Complex sentence: Many of the "vinca" alkaloids were first isolated from "Catharanthus roseus", including vinblastine and vincristine used in the treatment of leukemia and Hodgkin's lymphoma.
Split into simpler sentences: Many of the "vinca" alkaloids were first isolated from "Catharanthus roseus". The substances vinblastine and vincristine extracted from the plant are used in the treatment of leukemia and Hodgkin's lymphoma.