Antihypoxic and antioxidant activity of Hibiscus esculentus seed.

The antihypoxic and antioxidant activities of Hibiscus esculentus seeds were investigated employing eight in vitro assay systems. Antihypoxic activity was investigated in two models, haemic and circulatory. The effects were pronounced in both models of hypoxia. The antihypoxic effects were dose-dependent. The results indicated that the extracts have a protective effect against hypoxia induced lethality in mice. The extracts showed antioxidant activity in some models. IC50, for DPPH radical-scavenging activity was 234 ± 8.9 µg ml-1. The extracts showed weak nitric oxide-scavenging activity between 0.1 and 1.6 mg ml-1. The extracts showed weak Fe2+ chelating ability. IC50 were 150 ± 13 µg ml-1. The extracts also exhibited low antioxidant activity in the linoleic acid model but were capable of scavenging hydrogen peroxide in a concentration dependent manner. The total amount of phenolic compounds in each extract was determined as gallic acid equivalents and total flavonoid contents were calculated as quercetin equivalents from a calibration curve. Pharmacological effects may be attributed, at least in part, to the presence of phenols and flavonoids in the extracts. [ABSTRACT FROM AUTHOR]