Methods of Treatment:
Vinblastine: From Jamaica to a Cure
In 1952, Dr. Robert Laing Noble opened up an envelope sent to him from his older brother, Dr. Clark Noble. Robert Noble was then working at the University of Western Ontario in Canada, conducting research on cancer. His brother Clark had recently retired from medical research. The envelope that Clark sent to Robert contained twenty-five plant leaves, all from the Madigascar periwinkle plant.
Clark had become interested in the medicinal properties of the leaves of the Madigascar periwinkle. One of his patients in Jamaica had sent the leaves to him, with an explanation that Jamaicans often used a tea made from Madigascar periwinkle leaves to treat diabetes if insulin was unavailable. Since Clark had retired from research, he sent the leaves on to his brother Robert. Diabetes is a serious disease related to the levels of sugar in the blood. If these leaves contained a compound that would be effective in the treatment of diabetes, it would be a major medical breakthrough. Moreover, the Madigascar periwinkle had been used as medicine in other countries beyond Jamaica. It had a long history of use in places as far-flung as China, Central and South America, and the Caribbean, as a remedy for colds, insect stings, and eye infections. Robert Noble caught his brother's curiosity and set out to test the chemical and medicinal properties of the leaves.
In the course of these experiments, Robert Noble did not discover anything in the effects of the plant that would suggest it could be used to treat diabetes. It did not produce changes in sugar levels in the blood. However, through his search for these effects in the blood, Noble took note of an unexpected result. He saw that the plant reduced the number of white blood cells. Quickly, he speculated that if he could find the chemical compound responsible for this interruption in the chemical processes of white blood cell production, then he would have a potentially powerful drug for the treatment of cancers like leukemia.
Noble took up the hunt. Dr. Charles C. Beer signed on board for Noble's research team in 1954, and they continued their chemical search together. After four years of difficult work, Beer found the potent chemical extract of the leaves that was responsible for the white cell slowdown. Noble and Beer named this compound "vinblastine."
vinblastine
Noble and Beer expanded their team to include Gordon Svoboda of the pharmaceutical company Eli Lilly Company. Within a year, they had enough vinblastine ready for actual tests with cancer patients in Canada. The results were very strong. Vinblastine has gone on to become an important anticancer drug, effective in treating several different types of cancer when used in combination with other anticancer drugs. Both vinblastine and its chemical cousin, vincristine, act by binding to a substance called "tubulin" in cells, preventing the cells from making important changes necessary for cell division. Together, these compounds and others are known as "Vinca alkaloids," and they are the most common antimitotic ("against cell division") cancer therapeutics.
vincristine
For a challenge, look closely and see if you can you find the difference in molecular structure between vincristine and vinblastine. The difference is subtle, so look carefully. Amazingly, a very small difference in the molecular strucutre of a material can radically alter its proeprties.
For more information, at other Web sites...
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Dr. Robet Laing
Noble — biography from the Canadian Medical Hall of Fame.
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