RESUMO
Peruvian corn biodiversity is one of the highest in the world and may represent an important natural source of health relevant phenolic bioactive compounds whose potential needs to be investigated. This study investigated twenty-two Peruvian corn samples corresponding to five corn races (Arequipeño, Cabanita, Kculli, Granada and Coruca) in relation to their total phenolic contents (TPC), anthocyanin contents, Ultra-Performance Liquid Chromatography (UPLC) phenolic profiles and antioxidant capacity (ABTS and ORAC methods). Subsequently using both free and cell-wall bound phenolic fractions their health relevance targeting hyperglycemia (α-glucosidase and α-amylase inhibition) and obesity (lipase inhibition) potentials was evaluated using in vitro assay models. Antioxidant capacity and TPC were high in bound fractions from yellow-colored races in contrast to the purple-colored race (Kculli) which had high TPC (mainly anthocyanins) and antioxidant capacity in the free form. The major phenolic acids detected by UPLC were ferulic and p-coumaric acids. High α-glucosidase (32.5-76.1%, 25 mg sample dose) and moderate α-amylase inhibitory activities (13.6-29.0%, 250 mg sample dose) were found in all free fractions, but only samples from the Kculli race had lipase inhibitory activity (58.45-92.16%, 12.5 mg sample dose). Principal component analysis revealed that the variability of data was affected by the race and the α-glucosidase and lipase inhibitory activities positively correlated with anthocyanins and antioxidant capacity. Some accessions of Kculli, Granada and Cabanita races are promising for future breeding strategies focused on the development of improved corn varieties targeted for the design of functional foods relevant for hyperglycemia and obesity prevention.
RESUMO
Beneficial effects on overall gut health by phenolic bioactives-rich foods are potentially due to their modulation of probiotic gut bacteria and antimicrobial activity against pathogenic bacteria. Based on this rationale, the effect of the free and bound phenolic fractions from a Peruvian purple corn accession AREQ-084 on probiotic lactic acid bacteria such as Lactobacillus helveticus and Bifidobacterium longum and the gastric cancer-related pathogen Helicobacter pylori was evaluated. The free and bound phenolic composition was also determined by ultra-performance liquid chromatography. Anthocyanins were the major phenolic compounds (310.04 mg cyanidin-3-glucoside equivalents/100 g dry weight, DW) in the free phenolic fraction along with hydroxycinnamic acids such as p-coumaric acid derivatives, followed by caffeic and ferulic acid derivatives. The bound phenolic form had only hydroxycinnamic acids such as ferulic acid, p-coumaric acid, and a ferulic acid derivative with ferulic acid being the major phenolic compound (156.30 mg/100 g DW). These phenolic compounds were compatible with beneficial probiotic lactic acid bacteria such as L. helveticus and B. longum as these bacteria were not inhibited by the free and bound phenolic fractions at 10 to 50 mg/mL and 10 mg/mL of sample doses, respectively. However, the pathogenic H. pylori was also not inhibited by both purple corn phenolic forms at same above sample doses. This study provides the preliminary base for the characterization of phenolic compounds of Peruvian purple corn biodiversity and its potential health benefits relevant to improving human gut health. PRACTICAL APPLICATION: This study provides insights that Peruvian purple corn accession AREQ-084 can be targeted as a potential source of health-relevant phenolic compounds such as anthocyanins along with hydroxycinnamic acids linked to its dietary fiber fraction. Additionally, these phenolic fractions did not affect the gut health associated beneficial bacteria nor the pathogenic H. pylori. Purple corn can be targeted for design of probiotic functional foods integrated with their anthocyanin linked-coloring properties.