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

Abstract

© Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria. All rights reserved. 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.