The Nitric Oxide Connection

Centuries ago, shamans in Europe recognized the analgesic and anti-inflammatory effects of portions of the willow tree. We now know that the active ingredient from the tree was acetylsalicylic acid, commonly known as aspirin. In areas of the world where willow trees do not grow, other plants became staples for treating pain and inflammation.

In the Pacific rim countries and throughout the pacific islands, the Morinda citrifolia tree, commonly known as noni, served this role. Because research has failed, so far, to detect "aspirin" in the fruit, leaves, or roots of the noni tree, one wonders what other ingredient may be common to these two, very dissimilar trees. A clue may be found in the recent observation that aspirin stimulates an enzyme that produces nitric oxide. In research that began in the early 1990's, nitric oxide was shown to be produced by morphine, a very powerful pain killer. Could noni also stimulate nitric oxide and could nitric oxide be responsible, in part, for the common analgesic (and other) effects of these two dissimilar plants?

Noni is rich in nitrates and nitrites that have been shown to be converted to nitric oxide in presence of acid. Noni, after ingestion, is exposed to acid in the stomach. Even topical application of nitrates and nitrites to the skin exposes them to acid that ultimately generates nitric oxide. Of course, there are likely other phytochemicals in the noni plant that account for its myriad of health benefits.

Nitric oxide has many physiologic effects, the most well studied being its effect to dilate blood vessels; the Nobel Prize in Physiology or Medicine was awarded to three Americans in 1998 for their pioneering research on the cardiovascular benefits of nitric oxide. Dilating blood vessels improves blood flow and oxygen delivery to tissues and more oxygen reduces pain that occurs due to ischemia. In fact, nitroglycerin which is converted to nitric oxide, is often used to increase blood flow to coronary arteries and by this mechanism, chest pain (angina) is minimized.

Although nitric oxide is a very short-lived gas, it quickly activates an enzyme, guanylate cyclase (GC) and the vasodilatory effects of GC last several hours. One can assume the analgesic effect of both aspirin and noni also last several hours after activating GC.