Apocynaceae
Catharanthus roseus
Madagascar periwinkle · Rosy periwinkle
- Part used
- leafaerial
- Native range
- Madagascar; now naturalised and widely grown as an ornamental across the tropics
- Morphology
- A neat perennial subshrub to about eighty centimetres, glossy opposite leaves, and five-petalled pink or white flowers almost continuously.
- Also known as
- Vinca rosea
What is in it
Evidence
The traditional antidiabetic use was not confirmed. What researchers found instead was a marked drop in white blood cell counts, which led to vincristine and vinblastine and transformed the treatment of childhood leukaemia and Hodgkin lymphoma. The plant itself has no supported use.
Safety
The alkaloids are potent cytotoxics with severe neurotoxicity and bone marrow suppression. Vincristine is fatal if given by the wrong route, and hospital protocols worldwide are built around preventing that specific error. The raw plant is toxic and has no safe preparation.
Regulatory: Prescription cytotoxic drugs. The plant is not a permitted medicine ingredient.
Historical use
Used in Madagascar and, as it spread, in folk practice across the Caribbean, India and the Philippines — most commonly for diabetes, which is what brought it to laboratory attention in the 1950s.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
This is the best example anywhere of tradition pointing in the wrong direction and being useful anyway.
Researchers investigated it because Caribbean and Filipino folk practice used it for diabetes. It does not treat diabetes. But in testing it they noticed the white cell counts collapsing, and followed that instead — which produced two of the drugs that took childhood acute lymphoblastic leukaemia from almost always fatal to usually survivable.
Madagascar, where the plant is endemic and where much of the traditional knowledge originated, received essentially nothing. It is the case most often cited in arguments for the benefit- sharing provisions of the Nagoya Protocol, and it is the reason those arguments are not abstract.
Nomenclature verified against GBIF backbone taxonomy.