Relaxant Effect of Rhynchophylline from the Hooks and Stems of Uncaria sinensis on Penile Corpus Cavernosum Smooth Muscle in a rabbit

The relaxant effect of ethanol extract and its active indole alkaloid, rhynchophylline, from the hooks and stems of Uncaria sinensis was evaluated on penile corpus cavernosum smooth muscle (PCCSM) in a rabbit. The PCCSM relaxations induced by ethanol extract and fractions (1, 2, 3 and 4 mg/ml) were in a concentration-dependent manner and the relaxant effect of ethyl acetate fraction was the most significant. Rhynchophylline also induced PCCSM relaxation in a concentration- dependent manner and significantly enhanced udenafil-induced relaxation. Rhynchophylline relaxed the smooth muscle of rabbit penile corpus cavernosum and it can be an alternative medicine for patients who want natural products to improve penile erection or who do not completely respond to erectile dysfunction-treating medicine.