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Depigmenting Agents
Published in Vineet Relhan, Vijay Kumar Garg, Sneha Ghunawat, Khushbu Mahajan, Comprehensive Textbook on Vitiligo, 2020
A huge number of phenolic compounds have been tested as inhibitors of melanin synthesis. In one animal study, eight compounds were selected on the basis of their known depigmenting effects, including hydroquinone (H), 4-ethoxyphenol (4-EP), 4-methylcatechol (4-MC), 4-tert-butylcatechol (4-t-BC), monobenzone (M), hydroquinone bis (2-hydroxyethyl)-ether (HHEE), and catechol (C). These compounds were injected into animal skin as 10% and 20% solutions dissolved in 95% ethanol. Six of the eight compounds tested showed positive depigmenting effects at 10% except C and HHEE. Compounds showed increased necrosis at a concentration of 20% [10,38].
1D NMR WaterLOGSY as an efficient method for fragment-based lead discovery
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Claire Raingeval, Olivier Cala, Béatrice Brion, Marc Le Borgne, Roderick Eliot Hubbard, Isabelle Krimm
The WaterLOGSY factors and the calculated solvent-accessibilities for compounds 1, 4, and 7 are shown in Figure 8. As expected, the protons exhibiting weaker WaterLOGSY factors correspond to the most solvent-exposed protons in the corresponding protein-ligand 3 D structures. For weak-affinity ligands such as fragment-like compounds, the comparison of WaterLOGSY factors between two analogues may be used to assess the impact of a chemical group on the binding mode of the ligand. This is illustrated in Figure 8 for compound 1 (4-methylcatechol, see also Figure 2) and compound 7 (4-tert-butylcatechol) bound to PRDX5. According to the WaterLOGSY factors, the binding mode compound 7 is modified in comparison to that of compound 1. This observation is in agreement with the X-ray structure of the complex of compound 7 with PRDX5, in which two binding modes are observed (while only one binding mode was observed for compound 1) (Figure 8). Depending on the binding modes, the proton H1 is either buried into the protein or solvent-exposed. The experimental WaterLOGSY factor is averaged, and no privileged orientation is observed. This result shows that WaterLOGSY-based structural information can be particularly useful to compare the binding properties of similar compounds.
Development and evaluation of hollow mesoporous silica microspheres bearing on enhanced oral delivery of curcumin
Published in Drug Development and Industrial Pharmacy, 2019
Yang Gao, Shujiang Ding, Xiaoyan Huang, Zhaoyang Fan, Jianmei Sun, Yang Hai, Kai Li
2,2-Azo-bisisobutyronitrile (AIBN), polyvinylpyrrolidone (PVP K-30, >99.5%), 2,2′-Azobis (2-methylpropionamidine) dihydrochloride (>97.0%), hexadecyltrimethylammonium bromide (CTAB, >99.0%), ammonium hydroxide solution (28 wt%), tetraethoxysilane (TEOS, >99.9%) and ethanol (95%) were purchased from Sigma-Aldrich (St. Louis, MO). Styrene (>99.0%) obtained from Sigma-Aldrich was washed through an inhibitor remover column containing aluminum oxide for removing tert-butylcatechol. Curcumin, polyethylene glycol 400 (PEG 400), acetone, dichloromethane, dimethylsulfoxide (DMSO) and acetonitrile were purchased from Aladdin Bio-tech Inc. (Shanghai, China) All other regents were commercially available and of analytical grade.
Treatment update for vitiligo based on autoimmune inhibition and melanocyte protection
Published in Expert Opinion on Therapeutic Targets, 2023
Bo Xie, Yuqi Zhu, Yuqing Shen, Wen Xu, Xiuzu Song
Compared to IRE1α and ATF6, the PERK pathway is the most studied branch of the UPR system in melanocytes (Figure 3). The GRP78 dissociation from PERK (activated by the production of misfolded proteins) further accelerates the phosphorylation of eukaryotic initiation factor 2α (eIF2α) and ATF4 translation [138]. As a regulator of the expression of adaptive genes, the ATF4 activation represses the global translation, which is the conservative mechanism for melanocyte survival under environmental stress [139]. Then, the injured ERs are repaired and resume their role in homeostasis. In this state, eIF2α is dephosphorylated via DNA damage-inducible protein and G1 cell arrest mechanism [140]. In the PERK-eIF2α-ATF4 axis, nuclear erythroid 2-related factor 2 (Nrf2) is linked, promotes antioxidant response-related genes HO-1 expression, and is considered one of the mechanisms for antioxidant elements in melanocytes against UV and chemicals (e.g. monobenzyl ether of hydroquinone, 4-tert-butylcatechol, 4-tert-amylphenol, 4-tertiary butylphenol) [141]. In addition to Nrf2, the PERK-eIF2α-ATF4 axis is associated with autophagy through target gene regulation such as LAMP3 (lysosomal-associated membrane protein 3) [38,142]. Lu et al. [143] reported that the pretreatment of bilobalide, an active component of G. biloba, increased the phosphorylation of eIF2α and melanocyte protection. Jiaxi Chen et al. [144] showed that homocysteine (Hcy), a high-risk factor for cardiovascular diseases, was significantly elevated in the serum of progressive vitiligo patients. Elevated Hcy levels are considered a circulatory marker of oxidative stress and a risk factor for vitiligo that can induce melanocyte apoptosis through the PERK-eIF2α-ATF4-C/EBP homologous protein (CHOP) signaling pathway. Folic acid can protect melanocytes from Hcy-induced melanocyte apoptosis and inhibition of melanin synthesis, which may be of potential value in treating vitiligo [144].