Artemether (1), a tricylic sesquiterpene, containing peroxy
bridge and the O-methyl ether derivative of artemisinin (qinghaosu)
which is the principal antimalarial constituent of the
Chinese herb Artemisia annua (qing hao) [1]. Compound 1 is more
active than its parent compound, artemisinin [2] due to its better
lipophilicity and stability of the trioxane system [3]. It is active
againstthe erythrocytic stage of multidrug-resistant strains of Plasmodium
falciparum. Moreover, its clinical efficacy was tested in
malarial patients, and proven to be very effective and welltolerated
in P. falciparum infections [4–6]. Synthetic analogs of artemether
have been synthesized by various research groups to improve its
water solubility and bioavalibility but the structural complexity of
the artemether cause synthetic manipulation often difficult.
Biological structural modification using microorganism or plant
cell cultures have been frequently employed to achieve stereo- and
regiocontrol functionalization on unactivated carbon atoms, and
also as an excellent model in mimicking mammalian metabolism
[7]. Several reports on the usefulness of biocatalytic agents in
carrying out diverse chemical conversions have been published
[8,9]. Yet there is only few reports published on the bioconversion
of artemether by microorganisms and plant cell cultures [10,11].
In continuation of our biotransformational studies on bioactive
compounds [12–15], present study describes the biotransformation
of artemether (1) by fungal cell cultures Fusarium lini and
Macrophomina phaseolina and a plant suspension cell culture
Azadirachta indica. Five biotransformed products 2–6 were isolated
and structurally characterized by spectroscopic and the singlecrystal
X-ray diffraction techniques.