14E-1 |
A comparative study of antimicrobial, antimutagenic and antioxidant properties of phenolic compounds from purple corn and bilberry colorant extracts |
B. A. CEVALLOS-CASALS and L. A. Cisneros-Zevallos. Dept. of Horticultural Sciences, Texas A&M Univ., 2133 TAMU, College Station, TX 77843-2133 Anthocyanin-based colorants have attracted interest in recent years because of nutritional benefits conferred by their bioactivity. Bioactivity depends on phenolic type and concentration, therefore screening for bioactivity should be conducted on different phenolic compounds present in natural colorants. By presenting their bioactive properties, novel natural colorants might be attractive to industry and consumers. Our objective was to test bioactivity (antimicrobial, antimutagenic and antioxidant) of two phenolic fractions present in purple corn (Zea mays) and bilberry (Vaccinium myrtillus) colorants. An anthocyanin fraction (F-I) and a fraction containing phenolics other than anthocyanins (F-II) were obtained for determining bioactivity contribution. Phenolics were semi-purified with C-18 cartridges and fractionated with ethyl acetate. Antimicrobial activity was conducted with the broth microdilution method. Minimum Inhibitory (MIC) and Bactericidal (MBC) concentrations were expressed as mg chlorogenic-acid equivalents/mL. Antimutagenic activity was assayed with the Ames test and antioxidant activity with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). Stoichiometry of DPPH stabilization was expressed as the number of molecules of active phenolic hydroxyl groups/g chlorogenic-acid equivalent. Results showed that bilberry phenolics (MIC=7.7, MBC=12.9) had higher antimicrobial activity than purple corn phenolics (MIC=37.9, MBC=58.0). Regarding antimutagenic activity, purple corn phenolics at 0.11 mg/plate inhibited 56% mutation, while bilberry phenolics did not trigger antimutagenicity. Antiradical stoichiometric results showed that purple corn phenolics were more reactive towards DPPH than those from bilberry (1.06x1022 versus 8.63x1021 active hydroxyl molecules). F-1 from purple corn and bilberry was more reactive than F-II (Purple corn: F-1=1.80x1022, F-II=1.41x1022; Bilberry: F-1=1.76x1022, F-II=5.65x1021). F-1 for purple corn and bilberry had similar reactivity. Anthocyanins accounted for 80% and 73% of the total phenolics present in purple corn and bilberry colorants, respectively. These results show diverse bioactive properties phenolic compounds possess. Colorant selection will depend on the benefits desired. Bioactivity screening identifies different properties found in natural colorants for satisfying scientific, industry and consumer needs.
Session 14E, Nutraceuticals & Functional Foods: General I
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