Catharanthus roseus is a profusely branched, erect or decumbent perennial plant with stems that can become more or less woody. It grows from 30 – 100cm tall. A white latex is present in all parts of the plant. Recent discovery of the compound vincristine in the plant has led to its commercial cultivation, especially in Spain, China and the USA, since the compound has proved itself useful in the treatment of leukaemia. A popular garden ornamental, it is grown as a perennial in the tropics and as an annual in temperate regions, although it can overwinter as a pot plant in a conservatory. It is valued for its bushy habit and many large flowers carried above dark green foliage. It can also be kept as a cut flower; the branches will last for weeks or even months, producing new, but smaller, flowers all the time.
Madagascar periwinkle has long been used as a traditional medicine. Tests by pharmaceutical companies in the 1950’s showed the presence of a number of medically active alkaloids, especially the compound vincristine, which has been shown to have activity against leukaemia. The alkaloids, when isolated from the plant, are highly toxic but have also been shown to reduce the numbers of white blood cells, leading to applications which have revolutionized conventional cancer therapy. The plant is cultivated as a source of these alkaloids, a number of which are extracted and used allopathically. The isolated alkaloids are used to treat and other cancers.
The dried root is an industrial source of ajmalicine, which increases the blood flow in the brain and peripheral parts of the body. Preparations of ajmalicine are used to treat the psychological and behavioural problems of senility, sensory problems (dizziness, tinnitus), cranial traumas and their neurological complications.
The leaves and aerial parts of the plant have a wide range of traditional uses. Well known as an oral hypoglycaemic agent, the plant is also considered to be depurative, diaphoretic, diuretic, emetic, purgative and vermifuge. A decoction is taken to treat hypertension, asthma, menstrual irregularities, chronic constipation, diarrhoea, indigestion, dyspepsis, malaria, dengue fever, diabetes, cancer and skin diseases.