Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Seit Februar 2021 bietet Wolfgang Brandt, ehemaliger Leiter der Arbeitsgruppe Computerchemie am IPB, sein Citizen Science-Projekt zur Pilzbestimmung an. Dafür hat er in regelmäßigen Abständen öffentliche Vorträge zur Vielfalt…
Chaudhuri, S. R.; Kaluđerović, G. N.; Bette, M.; Schmidt, J.; Schmidt, H.; Paschke, R.; Steinborn, D.;Synthesis, characterization and cytotoxicity studies of platinum(II) complexes with amino acid ligands in various coordination modesInorg. Chim. Acta394472-480(2013)DOI: 10.1016/j.ica.2012.08.034
Reactions of [Pt(CO3)(PPh3)2]·CH2Cl2 (1) with non-substituted and alkyl substituted amino acids, NH(R)CH(R′)CO2H (R/R′ = H/Me, L1; H/iPr, L2; H/CH2CHMe2, L3; Me/H, L4; Et/H, L5), in the presence of Tl[PF6] in methanol afforded with liberation of CO2 the formation of platinum(II) complexes of the type [Pt(PPh3)2{NHR–CHR′–C(O)O-κN,κO}][PF6] (R/R′ = H/Me, 2; H/iPr, 3; H/CH2CHMe2, 4; Me/H, 5; Et/H, 6). Single-crystal X-ray diffraction analysis of complex 4 exhibited a square-planar coordination of the platinum atom having coordinated two triphenylphosphane ligands and a deprotonated κN,κO-coordinated leucine ligand (L3−H). On varying the pKa value of the amino group, platinum(II) complexes with different coordination modes of amino acid ligands were obtained. Thus, treatment of complex 1 with N-acetyl l-alanine (L6), possessing a comparatively highly acidic NH proton, in 1:1 ratio in methanol resulted in the formation of [Pt(PPh3)2{N(COMe)–CHMe–C(O)O-κN,κO}] (7), while reacting N-phenyl glycine (L7) having a moderately acidic NH proton with complex 1 afforded a mixture of complexes [Pt(PPh3)2{NPh–CH2–C(O)O-κN,κO}] (8) and [Pt(PPh3)2{NHPh–CH2–C(O)O-κO}2] (10). Treatment of complex 1 with two equivalents of L6/L7 in dichloromethane resulted in the formation of [Pt(PPh3)2{NHR–CHR′–C(O)O-κO}2] (R/R′ = COMe/Me, 9; Ph/H, 10). An analogous reactivity was observed for l-lactic acid on treating with complex 1 in 1:1 and 2:1 ratio resulting in [Pt(PPh3)2{O–CHMe–C(O)O-κO,κO′}] (11) and [Pt(PPh3)2{HO–CHMe–C(O)O-κO}2] (12). The identities of all complexes have been proven by NMR (1H, 13C, 31P) spectroscopic and high-resolution ESI mass-spectrometric investigations. In vitro cytotoxicity studies against human tumor cell lines (8505C, A2780, HeLa, SW480, and MCF-7) showed the highest activities for the neutral complex 7. Furthermore, complexes 7 and 9 against the A2780 cell line induced an apoptotic mode of cell death, which was further supported by morphological investigation and DNA laddering. Cell cycle perturbation studies showed that both complexes induced faster cell death than cisplatin.
Publikation
Vetter, C.; Kaluđerović, G. N.; Paschke, R.; Kluge, R.; Schmidt, J.; Steinborn, D.;Synthesis, characterization and in vitro cytotoxicity studies of platinum(IV) complexes with thiouracil ligandsInorg. Chim. Acta3632452-2460(2010)DOI: 10.1016/j.ica.2010.03.079
Reactions of [PtMe3(bpy)(Me2CO)][BF4] (2) with the thionucleobases 2-thiouracil (s2Ura), 4-thiouracil (s4Ura) and 2,4-dithiouracil (s2s4Ura) resulted in the formation of complexes of the type [PtMe3(bpy)(L-κS)][BF4] (L = s2Ura, 3; s4Ura, 4; s2s4Ura, 5). The complexes were characterized by NMR spectroscopy (1H, 13C, 195Pt), IR spectroscopy as well as microanalyses. The coordination through the C4S groups (4, 5) was additionally confirmed by DFT calculations, where it was shown that these complexes [PtMe3(bpy)(L-κS4)]+ (L = s4Ura, s2s4Ura) are about 5.8 (4b) and 3.3 kcal/mol (5b), respectively, more stable than the respective complexes, having thiouracil ligands bound through the C2X groups (X = O, 4a; S, 5a). For [PtMe3(bpy)(s2Ura-κS2)][BF4] (3) no preferred coordination mode could be assigned solely based on DFT calculations. Analysis of NMR spectra showed the κS2 coordination. In vitro cytotoxic studies of complexes 3−5 on nine different cell lines (8505C, A253, FaDu, A431, A549, A2780, DLD-1, HCT-8, HT-29) revealed in most cases moderate activities. However, 3 and 5 showed significant activity towards A549 and A2780, respectively, possessing IC50 values comparable to those of cisplatin. Cell cycle perturbations and trypan blue exclusion test on cancer cell line A431 using [PtMe3(bpy)(s2s4Ura-κS4)][BF4] (5) showed induction of apoptotic cell death. Furthermore, the reaction of [PtMe3(OAc-κ2O,O′)(Me2CO)] (6) with 4-thiouracil yielded the dinuclear complex [(PtMe3)2(μ-s4Ura–H)2] (7), which has been characterized by microanalysis, NMR (1H, 13C, 195Pt) and IR spectroscopy as well as ESI mass spectrometry. X-ray diffraction analysis of crystals yielded in an isolated case exhibited the presence of a hexanuclear thiouracilato platinum(IV) complex, possessing each three different kinds of methyl platinum(IV) moieties and 4-thiouracilato ligands. This exhibited the ability of 4-thiouracil platinum(IV) complexes to form multinuclear complexes.
Publikation
Vetter, C.; Wagner, C.; Schmidt, J.; Steinborn, D.;Synthesis and characterization of platinum(IV) complexes with N,S and S,S heterocyclic ligandsInorg. Chim. Acta3594326-4334(2006)DOI: 10.1016/j.ica.2006.06.007
The reactions of [PtMe3(OAc)(bpy)] (4) with the N,S and S,S containing heterocycles, pyrimidine-2-thione (pymtH), pyridine-2-thione (pytH), thiazoline-2-thione (tztH) and thiophene-2-thiol (tptH), resulted in the formation of the monomeric complexes [PtMe3(-κS)(bpy)] ( = pymt, 5; pyt, 6; tzt, 7; tpt, 8), where the heterocyclic ligand is coordinated via the exocyclic sulfur atom. In contrast, in the reactions of [PtMe3(OAc)(Me2CO)x] (3, x = 1 or 2) with pymtH, pytH, tztH and tptH dimeric complexes [{PtMe3(μ-)}2] (μ- = pymt, 9; pyt, 10; tzt, 11) and the tetrameric complex [{PtMe3(μ3-tpt-κS)}4] (12), respectively, were formed. The complexes were characterized by microanalyses, 1H and 13C NMR spectroscopy and negative ESI-MS (12) measurements. Single-crystal X-ray diffraction analysis of [PtMe3(pymt-κS)(bpy)] (5) exhibited a conformation where the pymt ligand lies nearly perpendicular to the complex plane above the bpy ligand that was also confirmed by quantum chemical calculations on the DFT level of theory.
Publikation
Schröder, G.; Unterbusch, E.; Kaltenbach, M.; Schmidt, J.; Strack, D.; De Luca, V.; Schröder, J.;Light-induced cytochrome P450-dependent enzyme in indole alkaloid biosynthesis: tabersonine 16-hydroxylaseFEBS Lett.45897-102(1999)DOI: 10.1016/S0014-5793(99)01138-2
Vinblastine and vincristine are two medically important bisindole alkaloids from Catharanthus roseus (Madagascar periwinkle). Attempts at production in cell cultures failed because a part of the complex pathway was not active, i.e. from tabersonine to vindoline. It starts with tabersonine 16-hydroxylase (T16H), a cytochrome P450-dependent enzyme. We now show that T16H is induced in the suspension culture by light and we report the cloning of the cDNA. The enzyme was expressed in Escherichia coli as translational fusion with the P450 reductase from C. roseus, and the reaction product was identified by mass spectrometry. The protein (CYP71D12) shares 47–52% identity with other members of the CYP71D subfamily with unknown function. The induction by light was strongly enhanced by a nutritional downshift (transfer into 8% aqueous sucrose). We discuss the possibility that the entire pathway to bisindoles can be expressed in suspension cultures.