Antibacterial and Antioxidant Activities of Aqueous and Hydroethanolic Extracts of Tetracera potatoria Afzel Ex G. Don Leaves

Abstract

The aim of this study is to evaluate the antibacterial and antioxidant activities of aqueous and hydroethanolic extracts of Tetracera potatoria leaves. Polyphenol, flavonoid, and total tannin contents were assessed by spectrophotometry in the aqueous and hydroethanolic extracts. Antibacterial and antioxidant activities were evaluated using solid medium diffusion and liquid medium dilution methods, and by DPPH and FRAP assays, respectively. Both extracts showed high contents of polyphenols (350 and 600 mg GAE/g extract), flavonoids (1000 and 2000 mg QE/g extract), and tannins (700 and 400 mg GAE/g extract). Sensitivity tests indicated that both extracts exhibit antibacterial activity with inhibition diameters ranging from 11 to 15 mm. Staphylococcus aureus, Salmonella sp., and Escherichia coli were more sensitive to the extracts compared to Pseudomonas aeruginosa. These two extracts strongly inhibit the growth of Salmonella sp., with minimum bactericidal concentrations (MBC) of 200 mg/mL compared to those of Staphylococcus aureus and Escherichia coli, which have minimum inhibitory concentrations (MIC) of 200 mg/mL. DPPH and FRAP tests revealed that both extracts possess remarkable antioxidant activity with IC50 values of 1.92 and 3.3 mg/mL, and iron-reducing capacity with IC50 values of 5.71 and 5.26mg/mL. The observed antibacterial and antioxidant activities can be attributed to polyphenols, flavonoids, and tannins. These results may justify the use of these leaves in traditional medicine.