Process for isolating artemisinin from Artemisia annua

#The present invention relates to a process for the isolation of artemisinin, an antimalarial agent from the herb of the Artemisia annua plant, comprising of extracting the herb with ethanol, partitioning of the extract between water and hexane, followed by evaporative crystallization of artemisinin from hexane phase to produce substantially pure artemisinin.

#Artemisinin (Qinghaosu) is a sesquiterpene lactone endoperoxide having potent antimalarial activity (Klayman D L, 1985, Science 228, 1049). Clinical studies on artemisinin and its semisynthetic derivatives such as artemether, artesunate and arteether have been used in the treatment of malaria, including severe complicated-, multiple drug resistant- and cerebral-malaria. As being structurally different from commonly used antimalarials the problem of resistance and cross-resistance (that is now seriously limiting the effectiveness of such drugs) is not observed for artemisinin and its derivatives. Recently, methods have been reported for chemical synthesis of artemisinin but large scale economical synthesis is still not possible. Thus, plant Artemisia annua remains the sole source of artemisinin for the industry. The present invention provides a rapid, simple and economical method for the isolation of artemisinin from plant Artemisia annua.

#Ancient methods (Klayman D L, Lin A J, Acton N, Scovill J P, Hoch J M, Milhous W K & Theoharides A D, 1984, Jour of Natural Products 47:715-717 and Rucker G, Mayer R & Manns D, 1986, Planta Medica, 3 : 245) involved the extraction of plant material with the petroleum ether followed by chromatographing the relatively crude extract on silica gel. The column was eluted with a mixture of 7.5% ethyl acetate in chloroform to obtain pure artemisinin. Later Singh A, Vishwakarma R A, Husain A, 1988, Planta Medica 64, 475-476 reported extraction of plant parts with n-hexane followed by chromatographing the extract on silica gel column. In this case elution was performed with the mixture of ethyl acetate and hexane. In these process major disadvantage was that the procedure depend upon chromatographing a relatively crude extract on silica gel. This needs large solute to adsorbent ratio 1:44, which is expensive.

#Accordingly, the present invention provides a process for the preparation of artemisinin from Artemisia annua, said process comprising:

#(i) extracting plant parts of Artemisia annua with a non-aqueous polar solvent;

#(ii) concentrating the extract of step (i) to recover the polar solvent;