Petroleum Research Today is a free monthly online journal that collates and summarizes the latest research about Petroleum, including details on crude oil, extraction, chemistry, pollution. | ||||||||
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Activation of the mu-opiate receptor by Vitex agnus-castus methanol extracts: implication for its use in PMS.Webster DE, Lu J, Chen SN, Farnsworth NR, Wang ZJ Department of Biopharmaceutical Sciences, College of Pharmacy, 833 South Woods Street, Room 335, University of Illinois, Chicago, IL 60612, USA. The dried ripe fruit of Vitex agnus-castus L. (VAC) is widely used for the treatment of premenstrual syndrome (PMS). A previous study reported that extracts of VAC showed affinity to opiate receptors; however, functional activity was not determined. We tested two different VAC extracts in receptor binding and functional assays. Our objectives were: (1) to confirm the opiate affinity; (2) to rule out interference by free fatty acids (FFA); (3) to determine the mode of action of VAC at the mu-opiate receptor. Methanol extracts of VAC were prepared either before (VAC-M1) or after (VAC-M2) extraction with petroleum ether to remove fatty acids. Both extracts showed significant affinities to the mu-opiate receptor, as indicated by the concentration-dependent displacement of [3H]DAMGO binding in Chinese hamster ovary (CHO)-human mu-opiate receptor (hMOR) cells. The IC50 values were estimated to be 159.8 microg/ml (VAC-M1) and 69.5 microg/ml (VAC-M2). Since the defatted extract not only retained, but exhibited a higher affinity (p<0.001), it argued against significant interference by fatty acids. In an assay to determine receptor activation, VAC-M1 and VAC-M2 stimulated [35S]GTPgammaS binding by 41 and 61% (p<0.001), respectively. These results suggested for the first time that VAC acted as an agonist at the mu-opiate receptor, supporting its beneficial action in PMS. Published 29 May 2006 in J Ethnopharmacol, 106(2): 216-21.
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