Microbiological synthesis of 16-ketopregnanes from steroidal sapogenins

Incubation of diosgenone (1, 25D-spirost-4-en-3-one) with Verticillium theobromae (Turconi) Mason et Hughes (CBS) afforded 20α-hydroxypregn-4<ne-3,16-dione (3) and 3α,11β,20α-trihydroxy-5α-pregnan-16-one (4). The same transformation products were also obtained by the use of Stachylidium bicolor Link (IFO 6647). Isolation and identification processes of the products are discussed.     

Epitaxial Growth of Sr x Ba1 − x Nb2O6 Thin Films Prepared from Sol-Gel Process

In this study, we prepared Sr _x Ba_{1 – x} Nb₂O₆ (x = 0.3, 0.5 and 0.7) thin film on 0.75 wt% La doped SrTiO₃ (100) and (110) single crystal substrates. A homogeneous coating solution was prepared with Sr and Ba acetates and Nb(OEt)₅ as raw materials, and acetic acid and diethlene glycol monomethyl ether as solvents. The substrates were coated with the solution by spin coating method. As-coated thin films were heated from 973 to 1273 K in air. The grains of the thin film on La doped SrTiO₃ (100) were pillar shaped and arranged in right angle to each other. On the other hand, the grains of these thin films on La doped SrTiO₃ were pillar shape and arranged in one direction. The crystallographic relationship of the thin film between Sr _x Ba_{1 – x} Nb₂O₆ and substrate that the 130 and 310 direction of the thin film on the substrate were oriented with c-axis in parallel to the substrate surface. On the other hand, (hk0) phase diffractions of Sr _x Ba_{1 – x} Nb₂O₆ thin film on the substrate (110) were investigated in the XRD theta-2theta measurement. It is expected that the Sr _x Ba_{1 – x} Nb₂O₆ (x = 0.3, 0.5 and 0.7) were highly oriented or epitaxial growing on La doped SrTiO₃ (110) single crystal substrate.     

Fabrication of mesoporous ZnO nanosheets from precursor templates grown in aqueous solutions

Mesoporous ZnO nanosheets were successfully prepared by pyrolytic transformation of zinc carbonate hydroxide hydrate, Zn₄CO₃(OH)₆·H₂O. The nanosheets were initially formed as assemblies on glass substrates during chemical bath deposition (CBD) in aqueous solutions of urea and zinc acetate dihydrate, zinc chloride, zinc nitrate hexahydrate, or zinc sulfate heptahydrate at 80°C. It was key to induce heterogeneous nucleation of Zn₄CO₃(OH)₆·H₂O by promoting a gradual hydrolysis reaction of urea and controlling the degree of supersaturation of zinc hydroxide species. Morphology of Zn₄CO₃(OH)₆·H₂O was largely influenced by the anions present in the CBD solutions. The Zn₄CO₃(OH)₆·H₂O nanosheets were transformed into wurtzite ZnO by heating at 300°C in air without losing the microstructural feature.     

NMR Spectroscopic Observation of a Metal‐Free Acetylide Anion

A metal‐free acetylide was observed by using NMR spectroscopy. Metal‐free acetylides are closely related to reactive intermediates (carbanions) in solution; therefore, they have been regarded as unobservable species. However, we generated this highly reactive and unstable species through the deprotonation of phenylacetylene by using the strong nonmetallic phosphazene base tBu‐P4. In the presence of tBu‐P4, the J coupling between the ethynyl carbon and hydrogen nuclei (¹J_C,H) of phenylacetylene disappeared; this indicates the deprotonation of the alkyne terminal. Furthermore, a large low‐field shift (approximately 90 ppm) of the alkyne carbon resonance was observed. We concluded that we have observed a metal‐free carbanion with a formal charge on an sp‐hybridized carbon atom for the first time.     

Reaction of [α-(trimethylsilyl)benzyl]ferrocenes with α-ferrocenylbenzyl cations

Although methanolysis of [α-(trimethylsilyl)benzyl]ferrocene (I) and [p-methyl-α-(trimethylsilyl)benzyl]ferrocene (II) in the presence of anhydrous ferric chloride merely gave α-ferrocenylbenzyl methyl ether (III) and p-methyl-α-ferrocenylbenzyl methyl ether (IV), respectively, acid-catalyzed methanolysis of (I) and (II) in the presence of an equimolar amount of (III) or (IV) afforded 1,2-diferrocenyl-l,2-diarylethanes. It is suggested that one electron oxidation of [α-(trimethylsilyl)benzyl]ferrocene by α-ferrocenylbenzyl cation generated from α-ferrocenylbenzyl methyl ether, and subsequent methanolysis of the resulting substituted ferricenium ion may occur to give the two species of α-ferrocenylbenzyl radical, which in turn undergo an approximately statistical coupling.     

Nigellamines A3, A4, A5, and C, new dolabellane-type diterpene alkaloids, with lipid metabolism-promoting activities from the Egyptian medicinal food black cumin

New dolabellane-type diterpene alkaloids, nigellamines A(3), A(4), A(5), and C, were isolated from the methanolic extract of an Egyptian medicinal food, black cumin (the seeds of Nigella sativa). Their absolute configurations were determined on the basis of chemical and physicochemical evidence. Nigellamines were found to lower triglyceride levels in primary cultured mouse hepatocytes, and in particular, the activity of nigellamine A(5) was equivalent to that of the hypolipidemic agent, clofibrate.     

A new Zn(II) coordination polymer with 4-pyridylthioacetate: assemblies of homo-chiral helices with sulfide sites

A coordination polymer [Zn(pyta)(OH)] (pyta = 4-pyridylthioacetate), was synthesized and structurally characterized; it is constructed by an alternating assembly of two types of homo-chiral helices, [Zn-OH] and [Zn-pyta], in which the sulfide moieties are fastened in the latter columns.     

Relaxations of selenium in crystalline and amorphous states

Complex shear modulus at 33 kc./sec. is measured at temperatures of ?150–150°C. for amorphous selenium and crystalline selenium with different crystallinities. The dielectric relaxation at 10 kc./sec. to 3 kc./sec. to 3 Mc./sec. is observed at temperatures of ?32–25°C. for iodine-doped crystalline selenium. It is concluded from the results of this study and of others' that selenium exhibits four relaxations, α, β γ, and δ, in order of descending temperature. The β relaxation is observed only in the amorphous sample above the glass temperature and is assigned to the primary relaxation. The α, γ, and δ relaxations are found in the crystalline selenium. The α relaxation, which is prominent in a highly crystalline sample, is assigned to the crystalline relaxation. The γ and δ relaxations increase in peak height with decreasing crystallinity and are attributed to the disordered region in the crystalline selenium. The dispersion map (logarithm of frequency versus reciprocal absolute temperature of loss maximum) of selenium is presented.     

KINETICS OF ENZYMATIC PHOTOREACTIVATION STUDIED WITH PHAGE T1 AND ESCHERZCHZA COLI Bs-1*

Abstract— The kinetics of enzymatic photoreactivation (PR) of u.v.-induced killing was compared among E. coli B_s-1, phage T1 in B_s-1 and phage T1 in irradiated B_s-1. The PR action spectrum showed no substantial difference between PR of B_s-1 and PR of T1 in B_s-1. The PR D₃₇ (i.e. the PR dose required to reactivate all but 37 per cent of the reactivable lethal lesions) was found to decrease linearly with decreasing U.V. dose whether U.V. was given to produce pyrimidine dimers in B_s-1 DNA, which then compete with irradiated T1 DNA for PR enzyme, or to B_s-1 or T1 DNA to produce dimers serving as substrate for the PR enzyme. A generalized Michaelis-Menten formula was used to analyze the data and the following conclusions were drawn. (1) The number of PR enzyme molecules per cell available for PR of T1 DNA inside the B_s-1 host is only a quarter of the number available for PR of the B_s-1 host itself. (2) The Michaelis constant K_m for reaction of host-DNA-damage and PR-enzyme becomes larger when the host damage acts as competitive inhibitor to PR of T1 DNA than when it is the substrate for PR enzyme. (3) PR enzyme retains almost all its initial catalytic efficiency even after about two-hundred rounds of catalytic functioning. Conclusions (1) and (2) suggest that PR enzyme is concentrated within the nuclear area surrounding the host DNA.     

Collective dynamics of sub- and supercritical methanol by inelastic X-ray scattering

Inelastic X-ray scattering experiments have been performed on methanol as a function of density from ambient to the supercritical state. Positive dispersion of the sound velocity, as compared to the hydrodynamic values, is 50% in the ambient condition and decreases to zero at 0.50 g cm⁻³ over the momentum transfer Q = 1–10 nm⁻¹ with lowering density; however, it increases again with a further decrease in density down to 0.20 g cm⁻³in the supercritical state only in the Q-range above 5 nm⁻¹. These results have been interpreted as the formation of small oligomers in the low-density supercritical methanol.