Antimicrobial and Antioxidant Activities of Zingiber officinale (Ginger) and Alpinia officinarum (Galangal)

Abstract

Two insufficiently explored cyanobacterial strains, Arthronema africanum Lukavsky and Nostoc commune Vaucher, were studied to identify their bioactive potential. Most pronounced antioxidant activity – highest amounts of phenolic compounds, flavonoids and total antioxidant activity were measured in the ethanol extracts. Furthermore, the aqueous extracts prepared from both strains, showed significantly higher antioxidant properties as compared with the polysaccharide fractions. Antimicrobial efficiency of cyanobacterial products was tested against 9 bacterial strains (2 Gram-positive and 7 Gram-negative strains), and 1 fungal strain – Candida albicans. Water extracts obtained from N. commune biomass were highly effective against most of the test-microorganisms. Each product isolated from N. commune inhibited growth of C. albicans, which result was considered as a very promising. Water extracts and cultural medium from A. africanum showed the highest antimicrobial activity. Besides, P. mirabilis, P. aeruginosa and C. albicans proved to be the most sensitive and their growth was inhibited by all A. africanum products. Based on their pronounced antibacterial and antioxidant properties, Nostoc commune and Arthronema africanum could be considered as potentially valuable strains for biotechnology and medicine. Hence, the further research would be focused on determining the metabolite composition of the products with the highest bioactivity for their eventual practical application.