Bioactive Properties of a Serine Protease Inhibitor Purified from Vicia ervilia Seeds

Legumes contain variable amounts of bioactive substances, including protease inhibitors, which have a protective role against herbivorous insects and bacterial, fungal, and viral pathogens. However, their potential for application in agricultural and medicinal practices requires additional investigation. Bitter vetch (Vicia ervilia (L.) Willd.) is an ancient crop that is now underutilized, and its potential for various applications has recently been reevaluated. In this study, we report the purification, characterization, and bioactive properties of a protease inhibitor against trypsin/chymotrypsin-type proteases (vPI) from bitter vetch seeds. The inhibitor was purified by extraction under acidic conditions, ammonium sulfate fractionation, and size-exclusion chromatography. Its inhibitory specificity, thermostability, pH stability, and antioxidant and antimycotic activity against Alternaria alternata, Alternaria solani, Aspergillus fumigatus, Aspergillus niger, Candida albicans, Fusarium solani, Mucor michei, Penicillium griseofulvum, and Rhizopus oryzae were evaluated. Purified vPI presented superoxide anion scavenging power and antifungal activity in response to all tested strains except M. michei. It had the strongest effect on F.solani and A. solani, and a moderate effect on P. griseofulvum and C. albicans. The treatment of A. alternata, R. oryzae, A. fumigatus, and A. niger demonstrated high efficacy within the initial 24h but declined thereafter. The usefulness and limitations of the vPI application in practice are discussed.