Inhibitors of the cleavage of aclacinomycins

Summary The reductive cleavage of the aclacinomycins A (I), Y (II), and B (III) by intact mycelia or subcellular fractions of the producer strain S. spec. AM 33352/F43 is suppressed in the presence of uncouplers, complex-forming agents, detergents, and some metal anions such as chromate. Increased concentration of the latter in complete cultures caused rearrangement of I to III.     

Inhibition of the transthylakoid gradient of electrochemical proton potential by the local anesthetic dibucaine

The effects of the local anesthetic dibucaine on coupling between electron transport and ATP synthesis-hydrolysis by the coupling-factor complex (CF₀CF₁ ATPase) were investigated in thylakoid membranes from Spinacia oleracea L. cv. Monatol. Evidence is presented that inhibition of ATP synthesis was produced by a specific uncoupling mechanism which was based on dibucaine-membrane surface interactions rather than on the interaction of dibucaine with the ATPase complex. Dibucaine reduced the osmotic space of thylakoid vesicles. At low pH of the medium it stimulated ATP hydrolysis beyond the rates obtained with optimum concentrations of ‘classical’ uncouplers. After addition of dibucaine, there was displacement of membrane-bound Mg²⁺ and strong thylakoid stacking in the presence of only low Mg²⁺ concentrations. Inhibition of ATP synthesis and transmembrane pH gradient increased with medium pH. Hydrolysis of ATP by isolated CF₁ and the CF₀CF₁ complex was only slightly affected by dibucaine. The data are discussed assuming the involvement of localized proton channels on the membrane surface in protonic coupling of electron transport and ATP synthesis. A hypothesis for the mechanisms of action of local anesthetics at the thylakoid membrane is presented.     

Influence of 1-double bond and 11 beta-hydroxy group on stereospecific microbial reductions of 4-en-3-oxo-steroids

The yeast Rhodotorula glutinis and the anaerobic bacterium Clostridium paraputrificum were used for stereospecific reductions of 4-chloro-11 beta-hydroxy-17 alpha-methyl-testosterone and the corresponding 1-dehydro compound to prepare 5 alpha- and 5 beta-H derivatives, respectively. C. paraputrificum was able to 5 beta-reduce both substances, whereas the 5 alpha-reduction by R. glutinis was inhibited by the structure elements 1-en and 11 beta-OH so that the substrate with both structure elements was not 5 alpha-reduced. The microbial conversion of the four steroids with and without 1-en and 11 beta-OH was compared in semiquantitative experiments. A number of new substances are described, 11 beta-hydroxy and 11-oxo derivatives of 5 alpha- and 5 beta-dihydro-4-chloro-17 alpha-methyltestosterone including some 3-OH compounds and characterized by NMR, mass spectrometric and further data.     

Hydrazonopropionic acids, a new class of hypoglycemic substances. 4. Hypoglycemic effect of 2-(3-methyl-cinnamylhydrazono)-propionate in the rat and guinea pig

The hydrazone-compound 2-(3-methyl-cinnamylhydrazono)-propionate (MCHP) significantly lowered the blood glucose concentration in fasted guinea pigs and rats. A significant decrease of blood glucose levels was observed in fasted guinea pigs already after an intraperitoneal injection of 20.5 mumol/kg MCHP, while much higher doses (about 1000 mumol/kg) were necessary to produce a hypoglycemic effect in the fasted rat. After oral administration MCHP (82.0 mumol/kg) significantly decreased the blood glucose concentration in guinea pigs. Furthermore MCHP caused a dose-dependent increase of plasma free fatty acid concentrations in guinea pigs and rats. In addition, MCHP decreased the concentrations of blood ketone bodies, plasma cholesterol and intrahepatic acetyl-coenzyme A in the guinea pig. All of these findings appear to be due to a reduced fatty acid utilization in the presence of MCHP resulting presumably in an intramitochondrial deficiency of acetyl-CoA. At hypoglycemic effective doses the intramitochondrial and cytoplasmatic redox ratios as well as the hepatic ATP/ADP ratio were not influenced by MCHP in fasted guinea pigs. Even at large doses (123 mumol/kg) MCHP decreased the activity of monoamino oxidase in guinea pigs only by less than 15%. Furthermore MCHP showed under our experimental conditions no relevant influence on the activity of various liver enzymes in plasma, the plasma concentration of creatinine, the plasma triglyceride-glycerol level and on the intrahepatic triglyceride-glycerol concentration of fasted guinea pigs. It is concluded that MCHP meets basic requirements for a potential oral antidiabetic agent.     

Influence of a 9-double bond on stereospecific microbial 4,5-reductions

By stereospecific microbial reduction with Rhodosporidium rubrum or Rhodotorula glutinis, 17 alpha-cyano-methyl-4-estren-17 beta-ol-3-one was metabolized to 17 alpha-cyanomethyl-5 alpha-estrane-3 beta,17 beta-diol (50%) and 17 alpha-cyanomethyl-5 alpha-estrane-3 alpha,17 beta-diol (30%). By Clostridium paraputrificum the same substrate was reduced stereospecifically to 17 alpha-cyanomethyl-5 beta-estrane-3 alpha, 17 beta-diol (70%). When the corresponding 9-dehydrogenated compound 17 alpha-cyanomethyl-4,9-estradien-17 beta-ol-3-one (STS 557, a new progestagen) was fermented, yeasts failed in 5 alpha-reducing the 4-double bond. Still Clostridium paraputrificum formed the expected 5 beta-reduced metabolite 17 alpha-cyanomethyl-5 beta-estr-9-ene-3 alpha,17 beta-diol (60%). Structures were elucidated by n.m.r. and mass spectra and partly by circular dichroism. By oxidation of the metabolites, the corresponding 3-oxo compounds 17 alpha-cyanomethyl-5 alpha-estran-17 beta-ol-3-one, 17 alpha-cyanomethyl-5 beta-estran-17 beta-ol-3-one and 17 alpha-cyanomethyl-5 beta-estr-9-en-17 beta-ol-3-one were prepared. The evident influence of the 9-double bond on reduction of the 4-en-3-oxo compound STS 557 preventing 5 alpha-reduction but permitting 5 beta-reduction is discussed in view of the distinctly diminished metabolism of this progestagen in mammals.     

Farbstoffgehalt und Grösse der Augen bei verschiedenen Mutanten von Drosophila melanogaster

Zusammenfassung Quantitative Untersuchungen über den Farbstoffgehalt der Drosophilaaugen haben schon wiederholt gezeigt, daß die Werte bei bestimmten Mutanten von der Erwartung abweichen. So fand man regelmäßig bei den rotäugigen Mutanten v bzw. cn weniger Pterin und bei der braunäugigen Mutante bw weniger Ommochrom als bei Wildfliegen.Wir haben diese Befunde zunächst mit Hilfe einer vereinfachten Extraktions- und Meßtechnik nachgeprüft und bestätigt. Die genauere Analyse ergab dann aber, daß das Farbstoffdefizit der Mutanten v, cn und bw lediglich darauf beruht, daß diese Tiere kleinere Augen haben als die Wildfliegen. Die Augenverkleinerung ist jedoch nicht, wie gelegentlich vermutet wurde, die Folge einer polyphänen Wirkung der Gene v, cn und bw, sondern nur eine besondere Eigenschaft bestimmter Fliegenstämme, die heute in fast allen Laboratorien gehalten werden.Die Erscheinung selbst beruht auf der Wirkung augenverkleinernder Modifikationsgene, die bei diesen Stämmen zufällig mit den Farbgenen gekoppelt sind, durch geeignete Kreuzungen aber eliminiert werden können. Unsere so erhaltenen neuen v-, cn- und bw-Stämme besitzen nicht nur ebenso große Augen wie die Wildfliegen, sondern enthalten auch die theoretisch erwarteten Mengen an Augenfarbstoffen. Der Zusammenhang zwischen der Größe der Augen und ihrem Farbstoffgehalt hat u. a. zur Folge, daß die Männchen, die ja stets kleinere Augen haben als die Weibchen, bei allen Mutanten weniger Augenpigment besitzen als jene.Der Farbstoffgehalt der Augen hängt außerdem von der Zucht-temperatur ab. Fliegen, die sich bei 18° C entwickeln, besitzen weniger Pterin aber mehr Ommochrom als solche, die bei 26° C aufgezogen werden. Auch die Melaninsynthese im Integument der Tiere wird durch Temperaturerniedrigung begünstigt; aus 18°-Zuchten stammende Fliegen sind deutlich dunkler als die entsprechenden 26°-Tiere.