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Bioactivities of Kernel Extracts of 18 Strains of Maize (Zea mays)

Lee, Chen-Hsien, Garcia, Hugo S., Parkin, Kirk L.
Journal of food science 2010 v.75 no.8 pp. C667
plant extracts, pigmentation, alpha-glucosidase, superoxide anion, enzyme inhibition, antifungal properties, Zea mays, strain differences, corn, glycemic effect, enzyme inhibitors, rats, antioxidant activity, ethanol, colored varieties, supercritical fluid extraction, cyanin, nitric oxide, Saccharomyces cerevisiae, free radical scavengers, animal models, genetic variation, phenolic compounds
Aqueous and ethanolic extracts of maize kernels from 18 varieties/strains were prepared for the evaluation of inhibitory activities toward α-glucosidase and scavenging activities toward nitric oxide (NO ) and superoxide ( O2−). All ethanolic extracts of maize strains tested inhibited yeast (Saccharomyces cerevisiae) α-glucosidase with the highest potency (49% to 54%) found for 2 purple and a yellow strains. However, inhibitory effects of maize extracts on rat intestinal α-glucosidase were as a whole about 10% as effective as with the yeast enzyme. Maize extracts were capable of scavenging NO at the level of 0.25 mg/mL to extents ranging from 24% to 50% and 26% to 57%, respectively, for aqueous and ethanolic extracts. All tested aqueous extracts were also capable of scavenging O2−, with efficacies ranging from 8% to 38%, at the level of 1.5 mg/mL, whereas almost none of the ethanolic extracts scavenged O2−,, except for one purple strain (approximately 10% effective). The effectiveness in the enzyme inhibition and antioxidant assays did not correlate with total phenolic and/or anthocyanin levels, nor with the nature of pigmentation among the maize strains evaluated. Practical Application: A diversity of pigmented maize strains was evaluated for biological activities related to mitigating oxidative stress and slowing down glucose absorption from the diet. Certain strains tended to be more abundant in these biological activities and have potential to be used in dietary regimes that are designed to promote human health.