In Vitro Antioxidant and Acetylcholinesterase Inhibitory Activities of Fractions from Centella asiatica (Linn.) Extract

Background: Alzheimer disease is a neurological disease related to age which is characteristic of excess of oxidative stress and deficit level of acetylcholine in the brain. Centella asiatica (Linn.) have several beneficial pharmacological activities such as antioxidant, anti-inflammatory and memory enhancing activities. Objective: To evaluate the phenolic contents, antioxidant and AChE inhibitory activities of different fractions of Centella asiatica grown in Vietnam. Methods: The leaves of Centella asiatica were extracted with ethanol 96% and fractionated with nhexane, ethyl acetate and butanol solvents. These fractions were investigated the antioxidant activity by DPPH assay and acetylcholinesterase (AChE) inhibitory activity by Ellman's colorimetric method. Results: Our results showed that the total phenolic content of BuOH fraction was the highest, being equivalent to 68.4 ± 2.4 mg quercetin/g of fraction. Our data also demonstrated that BuOH fraction had the strongest antioxidant activity with IC50 of 7.76 ± 0.74 μg/mL and AChE inhibitory activity with an IC50 value of 36.31 ± 2.45 μg/mL in a concentration-dependent manner, followed by EtOAc fraction and nhexane fraction with the weakest activity. Kinetic inhibition analysis indicated BuOH fraction of mixed inhibition type with Ki (representing the affinity of the enzyme and inhibitor) of 34.36 ± 2.34 μg/mL. Conclusion: Our data suggest that the BuOH fraction of Centella asiatica may be a promising source of AChE inhibitors for Alzheimer's disease.