| Abstract
| - Volatiles were isolated from the dried inner bark of Tabebuia impetiginosa using steam distillationunder reduced pressure followed by continuous liquid−liquid extraction. The extract was analyzedby gas chromatography and gas chromatography−mass spectrometry. The major volatile constituentsof T. impetiginosa were 4-methoxybenzaldehyde (52.84 μg/g), 4-methoxyphenol (38.91 μg/g), 5-allyl-1,2,3-trimethoxybenzene (elemicin; 34.15 μg/g), 1-methoxy-4-(1E)-1-propenylbenzene (trans-anethole;33.75 μg/g), and 4-methoxybenzyl alcohol (30.29 μg/g). The antioxidant activity of the volatiles wasevaluated using two different assays. The extract exhibited a potent inhibitory effect on the formationof conjugated diene hydroperoxides (from methyl linoleate) at a concentration of 1000 μg/mL. Theextract also inhibited the oxidation of hexanal for 40 days at a level of 5 μg/mL. The antioxidativeactivity of T. impetiginosa volatiles was comparable with that of the well-known antioxidants,α-tocopherol, and butylated hydroxytoluene. Keywords: Natural antioxidants; taheebo; volatile antioxidants; pau d'arco
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