A-Type Proanthocyanidins from the Stems of Ephedra sinica (Ephedraceae) and Their Antimicrobial Activities

Molecules

Xinyu Zang¹  Mingying Shang¹  Feng Xu¹  Jing Liang¹  Xuan Wang¹  Masayuki Mikage² 

[1] State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Xueyuan Road, Beijing 100191, China;Graduate School of Natural Science & Technology, Kanazawa University; Kakuma-machi, Kanazawa 441-1212, Japan

关键词: Ephedra sinica;    Ephedraceae;    A-type proanthocyanidin;    ephedrannin D₁;    ephedrannin Tr₁;    ephedrannin Te₁;    antimicrobial activities;   

DOI  :  10.3390/molecules18055172

来源: mdpi

【 摘 要 】

Phytochemical investigation of the n-BuOH-soluble fraction of the EtOH extract of the herbaceous stems of Ephedra sinica, which is known as Ephedrae Herba in Traditional Chinese Medicine, led to the isolation and identification of 12 A-type proanthocyanidins, containing five dimers, two trimers and five tetramers [i.e., (+)-epigallocatechin-(2α→O→7,4α→8)-(-)-catechin, named ephedrannin D₁, a dimer; epigallocatechin-(2α→O→7,4α→8)-epigallocatechin-(4α→8)-catechin (ephedrannin Tr₁), a trimer; and epigallocatechin-(2α→O→7,4α→8)-epigallocatechin-(4α→8)-epigallocatechin-(2α→O→7,4α→8)-gallocatechin, named ephedrannin Te₁, a tetramer). Tetramers composed of gallocatechin are reported for the first time in Ephedraceae. Catechin, epicatechin, gallocatechin, epigallocatechin and four known dimers were also isolated. The structures were elucidated by extensive spectroscopic analysis. The absolute configurations of the 4α linkages, which were confirmed by NOESY and CD experiments, are the outstanding characteristic of most of these isolated A-type proanthocyanidins. The antimicrobial activities of these compounds were tested by measuring the minimum inhibitory concentrations (MIC) against bacteria (both Gram positive and Gram negative) and fungi, and were found to be in the range of 0.00515–1.38 mM. Compounds 6, 8, 10 and 11 exhibited moderate antimicrobial activities against Canidia albicans.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.