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41.
Tyrosinase catalyzes two distinct sequential reactions in melanin biosynthesis: The hydroxylation of tyrosine to dihydroxyphenylalanine (DOPA) and the oxidation of DOPA to dopaquinone. Developing functional modulators of tyrosinase is important for therapeutic and cosmetic purposes. Given the abundance of thiourea moiety in known tyrosinase inhibitors, we studied other thiourea-containing drugs as potential tyrosinase inhibitors. The thiourea-containing drugs in clinical use were retrieved and tested for their ability to inhibit tyrosinase. We observed that methimazole, thiouracil, methylthiouracil, propylthiouracil, ambazone, and thioacetazone inhibited mushroom tyrosinase. Except for methimazole, there was limited information regarding the activity of other drugs against tyrosinase. Both thioacetazone and ambazone significantly inhibited tyrosinase, with IC50 of 14 and 15 μM, respectively. Ambazone decreased melanin content without causing cellular toxicity at 20 μM in B16F10 cells. The activity of ambazone was stronger than that of kojic acid both in enzyme and melanin content assays. Kinetics of enzyme inhibition assigned the thiourea-containg drugs as non-competitive inhibitors. The complex models by docking simulation suggested that the intermolecular hydrogen bond via the nitrogen of thiourea and the contacts via thione were equally important for interacting with tyrosinase. These data were consistent with the results of enzyme assays with the analogues of thiourea. 相似文献
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Acetyl thiourea chitosan polymer (ATUCS) has been synthesized and evaluated as corrosion inhibitor. The electrochemical behavior of mild steel in naturally aerated 0.5 M H2SO4 acid containing different concentrations of ATUCS has been studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements and surface examination via scanning electron microscope (SEM) technique. The results of EIS showed that the resistance (Rt) increases slightly with increasing immersion time indicating a slight decrease in corrosion rate of the steel with time. Also, the corrosion rate increases with either increasing temperature or decreasing the polymer concentration as observed by polarization technique. Electrochemical impedance spectroscopy measurements under open-circuit conditions confirmed well polarization results. ATUCS has shown very good inhibition efficiency (IE) in 0.5 M sulphuric acid solution reaches to 94.5% for 0.76 mM concentration. IE of this compound has been found to vary with the concentration of the polymer solution, immersion time and temperature. 相似文献
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DISSOLUTION THEORY OF GOLD IN ALKALINE THIOUREA SOLUTION(Ⅰ) Anodic Behavior on Gold in Alkaline Thiourea Solution Containing Na_2SO_3 总被引:2,自引:0,他引:2
Chai Liyuan Masazumi Okido Department of Nonferrous Metallurgy Central South University of Technology Changsha P. R.China Center for Integrated Research in Science Engineering Nagoya University Nagoya Japan 《中国有色金属学会会刊》1999,(1)
INTRODUCTIONSincethioureawasutilizedasthelixiviantofgoldearlyin1932[1],extractinggoldfromoreorscrapbyacidicthioureasolutionha... 相似文献
45.
在酸性溶液中用强酸树脂D001回收硫脲金 总被引:3,自引:0,他引:3
D001大孔强酸型离子交换树脂回收硫脲金的研究表明,溶液中共存离子对金吸附率与其生成硫脲配离子的稳定性有关,吸附有吸热过程,吸附热ΔH^θ=10.19kJ.mol^-1,表明树脂骨架的位阻是影响吸附平衡的因素。 相似文献
46.
The effect of sesame lignans on the thermal and storage stability of edible vegetable oils (soybean-SBO, sunflower-SFO and ricebran-RBO) was studied by (i) determining the total free radical scavenging activity (RSA) using DPPH, (ii) % total tocol retention, (iii) lignan profile and (iv) PUFA composition. The order of RSA and retention of total tocols of oils heated up to 120 min at frying temperature (FT) were RBO = SBO > SFO and RBO > SBO > SFO, respectively. Heating SBO or SFO at FT after addition of 1.2% lignans increased RSA of SBO to a greater extent than that of SFO, and increased retention of total tocols only in SBO. However, addition of lignans did not further increase the RSA of RBO. Heating oils with added lignans, increased sesamol and decreased sesamolin while sesamin was relatively resistant to heat. These findings suggest that sesame lignans may have potential application as natural antioxidants in the edible oil and food industry. 相似文献
47.
硫化矿的浸金研究—酸性硫脲溶液体系 总被引:1,自引:0,他引:1
本文研究了在用酸性硫脲溶液从硫化矿中浸金时,硫酸铁浓度、硫脲浓度、酸度、温度、搅拌速度、浸取时间、矿石粒度及固液比等实验条件对金、银浸出率的影响。并对所得结果进行了讨论。 相似文献
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