Effect of binary aqueous‐organic solvents on the reaction of phenacyl bromide with nitrobenzoic acid(s) in the presence of triethylamine

Second‐order rate constants (k₂) of the reaction between phenacyl bromide and equimolar mixture of nitrobenzoic acid(s)–triethylamine have been determined in dimethylformamide (DMF)/acetonitrile (ACN)/acetone and aqueous mixtures of these solvents by conductometric method at 30°C. The rates of nitrobenzoic acids are found to be in the order: 4‐NO₂ > 3‐NO₂ > 3,5‐(NO₂)₂. Changes in the rate just by the addition of water (1% (v/v)) into organic component is rationalized. Decrease in the values of k₂ on increasing water content in organic solvent is explained on the basis of preferential solvation phenomenon. Single and dual regression analysis using the various solvent parameters of aqueous mixtures (E_T(30), Z, π*, β, α, and Y) resulted in π* and α as the best parameters to explain solvation of nitrobenzoates. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 401–409, 2004     

Monitoring analytical measurements in presence of two component measurement error

Control charts are increasingly adopted by laboratories for effective monitoring of analytical processes. Analytical methods are mostly subject to two types of measurement errors, i—additive and ii—multiplicative, or proportional, error. These errors have been combined in a single model, namely the two component error model (TCME) proposed by [1]. In this study we present a comparison among the performance of three widely used location control charts, i.e. Shewhart, CUSUM and EWMA charts in presence of TCME model. This study will help quality practitioners to choose an efficient chart for the monitoring of analytical measurements.     

Synthesis of tricyclic pyrazolopyrimidine arylidene ester derivatives and their cytotoxic and molecular docking evaluations

Our research team has synthesized 33 tricyclic pyrazolopyrimidine arylidene ester derivatives using the lead compound CAM551 as a starting point. This was achieved by a designed five-step synthesis strategy. The synthesized compounds' inhibitory activities against HT-116 human colorectal adenocarcinoma cell line and HGC27 human gastric cancer cells were assessed through traditional MTT assays. The designed and synthesized compounds demonstrated superior inhibition against both types of cancer cells. Additionally, compound 7b , which contains a long-chain substituent, exhibited improved inhibition against hepatocellular carcinoma cells and a greater safety profile. These findings indicate that compound 7b has the potential as an antitumor lead compound for future research.     

己二酮糖硝基甲烷加合产物的结构确定

立体选择性地合成了1, 2∶4, 5-二-O-异亚丙基-3-C-硝基甲基-β-D-核-己-2-吡喃酮糖，确证了其绝对构型. 并用gCOSY、gHSQC、gHMBC、ROESY等2D NMR技术对它的¹H和¹³C NMR谱峰进行了全归属.     

Design,Synthesis and Biological Activity of Novel Furocoumarin Derivatives as Stimulators of Melanogenesis and Tyrosinase in B16 Cells

Sixteen novel and four known(4a, 4d, 4e, 4h) amine derivatives of furocoumarin were synthesized, then submitted to evaluation as stimulators of melanogenesis and tyrosinase in B16 murine cells. Among them, five compounds(4g, 4j-4m) showed potent activating effect on both melanogenesis and tyrosinase in vitro compared with positive control(8-MOP), the most widely used drugs for vitiligo in clinic. Noticeably, compounds 4h and 4j, which contain morpholine and piperazine, were recognized as the most effective stimulator of melanogenesis and tyrosianse in B16 cells separately. These derivatives may serve as lead compounds for further drug discovery for the treatment of vitiligo.     

Online background cleanup followed by high‐performance liquid chromatography with tandem mass spectrometry for the analysis of perfluorinated compounds in human blood

In this study, a novel method for the analysis of perfluorinated compounds in whole blood has been developed and validated. The method was developed by using a conventional reversed‐phase C₁₈ column as a trapping column for the elimination of background contamination and high‐performance liquid chromatography with tandem mass spectrometry for the target compounds analysis. The trapping column provided fast online separation of the background contamination of perfluorinated compounds. In this developed method, the limits of detection for different perfluorinated compounds ranged from 0.06 to 0.14 ng/mL. It is notable that the limit of detection (0.07 ng/mL) for perfluorooctanoic acid was improved significantly after the elimination of background contamination. The method was also validated in terms of sensitivity, accuracy, and precision. The recoveries ranged from 66.8 to 111.9%, with relative standard deviations from 2.1 to 15.3%. Our preliminary data suggest that the novel method based on trapping column cleanup followed by high‐performance liquid chromatography with tandem mass spectrometry could be applied in studies on the human exposure to perfluorinated compounds.     

Synthesis and biological evaluation of novel sulfonamide derivatives of tricyclic thieno[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones on melanin synthesis in murine B16 cells

Phototherapy with psoralens as photosensitizers is the commonly used method for the treatment of vitiligo. Considering the structure similarity between psoralens and thieno[2,3-d]pyrimidinones, a series of novel sulfonamide derivatives containing tricyclic thieno[2,3-d]pyrimidinone were synthesized and evaluated for melanin synthesis in murine B16 cells. All new compounds were characterized by ¹H NMR, ¹³C NMR, IR and HRMS (ESI). Among them, 6 compounds demonstrated excellent activity than positive control (8-methoxylpsoralen, 8-MOP) with more than 1.5-fold potency. Compound 11w with dichloro substitution at meta-positions in the benzenesulfonyl moiety was the most potent one (658.3 ± 8.7%), exhibiting 5.0-fold stronger activity than 8-MOP (130.9 ± 8.6%). The difluoro analog compound 11o increased melanin synthesis in murine B16 cells with a 4.35-fold potency as compared to 8-MOP. These compounds may serve as lead compounds for further drug discoveries for the treatment of vitiligo.     

Detection of Antibacterial and Antioxidant Compounds in the Essential Oil of Schizonepeta annua (Pall.) Schischk. Using High-Performance Thin-Layer Chromatography—Direct Bioautography and Gas Chromatography—Quadrupole Time-of-Flight Mass Spectrometry

JPC – Journal of Planar Chromatography – Modern TLC - Schizonepeta annua (Pall.) Schischk. is an endemic annual plant from the Lamiaceae family and it has been employed to cure...