Comparative study of the nootropic activity of the aqueous and methanolic extracts of onion and medharasayana

Nootropics are agents that enhance cognition and memory and are alleged to work by increasing the levels of neurochemicals in the brain, especially cholinergic transmission or by neutralizing free radicals. Onion (Allium cepa L.) is a known traditional medicina l plant that has been consumed for its putative nutritional and health benefits for centuries. Onion is a rich source of several phytonutrients such as thiosulphinate, vola tile sulfur compounds and ma ny polar components of phenolic origin. The present study was aimed to evaluate the cognitive and memory enhancing effect of aqueous as well as methanolic extract of onion bulb on mice. The effects were also compared with some commercially available memory enhancer supplements. The evaluation parameter, transfer latency, showed significant (p<0.01) change in methanolic extract when compared with the aqueous extract. Whole brain acetyl cholinesterase enzyme activity was studied which indicated that the methanolic extract of onion may be useful as a memory enhancer. The rich storehouse of antioxidants in the form of flavonoids and its ability to improve the cholinergic transmission may be attributed to the nootropic activity of onion extracts.