Effects of phenolic compounds of colored wheats on colorectal cancer cell lines

Abstract

In this study, the different colored wheat brans were analyzed and compared for phenolic content (PC), phenolic compositions, and the total antioxidant capacity (TEAC) with methods based on the ability to eliminate radicals of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH), and anthocyanin compositions. This study also aims to characterize the bioactive components of wheat grain genotypes as well as to test the protective and rescuer effects of their extracts on colorectal cancer (CRC) cell lines. PCs in the bound insoluble fraction of red wheat bran, blue wheat bran, and purple wheat bran were determined as 369.60, 446.95, and 486.79 mg gallic acid equivalents (GAE)/100 g wheat bran, respectively, while strong relationships were detected between PC and antioxidant activity (DPPH and ABTS) results. HPLC analysis of phenolic extracts demonstrated that ferulic acid was determined as the dominant phenolic acid in the bound fractions of red, purple, and blue wheats. In the free fractions, p-coumaric acid (11.55 µg/100 g wheat bran) was the dominant phenolic acid for red wheat bran, whereas ellagic acid (14.72 and 11.55 µg/100 g wheat bran) was the highest phenolic acid for purple and blue wheat brans, respectively. In bound fractions, ferulic acid was the highest phenolic acid for red (988.39 µg/100 g wheat bran), purple (1948.76 µg/100 g wheat bran), and blue (2263.96 µg/100 g wheat bran) wheat brans. On the other hand, Cyanidin-3-O-glucoside chloride was the predominant anthocyanin in free extracts of purple and blue wheat brans. In line with the antioxidant activities and phenolic acid concentrations, the blue wheat bran extracts increased CRC cell viability nonsignificantly in HT-29 and HCT-116 cell lines, whereas purple wheat bran extract had a significantly higher (P = 0.0361) rescuer effect compared to vehicle control under 50 µM H2O2 concentration. In conclusion, the in vitro data here show that blue and purple wheat brans are posing a novel means to increase the defense of cells against oxidative stress and cell death.