Catharanthus roseus is known as the Madagascar periwinkle
The plant has historically been used to treat a wide assortment of diseases. It was used as a folk remedy for diabetes in Europe for centuries. In India, juice from the leaves was used to treat wasp stings. In Hawaii, the plant was boiled to make a poultice to stop bleeding. In China, it was used as an astringent, diuretic and cough remedy. In Central and South America, it was used as a homemade cold remedy to ease lung congestion and inflammation and sore throats. Throughout the Caribbean, an extract from the flowers was used to make a solution to treat eye irritation and infections.
It also had a reputation as a magic plant; Europeans thought it could ward off evil spirits, and the French referred to it as "violet of the sorcerers."
Western researchers finally noticed the plant in the 1950's when they learned of a tea Jamaicans were drinking to treat diabetes. They discovered the plant contains a motherlode of useful alkaloids (70 in all at last count). Some, such as catharanthine, leurosine sulphate, lochnerine, tetrahydroalstonine, vindoline and vindolinine lower blood sugar levels (thus easing the symptoms of diabetes). Others lower blood pressure, others act as hemostatics (arrest bleeding) and two others, vincristine and vinblastine, have anticancer properties. Periwinkles also contain the alkaloids reserpine and serpentine, which are powerful tranquilizers.
Because the alkaloids in this plant can have serious side effects such as nausea and hair loss, it is not recommended that people attempt to medicate themselves with periwinkles.