Unpolished thai purple sticky rice (variety Luem Phua) aqueous extract antagonizing scopolamine-induced dementia in mice

Purple or black rice is one of the good sources of anthocyanins, a group of antioxidant polyphenols. In this study an aqueous extract of purple sticky rice variety Luem Phua (RE) was tested for the antagonistic effect against scopolamine-induced amnesia in mice using passive avoidance test.

Mice were fed with water or RE, 2.5 or 5g/kg and subcutaneously injected with water or 0.5mg/kg scopolamine, and received electrical foot shock in passive avoidance apparatus. Latency time was determined as a training trial followed by 4 test trials on 4 consecutive days. On the test day 1 and 2, a significant increasing in latency time could be observed in mice treated with 5g/kg RE when compared to the control. The latency time of the animals treated with 0.5mg/kg scopolamine was significantly seen on test day 3 and 4. Pretreatment with either 2.5 or 5mg/kg RE could ameliorate the scopolamine-induced memory deficit as the latency times were significantly longer when compared to the scopolamine-treated group on the test day 3 and 4. The results showed that the aqueous extract of unpolished Thai Luem Phua rice could enhance memory in mice, thus, this special rice might be potentially useful as dietary supplement.