Effects of Aqueous Extract of Unpolished Dark Purple Glutinous Rice, Var Luem Pua, on ROS in SK-N-SH Cells and Scopolamine-induced Memory Deficit in Mice

Purpose: To investigate the antioxidative and memory-enhancing effects of aqueous extract of unpolished Thai rice strain of Luem Pua (LP) in SK-N-SH cells and scopolamine-induced memory deficit in mice.Methods: In SK-N-SH cells, viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay while intracellular reactive oxygen species (ROS) levels were quantified after pretreatment with LP (0, 200, 600 and 1000 μg/mL) in the presence of hydrogen peroxide (H2O2). In mice, memory was impaired by injecting 2 mg/kg/day scopolamine, for 18 consecutive days. On each day, mice were also force-fed with LP 0, 90 or 180 mg/kg. On the last 5 days of treatment, memory was tested using passive avoidance (PA) and Morris water maze (MWM) tests.Results: At concentration up to 1,000 μg/mL LP had no effect on SK-N-SH cell viability and significantly reduce intracellular ROS levels of SK-N-SH cells with or without H2O2. Mice that received 90 or 180 mg/kg LP showed a significant decrease in latency time in PA test and an increase in escape latency time in MWM test. These  data suggest that LP antagonizes the effect of scopolamine on memory.Conclusion: LP extract has anti-oxidative and memory-enhancing effects in cell culture and mice. The rice may be a nutraceutical helpful for promoting brain health. Keywords: Dark purple rice, Leum Pua rice, Reactive oxygen species, Memory, Scopolamine, Cell culture

Quantification of the rice aroma compound, 2-acetyl-1-pyrroline, in uncooked Khao Dawk Mali 105 brown rice

Volatile components of uncooked Khao Dawk Mali 105 brown rice were extracted using indirect steam distillation under reduced pressure and controlled temperature in order to prevent cooking. Analysis of the fresh extract by capillary gas chromatography-mass spectrometry revealed that there were >140 volatile constituents. Among these, 70 volatiles were identified, including 2-acetyl-1-pyrroline (2AP), a key aroma compound of cooked rice. Further study concentrated on an improved method for the quantification of 2AP in uncooked brown rice. The method was simplified by utilizing a solvent extraction procedure. Quantitative analysis was performed using a capillary gas chromatographic system employing a flame ionization detector with the aid of a more selective column, CP-Wax 51, for amines. This improved chromatographic system had remarkable detection sensitivity for 2AP in the rice extracts so that 2AP in an extract of only 0.5 g of uncooked Khao Dawk Mali 105 brown rice could be detected.