Engineering of Human CYP3A Enzymes by Combination of Activating Polymorphic Variants

The use of human cytochrome P450 (CYP) enzymes is increasing for the production of drug metabolites used for drug safety testing and doping analysis. Major challenges are high-priced cofactors, poor stability, and comparatively low activities. We have shown previously that production of specific metabolites in milligrams to gram scale is feasible using human CYPs recombinantly expressed in fission yeast. In this study, we sought to improve the activities of human CYP3A enzymes by genetic engineering. Two side chains (Pro293 and Arg409) of known activating human CYP3A polymorphic variants were??separately or together??introduced into the wild-type forms of each of the three enzymes CYP3A4, CYP3A5, and CYP3A7, respectively. Different effects of the two mutations and their combination on enzyme activity were monitored using both polar and nonpolar substrates. Interestingly, the CYP3A7 double mutant displayed a strong increase in activity with respect to testosterone 6??-hydroxylation (300?% of wild-type activity) and luciferin-6??-pentafluoro-benzyl ether turnover (400?% compared to wild type), while the single mutant CYP3A5^Pro293 showed 370 and 400?% of wild-type activity towards 6??-hydroxylation of testosterone and 16??-hydroxylation of dehydroepiandrosterone, respectively. Overall, six out of seven newly created mutants displayed increased activity with at least one of the tested substrates. These results support the notion that pharmacogenetic knowledge can directly contribute to the improvement of biotechnological processes.     

(Metallo)porphyrins as Potent Phototoxic Anti‐Cancer Agents after Irradiation with Red Light

Novel photoactive (metallo)porphyrins were synthesised and characterised. When irradiated with light at a wavelength greater than 600 nm, these porphyrins act as photosensitisers and show high cytotoxicity towards two different human cancer cell lines with IC₅₀ values down to 0.4 μM . A paramagnetic copper(II) porphyrin is the first photosensitiser to display excellent phototoxicity, explained by the electron paramagnetic resonance (EPR) spin trapping of hydroxy radicals and experimentally confirmed by the discovery of elevated levels of reactive oxygen species (ROS) inside A2780 cells after irradiation with red light. This finding indicates that paramagnetic compounds should be considered for photodynamic therapy (PDT). Furthermore, an additive effect of cisplatin and a zinc porphyrin, both at subtherapeutic concentrations of 0.22 μm, was observed.     

Preparation and characterization of polymer layer systems for validation of 3D Micro X-ray fluorescence spectroscopy

For the validation of the quantification of the newly-developed method of 3D Micro X-ray fluorescence spectroscopy (3D Micro-XRF) samples with a low average Z matrix and minor high Z elements are best suited. In a light matrix the interferences by matrix effects are minimized so that organic polymers are appropriate as basis for analytes which are more easily detected by X-ray fluorescence spectroscopy.     

An Organic–Inorganic Hybrid Exhibiting Electrical Conduction and Single‐Ion Magnetism

The first three‐dimensional (3D) conductive single‐ion magnet (SIM), (TTF)₂[Co(pdms)₂] (TTF=tetrathiafulvalene and H₂pdms=1,2‐bis(methanesulfonamido)benzene), was electrochemically synthesised and investigated structurally, physically, and theoretically. The similar oxidation potentials of neutral TTF and the molecular precursor [HNEt₃]₂[M(pdms)₂] (M=Co, Zn) allow for multiple charge transfers (CTs) between the SIM donor [M(pdms)₂]^n? and the TTF^.+ acceptor, as well as an intradonor CT from the pdms ligand to Co ion upon electrocrystallisation. Usually TTF functions as a donor, whereas in our system TTF is both a donor and an accepter because of the similar oxidation potentials. Furthermore, the [M(pdms)₂]^n? donor and TTF^.+ acceptor are not segregated but strongly interact with each other, contrary to reported layered donor–acceptor electrical conductors. The strong intermolecular and intramolecular interactions, combined with CT, allow for relatively high electrical conductivity even down to very low temperatures. Furthermore, SIM behaviour with slow magnetic relaxation and opening of hysteresis loops was observed. (TTF)₂[Co(pdms)₂] ( 2‐Co ) is an excellent building block for preparing new conductive SIMs.     

Prediction of cyclooxygenase inhibitory activity of curcuma rhizome from chromatograms by multivariate analysis

The potential use of partial least square regression (PLS-R) models for the prediction of biological activities of a herbal drug based on its liquid chromatography (LC) profile was verified using various extracts of Curcuma phaeocaulis and their cyclooxygenase-2 (COX-2) inhibitory activities as the model experiment. The correlation of practically measured inhibitory activities and predicted values by PLS-R analysis was quite good (correlation coefficient=0.9935) and the possibility of transforming chromatographic information into a measure of biological activity was confirmed. In addition, furanodienone and curcumenol were identified as the major active anti-inflammatory constituents of C. phaeocaulis, through detailed analysis of the regression vector, followed by isolation of these compounds and their COX-2 inhibitory assays. The selectivity indices (SI), IC(50) of COX-1/IC(50) of COX-2, of both compounds were higher than that of indomethacin and it is considered that furanodienone and curcumenol are the most promising compounds as lead anti-inflammatory agents.     

1,x-elimination reactions: extending the limits of a classical organic reaction

Alpha,omega-dibromo derivatives in which the two terminal carbon atom are separated by an unsaturated spacer unit ("pi spacer") undergo 1,x-elimination reactions (with x=6, 8, 10, and 14), using Mori's reagent (nBu3SnSiMe3/CsF). The resulting cumulenic intermediates cyclodimerize in a subsequent step yielding novel macrocyclic acetylenic and bridged aromatic compounds (cyclophanes). Thus 1,6-eliminations were carried out with dibromide 17 to yield 1,3,7,9-cyclododecatetrayne (20) and with benzylbromide 24 to provide cyclophanes 26 and 27. By 1,8-eliminations the 16-membered macrocycle 33 could be prepared from enediyne 31, the benzannelated 1,5-cyclooctadiyne 41 from dibromide 38, and a mixture of cyclophanes 45 and 46 from the precursor 43. 1,10-Eliminations were carried out successfully with dibromides 47, 50, and 53 yielding the corresponding unsaturated cyclophanes ("cyclophynes") 49, 52, and 55. The influence of the solvent on the cyclodimerization 47-->49 was investigated, with acetonitrile providing the highest yields. The heterophanes 59 a and b were obtained by 1,10-elimination of the precursor dibromides 57 a and b, and in an elimination experiment involving a 1:1 mixture of the dibromides 50 and 57 b the "mixed dimer" 60 was isolated, besides the homodimers 52 and 59 b. The method reached its limits with the 1,14-elimination of 68, 70, and 74 providing the cyclophanes 69, 71, and 75 in varying amounts. Two final debrominations with 76 and 77, which in principle could undergo 1,16- and 1,20-eliminations reactions, respectively, failed. The structures of the new cyclophanes 49, 50, 59 a, and 59 b were established by X-ray structural analysis; all other structure assignments rest on the usual spectroscopic and analytical data.