ABSTRACT
Objective: The objectives of this study were to quantify γ-oryzanol in an ethanolic extract of Oryza sativa L. Indica (black rice) bran and to evaluate its activity as a tyrosinase inhibitor. Methods: Black rice bran was extracted via maceration in 96% ethanol, and the γ-oryzanol concentration in the extract was measured through high-performance liquid chromatography. The applicability of the extract as a skin lightening agent was determined by evaluating its tyrosinase inhibition activity. Results: The dry rice bran contained 118.572 mg/g of γ-oryzanol, and the extract inhibited tyrosinase activity at an IC50 of 74.8%. Conclusion: The black rice bran extract was sufficiently potent for use in skin lightening formulations.
ABSTRACT
Background & objectives: Enhanced muscle strength is seen when resistance exercise is combined with the consumption of nutritional supplements. Although there is a limited number of studies available about the efficacy of gamma oryzanol supplementation with resistance exercise in humans, but its usage as a nutritional supplement for strength is common in athletes. The aim of this study was to determine the effects of gamma oryzanol supplementation during 9-week resistance training on muscular strength and anthropometric measurements of young healthy males. Methods: In this double-blind clinical trial, changes of anthropometric measurements and muscular strength were studied after chronic resistance exercise and gamma oryzanol supplementation in 30 healthy volunteers (16 in supplement and 14 in placebo). Each day, gamma oryzanol supplement (600 mg) and placebo (the same amount of lactose) were consumed after training. The participants exercised with 80 per cent 1-Repetition Maximum (1-RM), for one hour and four days/week. Anthropometric measurements and subjects’ 1-RM for muscular strength were determined at the commencement and end of the 9-week study. Results: There was no significant difference between the baseline characteristics and target variables at baseline between the two groups. After gamma oryzanol supplementation, there was no significant difference in the means of anthropometric and skin fold measurements between the supplement and placebo groups. However, there were significant differences between the supplement and placebo groups for 1-RM of bench press and leg curl, which showed that gamma oryzanol improved muscle strength following resistance training. Interpretation & conclusions: Our findings indicated that 600 mg/day gamma oryzanol supplementation during the 9-week resistance training did not change anthropometric and body measurements, but it increased muscular strength in young healthy males. Further, studies need to be done in trained athletes, women, and in patients who suffer from muscular fatigue.
ABSTRACT
This study was carried out to investigate the supplementary effects of gamma-oryzanol extracted from rice bran on lipid metabolism in diabetic mice. We supplied 2 kinds of experimental diets (CO without and GO with 0.2% gamma-oryzanol) to diabetic mice for 8 weeks. Diet intake, body weight, organ weight, contents of serum and hepatic lipid profiles, and fecal lipid levels were measured. Though there was no significant difference in diet intake, body weight change and organ weight between experimental groups, the concentration of serum total cholesterol and hepatic total lipid, total cholesterol and HMG-CoA reductase activity was significantly lower in GO group treated with 0.2% gamma-oryzanol of diet than CO group after supplementary period of experimental diets. And total lipid, triglyceride, total cholesterol, and bile acid levels excreted to feces were significantly higher in GO group than CO group. These results suggest that gamma-oryzanol decrease the serum and hepatic lipid levels by lowing HMG-CoA reductase activity or increasing the contents of fecal lipid in diabetic KK mice.