Monday's Molecule #55 was morphine [(5α,6α) -7,8-didehydro-4,5-epoxy- 17-methylmorphinan-3,6-diol]. Morphine is an opiate. It is the main analgesic in opium. Morphine is generally recognized as the strongest pain killer known.Morphine is derived from the creamy latex found in the seed pods of the opium poppy, Papaver somniferum. It seems likely that the opium poppy is derived from wild poppies that grow in the Mediterranean basin. Selection for plants that produce more and more opium has led to the evolution of a new human-made species.
In addition to morphine, the seed pods contain a number of similar opiates; codeine, noscapine, papaverine and thebaine, that are less potent than morphine. It is not clear why wild poppies contain small amounts of these chemicals. Maybe they help prevent the seed pods from being eaten by some animals?
Although opium was widely used in China, it is almost certain that the opium poppy originated in the Middle East and was only imported into China about 400 AD. Historical records suggest that the ancient Sumerians and Egyptians knew about opium and probably used it as a recreational drug.
In addition to its action as a painkiller, morphine produces a sensation of euphoria and well being. Both effects are due to binding of morphine to specific opiate receptors in the brain. Morphine resembles endorphins, which are released in response to stress, and by binding to some opiate receptors further endorphine released is stimulated.The analgesic effect is due to binding to other opiate receptors that block pain transmission at nerve synapses.
See Brandon's Blog: Poison, Medicine, and Things that Grow for some more information on morphine and opiates. The article Toxic Talk (Ed. 8.1) explains the difference between opiates and opioids. Toxic Talk (Ed. 8.0) has a nice description of morphine showing a different view of the structure than the one shown above.
Pure morphine can be converted to codeine by a simple chemical reaction that adds a methyl group to one of the hydroxyl groups on morphine. Codeine is much less effective as a painkiller than morphine and even less effective at inducing euphoria. It has the benefit of being much less addictive (and legal).Heroin was first manufactured by English chemists in the 1870's. Later on it was manufactured and sold by the Bayer pharmaceutical company. Heroin is easily made by boiling morphine solutions (or opium) with acetic anhydride. This produces an acetylated form of morphine that is much more potent than morphine in all its properties . The enhanced effects are probably due to its increased solubility and more efficient transfer to the brain, where heroin is converted back to morphine. Heroin is more addictive than morphine, although susceptibility to opiate addition varies considerably from person to person.
[Image Credti: The rotating three-dimensional image of morphine is from Wikipedia]
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