Evaluation of Brans of Different Rice Varieties for their Antioxidative and Antihyperglycemic Potentials

Abstract

The aim of this study was to compare the antioxidant and antihyperglycaemic potentials of bran extracts of seven traditional rice varieties against those of three commercial varieties. The total polyphenolic content and antioxidant activities, the α‐amylase and α‐glucosidase inhibitory potentials of the rice bran extracts were studied in vitro using relevant assays. The results showed that the rice bran extracts of traditional varieties namely, Beras merah and Beras hitam displayed significantly higher α‐glucosidase inhibition (96.56 and 81.52%) and α‐amylase inhibition (88.44 and 84.27%) than the other varieties. Being high in polyphenolic content, they tended to display better anti‐oxidant capacities than the commercial varieties. Hence, brans of traditional rice varieties such Beras merah and Beras hitam could be potentially useful as raw materials for nutritional supplements and natural anti‐diabetic agents. Practical Application The findings of this study highlighted the anti‐oxidative, α‐amylase and α‐glucosidase inhibitory potentials of some rice brans obtained from Malaysian rice varieties. Since the traditional rice varieties (Beras Merah and Beras Hitam) exhibit significantly higher α‐amylase and α‐glucosidase inhibition, they could be harnessed as raw materials for preparation of ingredients for pharmaceuticals, and nutraceuticals intended for diabetes management. The findings might give impetus to the Malaysian paddy industry to expand cultivation of Beras Merah and Beras Hitam to produce more bran for value added product formulations for people with special dietary requirements.

Redox Homeostasis and Natural Dietary Compounds: Focusing on Antioxidants of Rice (Oryza sativa L.)

“…Since 2000, research interest on rice has been improved and the number of research articles related to its antioxidant properties dramatically increased more than 15 times [ 161 , 162 ]. Today, it is known that rice contains about 100 kinds of antioxidants, which can be essentially classified into two major groups: vitamins and phenolic–based compounds [ 163 , 164 , 165 ]. The mechanisms by which these bioactive compounds exert antioxidant activity have been investigated [ 166 , 167 ].…”

“…Phenolic compounds consist of at least one aromatic ring and one hydroxyl group [ 172 , 173 ]. This chemical structure is present in many active compounds including ferulic, cinnamic, p -coumaric, caffeic, sinapic, chlorogenic, gallic, vanillic, p -hydroxybenzoic, protocatechuic, and syringic acids, flavonoids, and their derivatives [ 163 , 164 , 165 ]. Those found more in pigmented rice are anthocyanins (cyanidin-3- O -glucoside, cyanidin-3- O -galactoside, cyanidin-3- O -rutinoside, peonidin-3- O -glucoside, and pelargonidin-3- O -glucoside) and proanthocyanidins, which are responsible for purple to black color and reddish color respectively, while the ferulic acid esters are more abundant in rice bran layer [ 174 , 175 , 176 , 177 , 178 , 179 ].…”

Bioactivity studies of different solvent extracts of partially defatted coconut testa obtained from selected coconut cultivars

“…This assay was performed by adopting the method described by Abubakar et al (2017) with minor modifications. A fifty µL of aliquot of sample solution (reconstituted crude extract with distilled water) was added to 96-well microplate and mixed with 150 µL of FRAP solution and allowed to incubate for 4 min at RT.…”

Evaluation of bran extracts of rice (<em>Oryza sativa</em>) and selected bean (<em>Phaseolus vulgaris</em> L.) varieties for their antioxidative and anti-hyperglycemic potentials

“…The inhibition of carbohydrate hydrolyzing enzymes present in human digestive tract would play a significant role in this scenario (Bhutkar and Bhise, 2012). Pancreatic α-amylase catalyzes the initial hydrolysis of starch into oligosaccharides (Kandra, 2003;Tangphatsomruang et al, 2005) while α-glucosidase which is a membrane-bound enzyme present in the small intestine will convert oligosaccharides to glucose (Abubakar et al, 2017;Agarwal and Gupta, 2016). Moreover, the maintenance of the balance between free radicals and radical scavenging capacity of the body is also an important factor when coming to diabetes.…”

“…This claim has been debated by the research community repeatedly. According to the recent literature, seed coats of different beans and grains are reported to exert considerable anti-oxidative and anti-hyperglycaemic effects, which is beneficial for managing diabetes (Abubakar et al, 2017;Adekola et al, 2017). In this study, we aimed to evaluate the anti-oxidative properties and anti-hyperglycaemic potentials of the extracts of rice bran and seed coats of selected beans grown in Malaysia.…”