Enzymatic Low-Molecular-Weight Modification of Mung Bean Protein Isolate: Effects on Physicochemical Characteristics and Cosmetic Bioactivities

In this study, we investigated the effects of enzymatic low-molecular-weight modification on the physicochemical characteristics and cosmetic-related bioactivities of mung bean protein isolate. Mung bean protein isolate (MBPI) was prepared by alkaline extraction and isoelectric precipitation, followed by sequential treatment with Viscozyme L and Protana Prime, and centrifugal filtration was then performed to obtain a low-molecular-weight fraction (LMBPI). Among the tested enzymatic treatment conditions, the selected condition produced the lowest mean particle size (160.09 ± 2.24 nm). The resulting hydrolysate showed a solubility of 93.98 ± 0.43%, compared with 89.08 ± 1.49% for untreated MBPI. SDS-PAGE and molecular weight distribution analyses showed that enzymatic treatment decreased the proportion of high-molecular-weight proteins and increased the low-molecular-weight fractions, with the 1–5 kDa fraction reaching 60% after centrifugal filtration. Compared with MBPI, LMBPI exhibited greater DPPH and ABTS radical scavenging activities and more effectively reduced nitric oxide and prostaglandin E2 production in lipopolysaccharide-stimulated RAW264.7 cells. LMBPI also showed higher tyrosinase and elastase inhibitory activities and reduced α-MSH-induced melanin production in B16F10 cells and UVA-induced matrix metalloproteinase-1 production in human dermal fibroblasts. These results indicate that enzymatic low-molecular-weight modification generated a smaller, lower-molecular-weight mung bean protein fraction with greater antioxidant, anti-inflammatory, anti-melanogenic, and anti-wrinkle-related activities than untreated MBPI, suggesting the potential of LMBPI as a multifunctional plant-derived cosmetic ingredient.