15-hydroxy-11-alpha-9-alpha-(epoxymethano)prosta-5-13-dienoic-acid and honokiol

Honokiol is a small-molecule polyphenol isolated from the species Magnolia obovata. We hypothesized that honokiol attenuated vascular contractions through the inhibition of the RhoA/Rho-kinase signalling pathway.. Rat aortic rings were denuded of endothelium, mounted in organ baths, and subjected to contraction or relaxation. Phosphorylation of 20kDa myosin light chains (MLC(20) ), myosin phosphatase targeting subunit 1 (MYPT1) and protein kinase C (PKC)-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase (MLCP) of 17kDa (CPI17) were examined by immunoblot. We also measured the amount of guanosine triphosphate RhoA as a marker for RhoA activation.. Pretreatment with honokiol dose-dependently inhibited the concentration-response curves in response to sodium fluoride (NaF) or thromboxane A(2) agonist U46619. Honokiol decreased the phosphorylation levels of MLC(20) , MYPT1(Thr855) and CPI17(Thr38) as well as the activation of RhoA induced by 8.0mm NaF or 30nm U46619.. These results demonstrated that honokiol attenuated vascular contraction through the inhibition of the RhoA/Rho-kinase signalling pathway.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Aorta; Biphenyl Compounds; Dose-Response Relationship, Drug; Lignans; Magnolia; Male; Muscle Contraction; Muscle, Smooth, Vascular; Myosin Light Chains; Myosin-Light-Chain Phosphatase; Phosphorylation; Plant Extracts; Pyridones; Rats; Rats, Sprague-Dawley; rho-Associated Kinases; rhoA GTP-Binding Protein; Signal Transduction; Sodium Fluoride; Vasoconstriction; Vasodilator Agents