Biotransformation of artemisinin (1) by Aspergillus niger was investigated. During 12 days at 28 °C and pH 6.0, A. niger transformed artemisinin into four products. They were identified as 3β-hydroxy-4,12-epoxy-1-deoxyartemisinin (2), artemisinin G (3), 3,13-epoxyartemisinin (4), and 4α-hydroxy-1-deoxyartemisinin (5). Products 2 and 4 are new compounds and are being reported here for the first time. The product 4 contains a 3,13-epoxy structure. This is the first report of epoxidation of artemisinin using microbial strains. The product 4 still has an intact peroxide bridge and therefore can be used as a scaffold for further structural modification using chemical and biological methods in the search for new antimalarial drugs.
BackgroundArtemisinin (1) and its derivatives are now being widely used as antimalarial drugs, and they also exhibited good antitumor activities. So there has been much interest in the structural modification of artemisinin and its derivatives because of their effective bioactivities. The microbial transformation is a promising route to obtain artemisinin derivatives. The present study focuses on the microbial transformation of artemisinin by Aspergillus terreus.ResultsDuring 6 days at 28 °C and 180 rpm, Aspergillus terreus transformed artemisinin to two products. They were identified as 1-deoxyartemisinin (2) and 4α-hydroxy-1-deoxyartemisinin (3) on the basis of their spectroscopic data.ConclusionsThe microbial transformation of artemisinin by Aspergillus terreus was investigated, and two products (1-deoxyartemisinin and 4α-hydroxy-1-deoxyartemisinin) were obtained. This study is the first to report on the microbial transformation of artemisinin by Aspergillus terreus.
The title compound, C 40 H 64 O 12 , crystallizes in a pseudomerohedrally twinned primitive monoclinic cell with similar contributions of the two twin components. There are two symmetry-independent half-molecules of nonactin in the asymmetric unit. Each molecule has a pseudo-S 4 symmetry and resides on a crystallographic twofold axis; the axes pass through the molecular center of mass and are perpendicular to the plane of the macrocycle. The literature description of the room-temperature structure of nonactin as an order-disorder structure in an orthorhombic unit cell is corrected. We report a low-temperature high-precision ordered structure of 'free' nonactin that allowed for the first time precise determination of its bond distances and angles. It possesses an unfolded and more planar geometry than its complexes with encapsulated Na + , K + , Cs + , Ca 2+ or NH 4 + cations that exhibit more isometric overall conformations.
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