Dittany (Origanum dictamnus) as a source of water-extractable antioxidants

Extracts of dittany (Origanum dictamnus L.) made with solvents of varying polarity were evaluated (i) by electron spin resonance (ESR) spectrometry using the spin trapping technique for their efficiencies as scavengers of free radicals, and (ii) by measurement of oxygen depletion in a methyl linoleate emulsion for their efficiencies as chain-breaking antioxidants. Aqueous extracts of dittany most efficiently scavenged hydroxyl radicals as generated by the Fenton reaction and this extract also most efficiently reduced oxygen consumption when initiated by metmyoglobin. Ethanol and acetone extracts of dittany showed less activity in both assays with methanol extract being intermediate. The high efficiencies found in the aqueous (and methanol) extracts of dittany were closely related to a high content of phenolic compounds in these extracts, while the amounts of phenolics in the ethanol and acetone extract were lower. In aqueous extracts, the antioxidative activity was confirmed in a turkey thigh meat homogenate, where development of thiobarbituric reactive substances was increasingly inhibited by increasing additions from 0.0018 mg dittany/g meat to efficient inhibition for 0.011 mg dittany/g meat and higher additions. Dittany should be further explored as a source of water-extractable antioxidants.