Foliar application of iron impacts flavonoid glycosylation and promotes flavonoid metabolism in coloured rice.

Coloured rice is known as a healthcare food owing its rich flavonoid content. To better understand the effects of iron on the flavonoid metabolism of coloured rice grains, different concentrations of FeSO4 were foliar sprayed on to red rice Yuhongdao 5815 (RR) and black rice Nanheinuo (BR). The results revealed the association of iron with the increased accumulation of anthocyanins in BR and proanthocyanins in RR along with enhancements in their antioxidant capacities and total flavonoid contents. Metabolomic analysis revealed that the differential metabolites between the iron treated coloured rice and the control primarily occurred because of the O-linked glycosylation of aglycones, which are involved in the flavonoid pathway. RR exhibited a significantly higher number of differential metabolites compared with BR. Thus, foliar FeSO4 application affects the O-linked glycosylation and positively regulates flavonoid metabolism.

Coloured Rice Phenolic Extracts Increase Expression of Genes Associated with Insulin Secretion in Rat Pancreatic Insulinoma ß-cells.

Glucose-induced oxidative stress is associated with the overproduction of reactive oxygen species (ROS), which may dysregulate the expression of genes controlling insulin secretion leading to ß-cell dysfunction, a hallmark of type 2 diabetes mellitus (T2DM). This study investigated the impact of coloured rice phenolic extracts (CRPEs) on the expression of key genes associated with ß-cell function in pancreatic ß-cells (INS-1E). These genes included glucose transporter 2 (Glut2), silent mating type information regulation 2 homolog 1 (Sirt1), mitochondrial transcription factor A (Tfam), pancreatic/duodenal homeobox protein 1 (Pdx-1) and insulin 1 (Ins1). INS-1E cells were cultured in high glucose (25 mM) to induce glucotoxic stress conditions (HGSC) and in normal glucose conditions (NGC-11.1 mM) to represent normal ß-cell function. Cells were treated with CRPEs derived from two coloured rice cultivars, Purple and Yunlu29-red varieties at concentrations ranged from 50 to 250 µg/mL. CRPEs upregulated the expression of Glut2, Sirt1 and Pdx-1 significantly at 250 µg/mL under HGSC. CRPEs from both cultivars also upregulated Glut2, Sirt1, Tfam, Pdx-1 and Ins1 markedly at 250 µg/mL under NGC with Yunlu29 having the greatest effect. These data suggest that CRPEs may reduce ß-cell dysfunction in T2DM by upregulating the expression of genes involved in insulin secretion pathways.

Brown Rice, a Diet Rich in Health Promoting Properties.

As a staple food crop rice caters to the energy needs of more than 4 billion people around the globe. Since the 1980s, rice breeding focused on breeding for superior grain quality with good texture, taste, palatability and aroma. The recent rise in double burden nutrition challenges suggests that there is a pressing need to focus on incorporating nutritional traits also in rice breeding efforts. The present rice based diet contains nutritional gaps mainly due to the milling process which removes health promoting compounds present in rice bran. Therefore, less milled or brown rice consumption is highly recommended to achieve nutrition sustainability. Brown rice contains relatively higher amounts of dietary fibre, moderate amount of proteins, unsaturated lipids, micronutrients and several bioactive compounds. Some landraces consumed as brown rice have low glycemic index properties; hence they might be helpful to counter the growing type II diabetes. Colored rice varieties with red or purple pericarps are known to possess high levels of bioactive compounds such as cyanidin-3-glucoside, various flavanoids and γ-oryzanol. Germinated brown rice has more potential health benefits, for example, 10-fold of γ-aminobutyric acid than milled rice. For future nutritional intervention, we recommend further explorations into the nutritional value of brown rice as well as to modify the endosperm for enhanced nutrition without altering the texture to ensure consumer acceptance.

Inhibitory effects of isolated compounds from black coloured rice bran on the complement classical pathway.

The present study evaluated the anticomplement effects of isolated compounds from black coloured rice bran in the classical pathway of the complement system. Using column chromatography, three compounds: oryzafuran, quercetin and protocatechuic acid, were isolated and evaluated for in vitro anticomplement activity. Oryzafuran showed the most potent inhibitory activity against the complement system, with 50% inhibitory concentration (IC50) values of 126.2 µg/mL. This is the first report of anticomplement activity of isolated compounds from black coloured rice bran.