Noppawat Pengkumsri

Physicochemical and antioxidative properties of black, brown and red rice varieties of northern Thailand

Rice, the seed of Oryza species, is the major cereal crop in most of the developing countries. Nearly 95% of global rice production is done in Asian countries, and about half of the world’s population consumes it. Some speciality rices are not commonly consumed. Colored rice is one of such variety. In these varieties, high amounts of anthocyanin pigment are deposited in the rice coat to form its black (also known as purple), brown and red colors. Minimum studies are there to explain the properties of these rice varieties of Thailand. Thus, the current study was aimed to assess the physicochemical and antioxidative properties of three rice varieties (Chiang Mai Black rice, Mali Red rice and Suphanburi-1 Brown rice) of different cultivars of northern Thailand. Rice bran extracts of these three cultivars were prepared with different solvents (polar and non-polar) for the evaluation of total phytochemical content and anti-oxidant free-radical-scavenging properties. Chiang Mai Black rice contained higher concentration of phenolic acid, flavonoids, and anthocyanins (Cyanidin 3-glucoside, peonidin 3-glucoside, cyanidin chloride). Chiang Mai Black rice is richer in free-radical-scavenging compounds and activities than the other tested varieties. Polar extractions of rice bran are high in anti-oxidative compounds and activities than non-polar extractions.

The influence of extraction methods on composition and antioxidant properties of rice bran oil

The current study was employed to assess the influence of the different extraction methods on total tocols, γ-oryzanol content, and antioxidant properties of Chiang Mai Black rice, Mali Red rice, and Suphanburi-1 Brown rice bran oil. Rice bran oil (RBO) was extracted by Hexane, Hot pressed, Cold pressed, and Supercritical Fluid Extraction (SFe) methods. High yield of RBO was extracted by hexane and SFe methods. Total and subgroups of tocols, and γ-oryzanol content were determined by HPLC. The hexane extracted sample accounts for high content of γ-oryzanol and tocols. Besides, all of RBO extracts contain a significantly high amount of γ-tocotrienol. In vitro antioxidant assay results indicated that superior quality of oil was recovered by hexane extraction. The temperature in the extraction process also affects the value of the oil. Superior quality of oil was recovered by hexane extraction, in terms of phytochemical contents and antioxidant properties compared to other tested extraction methods. Further, thorough study of factors compromising the quality and quantity of RBO recovery is required for the development of enhanced functional foods and other related products.

Germinated Thai Black Rice Extract Protects Experimental Diabetic Rats from Oxidative Stress and Other Diabetes-Related Consequences.

Background: Diabetes mellitus (DM), particularly type 2 DM (T2DM), is one of the most common metabolic disorder worldwide. The prevention measures and treatment strategies for DM are improving steadily. The current study explains the impact of germination on phytochemical content of Thai black rice (BR), and the influence of germinated BR extract (GBRE) supplementation on diabetic conditions in rats. Methods: BR was germinated and the phenolic, anthocyanin, and γ-aminobutyric acid (GABA) content of the extract were analyzed using HPLC and spectrophotometric methods. Streptozotocin-induced diabetic rats were supplemented with high and low doses of GBRE. The plasma glucose, insulin, cholesterol, triglyceride levels, antioxidant status, and antioxidant enzyme levels of treated animals were assessed using ELISA and spectrophotometric methods. Results: Germination enhanced the GABA content of BR, and GBRE intervention improved the total antioxidant capacity and antioxidant enzymes levels in diabetic rats. The plasma glucose, cholesterol, triglyceride levels, insulin resistance and glucose tolerance were reduced, and the degree of insulin secretion in rat plasma was significantly increased upon GBRE treatment. Both pre and post-treatment approaches showed the anti-diabetic ability of GBRE. In most of the analyzed parameters, GBRE was quite equal to the performance of drug-metformin. Conclusions: GBRE supplementation helps prevent and manage the consequences of DM.

Screening and characterization of β-glucosidase production by Saccharomyces cerevisiae -

Beta-Glucosidases (BGS) are, the group of hydrolase enzymes, involved in the degradation processes and many biological processes. Due to demand, intensive screening of BGS is required to explore the natural microbial source of BGS. The current study deals with isolation and identification of BGS producing S. cerevisiae from Thai fruits & beverages and assessment of impact of pH, temperature, and salt concentration on BGS production. About 34 samples were collected. Yeast cells were isolated by plate method and characterized. About ten different strains were isolated and identified. The strain has been confirmed as S. cerevisiae through ribosomal sequencing. The optimization of BGS production was achieved by Box-Behnken design and Response Surface Methodology and confirmed that pH 4.0, temperature at 40 C, and 0.5% of NaCl are optimum conditions. The kinetic analysis suggested that 24 h of incubation achieve the maximum yield. The reported S. cerevisiae strain could be the safer source for BGS. Further studies on enzyme recovery and purification will unbolt the way to attain high-quality microbial enzyme.

Dietary supplementation of Thai black rice bran extract and yeast beta-glucan protects the dextran sodium sulphate mediated colitis induced rat

The present study was employed to evaluate the impact of black rice bran (BRB) extract, and yeast β-glucan (YBG) supplementation on a dextran sodium sulfate (DSS)-induced colitis rat model. Serum level antioxidant enzymes, cytokines, and histopathological changes were studied by spectrophotometric, ELISA, HPLC, and microscopic analysis. The preventive effect of RB + YBG combinational treatment for DSS-induced colitis in rat was greater than that of RB extract and YBG regarding serum antioxidant level. The elevated expression of the studied inflammatory cytokines (IL-6, IL-17, IFN-γ) was effectively more attenuated by RB + YBG combinational treatment than other tested interventions, which was accompanied by an increase in anti-inflammatory cytokines (IL-10, TGF-β). The histological study supported that RB + YBG supplementation improves the health status of DSS-induced colitis rats. The results suggested that the supplementation of RB + YBG was a potent alternative nutrient based therapeutic agent for colitis and to prevent the development of cancer.

Impact of different pre-treatment strategies on the quality of fatty acid composition, tocols content and metabolic syndrome related activities of Perilla frutescens seed oil.

Article history: Received on: 02/11/2015 Revised on: 23/12/2015 Accepted on: 09/01/2016 Available online: 27/02/2016 Perilla frutescens (Nga-Mon) is an annual herbaceous plant, reported for its antioxidant, anti-allergic, antiinflammatory and neuroprotective properties. The current study was conducted to compare the different pretreatment techniques followed by hexane extraction for perilla seed oil and its pharmaceutical values. There are no significant differences in the yield of seed oil after pre-treatments except sonication. All the pre-treatments diminish the endogenous lipase activity, peroxidation and degradation of the oil. Fatty acid content analysis revealed that the nutrient quality, with respect to fatty acid content, of perilla seed was not compromised with any of the pre-treatments of current study. The results of αamylase, αglucosidase and protein glycation inhibition assays suggested that tested perilla seed oils are pharmaceutical candidate for the treatment of carbohydrate related diseases, especially for diabetes. Selection of appropriate pre-treatment strategies will helps to extract the perilla seed oil without any compromise in its quality. The current study suggested that moist heat with pressure can be an appropriate pre-treatment method for perilla seed oil extraction.