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Estrogens and congeners from spent hops (Humulus lupulus)
Lucas R Chadwick1, Dejan Nikolic, Joanna E Burdette
1UIC/NIH Center for Botanical Dietary Supplements Research, Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
Journal of Natural Products
|December 29, 2004
Summary
Researchers identified 22 compounds from spent hops, including new prenylated chalcones and flavanones. The primary estrogen, 8-prenylnaringenin, was found to be an artifact of chalcone isomerization.
Area of Science:
- Phytochemistry
- Natural Products Chemistry
- Organic Chemistry
Background:
- Spent hops (Humulus lupulus) are a byproduct of brewing with potential bioactive compounds.
- Previous extraction with supercritical CO2 yielded a methanol extract for further analysis.
- Estrogenicity is a key property guiding the isolation of compounds from Humulus lupulus.
Purpose of the Study:
- To isolate and identify estrogenic compounds from spent hops.
- To characterize new prenylated chalcones and flavanones.
- To investigate the formation of 8-prenylnaringenin.
Main Methods:
- Estrogenicity-directed fractionation of methanol extract.
- Isolation and purification of 22 compounds.
- Structure elucidation using 1D and 2D NMR, HRESIMS, and ESIMS-MS.
- 1H NMR spin system analyses for complex spectra.
Main Results:
- Identified 12 prenylated chalcones, 5 prenylflavanones, and other constituents.
- Reported three new chalcones and four previously unreported hop constituents.
- Determined that 8-prenylnaringenin and 6-prenylnaringenin are artifacts from chalcone DMX isomerization.
Conclusions:
- Spent hops contain a diverse array of prenylated chalcones and flavanones.
- The primary estrogenic compound 8-prenylnaringenin is an artifact, not a native constituent.
- Understanding compound formation pathways is crucial for accurate natural product analysis.