engleski

In vitro evaluation of the antioxidant effect of the volatile compounds from Satureja montana L.

Widely used artificial antioxidants, such as butylated hydroxytoluene and butylated hydroxyanisole are very effective in their role as antioxidants (Madsen et al. 1995). However, their use in food products has been failing off due to their instability, as well as due to a suspected action as promoters of carcinogenesis (Namiki 1990, Pokorny 1991). For this reason, there is a growing interest in the studies of natural additives as potential antioxidants. The antioxidant properties of many aromatic herbs are reported to be effective in this role mainly due to the presence of hydroxyl groups in their phenolic compounds (Herrmann et al. 1981, Brraco et al. 1981, Kramer, 1985). Savory (Satureja montana L.) is an aromatic plant growing wild in the Mediterranean region of Croatia. With regard to the presence of phenolic compounds in its essential oil, savory is known to possess some biological, especially antibacterial, activity. As a part of an investigation of natural antioxidants from Dalmatian aromatic plants, in this paper we report the detailed study of chemical composition and antioxidant activity of the savory volatile compounds in order to find the fraction or component with the highest protection against lipid oxidation. The analyses of the total essential oil, as well as of its fractions, were made by capillary gas chromatography coupled to mass spectrometry (Hewlett-Packard GC/MS system). The evaluation of antioxidant power was performed in vitro by the  -carotene bleaching method (Pratt, 1980). The antioxidant activity of volatile compounds from Satureja montana L. was compared with that of pure compounds. Antioxidant power decreased in the order BHT >  -tocopherol > CHO fraction > total essential oil > phenolic fraction > thymol > carvacrol > CH fraction. The CHO fraction was more potent than total essential oil and other fractions, but less effective than synthetic reference standard BHT and comparable in activity with natural antioxidant  -tocopherol. The fact that CHO fraction was more effective as antioxidant than phenolic fraction or its pure constituents thymol and carvacrol suggests that synergy among minor oxygen containing compounds plays a crucial role for antioxidant power of the savory essential oil. Also, the concentration of the oil influenced its antioxidant power, too. The control sample without addition of antioxidant oxidised most rapidly and descending bleaching rates were demonstrated for the increased concentration.

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