Natural-born painkiller found in human saliva

Saliva from humans has yielded a natural painkiller up to six times more powerful than morphine, researchers say.
The substance, dubbed opiorphin, may spawn a new generation of natural painkillers that relieve pain as well as morphine but without the addictive and psychological side effects of the traditional drug.
When the researchers injected a pain-inducing chemical into rats’ paws, 1 gram of opiorphin per kilogram of body weight achieved the same painkilling effect as 3 grams of morphine.