What is the evidence for medicinal value of carnivorous plants?

Throughout history, plants have been used for medicinal purposes. Many of the modern allopathic medicines used today are either directly or indirectly derived from plants. Examples include the cardiotonic and antiarrhythmic agent digoxin (derived from the foxglove—Digitalis purpurea), antimalarial quinine (derived from the bark of the cinchona tree—Cinchona officinalis), the mydriatic (pupil dilatory) agent belladonna (derived from the nightshade Atropa belladonna), aspirin (derived from the bark of the willow tree—Salix alba, etc.), taxol (derived from the yew tree—Taxus brevifolia) and vincristine (derived from the periwinkle—Catharanthus roseus (=Vinca rosea)). Although carnivorous plants have been used medicinally, to date not a single compound derived from carnivorous plants has been widely-accepted in modern allopathic medicine. Pinguicula spp., Dionaea muscipula, Drosera spp., Sarracenia purpurea, and Nepenthes spp. are the carnivorous plants frequently touted as having therapeutic potential. We herein review the existing literature on the medical uses of these plants.