Polyphenolic Compounds and Antimicrobial Activity of Quercus aucheri Leaves

摘要

Chromatographic studies(CC,VLC,MPLC,and PTLC)on ethyl acetate extract from the leaves of Quercus aucheri yielded 2 flavonoids(quercetin 3-OMICRON-alpha-L-arabinopyranoside(1),quercetin 3-OMICRON-beta-D-galactopyranoside(2))and 2 tannin precursors and a procyanidin [(isolated as peracetates of(+)-catechin(3a),(+)-gallocatechin(4a)and epicatechin-(4beta ->8)-catechin(5a))].The structures of the compounds were elucidated by UV,1D-NMR(~1H,~(13)C,TOCSY)and 2D-NMR(COSY,HSQC,HMBC)techniques.Different extracts(80% MeOH,EtOAc,n-BuOH and H_2O)from the leaves of Q.aucheri were investigated for their antimicrobial activity against 2 Gram-positive and 2 Gram-negative bacteria and 3 yeast-like fungi by a broth microdilution method.EtOAc extract,which showed the highest antimicrobial activity,was further used for isolation.