title: A red clover (Trifolium pratense) phase II clinical extract possesses opiate activity.
abstract: Trifolium pratense (TP) is one of the most common herbs for the relief of menopausal symptoms. Little is known about its mechanisms of action. In this study, we investigated the affinity of TP at the mu- and delta-opiate receptors. We found that a clinically used TP extract bound to the mu-opiate receptor with a high affinity (K(i)=9.7+/-1.6microg/ml). The same extract was also found to have affinity at the delta-opiate receptor with K(i) of 15.9+/-2.4microg/ml. These results for the first time suggest a potential new mechanism of action of TP at the opiate receptors. Given the essential role of the opioid system in regulating temperature, mood, and hormonal levels and actions, this may explain in part the beneficial effect of TP in alleviating menopausal symptoms.
authors.affiliation: Department of Biopharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA.
authors.forename: Hani P
authors.initials: HP
authors.lastname: Nissan
authors.forename: Jian
authors.initials: J
authors.lastname: Lu
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Booth
authors.forename: Henry I
authors.initials: HI
authors.lastname: Yamamura
authors.forename: Norman R
authors.initials: NR
authors.lastname: Farnsworth
authors.forename: Z Jim
authors.initials: ZJ
authors.lastname: Wang
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D017480:Receptors, sigma / Q000378:metabolism*; D029921:Trifolium
chemical_list: D010936:Plant Extracts; D017450:Receptors, Opioid, mu; D017480:Receptors, sigma