Evaluation of Antioxidant and Acteylcholinesterase-inhibitory Properties of Methanol Extracts of Nauclealatifolia, Cymbopogon citratus and Cocos nucifera: An In vitro Study

Aims: To evaluate the in vitro antioxidant and acetylcholinesterase (AChE)-inhibitory potentials of methanol extracts of Nauclea latifolia (NL), Cymbopogon citratus (CC) and Cocos nucifera (CN).
Study Design/Methodologies: The antioxidant and AChE- inhibition activities were evaluated using standard in vitro methods viz; DPPH (2,2-diphenyl-1-picrylhydrazine), nitric oxide (NO.), hydroxyl radical (OH.) and hydrogen peroxide (H2O2) radical scavenging assays as well as reducing power, Fe2+/ascorbate-induced lipid peroxidation (LPO) and AChE inhibition assays.
Place and Duration of the Study: The study and analyses were carried out at the Department of Biochemistry, University of Ibadan between March and June 2012.
Results: Extract of NL has the highesttotal phenol and flavonoids contents. The antioxidant activities of the extracts followed the order; CN> NL> CC. Based on DPPH radical scavenging, extract of CN was the most effective. The DPPH scavenging potential of CN, NL and CC were 88%, 82% and 76%, respectively relative to catechin (standard) (91%). The IC50 for the scavenging of hydroxyl radicals by CN, CC and NL were 145.3, 148.8 and 162.3 μg/mL, respectively while catechin is 178.6μg/mL. The reducing powers of CN and NL were statistically similar to catechin. At100 μg/mL, extracts of CN, CC and NL inhibited hepatic LPO by 41%, 22% and 29% respectively. Importantly, extract of CN significantly (p<0.05) inhibited brain LPO and promotes NO. scavenging by 48% and 23%, respectively. Also, CN at 250 and 500 μg/mL significantly (p<0.05) inhibited AChE activities by 33% and 75%, respectively.
Conclusion: CC, NL and CN exhibited strong antioxidant activities but only CN has significant AChE-inhibitory potential.