Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/4/2002
Publication Date: 12/3/2002
Citation: Park, B-S., Lee, K-G., Shibamoto, T., Lee, S-E., Takeoka, G.R. 2002. Antioxidant activity and characterization of volatile constituents of taheebo (Tabebuia Impetiginosa Martius ex DC). Journal of Agricultural and Food Chemistry. Vol 51, p. 295-300. Interpretive Summary: Autoxidation of lipids is a major deteriorative process affecting both the sensory and nutritional quality of foods. To prevent and retard lipid oxidation, synthetic antioxidants such as butylated hydroxyanisole, (BHA), butylated hydroxytoluene (BHT) and tertiary butylhydroquinone (TBHQ) and propyl gallate (PG) have been added to lipid-containing foods. However, potential health hazards of synthetic antioxidants in foods, including possible carcinogenicity, have sparked an interest in natural antioxidants. Naturally occurring antioxidants of plant origin such as Vitamins C and E, phenolic compounds (including flavonoids and phenolic acids) and volatile compounds in herbs and spices, are becoming increasingly important, not only in foods but also in preventive medicine. These natural constituents possess the ability to reduce oxidative damage associated with diseases such as cancer, cardiovascular disease, cataracts, diabetes, arthritis, immune diseases, aging and brain dysfunction. This study investigated the antioxidant activity of the volatile constituents of taheebo, a herb derived from the bark of various South and Central American Tabebuia species. Taheebo volatiles were identified and the antioxidant activity of individual constituents was investigated. Phenolic constituents were found to possess strong antioxidant activity. It was found that the antioxidant activity of taheebo volatiles was comparable to that of the well-known antioxidants, alpha-tocopherol and BHT.
Technical Abstract: Volatiles were isolated from the dried inner bark of Tabebuia impetiginosa using steam distillation under reduced pressure followed by continuous liquid-liquid extraction. The extract was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The major volatile constituents of T. impetiginosa were 4-methoxybenzaldehyde (52.84 ug/g), 4-ethoxyphenol (38.91 ug/g), elemicin (34.15 ug/g), trans-anethole (33.75 ug/g) and 4-methoxybenzyl alcohol (30.29 ug/g). The antioxidant property of the volatiles was evaluated using two different assays. The extract exhibited a potent inhibitory effect on the formation of conjugated diene hydroperoxides (from methyl linoleate) at a concentration of 1000 ug/mL. The extract also inhibited the oxidation of hexanal for 40 days at a level of 5 ug/mL. The antioxidative activity of T. impetiginosa volatiles was comparable with that of the well-known antioxidants, alpha-tocopherol and BHT.