Biologically active substances of the annual wormwood (Artemisia annua L.) and their use in the therapy of malaria

Abstract

v Praze, katedra botaniky 2 Jihočeská univerzita v Českých Budějovicích, Zdravotně sociální fakulta, katedra radiologie a toxikologie Summary The annual wormwood (Artemisia annua L.) is a plant from the family Asteraceae. It comes from China, where it is an important part of the traditional Chinese medicine. Terpenoids (particularly sesquiterpenic lactones), flavonoids, coumarins and other metabolites of shikimic acid are the prevalent substances in the species A. annua, as is also the case in many other species of the genus Artemisia. The most important substance is biologically active sesquiterpene artemisinine (Qinghaosu). Artemisinine, sesquiterpenic lactone with endoperoxide bond, found in above-ground parts of A. annua, is more effective, more rapid and less toxic in the treatment of malaria compared to chloroquine. Malaria is currently the most severe infectious disease worldwide with at least 300 million reported cases annually. The annual wormwood is the main natural botanical source of artemisinine and potential source of essential oil for the manufacture of perfumes. Contents of artemisinine are very dependent on the plant ecotype, ecological conditions and seasonal and geographical variations. The annual wormwood is currently cultivated in China, Vietnam, India, Romania, Kenya and Tanzania. Methods of the chemical and biological synthesis of artemisinine are ever being studied due to poor yields from natural sources, but the natural or cultivated forms of A. annua are still the main sources of this substance. The medicinal value of artemisinine is unfortunately limited due to its low solubility in both oil and water, which resulted in developing semi-synthetic derivatives exerting pharmacological characteristics superior to those of the original substance. The most important derivatives of this type are artemether, arteether and artesunate, which exert higher efficacy and also higher solubility and metabolic and hydrolytic stability compared to artemisinine. In addition, artemisinine and its semisynthetic derivatives are characterized by their strong anti-cancer activity, antibacterial effects and by possibility of their use as pesticides.