Ralationships Between Structure And Antibacterial Activity Of Neochamaejasmine B Ⅱ

The pop field in natural product research and exploiture is mainly about searching and filtrating active materials from natural product, meanwhile, using the monomer compound which has good activity as the template and study on systemic structure rebuild and modification, then its SAR. Neochamaejasmine B, a biflavonoid possessing a C₃/C₃'' linkage which was separated from the root of Stellera chamaejasme L. had the broad-spectrum strong antibacterial activity. It was also viewed as an natural active leadind compound which had high potential value of exploitation. In order to futher know about the relationships between structure and antibacterial activity of neochamaejasmine B, a series of derivatives were synthesized by use of selectively chemical modification method. Through determination and evaluation of antibacterial activity of all derivatives, the relationship between functional groups and antibacterial activity of neochamaejasmine B was disclosed.The methylate derivatives of Compounds (A₁, A_2-1, E₃, E₁, E₄, M₃ and C_3-1) were prepared obtained from neochamaejasmine B by use of Me₂SO₄ as the methylation reagent.The single carbonyl reduction derivative (D₃) was prepared by use of NaBH₄ as the reductant. Based on the analysis of their spectral data (ESI-MS, ¹H NMR, ¹³C NMR), the seven derivatives were identified as (±)- 7,7'' -dimethoxy- 4',4''',5,5''–tetrahydroxy -3,3''-bi- flavanone (A₁); 7''-methoxy-7,4',4''',5,5''-pentahydroxy-3,3''-biflavanone (A_2-1); 7,7'',4'–trime- thoxy-4''',5,5''-trihydroxy-3,3''-biflavanone and 7,7'',4'''-trimethoxy-4',5,5''-trihydroxy-3,3''- biflavanone (1 : 2) (E₁); 7,7''-dimethoxy-4',4''',5,5''-tetrahydroxy-3,3''-biflavanone (E₃); 7,7'',4',4'''–tetramethoxy-5,5''-dihydroxy-3,3''-biflavanone (E4); (±)-neochamaejasmine B (M₃); 4-dihydroneochamaejasmine B (D₃); 4'-methoxy-7,7'',4''',5,5''–pentahydroxy-3,3'' -biflavanone or 4'''-methoxy-7,7'',4',5,5''–pentahydroxy-3,3''-biflavanone (C_3-1).The antibacterial activity of neochamaejasmine B and its seven derivatives, penicillin Na and Ceftriaxone Sodium were tested with dish diffusion of Neo-Sensitab in vitro against S. aureas, S.agalactiae, E. coli and Samonellal. Analysising the relationship between structure and antibacterial activity of neochamaejasmine B, it was concluded that 7-OH and 7''-OH of neochamaejasmine B were the main active groups, and that 4'-OH and 4'''-OH were the secondary active groups. When 4'-OH or 4'''-OH was methylated, the antibacterial activity of 7,7''-dimethoxy neochamaejasmine B became stronger for Samonellal. 5-OH and 5''-OH were nonactive groups. Phenolic hydroxyl at different positions had great effect on the selectivity of neochamaejasmin B. The configuration of chiral carbon atom of neochamaejasmine B had less contribution to its antibacterial activity, and that carbonyl group was not the main active group.