Evaluation of antioxidant capacity and membrane stabilizing potential of stem and root of Cyphospenna adenocaulis (Steud)
Comparative analyses of the antioxidant and membrane stabilizing activities of ethanolic extracts of leaf and root of Cyphospenna adenocaulis (Steud) were investigated with a view to further investigate the biological activities of the plant. Both the leaf and root of C. adenocaulis were extracted with 70% ethanol to yield the ethanolic leaf extract (ELE) and ethanolic root extract (ERE) respectively. Phytochemical analyses of the ELE and ERE revealed the presence of flavonoids, tannins, saponins and cardiac glycosides while alkaloids were present in the ERE. The total phenolic and flavonoid contents of the ELE was estimated as 108.0 ± 0.27 mg/g TAE (tannic acid equivalent) and 33.4± 0.32 mg/g QE (Quercetin equivalent) while the ERE contained 182.6 ±0.38 mg/g TAE and 103± 0.43 mg/g QE, respectively. The antioxidant activities of ELE and ERE were investigated using various in vitro assay systems. Both extract exhibited dose-dependent DPPH radical scavenging activity, appreciable reducing power and inhibition of lipid peroxidation in bovine liver homogenate. ELE and ERE were able to protect red blood cell (RBC) membrane against hypotonic and heat induced lyses in a concentration dependent manner. The modes of action were monophasic at various concentrations assayed and were comparable to the standard non-steroidal anti-inflammatory drug used as positive control. The extracts (ELE and ERE) of C. adenocaulis possess appreciable and potent antioxidant and membrane stabilization potentials, however, the ERE displayed a stronger antioxidant and membrane stabilizing activities.
Key words: Flavonoids, antioxidant, anti-inflammatory, lipid peroxidation, membrane stabilization.