Abstract

The in vitro antioxidant activity of aqueous and hydroethanolic extracts of Guibourtia tessmannii was evaluated by determination of flavonoid, anthocyanidins and tannins content. Scavenging activity on NO° and OH° radicals, metal chelating activity and antilipoperoxidative activity (thermal and chemical peroxidation of olive oil and hepatic lipid peroxidation) were also carried out. Results have shown that hydroethanolic extracts of G. tessmannii had more polyphenols content that aqueous extracts. Antiradical activity has shown that aqueous extract had more effect on NO° radical (IC₅₀: 2309.272 µg/ml) than hydroethanolic extracts (IC₅₀: 10698.500 µg/ml). Inhibitory effect on hydroxyl radical revealed that hydroethanolic extract had the best inhibitory effect than aqueous extract (IC₅₀: 1923.939 and 19750.000 µg/ml, respectively). Metal chelating activity has revealed that extracts of G. tessmannii had high chelating activity. Aqueous and hydroethanolic extracts had IC₅₀: 185.515 and 162.786 µg/ml, respectively. Thermal and chemical peroxidation of olive oil showed that extracts of G. tessmannii inhibit peroxidation of olive oil but aqueous extracts (IC₅₀: 0.489 µg/ml) had best effect than hydroethanolic extracts. Anti-lipid peroxidation activity of G. tessmannii revealed that hydroethanolic extracts of G. tessmannii had the best inhibition profile on hepatic lipid peroxidation ((IC₅₀: 1.711 × 10^-5 µg/ml) than aqueous extracts (IC₅₀: 0.667 µg/ml). The study indicated that G. tessmannii possessed the highest antioxidant activity and phenolic compounds concentrations and has potential applications in health against nutritional diseases.

Key words: Guibourtia tessmannii, peroxidation, antioxidant.

Abbreviation

TCA, Trichloroacetic acid; TBA, thiobarbituric acid; EDTA, ethylenediamine tetraacetic acid; MDA, malondialdéhyde; TBARs, thiobarbituric acid reactive substances; PUFAs, polyunsaturated fatty acids.