ABSTRACT: Quinine is a bitter compound from the bark of cinchona tree commonly found in tropical regions of the world and is a widely used antimalarial drug with neuromodulatory effect that is not fully understood nor defined. Hence this study sought to investigate the effect of quinine on cholinesterase (acetylcholinesterase and butyrylcholinesterase), monoamine oxidase, E-NTPDase and Na+/K+-ATPase in rat brain homogenates in vitro. The results revealed that quinine exerted inhibitory effects on acetylcholinesterase, butyrylcholinesterase, monoamine oxidase, and Na+/K+ ATPase activities in a concentration-dependent manner (0 – 13 μM) with IC50 values of 382.3 nM, 17.1 nM, 125.8 nM and 483.3 nM respectively. However, quinine stimulated E-NTPDase activity in a concentration dependent pattern with an IC50 value of 8.2 nM. The observed alteration in the activities of these critical enzymes involved in neurotransmission and/or neuromodulation could be partly responsible for some neurochemical side effect of quinine. However, further molecular studies in experimental animals are necessary to validate this observed alterations.
Keywords: Quinine; alkaloids; cinchona; neuromodulation; neurotransmission
JoST. 2021. 11(2): 1-9
Accepted for Publication, September 16, 2021
