Antimicrobial activity of hydrogel loaded with Capsicum annuum, Auricularia auricula judae and Kappaphycus alvarezii.

Abstract

Antimicrobial activity refers to any substance that demonstrates the ability to reduce or inhibit the presence of microbes. Many substances derived from living organisms are claimed to play an essential role in inhibiting the growth of microorganisms. Thus, it is advisable to incorporate them into a functional system for delaying or inhibiting microbial activities. As a synthetic polymeric network, the hydrogel retaining a significant amount of water within its structure, is widely used in the healthcare industry. Due to water being one of their main constituents, microbial contamination in the hydrogel is challenging. Here, a simple method is proposed by investigating the antibacterial activities of gellan gum hydrogel loaded with hot water extracts of Capsicum annuum, Auricularia auricula judae and Kappaphycus alvarezii. Disc diffusion assay is used to evaluate the crude extracts' antimicrobial activity and their hydrogel against gram-positive and gram-negative bacteria including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus cereus. A. auricula-judae crude extract showed antimicrobial activity on P. aeruginosa and S. aureus. In contrast, hydrogel supplemented with A. auricula-judae only showed antimicrobial activity against P. aeruginosa. K. alvarezii crude extract showed antimicrobial activity on both P. aeruginosa and S. aureus. On the other hand, the inhibition zones formed by hydrogel supplemented with K. alvarezii on P. aeruginosa and S. aureus were smaller than the inhibition zones created by K. alvarezii crude extract. C. annuum crude extract only showed antibacterial activity on P. aeruginosa. No inhibition was observed in all test bacteria for the C. annuum with hydrogel. No inhibition zone was formed by A. auricula judae, K. alvarezii, C. annuum and hydrogel on B. cereus and E. coli. As a result, the antimicrobial activity of the crude extracts was higher than its product, hydrogel supplemented with crude extracts respectively. The hydrogel supplemented with A. auricula-judae, K. alvarezii and C. annuum show limited potential in antimicrobial activity, especially toward B. cereus and E. coli.