New enantiomeric isoquinoline alkaloids from Coptis chinensis

A pair of new enantiomeric isoquinoline alkaloids, (+)-and (-)-5-hydroxyl-8-oxyberberine (1), along with nine known analogs (2-10) were isolated from the rhizoma of Coptis chinensis. Their structures with absolute configurations were elucidated on the basis of spectroscopic methods, X-ray diffraction analysis, and quantum chemical calculation. The antibacterial activities of 1-10 were also evaluated. Berberine (8) displayed synergism against methicillin-resistant Staphylococcus aureus (MRSA) in combination with ceftazidime and cefepiem. (C) 2013 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.