Wednesday, April 18, 2012

A cancer-fighting plant

Species name: Catharanthus roseus

Common name: Madagascar periwinkle, cape periwinkle, "Old Maid"

Location: Ontario

This species of ornamental plant is one of the most impressive plants we have in Canada, not just for its showy flower display that lasts all spring and summer (and, depending on weather, sometimes well into the fall). Native to Madagascar (this is one of the few instances where common names really do reflect origins!), this Madagascar periwinkle had been brought to North America as an ornamental plant by early European settlers (who likely stole it from Madagascar on one of their many "expeditions"). Fortunately for the plant and unfortunately for native wildflowers, it has really taken off and is now one of the most invasive plants in Southern Ontario. Granted, it is strikingly beautiful...but we've got our own native wildflowers that would be just as nice growing in your garden! Ironically, in its native habitat it is a threatened plant due to habitat destruction from land conversion (from forested areas to agriculture).

Madagascar periwinkle is a perennial plant, meaning it lives for many years and sets seed many times over its lifetime. It is also an evergreen, meaning it doesn't lose its leaves. Even in Canadian winters, if you dig under the snow the bright green leaves will still be firmly attached to the plant. It is incredibly efficient at growing a vast root network to seek out water, so when the rest of your plants start to wilt from drought this one will be unaffected.

There are many hundred cultivars of Madagascar periwinkle growing in gardens around the world. In my garden at home, we have the "Grape Cooler" variety which has been selected for cold tolerance (why it can survive even under a thick layer of snow) and a purple flower colour. Native varieties of this plant often have much lighter flowers, from pink to white, with a very dark centre to attract insects to the nectar tube. Another great example of how plants have evolved mechanisms to coerce animals to help them reproduce.

This plant is vitally important in Traditional Chinese Medicine, and is becoming more and more important in local Western medicine, too. The Chinese have been using this plant for centuries as a cure for diabetes, malaria, and Hodgkin's disease. I'm not sure if it's actually effective against either diabetes or malaria, but extracts from the leaves are currently used as one of the most popular Western drugs to treat and cure leukemia (and to some extent, to treat Hodgkin's disease). This can be contrasted against a featured plant in a previous blog, bloodroot (one of the most notorious plant-based fake cancer cures).

Vinblastine and vincristine, the two biologically active pharmaceutical chemicals in Madagascar periwinkle were discovered here at the University of Western Ontario (sorry, but I will never call it Western University!) in the 1950s. At the time, it was noted by Dr. Noble and Dr. Beer that when Madagascar periwinkle was made into a tea and consumed, it lowered the number of white blood cells in the body. Normally this would not be a good thing (which is why you shouldn't ever eat this plant, raw or cooked!), but if you have a disease that specifically attacks white blood cells it might be a good treatment or cure. It went into clinical trials, was demonstrated to be incredibly effective against lymphoma, leukemia and Hodgkin's, and the extracts were made into a commercially available drug (trade name was formerly Oncovin, I'm not sure what it's called now that it's out of patent). The two chemicals are no longer extracted from the plant, but rather synthesized in the lab since it's so much cheaper and more practical.