Antioxidant properties of marigold extracts

The influence of methanolic and water extracts of growing wild marigold, Calendula arvensis L. (GWM) and cultivated marigold, Calendula officinalis L. (CM), in a concentration range of 0.10-0.90 mg/ml, was evaluated on three different free-radical species: 2,2diphenyl-1-picrylhydrazyl free radical (DPPH), hydroxyl radical and lipid peroxyl radical using electron spin resonance (ESR) spectroscopy. These extracts of CM and GWM, scavenged all types of investigated radicals in dependence on their applied concentrations. Generally, CM extracts possessed better scavenging and antioxidant activity than GMW extracts, while methanolic extracts exhibited lower activities than water extracts. Water extracts of CM had the best antioxidant properties; 0.75 mg/ml extracts completely eliminated hydroxyl radical, which was generated in Fenton system. The same concentration of this extract scavenged 92% DPPH and 95% peroxyl radical during lipid peroxidation. Antioxidant properties were in correlation with the contents of total phenolic compounds (14.49-57.47 mg/g) and flavonoids (5.26-18.62 mg/g) in extracts. The formation of o-semiquinone radicals from rutin and caffeic acid in lipid peroxidation system proved the mechanism (hydrogen donating and/or one-electron reduction) of free-radical scavenging activity. The ESR data demonstrate that methanolic and water extracts of CM possess similar free radicals scavenging and antioxidative activity as synthetic antioxidants BHA. (C) 2004 Elsevier Ltd. All rights reserved.