Pink periwinkle/cape periwinkle

Catharanthus roseus, commonly known as bright eyes, Cape periwinkle, graveyard plant, Madagascar periwinkle, old maid, pink periwinkle, rose periwinkle, is a species of flowering plant in the family Apocynaceae. It is native and endemic to Madagascar, but grown elsewhere as an ornamental and medicinal plant. It is a source of the drugs vincristine and vinblastine, used to treat cancer. It was formerly included in the genus Vinca as Vinca rosea.

Traditional Uses

The species has long been cultivated for herbal medicine, as it can be traced back to 2600 BC Mesopotamia. In Ayurveda (Indian traditional medicine) the extracts of its roots and shoots, although poisonous, are used against several diseases. In traditional Chinese medicine, extracts from it have been used against numerous diseases, including diabetes, malaria, and Hodgkin's lymphoma. In the 1950s, vinca alkaloids, including vinblastine and vincristine, were isolated from Catharanthus roseus while screening for anti-diabetic drugs. This chance discovery led to increased research into the chemotherapeutic effects of vinblastine and vincristine. Conflict between historical indigenous use, and patent from 2001 on C. roseus-derived drugs by western pharmaceutical companies, without compensation, has led to accusations of biopiracy.

Medicinal

Vinblastine and vincristine, chemotherapy medications used to treat several types of cancers, are found in the plant and are biosynthesised from the coupling of the alkaloids catharanthine and vindoline. The newer semi-synthetic chemotherapeutic agent vinorelbine, used in the treatment of non-small-cell lung cancer, can be prepared either from vindoline and catharanthine or from the vinca alkaloid leurosine, in both cases via anhydrovinblastine. The insulin-stimulating vincoline has been isolated from the plant.

Despite the medical importance and wide use, the desired alkaloids (vinblastine and vincristine) are naturally produced at very low yields. Additionally, it is complex and costly to synthesize the desired products in a lab, resulting in difficulty satisfying the demand and a need for overproduction. Treatment of the plant with phytohormones, such as salicylic acid and methyl jasmonate, have been shown to trigger defense mechanisms and overproduce downstream alkaloids. Studies using this technique vary in growth conditions, choice of phytohormone, and location of treatment. Concurrently, there are various efforts to map the biosynthetic pathway producing the alkaloids to find a direct path to overproduction via genetic engineering. C. roseus is used in plant pathology as an experimental host for phytoplasmas. This is because it is easy to infect with a large majority of phytoplasmas, and also often has very distinctive symptoms such as phyllody and significantly reduced leaf size.

Rosinidin is the pink anthocyanidin pigment found in the flowers of C. roseus. Lochnericine is a major alkaloid in roots.

Toxicity

C. roseus can be extremely toxic if consumed orally by humans, and is cited (under its synonym Vinca rosea) in the Louisiana State Act 159. All parts of the plant are poisonous. On consumption, symptoms consist of mild stomach cramps, cardiac complications, hypotension, systematic paralysis eventually leading to death.