Acetylcholinesterase Inhibitors from Croton sylvaticus Ethyl Acetate Leaf Extract and their Mutagenic Effects

Abstract

Croton sylvaticus is a medicinal plant widely employed in the management of inflammatory conditions, infections and oxidative stress related diseases such as insomnia, abdominal and internal inflammations. The activities demonstrated by the plant extracts support that its constituents possess the ability to reduce oxidative damage to body cells. Repeated column fractionation of the ethyl acetate fraction of a 20% aqueous methanol leaf extract using acetylcholinesterase (AChE) activity directed on Sephadex LH-20 afforded three compounds identified by mass spectrometry, and 1D and 2D NMR spectroscopy as: 2′-(3″,4″-dihydroxyphenyl)-ethyl-4-hydroxybenzoate (1), 3, 3′, 4′, 5, 7-pentahydroxyflavone (quercetin) (2), and 3, 4′, 5, 7-tetrahydroxyflavone (kaempferol) (3). These compounds are reported from the leaf extracts of C. sylvaticus for the first time and compound 1 is a new natural product. The microplate technique was used to determine the inhibitory effects of the plant extracts (crude and solvent fractions) and isolated compounds against AChE. The IC50 values of the compounds ranged from 60.7 to 415.0 μg/mL, with compound 2 having the best inhibitory activity; the IC50 values of the plant crude extract and solvent fractions ranged from 235.0 to 4695.0 μg/mL. The ethyl acetate fraction had the best inhibitory activity (IC50=235.0 μg/mL). The three compounds showed no mutagenic effects against Salmonella typhimurium tester strains TA98 and TA100. The activity demonstrated by these compounds suggests that they could be effective in the management of neurodegenerative disorders.