Screening for Rho-kinase 2 inhibitory potential of Indian medicinal plants used in management of erectile dysfunction

The aim of the study: Activation of Rho-kinase 2 (ROCK-II) results in contraction of corpus cavernosum smooth muscle and ROCK-II inhibitors relax corpus cavernosum in vitro and in vivo hence, plant extracts capable of inhibiting ROCK-II enzyme may be useful in management of erectile dysfunction (ED). The aim of the study was to screen selected Indian medicinal plants, having similar ethnopharmacological use for ROCK-II inhibition. Materials and methods: Some Indian medicinal plants reported as aphrodisiacs in Ayurveda and modern scientific literature were collected, authenticated and extracted. Direct methanol and successive aqueous extracts of these plants were screened for ROCK-II inhibitory activity using HTRF (R) KinEASE (TM) STK S2 Kit (Cisbio Bioassays). Relaxant effect of potent extract was recorded on isolated rat corpus cavernosum. Results: Methanolic and successive aqueous extracts of 30 plants were screened for ROCK-II inhibition and 15 herbal extracts showed inhibition ranging between 50 and 88% at 50 mu g/mL. While IC50 of Y-27632, a standard ROCK-II inhibitor, was found to be 163.8 +/- 1.2 nM. The Methanolic extract of Terminalia chebula (METC) with IC50 value of 6.09 +/- 0.17 mu g/mL was found to be most potent and relaxed isolated rat corpus cavernosum significantly (p<0.01). Chebulagic and chebulinic acid of METC were found to inhibit ROCK-II and might be responsible for the inhibitory potential of the extract. The traditional use of plants like Butea frondosa, Syzygium aromaticum, Butea superba, Chlorophytum borivilianum and Mucuna pruriens, as aphrodisiacs and for male sexual disorder (MSD) might be in part due to the ROCK II inhibitory potential of these plants. Conclusion: Some of the Indian medicinal plants have ROCK-II inhibitory potential and those deserve further investigation. (C) 2012 Elsevier Ireland Ltd. All rights reserved.