Anti-hyperglycaemic and anti-hyperlipidaemic effects of black and red rice in streptozotocin-induced diabetic rats

Abstract

Increasing numbers of diabetic patients, especially those with type II, can link their condition to changes in eating habits. Black rice and red rice are not only a source of carbohydrate but also rich sources of antioxidants, especially proanthocyanidins and anthocyanins. This study determines the effect consuming a black rice extract (BRE) or a red rice extract (RRE) on streptozotocin-induced diabetic rats. Blood levels of glucose, triglycerides, and cholesterol in the diabetic group were determined and compared to that of the control group. The results demonstrate that consumption of BRE, 50 mg/kg body weight (BW), or RRE, 100 mg/kg BW, could significantly reduce the blood glucose level of the diabetic rats after eight weeks. Consumption of BRE, 100 mg/kg BW or RRE, 50 mg/kg BW, also clearly decreased the triglyceride level. The cholesterol level in the diabetic group fed with BRE or RRE decreased as well. Thus daily consumption of black rice, red rice, or having their extracts in food supplements may prevent the onset of diabetes.

The Genetic Basis and Nutritional Benefits of Pigmented Rice Grain

“…Dietary anti-oxidants represent an effective means of combating the accumulation of harmful reactive oxygen species and of balancing the redox status of the body (Krishnanunni et al, 2014). Analysis of extracts made from pigmented rice grain has shown that the phenolic compounds tocopherol and anthocyanin are efficient neutralizers of reactive oxygen species (Zhang et al, 2015;Ghasemzadeh et al, 2018), while animal tests have proven that these compounds are bioavailable (Tantipaiboonwong et al, 2017). Several studies have shown that the elevated anti-oxidation activity exhibited by pigmented rice grains (most markedly by black rice) can be used to mitigate the inflammatory response (Chakuton et al, 2012;Petroni et al, 2017).…”

“…Extracts of black rice bran have also been shown to induce the repair and regeneration of pancreatic beta cells (Wahyuni et al, 2016). Overall, the antidiabetic effects of pigmented rice seem to arise from a synergistic effect of anthocyanin, proanthocyanidin, vitamin E, γ-oryzanol, and various flavonoids (Tantipaiboonwong et al, 2017). Black rice extracts reduced blood glucose levels more quickly than did extracts from red rice, a difference which was attributed to the presence of cyanidin 3-glucoside, a compound which activates insulin sensitivity, glucose uptake, and adiponectin secretion (Matsukawa et al, 2016;Tantipaiboonwong et al, 2017).…”

“…Overall, the antidiabetic effects of pigmented rice seem to arise from a synergistic effect of anthocyanin, proanthocyanidin, vitamin E, γ-oryzanol, and various flavonoids (Tantipaiboonwong et al, 2017). Black rice extracts reduced blood glucose levels more quickly than did extracts from red rice, a difference which was attributed to the presence of cyanidin 3-glucoside, a compound which activates insulin sensitivity, glucose uptake, and adiponectin secretion (Matsukawa et al, 2016;Tantipaiboonwong et al, 2017). However, many of the black rice are low in its amylose content and upon milling most of the anthocyanins accumulated in aleurone will be lost, thus not necessarily would possess low GI property when consumed in the form of milled rice (Kang et al, 2011).…”

“…In red rice, caffeic acid has been identified as a minor phenolic acid, while this compound is not detectable in brown rice (Gunaratne et al, 2013;Zhang et al, 2015;Irakli et al, 2016;Shao et al, 2018). Additional phenolic acids identified include syringic acid in the extract of brown, red, and black rice (Ghasemzadeh et al, 2018;Shao et al, 2018), pinellic acids in red and white rice (Kim et al, 2014), hydroxybenzoic acid in black rice extracts (Tantipaiboonwong et al, 2017), and gallic acid in the extracts of the red rice mutant AM-425 (Chiou et al, 2018). Four diferulic acids (phenolic acid dehydrodimers) are present in the insoluble-bound (Table 1; Zhang et al, 2015).…”

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“…Protocatechuic acid (PCA) is a phenolic compound, the main metabolite of anthocyanin, which has been reported to display various pharmacological properties 7 . In the present investigation, we proposed the hypothesis that PCA exerts antiobesity, antihyperlipidemic, antidiabetic effects in the high fatty diet with a low dose of alloxan-induced in diabetic rats 8,9,10,11 .…”