Synthesis of novel azo compounds containing 5(4H)-oxazolone ring as potent tyrosinase inhibitors

Six new azo dyes containing of 5(4H)-oxazolone ring were prepared by diazotization of 4-aminohippuric acid and coupling with N,N-dimethylaniline, 1-naphthol and 2-naphthol and condensation with 4-fluoro benzaldehyde or 4-trifluoromethoxy benzaldehyde. The new compounds were fully characterized by spectroscopic techniques. All synthesized compounds exhibited high tyrosinase inhibitory behavior. The results of mushroom tyrosinase inhibition assays indicate that the 4-trifluoromethoxy derivatives have high degrees of inhibition and N,N-dimethylaniline derivatives are better for tyrosinase inhibition than 1-naphthol and 2-naphthol derivatives. All synthesized azo compounds (4a-4f) showed the most potent mushroom tyrosinase inhibition, comparable to that of Kojic acid and l-mimosine, as reference standard inhibitors. © 2013 Elsevier Ltd. All rights reserved

Microwave saturation of the Rydberg states of electrons on helium

We present measurements of the resonant microwave excitation of the Rydberg energy levels of surface state electrons on superfluid helium. The temperature dependent linewidth agrees well with theoretical predictions and is very small below 300 mK. Absorption saturation and power broadening were observed as the fraction of electrons in the first excited state was increased to 0.49, close to the thermal excitation limit of 0.5. The Rabi frequency was determined as a function of microwave power. The high values of the ratio of the Rabi frequency to linewidth confirm this system as an excellent candidate for creating qubits.Comment: 4 pages, 4 figure

Temperature-dependent energy levels of electrons on liquid helium

We present measurements of the resonant microwave absorption by the Rydberg energy levels of surface state electrons on the surface of superfluid liquid helium, in the frequency range 165 - 220 GHz. The resonant frequency was strongly temperature dependent from 0.1 to 2 K. The experiments are in agreement with recent theoretical calculations of the renormalisation of the electron energy levels due to zero-point and thermal ripplons, analogous to a condensed matter Lamb shift. The temperature-dependent contribution to the linewidth for excitation to the first excited state at 189.6 GHz is compared with other measurements and theoretical predictions.Comment: 24 pages, 9 figure

Male subfertility effects of sub-chronic ethanol exposure during stress in a rat model

Background: Stressful conditions increase alcohol consumption in men. Clinical studies link disruption of the neuroendocrine stress system with alcoholism, but the effect of alcohol in a stress condition on male fertility is still relatively poorly understood. This project was undertaken to evaluate the effect of sub-chronic alcohol in a stress condition on male fertility in a rat model. Methods: Male Sprague–Dawley rats were randomly divided into a control group, a stress group that was exposed to restraint stress, an ethanol group that was injected with ethanol daily, and a stress + ethanol group that was injected with ethanol daily and was exposed to restraint stress, simultaneously. Furthermore, testis tissue was evaluated histomorphometrically and immunohistochemically for apoptosis using a TUNEL assay after 12 days. Epididymis sperm analysis was done. Blood cortisol and testosterone were measured and expression of hypothalamic kisspeptin (Kiss1), RFRP-3, and MC4R mRNA were evaluated. Results: Ethanol exposure during restraint stress did not alter body weight. Ethanol exposure decreased the cellular diameter and area, and stress increased the cellular diameter and area, in comparison with the control group. In the stress group, in comparison with the other groups, the number of seminiferous tubules decreased and the numerical density of seminiferous tubules increased. In addition, ethanol exposure and/or stress reduced semen analysis parameters (sperm viability and motility), but did not change serum testosterone concentrations. Apoptosis increased in spermatogonia with ethanol exposure, but spermatocytes were not affected. Our data present the novel finding that ethanol and stress reduced hypothalamic Kiss1 mRNA expression, while ethanol exposure decreased hypothalamic RFRP-3 and MC4R mRNA expression. Conclusions: Ethanol decreased cortisol hormone level during the restraint stress condition and attenuated hypothalamic reproductive-related gene expressions. Therefore, ethanol exposure may induce reduction of sperm viability, increased sperm mortality, and increased apoptosis, with long-term effects, and may induce permanent male subfertility