Caffeic acid free radical scavenging activity

An extract from Lactuca indica showed significant free radical scavenging activity, and protected phixl74 supercoiled DNA against strand cleavage and reduced oxidative stress in human promyelocytic leukemia HL-60 cells. On account of protocatechulic acid, methyl p-hydroxybenzoate, caffeic acid, 3,5-dicaffeoylquinic acid, luteolin 7-O-fT glucopyranoside, and quercetin 3-0-(3-g 1 ucopyranoside are the major antioxidative constituents (111). 

The antioxidants or quenchers of free radicals are known to minimize skin photoaging and the protective action of sun screens correlates closely to their free radical scavenging activity [49,50]. This prompted us to use the prevention of photodynamic yeast cell damage to comparatively investigate the protective activity of the four hydroxycoumarins esculin, esculetin, fraxin and fraxetin, and a widely used sun screen p-aminobenzoic acid (PABA). We applied the same test to characterize the protective activity of four Fraxinus ornus bark preparations containing these coumarins in different concentrations and to examine the activity of caffeic acid (16), a minor constituent of these preparations [51]. 

The relationships between chemical stractures of HCA conjugates and their antioxidant and free radical scavenging activity have been reported [5,50,106,108,110,126]. Although this may vary with temperature and the nature of the test used, antioxidant activity was always higher for free caffeic acid than... 

Free radical scavenging activities of different phenolic acids, caffeic acid (CA), ferulic acid (FA) and p-coumaric acid (p CA) and natural antioxidants alpha tocopherol (alpha-toco) and BHA a synthetic antioxidant were compared with sinapic acid (SA). As indicated in Figure 15.10 under the tested conditions, the radical scavenging activity of the phenolic acids in the DPPH system decreased in the following order ... 

Wu, W. M., L. Lu, Y. Long et al. 2007. Free radical scavenging and antioxidative activities of caffeic acid phenethyl ester (CAPE) and its related compounds in solution and membranes A structure-activity insight. Food Chem. 105 107-115. 

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