Spectrofluorimetric determination of 16α-hydroxyestrone by a reaction with hexacyanoferrate(III) and arginine in alkaline solution

The reaction of 16α-hydroxyestrone with hexacyanoferrate(III) and arginine in alkaline solution at 95°C produces a fluorescent compound that is measured at 490 nm (λ_(ex) = 395 nm). Most other steroids do not interfere. The calibration is linear for 0.5–50 μg of analyte.     

Cembrenene and mayol,two new cembranoid diterpenes from the soft coral sinularia mayi

Two new cembranoid diterpenes, cembrenene (1) and mayol (2), have been isolated from Sinularia mayi L?ttschw, along with the first reported cembrene (3) from marine organism. The structures were determined from spectral data and chemical transformations.     

New oxygenated himachalenes in male-specific odor of the Chinese windmill butterfly,Byasa alcinous alcinous

Male adults of the Chinese windmill Byasa alcinous alcinous (Papilionidae) are well known to have a strong musk-like odor, in which two oxygenated himachalene compounds, together with six sesquiterpene hydrocarbons, were newly discovered. γ-Himachalen-4-yl acetate (1) was the predominant compound isolated from the solvent extract of the males. The structure of 1 was determined using MS and NMR, and its relative configuration was established as 1S^*,4R^*,6R^* by NOE analysis with the help of quantum mechanical computation. Interestingly, the amount of 1 in males increased until 7 days after eclosion, suggesting that this compound is involved in sexual maturation for mating. Another new compound was identified as γ-himachalen-4-ol (2) by comparison with the retention time and mass spectrum of the hydrolysate of 1. Since males of other papilionid species have general volatiles omnipresent in plants and insects, the presence of species-specific volatiles in males is characteristic of B. alcinous alcinous.     

Involvement of interleukin-10 promoter polymorphisms in nonmelanoma skin cancers-a case study in non-Caucasian skin cancer patients

Interleukin 10 (IL-10) is a potent immunosuppressive cytokine, therefore elevated IL-10 expression has been implicated in inhibition of antitumor immune response. IL-10 gene promoter polymorphism has been shown to be involved in susceptibility to skin cancers, but there has been no report focusing on susceptibility to skin cancers among non-Caucasian populations. We enrolled 129 patients with skin cancers and 50 age- and sex-matched healthy controls between April 2004 and March 2007. Genomic DNA was extracted from patients' blood samples and IL-10 promoter polymorphisms were identified using polymerase chain reaction-restriction fragment length polymorphism or direct sequencing. The distribution of the frequency of allele or haplotype of IL-10 gene promoter in Japanese was quite different from that of Europeans. No significant differences could be demonstrated in the frequency of allele or haplotype of IL-10 gene promoter between the patient group and the control group. However, the frequency of the low-IL-10 expression haplotype was significantly high in Bowen's disease subgroup. The frequency of low expression IL-10 promoter genotype was significantly less (P = 0.009, chi(2) = 6.74) in the group of nonmelanoma skin cancer generated on sun-exposed areas in comparison with that on covered areas. Our results indicated that low expression haplotype of IL-10 in Bowen's disease may inhibit the escape of tumor cells from immune surveillance, resulting in suppression of tumor growth and tumor invasion to the dermis. Moreover, high IL-10-expressing haplotype of IL-10 promoter may be a risk factor for photocarcinogenesis.     

Bi(OTf)3-catalyzed 5-exo-trig cyclization via halide activation

Lewis acid activation of allyl halides utilizing Bi(OTf)₃ resulted in cationic cyclization of alkenes with high efficiency. While other Lewis acids could catalyze this process with highly substituted alkenes, bismuth salts demonstrated unique reactivity in come cases. This suggested that bismuth triflate possesses interesting halophilic properties.     

Rational tuning of the thiolate donor in model complexes of superoxide reductase: direct evidence for a trans influence in Fe(III)-OOR complexes

Iron peroxide species have been identified as important intermediates in a number of nonheme iron as well as heme-containing enzymes, yet there are only a few examples of such species either synthetic or biological that have been well characterized. We describe the synthesis and structural characterization of a new series of five-coordinate (N4S(thiolate))Fe(II) complexes that react with tert-butyl hydroperoxide ((t)BuOOH) or cumenyl hydroperoxide (CmOOH) to give metastable alkylperoxo-iron(III) species (N4S(thiolate)Fe(III)-OOR) at low temperature. These complexes were designed specifically to mimic the nonheme iron active site of superoxide reductase, which contains a five-coordinate iron(II) center bound by one Cys and four His residues in the active form of the protein. The structures of the Fe(II) complexes are analyzed by X-ray crystallography, and their electrochemical properties are assessed by cyclic voltammetry. For the Fe(III)-OOR species, low-temperature UV-vis spectra reveal intense peaks between 500-550 nm that are typical of peroxide to iron(III) ligand-to-metal charge-transfer (LMCT) transitions, and EPR spectroscopy shows that these alkylperoxo species are all low-spin iron(III) complexes. Identification of the vibrational modes of the Fe(III)-OOR unit comes from resonance Raman (RR) spectroscopy, which shows nu(Fe-O) modes between 600-635 cm(-1) and nu(O-O) bands near 800 cm(-1). These Fe-O stretching frequencies are significantly lower than those found in other low-spin Fe(III)-OOR complexes. Trends in the data conclusively show that this weakening of the Fe-O bond arises from a trans influence of the thiolate donor, and density functional theory (DFT) calculations support these findings. These results suggest a role for the cysteine ligand in SOR, and are discussed in light of the recent assessments of the function of the cysteine ligand in this enzyme.     

Superperiodic assembly of 2,6-diethynylpyridine through weak hydrogen bonds at the 1-phenyloctane/HOPG interface

Regardless of the absence of alkyl chains and conventional hydrogen bonding sites as well as its small size, 2,6-diethynylpyridine forms an ordered array at the interface between 1-phenyloctane and highly oriented pyrolytic graphite (HOPG) under room temperature conditions, as revealed by scanning tunneling microscopy. We propose a model for the superperiodic molecular arrangement with reference to the bulk crystal structure, in which the surface pattern is governed by weak C-H...N and C-H...pi hydrogen bonds as well as the periodic potential of the underlying graphite surface.     

Adsorption properties and photocatalytic activity of TiO2 and La-doped TiO2

Photocatalysts of TiO₂ and La-doped TiO₂ were prepared by calcining the pure TiO₂ sols and the sols mixed with La(NO₃)₃⋅6H₂O at 873 K, respectively. These photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and N₂ adsorption-desorption isotherms measurement. As results, the BET surface area, pore diameter, mesopore volume and micropore volume slightly increased, while the crystallite size and the phase structure were little affected by lanthanum doping. The equilibrium adsorption of methylene blue (MB) on the photocatalysts were measured in a dark room. The adsorption isotherms were confirmed to fit to the Langmuir theory. Photocatalytic activities of the photocatalysts were studied by employing the photocatalytic degradation of MB in water and degradation of acetaldehyde in air under UV-irradiation using a black light. Kinetic analysis revealed that the rate controlling steps could be the surface reaction of the adsorbed MB on the catalyst surface for MB degradation and the reaction of adsorbed acetaldehyde with the gaseous acetaldehyde for degradation of acetaldehyde, respectively.