PHYTOCHEMICAL COMPOSITION, ANTIMICROBIAL ACTIVITY, ANTIOXIDANT POTENTIAL, AND ACUTE TOXICITY STUDIES OF PSIDIUM GUAJAVA (GUAVA) LEAF EXTRACT

Nestor Tordzagla*, Francis Kwaku Dzideh Amankwah, Evans Paul Kwame Ameade

Plant species have been used in treatment of microbial infections as well as other health conditions due to their medicinal properties. The aim of this study was to investigate antimicrobial activity, antioxidant potential, and acute toxicity studies on Psidium guajava leaf extract. Qualitative phytochemical composition was determined in accordance with reference experimental protocols. The antimicrobial assays were done using eleven bacterial strains and a fungal strain. The determination of minimum inhibition concentrations (MICs) and minimum bactericidal concentrations (MBCs) were carried out by broth dilution method using 96 well plates. The extract was also evaluated for its antioxidant property by employing the DPPH radical scavenging method and the total antioxidant capacity test. The toxicity study of Psidium guajava extract was carried out in Sprague-Dawley rats (n= 6). The phytochemical screening revealed the presence of cardiac glycosides, saponins, tannins, flavonoids, reducing sugars, alkaloids, and terpenoids. The results of the antimicrobial study showed appreciable antimicrobial activity against the bacteria strains used, with the mean MIC values from 1.563 mg/mL to 12.50 mg/mL and MBC values ranged from 12.50 mg/mL to 50.00 mg/mL. For antioxidant potential of the extract, scavenging activity increases with increasing concentration. The antioxidant activity of the extract became comparable to ascorbic acid at the highest concentration tested (500 µg/mL), demonstrating concentration-dependent scavenging effectiveness. Acute toxicity study indicated no noticeable adverse effects on experimental animals. This suggests that the LD50 of the extract could exceed 5000 mg/kg. Psidium guajava leaf is a potential source of a novel antimicrobial and antioxidant agents.