Antioxidant, anti-inflammatory, and anti-allergic activities of the sweet-tasting protein brazzein

Sweet-tasting proteins may be useful as low-calorie sugar substitutes in foods, beverages, and medicines. Brazzein is an attractive sweetener because of its high sweetness, sugar-like taste, and good stability at high temperature and wide pH ranges. To investigate the bioactivities of brazzein, the antibacterial, antifungal, antioxidant, anti-inflammatory, and anti-allergic activities were determined in vitro. Brazzein showed no antibacterial and antifungal activities, although it showed approximately 45% or greater similarity to defensin, which has antimicrobial effects, and drosomycin, which is used as an antifungal agent. However, brazzein exhibited strong antioxidant effects, showing ABTS radical scavenging activity (IC50 = 12.55 μM) and DPPH activity (IC50 > 30 μM). Brazzein also showed anti-inflammatory activity and anti-allergic activity in a β-hexosaminidase assay (IC50 > 15 μM) and cyclooxygenase-2 inhibition assay (IC50 = 12.62 μM), respectively. These results suggest that brazzein has antioxidant, anti-inflammatory, and anti-allergic activities and considerable potential as a functional sweetener.