Antimicrobial and Antioxidative Activities in the Stem Extracts of Derris trifoliata, a Mangrove Shrub

Aims: An in-depth study on the phytochemical contents, antimicrobial and antioxidative activities of stem tissue of Derris trifoliata Lour. (Fabaceae), a mangrove shrub from Sundarban estuary, India.

Methodology: Phytochemical analyses were carried out using established methods for quantitative determination of phenolics, flavonoids, tannins, alkaloids and saponins. Antimicrobial potential of various extracts of D. trifoliata were evaluated by disc diffusion technique against two Gram-positive (Bacillus subtilis and Bacillus coagulans), two Gram-negative (Escherichia coli and Proteus vulgaris) bacteria and one fungus (Saccharomyces cerevisiae). The antioxidative efficacy was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. The tissue extracts were subjected to thin layer chromatography (TLC) separation and the fractions with antimicrobial and antioxidative properties were identified using TLC-bioautography.

Results: Phytochemical analyses showed the presence of appreciable amount of phenolics, flavonoids and alkaloids. All the extracts have shown activity against B. subtilis and B. coagulans, among which the methanolic has been found to be most effective. The antimicrobial activities of the extracts were found to be stable despite drastic pH and thermal treatments. The antioxidative property was also found to be quite appreciable and was considerably stable after thermal treatments. A number of the phytochemical fractions were found to possess antimicrobial/ antioxidative properties when subjected to TLC-bioautography.

Conclusion: The study suggests Derris trifoliata stem as a potential source of bioactive compounds with stable antimicrobial and antioxidative properties and can be used as natural antimicrobial/antioxidative agents in clinical, pharmaceutical and food processing industries.