Bioactivity study of protease digested peptides from Moringa Oleifera seeds

Abstract

Moringa oleifera is an important plant for centuries due to its nutritional properties, medicinal importance, and lately, wastewater treatment. Almost all parts of this plant contribute to its nutritional properties. Many studies have reported the importance of the bioactivity of the proteins from M. oleifera seed like antioxidant, antidiabetic, antihypertensive and wastewater treatment, but there is no investigation on the bioactivity of digested products of M. oleifera fresh seed proteins that could be used for therapeutic activity. The objectives of this research were to determine the antioxidant and a-amylase inhibition activities of Moringa oleifera fresh seed proteins and their digested products. The seed protein was extracted using Tris-HCl buffer followed by quantification by Bradford Assay and quality checked by Sodium Dodecyl-Sulphate Polyacrylamide gel electrophoresis (SDS-PAGE). Then, proteins were digested using proteolytic enzymes (pepsin, trypsin, and chymotrypsin). Next, the antioxidant activity was determined by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and Ferric reducing antioxidant power (FRAP) assay. After that, the alpha-amylase inhibition was determined by a-amylase inhibition assay. All digested products showed higher antioxidant activity than undigested protein. Pepsin digestion products showed the highest Radical scavenging activity about 30.86±2.86 %RSA than other digestion products. But in terms of FRAP assay, trypsin digestion products showed better ability about 5.51±0.009 Fe2+/g than pepsin and chymotrypsin digestion. Based on the a-amylase inhibition assay, all digested products showed good inhibitory activity, but, interestingly, the undigested protein had higher inhibition activity than digestion products. In conclusion, this study showed that digestion with proteases has improved the antioxidant activity of M. oleifera fresh seed proteins. In addition, the digestion products have inhibition of a-amylase activity but digestion did not increase the inhibitory activity. The results provide information on antioxidant and enzyme inhibitory as well as comparison of M. oleifera seed protein and the effect of protein digested by different proteases that could contribute to pharmaceutical and functional food.