Phytochemical Compositions and In vitro Antioxidant Capacity of Methanolic Leaf Extract of Axonopus Compressus (P. Beauv.)

Aims: We evaluated the phytochemical contents and antioxidant capacity of the methanolic leaf extract of the Nigerian Axonopus compressus. This is a preliminary investigation to determining the active principle which may be involved in the antidiabetic mechanism of the plant.

Study Design: Phytochemicals and antioxidant capacity were determined using chromatographic and spectrophotometric detection methods of cold leaf extracts of Axonopus compressus.

Place and Duration of Study: Department of Biochemistry, College of Natural and Applied Sciences, Michael Okpara University of Agriculture Umudike Abia State, Nigeria.

Methodology: Antioxidant activities were investigated by three tests namely: 2,2-diphenyl-1-picryl hydrazyl (DPPH), Fe3+ to Fe2+ transformation (ferric reducing antioxidant power, FRAP) and a modified version of TBARS assay. These in vitro antioxidant models were carried out after cold extraction maceration. The antioxidant capacity was measured at varying concentrations (10 ~ 400 μ/ml) of the extract required to quench the free radicals by 50% (IC50) and expressed as % inhibition. Phytochemicals were determined by standard detection and spectrophotometric methods.

Results: The phytochemicals: saponin (1.2±0.1), alkaloid (2.10±0.12), tannin (0.71±0.4), flavonoid (1.92±0.13) and polyphenol (1.78±0.21) in mg/100g were strongly detected. The leaf extract was found to have a concentration dependent antioxidant activity comparable with that of ascorbic acid. Axonopus compressus’s DPPH reduction was highest at 400μg/ml (92.00 ± 0.002%) with IC50 of 52.2μg/ml. The ferric reducing power of the extract at 400μg/ml (78±1.83% [FRAP:0.92]) and the inhibition of lipid peroxidation measured as TBARS was 92.±1.21%

Conclusion: The presence of these phytochemicals and the high antioxidant power may explain the astringent action of the plant observed in its ethnomedicinal use especially in the treatment of diabetes. Our findings therefore, suggest that Axonopus compressus possess a strong antioxidant property that may substantiate its ethnomedicinal efficacy.