ABSTRACT

Psidium guajava is a tropical plant with a wide range ofmedicinal applications. It belongs to the Myrtaceae family and can be used in herbal medicine for the treatment of various diseases and ailments such as stomach aches, dysentery, vertigo, jaundice, cerebral ailments, skin infections, diabetes, diarrhea, wound healing, inflammations, and bacterial infections. This study probed the phytochemical constituents, antimicrobial and anti-diabetic properties of Psidium guajava leaf extract. The air dried and pulverized leaves of Psidium guajava were extracted with distilled n-methanol and partitioned using equal ratio of chloroform and water. Isolation and purification were carried out using column and thin layer chromatographic techniques. Fraction Bll gave a single spot on thin layer chromatography with a retention factor (Rf) value of 0.37. Characterization offraction Bll was done using FT-IR , ’H-NMR, 13C-NMR, COSY, HSQC and HMBC and a 3-(P-Coumaryl) Ursolic acid was proposed as the structure ofthe compound. The phytochemical constituents ofPsidium guajava leaf revealed the presence of alkaloids (16.17 ± 0.13 mg/100 g), tannins (1.13±0.05 mg/100 g), Saponins (138.6±0.82 mg/100 g), flavonoids (152.83±0.85 mg/100 g), phenol (1.34±0.02 mg/100 g), and terpenoids (12.85±0.31 mg/100 g) with flavonoids having the highest concentration and tannins the lowest. Results of the antibacterial potency of methanol extract of the leaves against selected clinical isolates determined in the agar well diffusion technique showed a concentration-dependent activity. Escherichia coli was susceptible/sensitive to the extract at 200 mg with an inhibition zone size of 16.5 mm. At a similar concentration for Staphylococcus aureus, Proteus mirabilis, and salmonella species, the zone sizes were 11.0 mm, 12.0 mm, and 13.5 mm respectively. Findings from this study showed that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of the extract against the isolates ranged between 12.5 mg/ml to 100 mg/ml. Results obtained from accu check for the antidiabetic potency of methanol extract showed significant decrease in blood glucose levels oftreatment groups against diabetic group. Therefore, the Psidium guajava at both dosages displayed beneficial antihyperglycemic effects in diabetic rats, with the higher dose (400 mg/kg) showing enhanced efficacy. This suggests that methanol extract ofPsidium guajava extracts may provide a promising alternative for diabetes management by positively regulating blood glucose levels. Therefore, these findings support the traditional use ofPsidium guajava leaves in folk medicine and provide a scientific basis for their potential development as natural remedies for infectious diseases and diabetes.