Opiorphin in the human saliva.

You may not have realised it, but you currently have extremely powerful and untested pharmaceuticals in your mouth.
In the early 2000's, Scientists discovered that rat saliva contains sialorphin, which is also a powerful pain killer. They then began to wonder if human saliva also contained something of that nature as rats are in many ways analogous to humans.

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Opiorphin which is found in the human saliva has been known to have painkilling effects six times stronger than morphine. Opiorphin works by stopping the normal break up of enkephalins, natural pain killing opiods in the spinal cord. Opiorphin is a relatively simple molecule consisting of a five amino acid polypeptide, Gin-Arg-Phe-Ser-Arg.

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Opiorphin pentapeptide originates from the N-terminal region of the protein PROL1 (proline-rich, lacrimal 1).Opiorphin inhibits three proteases: neutral ecto-endopeptidase (MME), ecto-aminopeptidase N (ANPEP) and perhaps also a dipeptidyl peptidase DPP3. Such action extends the duration of enkephalin effect where the natural pain killers are released physiologically in response to specific potentially painful stimuli, in contrast with administration of narcotics, which floods the entire body and causes many undesirable adverse reactions, including addiction liability and constipation.In addition, opiorphin may exert anti-depressive and antipanic action.

Opiorphin is a potent yet non-addictive analgesic without drug tolerance effects. Therapeutic application of opiorphin in humans would require modifying the molecule to avoid its rapid degradation in the intestine and its poor penetration of blood-brain barrier.

Scientists compared rat reactions on opiorphin and on various quantities of morphine. They made a bed of not so sharp nails and watched the rat attempt to walk on it. It turned out that the rats needed six times more morphine to a dose of opiorphin in order to walk comfortably on the bed of nails.

Why Isn't Opiorphin Used As An Alternative To Morphine And Its Likes?

This is because Opiorphins are easily degraded in the plasma.
Morphine can easily be obtained from plants and easily induces its action by binding to opioid receptors and then it immediately induces analgesia.
Sadly, morphine tolerance happens very often and this calls for using higher doses of morphine which increase its liable side effects

Opiorphin has none of the side effects but because of the fact that it is easily degraded in the human body, its use isn't recommended yet for the clinical setting. Scientists are working hard and researching daily, hoping to find a way to perfectly modify the molecules of Opiorphin in order to harness its great properties as this will help curb all the hectic side effects of narcotics.

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Reference:

Opiorphin

A painkiller six times stronger than morphine

A Natural Pain Killer

Facts about the saliva