CCC Sample Cutting for Isolation of Prenylated Phenolics from Hops

Abstract

One of the most potent estrogenic substances from the plant kingdom is the prenylated flavanone, 8‐prenylnaringenin (8PN), present in hops (Humulus lupulus L., Cannabaceae) in low (<10 ppm) concentrations. The prenylated chalcone desmethylxanthohumol (DMX), which is also present in this plant material, serves as a precursor to 8PN. A method for the preparative isolation of these and related bioactive phytochemicals has been developed that involves the use of multiple chromatographic techniques including complementary countercurrent chromatography (CCC) solvent systems. This paper describes the isolation of 8PN and DMX employing “sample‐cutting CCC”. The Hexanes‐EtOAc‐MeOH‐H₂O (HEMWat) solvent systems found to be effective for isolation of prenylated phenolics from hops range from HEMWat 8‐2‐8‐2 for diprenylxanthohumol and 6,8‐diprenylnaringenin, to HEMWat 6‐4‐6‐4 for xanthohumol (XH), 6PN and 8PN, to HEMWat 5‐5‐5‐5 for DMX, hydroxylated derivatives of XH, and humulinones.

Keywords:

• Sample cutting
• Prenylated phenolics
• Isolation
• CCC
• Hops

Acknowledgments

The authors gratefully acknowledge Mr. Jim Boyd from Yakima Chief, Inc. (Sunnyside, WA, www.yakimachief.com) for providing the plant material used in this investigation. We also thank the National Center for Complementary and Alternative Medicine, the Office of Dietary Supplements, the Office of Research on Women's Health, and the National Institute of General Medical Sciences (NIH grant P50 AT00155), for funding this work. Furthermore, we are indebted to the late Dr. E. Chou, Baltimore, for his expert CCC support.