title: Synthesis and antimicrobial activity of 9-o-substituted palmatine derivatives.
abstract: A series of new palmatine derivatives with alkyl or alkyl with N-heterocyclic structures were designed and synthesized at C-9-O according to the principle of association. These compounds were characterised by (1)H NMR, (13)C NMR, ESI-MS and elemental analysis, and tested for their antimicrobial activity in vitro to evaluate structure-activity relationships. The results indicated that 9-O-substituted palmatine derivatives exhibit varying degrees of antimicrobial activity. Antibacterial activities of compounds (3a-f) against Gram +ve bacteria increased 2- to 64-fold than that of palmatine. The compounds (3a-f) possessed relatively weaker inhibitory effects against Gram -ve bacteria and fungi than that against Gram +ve bacteria. Antimicrobial activities of compounds (5a-e) are lower than that of compounds (3a-f). Compound 3d showed the highest antimicrobial activity of all the compounds. The LD50 values of compounds (3a-f) decreased as the alkyl side chain was elongated. Compound 3f showed least toxicity.
authors.affiliation: Chemistry and Chemical Engineering School, Henan University of Technology, Zhengzhou 450001, Henan, P. R. China.
authors.forename: Z C
authors.initials: ZC
authors.lastname: Li
authors.affiliation: Chemistry and Chemical Engineering School, Henan University of Technology, Zhengzhou 450001, Henan, P. R. China.
authors.forename: X B
authors.initials: XB
authors.lastname: Kong
authors.affiliation: Chemistry and Chemical Engineering School, Henan University of Technology, Zhengzhou 450001, Henan, P. R. China.
authors.forename: W P
authors.initials: WP
authors.lastname: Mai
authors.affiliation: Chemistry and Chemical Engineering School, Henan University of Technology, Zhengzhou 450001, Henan, P. R. China.
authors.forename: G C
authors.initials: GC
authors.lastname: Sun
authors.affiliation: Chemistry and Chemical Engineering School, Henan University of Technology, Zhengzhou 450001, Henan, P. R. China.
authors.forename: S Z
authors.initials: SZ
authors.lastname: Zhao
keywords: 9-O-substituted palmatine derivatives; antimicrobial activity; structure-activity relationships; synthesis; toxicity