Inhibition of rat prostate smooth muscle contractility by extracts of Costus speciosus(crepe ginger)

Background:This study examined the chemistry and biological effects of Costus speciosus(J.Koenig)Sm.(C.speciosus)which has been traditionally used by Sarawak natives to treat urological disorders for centuries.Methods:This study assesses the efficacy of C.speciosus in treating urological disorders by investigating its effects on the contractility of isolated prostate glands since this is the most effective way to relieve lower urinary tract symptoms that accompany benign prostatic hyperplasia.Plants were collected and extracts of C.speciosus rhizome,root,leaf and stem were made using water at different temperatures.Results:C.speciosus rhizome and root decoction(boiling,about 100℃)combination extract(2 mg/mL)inhibited electrical field stimulation-induced neurogenic contractions of isolated rat prostatic gland by 44±8%(p=0.01,n=4);whereas room temperature(about 20℃)rhizome and root combination extract inhibited electrical field stimulation contractions by 62±8%(p=0.003,n=4).C.speciosus rhizome(p=0.0004,n=6),root(p<0.0001,n=6)and stem(p=0.0057,n=6)room temperature extracts inhibited electrical field stimulation-induced contractions of rat prostatic smooth muscle but leaf extract did not(p=0.09,n=6).Contractions mediated by exogenous administration of noradrenaline,acetylcholine,adenosine 5’-triphosphate or tyramine were only weakly inhibited by rhizome extract.Fractions of C.speciosus rhizome room temperature extract separated by preparative high-performance liquid chromatography and evaluated by isolated organ bath bioassay revealed that inhibitory activity of the extract was due to highly polar soluble components present in the extract.Conclusion:C.speciosus extracts exert a direct inhibitory effect on prostate tissue which is likely to be therapeutically beneficial in treating lower urinary tract symptoms associated with benign prostatic hyperplasia.