Separation and preparation of xanthochymol and guttiferone E by high performance liquid chromatography and high speed counter-current chromatography combined with silver nitrate coordination reaction

- π bond isomers xanthochymol and guttiferone E were well separated by HPLC.
- Pre-treated with AgNO3 solution, the isomers were separately isolated by HSCCC.
- Guttiferone E was eluted before xanthochymol (terminal π bond) in AgNO3-HSCCC.

Xanthochymol (XCM) and guttiferone E (GFE), a pair of π bond benzophenone isomers from Garcinia xanthochymus, were once reported to be difficult or impossible to separate. The present study reports the successful separation of these two isomers through high performance liquid chromatography (HPLC), as well as their effective isolation using high speed counter-current chromatography (HSCCC) based on the silver nitrate (AgNO3) coordination reaction. First, an effective HPLC separation system was developed, achieving a successful baseline separation with resolution of 2.0. Based on the partition coefficient (K) resolved by HPLC, the two-phase solvent system was determined as n-hexane, methanol and water with the uncommon volume ratio of 4:6:1. A crude extract of Garcinia xanthochymus (0.2 g) was purified by normal HSCCC and refined with AgNO3-HSCCC. Monomers of XCM and GFE were identified by HPLC, mass spectrometry (MS) and nuclear magnetic resonance (NMR). The results demonstrate the separation and isolation of π bond benzophenone isomers using ordinary octadecyl silane (C18) columns and HSCCC.