Polyphenol recovery from sorghum bran waste by microwave assisted extraction: Structural transformations as affected by grain phenolic profile.

Sorghum milling waste stream (bran), contains diverse phenolic compounds with bioactive properties. The study determined the potential of microwave assisted extraction (MAE) to recover the bran phenolic compounds. Red, white, and lemon-yellow pericarp sorghum brans were subjected to MAE and phenolic yield and structural transformation vs conventional extraction (control) assessed by UPLC-MS/MS, Folin-Ciocalteu and Trolox equivalent antioxidant capacity methods. Phenols yield increased from 3.7-20.3 to 12.6-75.5 mg/g, while antioxidants capacity increased average 3.3X in MAE extracts vs controls. Hydroxycinnamic acids increased most dramatically (3.0-32X) in MAE extracts (0.08-2.64 to 2.57-8.01 mg/g), largely driven by release of cell-wall derived feruloyl- and coumaroyl-arabinose. MAE hydrolyzed flavonoid glycosides into aglycones, and depolymerized condensed flavonoid heteropolymers into flavanones, flavanols and (deoxy)anthocyanidins. Thus, MAE dramatically enhances yield of valuable phenolics from sorghum bran waste, but also alters the phenolic profile in ways that may influence their chemical and biological properties.

CRISPR/Cas9-Mediated Mutagenesis of the Granule-Bound Starch Synthase Gene in the Potato Variety Yukon Gold to Obtain Amylose-Free Starch in Tubers.

Potato (Solanum tuberosum L.) is the third most important food crop after rice and wheat. Its tubers are a rich source of dietary carbohydrates in the form of starch, which has many industrial applications. Starch is composed of two polysaccharides, amylose and amylopectin, and their ratios determine different properties and functionalities. Potato varieties with higher amylopectin have many food processing and industrial applications. Using Agrobacterium-mediated transformation, we delivered Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR/Cas9) reagents to potato (variety Yukon Gold) cells to disrupt the granule-bound starch synthase (gbssI) gene with the aim of eliminating the amylose component of starch. Lugol-Iodine staining of the tubers showed a reduction or complete elimination of amylose in some of the edited events. These results were further confirmed by the perchloric acid and enzymatic methods. One event (T2-7) showed mutations in all four gbss alleles and total elimination of amylose from the tubers. Viscosity profiles of the tuber starch from six different knockout events were determined using a Rapid Visco Analyzer (RVA), and the values reflected the amylopectin/amylose ratio. Follow-up studies will focus on eliminating the CRISPR components from the events and on evaluating the potential of clones with various amylose/amylopectin ratios for food processing and other industrial applications.

Stability of 3-deoxyanthocyanin pigment structure relative to anthocyanins from grains under microwave assisted extraction.

Sorghum derived 3-deoxyanthocyanin (DXA) pigments are stable relative to their anthocyanin analogs, and are of growing interest in food applications. However, the 3DXA are poorly extractable from grain tissue. This work aimed to determine the relative stability and extractability of sorghum 3-DXA vs anthocyanins from maize and cowpea under microwave-assisted extraction (MAE). UV-Vis and UPLC-MS/MS spectrometry were used to characterize the properties. The 3-DXA remained structurally stable to MAE conditions up to 1200 W/100 °C/30 min. MAE increased sorghum 3-DXA yield 100% versus control (3100 vs 1520 mg/g). On the other hand, both maize and cowpea anthocyanins were unstable and rapidly degraded under MAE. Cell wall-derived ferulate esters were detected in sorghum and maize MAE extracts, indicating cell wall degradation occurred during MAE. Thus the enhanced extraction of 3-DXA under MAE was due to their structural stability, along with improved diffusion from cell matrix due to microwave-induced sorghum cell wall disruption.

Complementary effects of cereal and pulse polyphenols and dietary fiber on chronic inflammation and gut health.

Cereal grains and grain pulses are primary staples often consumed together, and contribute a major portion of daily human calorie and protein intake globally. Protective effects of consuming whole grain cereals and grain pulses against various inflammation-related chronic diseases are well documented. However, potential benefits of combined intake of whole cereals and pulses beyond their complementary amino acid nutrition is rarely considered in literature. There is ample evidence that key bioactive components of whole grain cereals and pulses are structurally different and thus may be optimized to provide synergistic/complementary health benefits. Among the most important whole grain bioactive components are polyphenols and dietary fiber, not only because of their demonstrated biological function, but also their major impact on consumer choice of whole grain/pulse products. This review highlights the distinct structural differences between key cereal grain and pulse polyphenols and non-starch polysaccharides (dietary fiber), and the evidence on specific synergistic/complementary benefits of combining the bioactive components from the two commodities. Interactive effects of the polyphenols and fiber on gut microbiota and associated benefits to colon health, and against systemic inflammation, are discussed. Processing technologies that can be used to further enhance the interactive benefits of combined cereal-pulse bioactive compounds are highlighted.

Complementary cereals and legumes for health: Synergistic interaction of sorghum flavones and cowpea flavonols against LPS-induced inflammation in colonic myofibroblasts.

SCOPE: Cereals and legumes are traditionally consumed together in many cultures, and may provide complementary health benefits beyond what is known about improved indispensable amino acid intake. Here, we use an in vitro model of inflammatory pathways to investigate whether the different flavonoids in sorghum and cowpea could synergistically reduce inflammation. METHODS AND RESULTS: Interactive effect of combining apigenin and quercetin, as well as extracts (70% acetone, v/v) from a flavone-dominated white sorghum and flavonol-dominated white cowpea, against LPS-induced NF-κB and downstream cytokines (TNF-α, IL-6, IL-8) gene and protein expression was evaluated using the CCD18Co colon myofibroblasts. Combination of apigenin and quercetin, and sorghum and cowpea extracts synergistically downregulated LPS-induced NF-κB gene and protein expression in a dose-dependent manner, with additive effect producing IC50 values that were 14.6 and 14.0 times, respectively, higher than 1:1 combined treatments. Similar strong synergistic interactions were observed for the downstream cytokines (IC50 values for additive effect 8.3-21 times higher than combined treatments). Furthermore, the ratios of the different combined treatments significantly affected the magnitude of synergy. CONCLUSION: Combining the structurally related cereal flavones and legume flavonols elicit strong synergistic anti-inflammatory response in LPS-stimulated nonmalignant colonocytes, likely by targeting interdependent mechanisms.

Effect of Condensed Tannin Profile on Wheat Flour Dough Rheology.

Proanthocyanidins (PA) cross-link proteins and could expand wheat gluten functionality; however, how the PA MW or gluten profile affect these interactions is unknown. Effect of PA MW profile (sorghum versus grape seed PA) on dough rheology of high versus low insoluble polymeric protein (IPP) wheat flour was evaluated using mixograph, large (TA.XT2i) and small (HAAKE Rheostress 6000) deformation rheometry. Sorghum PA (93% polymeric) more effectively (p < 0.05) strengthened both glutens than grape seed PA (45% polymeric), without reducing gluten extensibility. These effects were higher in low IPP (weak gluten) flour, e.g., sorghum PA doubled IPP, increased mix time by 75%, dough elasticity by 82%, and peak angle by 17° versus control. Grape seed PA increased IPP by 75% and elasticity by 36%, but reduced peak angle by 15°, indicating reduced mixing tolerance. Sorghum PA, but not grape seed PA, increased (p < 0.05) all above parameters in high IPP dough. Polymeric PA more effectively strengthened gluten than oligomeric PA, likely via more efficient protein cross-linking to overcome strong antioxidant effect of PA. High MW PA may be useful natural gluten strengtheners for diverse applications.

Enhanced action of apigenin and naringenin combination on estrogen receptor activation in non-malignant colonocytes: implications on sorghum-derived phytoestrogens.

Activation of estrogen receptor-ß (ERß) is an important mechanism for colon cancer prevention. Specific sorghum varieties that contain flavones were shown to activate ER in non-malignant colonocytes at low concentrations. This study aimed to determine positive interactions among estrogenic flavonoids most relevant in sorghum. Apigenin and naringenin were tested separately and in combination for their ability to influence ER-mediated cell growth in non-malignant young adult mouse colonocytes (YAMC). Sorghum extracts high in specific flavanones and flavones were also tested. Apigenin reduced ER-mediated YAMC cell growth comparable to physiological levels of estradiol (E2, 1 nM) at 1 µM; naringenin had similar effect at 10 µM. However, when combined, 0.1 µM apigenin plus 0.05 µM naringenin produced similar effect as 1 nM E2; these concentrations represented 1/10th and 1/200th, respectively, of the active concentrations of apigenin and naringenin, demonstrating a strong enhanced action. A sorghum extract higher in flavones (apigenin and luteolin) (4.8 mg g(-1)) was more effective (5 µg mL(-1)) at activating ER in YAMC than a higher flavanone (naringenin and eriodictyol) (28.1 mg g(-1)) sorghum extract (10 µg mL(-1)). Enhanced actions observed for apigenin and naringenin were adequate to explain the level of effects produced by the high flavone and flavanone sorghum extracts. Strong positive interactions among sorghum flavonoids may enhance their ability to contribute to colon cancer prevention beyond what can be modeled using target compounds in isolation.

Polyphenolic extracts from cowpea (Vigna unguiculata) protect colonic myofibroblasts (CCD18Co cells) from lipopolysaccharide (LPS)-induced inflammation--modulation of microRNA 126.

Cowpea (Vigna unguiculata) is a drought tolerant crop with several agronomic advantages over other legumes. This study evaluated varieties from four major cowpea phenotypes (black, red, light brown and white) containing different phenolic profiles for their anti-inflammatory property on non-malignant colonic myofibroblasts (CCD18Co) cells challenged with an endotoxin (lipopolysaccharide, LPS). Intracellular reactive oxygen species (ROS) assay on the LPS-stimulated cells revealed antioxidative potential of black and red cowpea varieties. Real-time qRT-PCR analysis in LPS-stimulated cells revealed down-regulation of proinflammatory cytokines (IL-8, TNF-α, VCAM-1), transcription factor NF-κB and modulation of microRNA-126 (specific post-transcriptional regulator of VCAM-1) by cowpea polyphenolics. The ability of cowpea polyphenols to modulate miR-126 signaling and its target gene VCAM-1 were studied in LPS-stimulated endothelial cells transfected with a specific inhibitor of miR-126, and treated with 10 mg GAE/L black cowpea extract where the extract in part reversed the effect of the miR-126 inhibitor. This suggests that cowpea may exert their anti-inflammatory activities at least in part through induction of miR-126 that then down-regulate VCAM-1 mRNA and protein expressions. Overall, Cowpea therefore is promising as an anti-inflammatory dietary component.

Phenolic composition and inhibitory effect against oxidative DNA damage of cooked cowpeas as affected by simulated in vitro gastrointestinal digestion.

Cowpeas contain phenolic compounds with potential health benefits. The effect of simulated gastrointestinal digestion on phenolic composition of cooked cowpeas and the ability of the digests to inhibit radical-induced DNA damage was determined. A red and a cream-coloured cowpea type were used. The phenolic composition of acetone extracts and enzyme digests of cooked cowpeas was determined using UPLC-MS. Compounds such as p-hydroxybenzoic acid, p-coumaric acid, coumaroylaldaric acid and feruloylaldaric acid were present in the acetone extracts of the cooked cowpeas but were not detected in the enzyme digests. Glycosides of quercetin and myricetin decreased upon in vitro gastrointestinal digestion of cooked cowpeas whereas flavan-3-ols were hardly present except catechin glucoside. The enzyme digest of the red cowpea type was about thrice as effective as that of the cream cowpea type in protecting DNA from oxidative damage. The observation that enzyme digests of cooked cowpeas inhibited radical-induced DNA damage suggests that cowpea phenolics retain some radical scavenging activity after gastrointestinal digestion.

New highly stable dimeric 3-deoxyanthocyanidin pigments from sorghum bicolor leaf sheath.

The growing interest in natural alternatives to synthetic petroleum-based dyes for food applications necessitates looking at nontraditional sources of natural colors. Certain sorghum varieties accumulate large amounts of poorly characterized pigments in their nongrain tissue. We used High Performance Liquid Chromatography-Tandem Mass Spectroscopy to characterize sorghum leaf sheath pigments and measured the stability of isolated pigments in the presence of bisulfite at pH 1.0 to 7.0 over a 4-wk period. Two new 3-deoxyanthocyanidin compounds were identified: apigeninidin-flavene dimer and apigenin-7-O-methylflavene dimer. The dimeric molecules had near identical UV-Vis absorbance profiles at pH 1.0 to 7.0, with no obvious sign of chalcone or quinoidal base formation even at the neutral pH, indicating unusually strong resistance to hydrophilic attack. The dimeric 3-deoxyanthocyanidins were also highly resistant to nucleophilic attack by SO(2); for example, apigeninidin-flavene dimer lost less than 20% of absorbance, compared to apigeninidin monomer, which lost more than 80% of absorbance at λ(max) within 1 h in the presence of SO(2). The increased molecular complexity of the dimeric 3-deoxyanthocyanidins compared to their monomers may be responsible for their unusual stability in the presence of bisulfite; these compounds present new interesting opportunities for food applications.

Sorghum phenolics demonstrate estrogenic action and induce apoptosis in nonmalignant colonocytes.

Evidence indicates sorghum may be protective against colon cancer; however, the mechanisms are unknown. Estrogen is believed to protect against colon cancer development by inducing apoptosis in damaged nonmalignant colonocytes. Three sorghum extracts (white, red, and black) were screened for estrogenic activity using cell models expressing estrogen receptor α (ER-α; MCF-7 breast cancer cells) and ß [ER-ß; nonmalignant young adult mouse colonocytes (YAMC)]. Black and white sorghum extracts had significant estrogenic activity mediated through both estrogen receptors at 1-5 and 5-10 µg/mL, respectively; but red sorghum did not. Activation of ER-ß in YAMC reduced cell growth via induction of apoptosis. Only the black and red sorghums contained 3-deoxyanthocyanins; however, these compounds were non-estrogenic. Flavones with estrogenic properties, luteolin (0.41-2.12 mg/g) and apigenin (1.1-1.4 mg/g), and their O-methyl derivatives (0.70-0.95 mg/g) were detected in white and black sorghums, but not in the red sorghum. On the other hand, naringenin, a flavanone known to interfere with transcriptional activities of estrogen, was only detected in the red sorghum extract (as its 7-O-glycoside) at relatively high concentration (11.8 mg/g). Sorghum flavonoid composition has important implications on possible modes of chemoprotection by sorghum against colon carcinogenesis.

Sorghum 3-deoxyanthocyanins possess strong phase II enzyme inducer activity and cancer cell growth inhibition properties.

3-Deoxyanthoxyanins (3-DXA) possess unique chemical and biochemical properties and may be useful in helping reduce incidence of gastrointestinal cancer. This study tested sorghum extracts rich in 3-DXA as well as isolated and synthetic 3-DXA for potential to induce activity of phase II enzymes in murine hepatoma cells using the NAD(P)H:quinone oxidoreductase (NQO) assay and to inhibit proliferation of the HT-29 human colon cancer cells using MTT and PicoGreen assays. Crude black sorghum extract that contained high levels of methoxylated 3-DXA was a strong inducer of NQO activity (3.0 times at 50 microg/mL), compared to red or white sorghum extracts with low or no methoxylated 3-DXA (1.6 times at 200 microg/mL). All sorghum extracts had strong antiproliferative activity against HT-29 cells after 48 h of incubation (IC(50) = 180-557 microg/mL). Among isolated fractions, nonmethoxylated 3-DXA were very effective against HT-29 cell growth (IC(50) = 44-68 microM at 48 h), but were noninducers of NQO. On the other hand, the methoxylated 3-DXA had both strong antiproliferative activity (IC(50) < 1.5-53 microM) and NQO inducer activity (2-3.7 times). Dimethoxylated 3-DXA were more potent than monomethoxylated analogues. Methoxylation of 3-DXA is essential for NQO activity and also enhances tumor cell growth inhibition.

Decorticating sorghum to concentrate healthy phytochemicals.

The growing prominence of nutrition-related health problems demands strategies that explore nontraditional natural ingredients to expand healthy food alternatives. Specialty sorghums were decorticated using a tangential abrasive dehulling device (TADD) to remove successive bran layers, which were collected at 1 min intervals and analyzed for phenols, tannins, 3-deoxyanthocyanins, dietary fiber, and antioxidant activity. The first two bran fractions had the highest levels of phenols and antioxidant activity (3-6 times as compared to whole grain). Brown (tannin-containing) and black sorghums had at least 10 times higher antioxidant activity than white sorghum or red wheat brans. Black sorghums had the highest 3-deoxyanthocyanin content (up to 19 mg/g bran). Dietary fiber in sorghum brans ranged between 36 and 45%, as compared to 48% for wheat bran. Specialty sorghum brans are rich in valuable dietary components and present promising opportunities for improving health attributes of food.