Madagascar periwinkle, a popular ornamental plant, contains two very important alkaloids—vincristine and vinblastine. These are used in the treatment of various types of cancers that were almost always deadly in the past.
Vincristine has helped increase the survival rate for childhood leukemia from 10% to 90%. It is also used to treat some lung cancers and Hodgkin’s disease.
Vinblastine is used as a chemotherapy drug with other medications to treat Hodgkin's disease, some types of lung cancer, bladder cancer, brain cancer, melanoma, and testicular cancer.
Periwinkle alkaloids are effective in chemotherapy because they inhibit cancer cell division. The compounds were once derived from periwinkle extracts, but they are now produced synthetically.