Erectile dysfunction (ED) or male impotence is defined as inability of a man to achieve or maintain penile erection sufficient for sexual activity. It is primarily a neuronal and endothelial dysfunction of the corpus cavernosum of penile tissue, and is partly characterized by reduced production of nitric oxide (NO). Other factors that may contribute to the pathogenesis of ED include androgen deficiency in aging men, hypertension, high cholesterol levels, atherosclerosis, diabetes mellitus, diseases of the prostate and heart, and anatomical deformity of the penis. ED may also be caused by some medications, prostate surgery and spinal cord injury. Psychological and social conditions such as stress, depression and unhappy marital relationship may contribute to the problem. Chronic infections and inflammation can also contribute to the disease process. ED is linked to an increased risk for cardiovascular diseases and stroke. Several orally active drugs (sildenafil, vardenafil, tadalafil, avanafil) are currently prescribed for treating ED to improve the arterial blood flow to the penile tissue. Medicinal plants and their extracts have been used in traditional medicine in southwest Asia and other countries to treat ED. The current review focuses on four medicinal plants that have been used as aphrodisiacs for enhancing sexual performance and for the treatment of ED. These plants include Eurycoma longifolia Jack (tongkat ali); Chlorophytum borivilianum (safed musli); Withania somnifera (ashwagandha); and Pausinystalia johimbe (formerly known as Corynanthe johimbe). Suggested mechanisms of action for each of the plant extracts will be discussed.
