Antioxidant and Antibacterial Activity of Anacardium occidentale and Psidium guajava Methanolic Leaf Extracts

Aim: This study evaluates the antioxidant and antibacterial activity of Anacardium occidentale and Psidium guajava methanolic leaf extracts.

Place and Duration of Study: The study was carried out in the Biochemistry and Microbiology Laboratory, Department of Science Laboratory Technology, School of Pure and Applied Science, Lagos State Polytechnic, Ikorodu, Lagos- Nigeria for the period of three months between August and October 2015.

Methodology: Lycophene and β-carotene was assessed using the method of Nagata and Yamashita while total phenolic and total flavonoid content was assessed by the Folin-Ciocalteau assay and aluminum chloride colorimetric assay respectively. The antioxidant activity was evaluated using the DPPH radical scavenging activity. Antimicrobial activity was assessed by the agar well diffusion technique and mode of action was evaluated by studying the leakage of UV260 and UV280 absorbing materials spectrophotometrically.

Results: A. occidentale and P. guajava methanolic leaf extracts evaluated in this study possessed significant amount of antioxidant compounds lycophene, β-carotene, total phenol and flavonoids. The extracts exhibited antioxidant activity by scavenging DPPH radicals in a dose dependent pattern with IC50 of 47.45, 43.49, 41.46 and 27.21 μg/mL for A. occidentale, P. guajava, vitamin C and Gallic acid respectively. Also, the plant extracts exhibited antimicrobial activity against E. coli, S. aureus, P. auraginosa and C. albicans and disrupted microbial membrane evident in the increase in absorbance values of UV260 and UV280 absorbing materials with time.

Conclusion: A. occidentale and P. guajava methanolic leaf extracts possess antioxidant and antimicrobial activity and serve as potential source of drugs.