Chemical and biological investigations of Albizia chinensis (Osbeck.) Merr

A total of five compounds,namely lupeol (1),α-amyrin (2),stigmasterol (3),β-sitosterol (4) and 7,3'-dimethoxyluteolin (5) were isolated from a methanol extract of albizia chinensis stem bark. the structures of the isolated compounds were established using nuclear magnetic resonance (nmr) spectroscopic studies,as well as using comparative thin layer chromatography (co-tlc) with standards. the methanol extract of the a. chinensis stem bark and its n-hexane-,carbon tetrachloride-,chloroform- and aqueous-soluble partitionates were evaluated for antioxidant activity with 1,1-diphenyl-2-picrylhydrazyl (dpph),folin-ciocalteu reagent and phosphomolybdenum total antioxidant assays,where butylated hydroxytoluene (bht) and ascorbic acid were used as standards. the carbon tetrachloride-soluble fraction contained a moderate amount of phenolic compounds (60.76 ± 0.45 mg of gae/g of extract) and it exhibited significant free radical-scavenging activity (ic50 10.21 ± 0.84 μg ml-1). a positive correlation was observed between the total phenolic content and the total antioxidant capacity of a. chinensis. the general toxicity was determined using a brine shrimp lethality bioassay,where the carbon tetrachloride (lc50 0.608 ± 0.19 μg ml-1) and hexane (lc50 0.785 ± 0.26 μg ml-1) soluble partitionates had considerable bioactive properties. the crude extract and its chloroform- and aqueous-soluble fractions displayed significant antimicrobial activity against eighteen microorganisms with inhibition zones ranging from 7.0 mm to 26.0 mm.