Background: Spilanthes filicaulis is a tropical herb implicated as a memory enhancer in
Objective: The study investigated acetyl/butyryl cholinesterase inhibitory and antioxidant activities
of different extracts of S. filicaulis whole plant and correlated them to its phytochemical constituents.
Methods: The powdered whole plant was successively extracted with n-hexane, ethyl acetate and
methanol. Acetyl cholinesterase (AChE) and Butyryl cholinesterase (BuChE) inhibitory activity were
evaluated by Ellman colorimetry assay. Antioxidant activity was tested using 1, 1-diphenyl-2-picrylhydrazyl
(DPPH) radical scavenging, ferric reducing power and nitric oxide scavenging assays. Total
phenolic, flavonoid and tannin were estimated using standard methods. Correlation was determined
using Quest Graph™ Regression Calculator.
Results: Various extracts exhibited concentration-dependent AChE and BuChE inhibitory activity
with ethyl acetate extract being the highest with IC50 of 0.77 μg/mL and 0.92 μg/mL for AChE and
BuChE respectively. The ethyl acetate extract also showed the highest reducing power when compared
with the other extracts. The methanol extract had slightly higher phenolic and flavonoid content
and showed the highest DPPH radical scavenging effect. DPPH scavenging, AChE and BuChE
inhibition had high correlation with the total flavonoid content with R2 values of 1.00, 0.800 and
0.992 respectively while nitric oxide scavenging had high correlation with phenolics and tannins with
R2 = 0.942 and 0.806 respectively.
Conclusion: These results show that the extracts of the whole plant of S. filicaulis possess significant
AChE/BuChE inhibitory and antioxidant properties, mostly due to its flavonoid content, suggesting
the possible use of the plant in neurodegenerative diseases such as AD.