Some functional properties, antioxidant and bactericidal activities of Garcinia kola Heckel protein hydrolysates: in vitro

The therapeutic use of food proteins and their derivatives is gaining more attention to replace synthetic compounds which has been linked to many side effects after prolonged use. This study aimed to determine the functional properties as well as the antioxidant and bactericidal potentials of Garcinia kola seed protein hydrolysates. Proteins were obtained with alkaline solubilization and acidic precipitation, and further hydrolyzed with specific proteases under optimum conditions. Functional properties were assessed using standard methods. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and Fe2+-chelating assays were used to estimate antioxidant potentials. Bacterial inhibition of Staphylococcus aureus, Escherichia coli and Proteus vulgaris was assayed by zone of inhibition. Protein hydrolysates obtained by pancreatin digestion exhibited the lowest hydrolysis degree. However, all protein hydrolysates showed excellent solubility across an extensive wide pH scale with the highest solubility at pH 11 and 12. All protein hydrolysates revealed significant (p < 0.05) antioxidant contents, with pepsin and trypsin hydrolysates generally showing the most DPPH radical scavenging (58.3%) and Fe2+-chelating activities (93.4%), respectively. Furthermore, hydrolysates obtained from pepsin digestion inhibited all test bacteria species and had the highest bactericidal activity. Thus, G. kola protein hydrolysates may be used as a natural source of antioxidants and antibiotics for bacterial infections. © 2022, The Author(s) under exclusive licence to Society for Plant Research.