Effects of a Proprietary StandardizedOrthosiphon stamineusEthanolic Leaf Extract on Enhancing Memory in Sprague Dawley Rats Possibly via Blockade of Adenosine A2AReceptors

摘要

The aim of the study was to explore a propriety standardized ethanolic extract from leaves ofOrthosiphon stamineusBenth in improving impairments in short-term social memoryin vivo,possibly via blockade of adenosine A2Areceptors (A2AR). The ethanolic extract ofO. stamineusleaves showed significantin vitrobinding activity of A2AR with 74% inhibition at 150 μg/ml and significant A2AR antagonist activity with 98% inhibition at 300 μg/mL. A significant adenosine A1receptor (A1R) antagonist activity with 100%inhibition was observed at 300 μg/mL. Its effect on learning and memory was assessed via social recognition task using Sprague Dawley rats whereby the ethanolic extract ofO. stamineusshowed significant (p<0.001) change in recognition index (RI) at 300 mg/kg and 600 mg/kg p.o and 120 mg/kg i.p., respectively, compared to the vehicle control. In comparison, the ethanolic extract ofPolygonum minusaerial parts showed small change in inflexion; however, it remained insignificant in RI at 200 mg/kg p.o. Our findings suggest that the ethanolic extract ofO. stamineusleaves improves memory by reversing age-related deficits in short-term social memory and the possible involvement of adenosine A1and adenosine A2Aas a target bioactivity site in the restoration of memory.