Location: Grain Quality and Structure Research
Project Number: 3020-43440-002-033-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 31, 2023
End Date: Aug 30, 2026
Objective:
1) Analytically compare the polyphenol profile of raw and cooked whole-grain S. bicolor flour.
2) Assess Sorghum flour’s polyphenol metabolite profile produced by human and bacterial cells.
3) Assess nutrient-gene expression effects of extracts from raw, cooked, and bacterially-metabolized S. bicolor on molecular signaling pathways relevant to carcinogenesis and chemoprevention.
Approach:
Recently, the USDA ARS Kansas has been investigating extracts of high-polyphenol S. bicolor varietals. Understudied thus far are the complex factors that determine the bioavailability of these Sorghum micronutrients: thermal processing, host digestion, and metabolism by microbes in the human GI system. These metabolites may undergo further modifications upon entering systemic circulation of the host, ultimately determining the potential efficacy. Therefore, we propose to compare high-polyphenol brown and low-polyphenol white S. bicolor’s chemopreventive potential, accounting for food preparation and metabolism by both human cells and intestinal bacteria with the following specific aims:
Aim 1. Analytically compare the polyphenol profile of raw and cooked whole-grain S. bicolor flour. will generate extracts from raw and cooked samples with ethanol/water We will quantify the total polyphenol content and determine the relative concentration of specific polyphenols via HPLC/MS.
Aim 2. Assess Sorghum flour’s polyphenol metabolite profile produced by human and bacterial cells. Using human cell culture models incubated with extracts from raw or cooked S. bicolor, we will assess uptake and metabolism with permeable cell culture inserts using human colon cancer Caco-2 cells and human liver cells. Extracts will be added to the apical chamber for 24h. Cell culture medium will be collected from apical and basolateral chambers, and concentration of metabolites will be determined. Extracts from raw and cooked Sorghum will also be added to a mix of specific bacterial strains for up to 24 hours. Bacteria will be pelleted. The supernatant will be sterile-filtered, and polyphenols will be determined.
Aim 3 Assess nutrient-gene expression effects of extracts from raw, cooked, and bacterially-metabolized S. bicolor on molecular signaling pathways relevant to carcinogenesis and chemoprevention. We plan to analyze raw, cooked, and bacterially-metabolized whole-grain S. bicolor in models that include both human colon and liver cells, which more closely mimics the regulation of nutrient absorption in vivo. Colon and liver cancer cells will be harvested for DNA, RNA, and protein analyses (see Aim 2). Signaling pathways of interest include in particular those anticipated to regulate inflammatory colitis and colorectal cancer.
In summary, we will identify phytonutrients present in raw and cooked whole grain flour of Sorghum bicolor. We will distinguish between human and bacterial metabolites generated in the human digestive tract, and assess their ability to exert changes in gene expression relevant to inflammatory colitis and colon cancer. The proposed studies have the potential to identify novel gene-nutrient interactions. The approaches presented are innovative, because both human and bacterial metabolism in addition to domestic food preparation techniques are considered. Furthermore, they will significantly enrich the training of students. Using the results from this proposal as preliminary data, future studies to investigate S. bicolor’s effects in vivo using mouse models of inflammatory colitis and colorectal tumorigenesis are planned.
