L-Arginine

Smooth muscle relaxation is an essential component of the male penile erection. This process is mediated by the chemical nitric oxide. Nitric oxide is released into the penis directly by penile nerves and by endothelial cells (lining the interior surface of blood vessels). Vasodilation of the arteries in the penis is required in order to ensure the increased blood flow required for a full erection. Nitric oxide promotes vasodilation by the relaxation of the underlying smooth muscle in arterial blood vessels and in the corpus cavernosum of the penis, thereby permitting the necessary levels of blood  to lead to an erection during sexual stimulation. Arginine is the substrate molecule used by the vascular endothelial cells for the production of nitric oxide. Arginine is the only substrate used by the body for the synthesis of nitric oxide. Without Nitric Oxide, the vascular system is unable to vasodilate, which results in dysfunctional endothelium and poorly functioning cardiovascular system. Dysfunctional endothelium has been associated with hypertension, angina, peripheral vascular disease and erectile dysfunction. By promoting a healthy functioning vascular endothelium, arginine can play an important role in maintaining sexual longevity.

• Increases the production of nitric oxide
• Enhances erectile function
• Improves circulation
• Stimulates release of growth hormone
• Used in the synthesis of creatine, an important intracellular energy shuttle
• Lowers blood pressure
• Protects against atherosclerotic cardiovascular disease
• Improves immune function
• Stimulates wound healing 

 Horny Goat Weed

The active ingredient is icariin which improves erectile function by enhancing cGMP (cyclic guanosine monophosphate) levels, in the cavernous smooth muscle cells of the penis. Icariin does this by inhibiting the action of the PDE5 enzyme, which breaks down cGMP. The compound cGMP is synthesized through the actions of nitric oxide. Icariin also reduces levels of the stress hormone cortisol, which has many negative effects on the body, including those associated with the sexual response.

 Muira Puama

A brazilian herb which is also known as "potency wood". Helps to enhance sexual desire (libido), as well as the ability to initiate and maintain an erection.

 Nettles

Nettles plays two important roles in male sexual health. First, it increases levels of biologically active "free" testosterone. Normally, sex hormone binding globulins (SHBGs) will attach to testosterone, which is then rendered inactive. However, nettles preferentially binds to SHBGs (instead of testosterone), thereby increasing levels of free testsoterone. Secondly, nettles has a vasorelaxation effect in the blood vessels, mediated through endothelial cell nitric oxide release.

 Avena Sativa and Tribulus Terrestris

Traditionally used by many cultures for enhancing sex drive (libido) and for ensuring long duration. 

REFERENCES:

(1) Ghalayini IF.  Nitric oxide-cyclic GMP pathway with some emphasis on cavernosal contractility. Int J Impot Res. 2004 Dec;16(6):459-69.

(2) Toda N, et al.  Nitric oxide and penile erectile function. Pharmacol Ther. 2005 May;106(2):233-66. Epub 2005 Mar 2.

(3) Yetik-Anacak G, et al.  Nitric oxide and the endothelium: history and impact on cardiovascular disease. Vascul Pharmacol. 2006 Nov;45(5):268-76. Epub 2006 Aug 17.

(4) Giles TD.  Aspects of nitric oxide in health and disease: a focus on hypertension and cardiovascular disease. J Clin Hypertens (Greenwich). 2006 Dec;8(12 Suppl 4):2-16.(6) Xin ZC, et al.  Effects of icariin on cGMP-specific PDE5 and cAMP-specific PDE4 activities.  Asian J Androl. 2003 Mar;5(1):15-8.

(5) Jiang Z. et al. Effect of icariin on cyclic GMP levels and on the mRNA expression of cGMP-binding cGMP-specific phosphodiesterase (PDE5) in penile cavernosum. J Huazhong Univ Sci Technolog Med Sci. 2006;26(4):460-2.

(6) Pan Y, et al. Effects of icariin on hypothalamic-pituitary-adrenal axis action and cytokine levels in stressed Sprague-Dawley rats. Biol Pharm Bull. 2006 Dec;29(12):2399-403.

(8) Testai L, et al. Cardiovascular effects of Urtica dioica L. (Urticaceae) roots extracts: in vitro and in vivo pharmacological studies. J Ethnopharmacol. 2002 Jun;81(1):105-9.