Beta-Artemether (12beta-O-menthyldihyroartemisinin), a potent antimalarial drug has been synthetised from dihydroartemisinin using nonpolar waterimmiscible solvents and boron trifluorid etherate as a catalyst. Using this methods we always obtain a mixture of beta and alpha artemether with the ratio from 3/1 to 4/1 and the yield of beta-artemether is about 60%. Using polar waterimmiscible solvents in place of nonpolar waterimmiscible solvents in the synthesis can improve the ratio of beta/alpha artemether to 20/1 and the yield of beta-artemether increase to about 70% beta-artemether.
Artemether ; Pharmaceutical Preparations ; therapeutics ; malaria

Microbial transformation is an efficient enzymatic approach for the structural modification of exogenous compounds to obtain derivatives. Compared with traditional chemical synthesis, the microbial transformation has in fact the undoubtable advantages of strong region-and stereo-selectivity, and a low environmental and economic impact on the production process, which can achieve the reactions challenging to chemical synthesis. Because microbes are equipped with a broad-spectrum of enzymes and therefore can metabolize various substrates, they are not only a significant route for obtaining novel active derivatives, but also an effective tool for mimicking mammal metabolism in vitro. Artemisinin, a sesquiterpene with a peroxy-bridged structure serving as the main active functional group, is a famous antimalarial agent discovered from Artemisia annua L. Some sesquiterpenoids, such as dihydroartemisinin, artemether, and arteether, have been developed on the basis of artemisinin, which have been successfully marketed and become the first-line antimalarial drugs recommended by WHO. As revealed by pharmacological studies, artemisinin and its derivatives have exhibited extensive biological activities, including antimalarial, antitumor, antiviral, anti-inflammatory, and immunomodulatory. As an efficient approach for structural modification, microbial transformation of artemisinin and its derivatives is an increasingly popular strategy that attracts considerable attention recently, and numerous novel derivatives have been discovered. Herein, this paper reviewed the microbial transformation of artemisinin and its artemisinin, including microbial strains, culture conditions, product isolation and yield, and biological activities, and summarized the advances in microbial transformation in obtaining active derivatives of artemisinin and the simulation of in vivo metabolism of drugs.
Animals ; Antimalarials/pharmacology* ; Antiviral Agents ; Artemether ; Artemisinins ; Mammals