.82% and 34.74%, respectively. These were not significantly different from the activity of the standard, ascorbic acid. A general decrease in DPPH radical scavenging activity of the samples was observed with increased digestion time. These observations were coherent with the in silico analysis of the putative major protein, lectin, which showed that its enzymatic hydrolysis releases ACE inhibitor and antioxidant peptides.