Abstract
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. IC 50 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 Fe 2+ chelating ability. IC 50 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.
Highlights
Free radicals cause the oxidation of biomolecules which leads to cell injury and death (McCord 2000)
There are literature data affirming that the administration of sodium fluoride increases the blood histamine content and decreases the oxygen carrying capacity (Sumina et al 1978)
A significant protective effect on other forms of hypoxia such as hypobaric hypoxia has been reported by Ginkgo biloba regarding an extract that contains flavonoids (Karcher et al 1984)
Summary
Free radicals cause the oxidation of biomolecules (e.g., protein, amino acids, lipid and DNA) which leads to cell injury and death (McCord 2000). The oxidative stress caused from an imbalance between the generation and the neutralization of free radicals by antioxidant mechanisms is responsible for many human diseases including aging, cancer and neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease and Huntington’s diseases (Ebrahimzadeh et al 2008a). Their deteriorative effects can be diminished by natural antioxidants available in foods. Oxidative reactions limit the shelf life of fresh and processed food stuffs and are a serious concern in the food industry (Sokmen et al 2004) Synthetic antioxidants such as butylhydroxyanisole (BHA) or butylhydroxytoluene (BHT) are used to decelerate these processes.
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