Relaxant Activities of Extracts from Uvaria rufa Blume and Caesalpinia sappan L. on Excised Rat’s Prostate Strips

Aims: To determine the relaxant activity of various extracts from the stems of Uraria rufa Blume and Caesalpinia sappan L. on rats’ prostate strips in vitro.

Study Design: The relaxant efficacies of ethyl acetate and ethanolic extracts from the stems of U. rufa (UEA and UEOH) and C. sappan (CEA and CEOH) were tested on isolated rats’ prostate tissue pre-contracted by adrenaline.

Place and Duration of Study: Department of Biology, Faculty of Science, Chiang Mai University, between February and September 2018.

Methodology: A prostate strip was isolated, mounted in an organ bath filled with Krebs-Henseleit solution and induced to contract by adrenaline. The contracted strip was then exposed to each extract at 250 µg/mL for 30 minutes. The tension was recorded. Relaxant efficacies of various extracts were determined in prostate strips pre-contracted by adrenaline at 10 µM. All extracts were also determined for their bioactive components and the contents of total phenolics and total flavonoids.

Results: The results showed that all of the extracts, as well as tamsulosin, a synthetic drug, exhibited relaxant effects (P < 0.001) on prostate smooth muscles. The UEA exhibited the most potency in relaxing the prostate smooth muscle with a maximal effect of 72.09 ± 2.15 %. The half-maximal effective concentration (EC50) values of the UEA, CEOH, UEOH and CEA were 140.23 ± 9.74, 226.35 ± 7.16, 235.35 ± 24.96 and 236.24 ± 5.05 µg/ml respectively, while tamsulosin was 86.83 ± 8.96 µg/ml. All extracts contained flavonoids, phenolics, sterols, tannins, phlobatannins, terpenoids, cardiac glycosides, alkaloids and reducing sugars. The highest contents of phenolics and flavonoids were found in CEOH and CEA respectively.

Conclusion: We concluded that the ethyl acetate from the stems of U. rufa was the most potent in relaxing the prostate smooth muscles, and it may be useful to relieve the urological symptoms caused by benign prostatic hyperplasia (BPH).