Hydrogen sulfide (H2S) is a colorless, poisonousness, flammable gas with the characteristic foul odor of rotten eggs. A few breath of air containing high levels H2S can cause death, while lower long-term exposure can cause eye irritation, headache, and fatigue.

The human body produces small amounts of hydrogen sulfide and uses it as signaling molecule. It has a variety of physiological effects. For instance, it relaxes the vascular endothelium and smooth muscle cells, which is important to maintaining clean arteries as one ages. It is an important signaling molecule because of its significant effects on the cardiovascular and nervous systems.

Hydrogen sulfide appears to slow aging by inhibiting free-radical reactions via the activation of SIRT1 and probably through its Interactions with Klotho.

Klotho seems to be upregulated by hydrogen sulfide and extends lifespan via a number of different pathways, some of which promote production of endogenous antioxidants.

H2S produced in the kidneys has direct angiotension-converting enzyme (ACE) inhibiting activity. It is therefore an ACE inhibitor, just like certain drugs that mitigate high blood pressure.

Plasma hydrogen sulfide declines with age and is lower in spontaneously hypertensive rats. A lack of hydrogen peroxide is in general implicated in cardiovascular disease. Declining hydrogen sulfide levels also underline neurological health. Endogenous hydrogen sulfide is lower in animal model of Parkinson disease and depressed in the brains of patients with Alzheimer's disease. Hydrogen sulfide may also protective in animal models as well as humans against cancer [23297346].