Identification of two isomeric meroterpenoid naphthoquinones from Cordia linnaei by liquid chromatography mass spectrometry and liquid chromatography-nuclear magnetic resonance spectroscopy

The structures of two meroterpenoid naphthoquinones have been elucidated in a fraction of the dichloromethane extract from Cordia linnaei Stearn (Bora ginaceae). These naphthoquinones were shown to be closely related structura l isomers not separable by preparative chromatographic methods. High perfor mance liquid chromatography coupled with mass spectrometry and nuclear magn etic resonance (NMR) spectroscopy was used for their structure determinatio n within the mixture. Assignment of proton and carbon signals was achieved by a combination of on-how liquid chromatography-proton NMR, and NMR experi ments on the crude fraction. Copyright (C) 1999 John Wiley & Sons, Ltd.