OPIATES from the Poppy                                 [home]   [topic page]

The poppy (Papaver somniferum) was grown for the opium, the latex or dried sap of the seed head and stalk, which contains a mixture of closely related alkaloids. It originates from the Balkans, Turkey and what is now Iran and Iraq. Over the centuries, however, it has been taken extensively into the Far East including India, Northern Burma and Thailand and China.

The alkaloids are now extracted from dried poppyheads and stalks ( poppy straw ) using ethanol and water. This technique was developed by the Hungarian, Janos Kabay, in the 1920-30s period. The alkaloids are then extracted by precipitation processes.

Two poppy forms are grown in Tasmania.

Those closest to the original wild poppy of the Balkans and the Middle East are grown for the production of MORPHINE ( C₁₇H₁₉NO₃ ), one of the components of opium. Approximately 10% by weight of opium ( but only about 2% of poppy straw ) is morphine.

The other poppy variety which has been developed in Tasmania is a genetically different form grown to produce THEBAINE, another alkaloid of tremendous value to the pharmaceutical industry.

Within the poppy, the synthesis is thebaine to codeine to morphine. There are 3 biochemical steps converting thebaine to codeine and one step further to morphine. A second path exists, thebaine to oripavine to morphine. This pathway is not dominant in the morphine poppy but leads to substantial quantities of oripavine in the thebaine variety.

Oripavine is very similar to codeine and is actually a better starting point for many synthetic opiates. It is usually a minor chemical but the thebaine strain produces quite a large percentage of oripavine. This can easily be converted to thebaine using a "methylation" step. (The H is replaced by CH₃ , methyl, off the benzene ring.)

Looking at the diagrams of thebaine, codeine, oripavine and morphine, it can be seen that the molecules have very much a common central core. Parts on the outer of the molecules differ - thebaine is more complex than codeine which again is more complex than morphine. Notice that the cyclo-hexene ring is a cyclo-hex-2-ene ring in thebaine and oripavine.

Tasmanian Alkaloid researchers used mutagenesis to isolate a plant which stopped alkaloid development at thebaine rather than morphine. They were able to work out how to check en masse the latex of many plants - 1000 plants each week - which left the plant intact and viable. They then propagated this variety.

The thebaine strain differs from the morphine strain by one just one recessive gene.

Much of the Tasmanian crop is now given over to this variant. It is more toxic than the morphine variants and can cause fits if ingested!

Other alkaloids within the opium which are classed as opiates include noscapine and papaverine. These are not greatly used by the pharmaceutical industry but may be in the future.

Sources:

Chemistry of Opioid Analgesics PHA 422 Neurology Pharmacotherapeutics http://wizard.pharm.wayne.edu/medicine/opioid.html