Abstract:
Back ground: Infectious diseases are becoming threats to public health globally and oxidative stress has been implicated in the pathophysiology of various diseases. The use of plants for the welfare of human being has long history. The exudates of the leaf of Aloe macrocarpa Tod have been used for the treatment of wounds and chronic diseases in North Gondar. The aim of this study was to investigate antibacterial and antioxidant activities of the latex, gel, and 80% methanol gel extracts of Aloe macrocarpa Tod.
Methods: The latex and gel of Aloe macrocarpa Tod were collected in sterile way and dried at 40oC in oven. The dried crude gel was further extracted using 80% methanol. The extracts were evaluated for their in vitro antibacterial and antioxidant effects. Antibacterial test was conducted against three Gram positive and four Gram negative bacteria by agar well diffusion and macro-broth dilution methods; antioxidant activity evaluation was conducted by DPPH assay. Preliminary phythochemical analysis of all extracts and acute toxicity tests of the latex and gel were conducted using standard methods.
Results: The three extracts showed different degrees of inhibitory activities against tested bacteria at 2, 1 and 0.5 mg/ml in a dose dependant manner and the results were statistically significant (P≤0.05). Zone of inhibition ranged from 0.00 to 23.00±0.577 mm for all bacteria. The minimum inhibitory concentration values ranged from 31.25- 4000, 31.25 - 2000 and 62.5- 8000 μg/ml for latex, 80% methanol gel extract, and crude gel, respectively. The lowest minimum bactericidal concentration was 31.25 μg/ml against Salmonella typhi by latex. Latex revealed the greater antioxidant activity with IC50 value of 15.5 μg/ml followed by 80% methanol gel extract (19.5 μg/ml) and crude gel extract (36 μg/ml). Phytochemical analysis indicates the likely presence of alkaloids, flavonoids, phenols, tannins, terpenoids, steroid, anthraquinones and saponins. Besides, no sign of toxicity or mortality was observed in mice at 2000 mg/kg.
Conclusion: These results support the use of the plant in the treatment of wounds and chronic diseases associated with oxidative stress; however, further studies are required as to the nature of active compounds responsible for the effects observed.
