ANTIOXIDANT, ANALGESIC AND ANTIMICROBIAL ACTIVITIES OF DIFFERENT FRACTIONS FROM METHANOLIC EXTRACT OF PSIDIUM GUAJAVA L. LEAVES

Psidium guajava Linn. the most popular and widely cultivated fruiting plant all over Bangladesh. The present study was aimed to investigate the antioxidant, analgesic and antimicrobial activities of n-hexane (HPG), chloroform (CLPG) and ethyl acetate fractions (ET APG) obtained from methanol extract of Psidium guajava (MPG) leaves. The in-vitro antioxidant activity of fractions HPG, CLPG and ET APG were determined using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and ascorbic acid was used as standard. The IC₅₀ value of HPG, CLPG and ET APG were 29.96 µg/ml, 26.84 µg/ml and 24.29 µg/ml respectively whereas the IC₅₀ value of ascorbic acid was 6.23 µg/ml. Analgesic activity of HPG, CLPG and ET APG extracts (400 mg/kg) were evaluated using acetic acid-induced writhing model of pain in mice and demonstrated significant reduction of pain in mice with the effect of 56.10%, 60.51% and 70.12% respectively (p<0.05) and were comparable to that of standard, diclofenac sodium (77.22%). Preliminary phytochemical screening of different fractions showed the presence of bioactive constituents like alkaloids, saponin, flavonoids, tannins and triterpenoids. Further, HPG, CLPG and ET APG fractions (500 µg/ml) showed antibacterial activity as measured by zone of inhibition on gram-positive bacteria such as Staphylococcus aureus, Bacillus subtilis and gram-negative bacteria such as Salmonella paratyphi, Salmonella typhi and Shigella dysenteriae and compared with azithromycin (50 µg/ml) as a reference standard. The different fractions from Psidium guajava possesses antioxidant, analgesic and antimicrobial activities might be used as a therapeutic alternative in the treatment of infection and pain; and can protect against oxidative stress-induced tissue damage.