New antioxidant and cholinesterase inhibitory constituents from Lonicera quinquelocularis

A phytochemical investigation on the ethyl acetate soluble fraction of Lonicera quinquelocularis (whole plant) led to the isolation of three new and two known compounds. The crude extract and the various soluble fractions were screened for cytotoxic activities. The ethyl acetate soluble fraction was found to be more cytotoxic. The chloroform soluble fraction showed moderate activity while the other fractions and crude extract were weakly cytotoxic. The isolated compounds were tested for antioxidant, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Almost all the compounds showed profound antioxidant activities in DPPH free radical scavenging assay. The 50% inhibitory effect (IC50) values  of compounds 3 and 5 against AChE were determined to be 1.65 and 3.43 μM, while the values obtained against BChE were 5.98 and 9.84 μM, respectively. Compounds 2 and 4 showed weak inhibition profile. Key words: Lonicera quinquelocularis, phthalates and benzoates, cholinesterase inhibition, antioxidant activity.