Antioxidant and Antimicrobial Activities of Naturally Occurring Flavonoids from M. heterophylla and the Safety Evaluation in Wistar Rats

Background: Maytenus heterophylla (M. heterophylla) is commonly used in African traditional medicine for the management of various ailments. The present study evaluated the antioxidant, antimicrobial and safety properties of the Flavonoid extract of M. heterophylla in Wister rats. Methods: The Flavonoid was subjected to antibacterial study via agar well diffusion method, and antioxidant study using 2, 2′-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant properties (FRAP) assays. Subacute toxicity were carried out by the oral administration of the extract at a daily dose of 50 or 100mg/kg for 28 days. Results:   The extract produced significant antioxidants activities with IC50 of 33.07±0.84 µg/mL & 38.08±0.89 μg/mL in DPPH and FRAPS models respectively. It produced a dose-dependent inhibition of S. aureus, E.coli, P. aeruginosa, K. pneumonia and S. Typhi with MIC between 12.5µg/mL to 25µg/mL. The flavonoid was safe on acute exposure to rats (LD50> 5000 mg/kg). However, the  chronic exposure significantly (p<0.05) decreased the creatinine, bilirubin concentrations and increased  aspartate transaminase (AST) activities while the total protein, albumin, alanine transaminase (ALT), alkaline phosphatise (ALP), urea, chloride, potassium and sodium concentrations were comparable with those in the controls. The organs-body weights ratios also compared well with the controls (p<0.05). Conclusions: The findings showed that the Flavonoid extract of M. heterophylla was relatively non-toxic following acute or chronic exposures at 50-100 mg/kg. The flavonoid extract may potentially serve as a candidate agent for the development of an anti-microbial drug and to enhance the antioxidant capacity in rats.