In a complete turnaround from 20 years ago, only a small number of pharmaceutical companies now continue with active research programmes in medicinal plant chemistry. But no matter which route in drug discovery is taken, serendipitous discoveries often play a part along the way. A beautiful pink flower from the island of Madagascar off the coast of east Africa called the Madagascar periwinkle Catharanthus roseus , also known as the rosy periwinkle, has long been used by traditional medicinal healers for treating diabetes.
Further research led to isolation of two biologically active chemical substances produced naturally in the plant — vincristine and vinblastine — and to their identification as anti-cancer agents.
These compounds have both been used as chemotherapy drugs since the early s. Vincristine is used against various blood and solid cancers including acute lymphoblastic leukaemia and Hodgkin lymphoma. Vinblastine is most often used in bladder cancer treatment but is also effective against other blood and solid cancers including Hodgkin lymphoma. Both are frequently used in combination with other chemotherapy drugs. The Madagascar periwinkle is a tropical perennial often grown as an annual in temperate climates.
It is a member of the dogbane family Apocynaceae. The Madagascar periwinkle was first named Vinca rosea by the great Swedish botanist Carolus Linnaeus in the s, but was reclassified and placed in the genus Catharanthus in It took many more years before the full benefits of this plant were realised.
The first chemistry and drug trials were not conducted until the s. During this period, the large US pharmaceutical company Eli Lilly was testing hundreds of plant extracts a year for biological activity in the hope of finding a lead to the development of a new drug.
In December , an extract of the plant was submitted for biological testing. Gordon learned in January that the extract exhibited very high potency in anti-cancer tests. They can be classified as alkaloids, a large group of natural products consisting of several ring structures containing one or more nitrogen atoms.
As such, access to these chemicals is only possible through extraction from the Madagascan periwinkle. Methods have been developed to synthesise these drugs starting from precursors, called catharanthine and vindoline, also isolated from the plant.
In this context, the possibility to increase the yield through synthetic biology would allow to overcome the challenges of having a steady supply and possibly decrease the price of the drugs, allowing more people to have access to treatment.
Particularly she is trying to investigate the whole sequence of metabolic events that the Madagascan periwinkle deploys in order to produce vinblastine and vincristine. In the past few years, her research group has been able to identify key genes involved in their production but a few are still missing.
Once the whole pathway is completed, it will be possible to engineer other organisms, either microorganisms or plants, to increase the world supply of these valuable chemicals. Hopefully, her efforts will allow us to harness the medicinal potential of this remarkable plant, known to people leaving in tropical climates as a weed and to western gardeners as an easy-to-grow ornamental, which has already saved thousands of lives. International Journal of Immunopathology and Pharmacology 21, 1: Tsunetsugu, T.
Kasetani, T. Kagawa and Y. Environmental Health and Preventive Medicine 15, 1: Related Articles. From protest buttons to full embrace Read More. Back to the beginning; a day on the Bay Read More. Follow Us. Donations are tax-deductable as allowed by law. Privacy Policy Terms of Use. This discovery, coupled with innovative extraction techniques, led to the development of vincristine and vinblastine, drugs that have helped doctors achieve remission rates of 90 percent or more in cases of childhood lymphocytic leukemia.
When Lilly released vincristine, under the trade name Oncovin, it was enormously expensive to produce. Norman R. Gordon Svoboda, another scientist who played a critical role in the research, has said that it was difficult to obtain sufficient quantities of Catharanthus leaves to refine more than small amounts of the two alkaloids.
Concerns about the political situation in Madagascar and in India led Lilly to buy from newly established periwinkle plantations in Texas, where the leaves were harvested mechanically. Upon initial release of Oncovin, Lilly announced that it would be distributing the drug at cost.
Later the company quietly shifted the drug into the for-profit category.
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