Epimedium extract (Horny Goat Weed) (11), (Figure 9): the Chinese refer to this herb as ‘yin yang huo’, which has been loosely translated as ‘licentious goat plant’; hence, its common name is well known as ‘horny goat weed’ by many Western cultures. Scientifically, studies have shown that Epimedium may restore low levels of both testosterone and thyroid hormone, bringing low levels back to their normal levels (5), which may account for some of its benefits in improving sexual libido. Other benefits to Epimedium involve increased muscle mass. Used for fatigue and aging, And vasodilatation effect; thus, most frequently used in treatment of sexual dysfunction in Traditional Chinese Medicine (12). The active substance from horny goat weed was reported by Xin Zhong Cheng at Beijing Medical University as Icarin—acts by increasing sexual activities and ICP levels in castrated rats after long term oral administration. It has no effects on serum testosterone level in castrated rats after long term oral administration. Instead Icariin increases nNOS and iNOS mRNA and protein expression in the corpus cavernosum after long term oral administration and hence may have long term efficacy on erectile dysfunction after oral administration.

Muira puama (Ptychopetalum olacoides): although used in Asia, this potency wood is actually the best known Amazonian folk medicine which increases libido and penile hardness. It acts as a nerve stimulant to heighten receptiveness to sexual stimuli as well as physical sensation of sex (9). Rich in sterols e.g., sitosterol, campesterol and lupol it activates the body’s receptors for hormones like testosterone to heighten libido and enhance performance (5). Also present are volatile oils like champor which helps restore sex drive and inner depth of libido and mental ability to be aroused.

The Plant: It’s true, the name’s hilarious. But as it turns out, it’s not just one plant: supplement manufacturers might put any one of 15 different species from this genus of shade-loving perennials inside that pill. That’s important to keep in mind, because the types and amounts of biologically active molecules the plant contains can differ from species to species.
Yohimbe. Before Viagra and the other prescription erectile dysfunction drugs became available, doctors sometimes prescribed a derivative of the herb yohimbe (yohimbine hydrochloride) to their patients suffering from ED. But experts say the medication is not particularly effective, and it can cause jitteriness and other problems. "It's not a great drug," says McCullough. "And I suspect the herb is not as potent as the pharmaceutical version." What's more, evidence shows that yohimbe is associated with high blood pressure, anxiety, headache, and other health problems. Experts discourage its use.

Currently, there are four orally active drugs are available to treat ED. These include: sildenafil citrate (Viagra [Pfizer, USA]), vardenafil hydrochloride (Levitra [Bayer, Germany]), tadalafil (Cialis [Eli Lilly, USA]) and avanafil (Stendra, Spedra [Vivus Inc, USA]). These drugs inhibit the enzyme phosphodiesterase type 5 (PDE-5), which is responsible for the hydrolysis of cGMP. PDE-5 inhibitors and cGMP act as effectors of dilation of smooth muscle of cavernosal bodies. PDE-5 inhibitors are contraindicated in patients taking any kind of nitrate therapy for angina, and may not be appropriate for men with certain health conditions, such as severe heart disease, heart failure, history of stroke or heart attack, uncontrolled high blood pressure or diabetes, and patients with pigmental retinopathy. PDE-5 inhibitors are less effective in men with diabetes and men who have been treated for prostate cancer. PDE-5 inhibitors are also not effective in men with retinitis pigmentosa, a genetic disease involving PDE-5 deficiency. The common side effects of PDE-5 inhibitors include gastrointestinal upset, headache, nasal congestion, back pain and dizziness. The PDE-5 inhibitors may interact with other medications including antihypertension drugs. Nonetheless, the PDE-5 inhibitors are generally safe and effective for most men. The primary mechanism of action of these drugs is through the mediation of NO. NO is one of the key molecules involved in ED. It is a short-lived, highly permeable, pleiotropic, gaseous molecule, secreted from the postganglionic cavernosal parasympathetic nerves, endothelium of the cavernosal blood vessels, platelets in the cavernosal sinuses and phagocytic cells (monocytes, macrophages and neutrophils). NO acts on platelets to inhibit platelets adhesion and aggregation. NO causes relaxation of the smooth muscle of the cavernosal blood vessels of the penis, leading to vasodilation, tumescence and stimulation. Release of NO in the corpus cavernosum of the penis during stimulation activates the enzyme guanylate cyclase, which results in increased levels of cGMP, producing smooth muscle relaxation in the corpus cavernosum and resulting in increased blood flow (5). NO is mainly produced from cavernosal nerves, which are nonadrenergic, noncholinergic nerves within the penis, and acting via its second messenger cGMP. It has been suggested that maintaining normal body weight and mild exercise, as well as dietary supplementation of folic acid, zinc, calcium, vitamin C, vitamin E and L-arginine, a precursor of NO, can support the biochemical pathway leading to NO release [6]. NO is an effector molecule that is involved in a number of intracellular functions such as vasorelaxation, endothelial regeneration, inhibition of leukocyte chemotaxis and platelet adhesion [7]. A small proportion of autonomic nerves do not release either Ach or norepinephrine [8]. For example, the cavernous nerves predominantly release NO in the penis. The exact mechanism is not known, but it is believed to be through increased intracellular calcium. Another gaseous molecule produced in the corpora cavernosa is hydrogen sulphide (H2S), which is also known to be involved in erectile function [9]. H2S activates ATP-sensitive potassium channels in smooth muscle cells. Some reports indicate that NO acts in large vessels and H2S in small vessels. A high level of tumour necrosis factor-alpha has been shown in ED patients [10]. Although current ED therapies using PDE-5 inhibitors are safe and effective, approximately 40% of ED patients do not respond to currently available treatment [11,12]. For these patients, herbal therapy may be useful.
Erectile dysfunction (ED) is commonly called impotence. It’s a condition in which a man can’t achieve or maintain an erection during sexual performance. Symptoms may also include reduced sexual desire or libido. Your doctor is likely to diagnose you with ED if the condition lasts for more than a few weeks or months. ED affects as many as 30 million men in the United States.