Effect of Tianma Gouteng Decoction with subtractive ingredients and its active constituents on memory acquisition.

Accumulating evidence indicates that the high blood pressure (BP) is a potent risk factor for dementia in the elderly. In line with this theory, we had found the mixture of Chinese herbs (TGD) which were traditionally used to treat hypertension, could enhance the cognitive function. The aim of this study was to decrease the number of herbs used from 11 (TGD) to 4 herbs (TGDS) and further to search the active constituents. After administering a dose of 10 g/kg of TGDS0 to ICR mice, no cholinergic symptoms of lacrimation, salivation, emesis, eyeclosure, increased respiration and fibrillation were observed. All the mice survived without any deaths after 24 hours and 7 days. No changes were observed in control and experimental groups on locomotor activity (no stimulant or sedative effects). It was also revealed that TGDS could prolong the step-through latency at the dose of 1.0 and 2.5 g/kg on passive avoidance tasks in mice. This result was the same as the previous study. The active constituents which enhanced the memory acquisition were discovered in the butanol layer and ethyl acetate layer after the extraction.