Synthesis of 13C-labeled parabens from isotopically enriched phenols using the Houben–Hoesch reaction

Parabens are antimicrobial additives found in a wide array of consumer products. However, the halogenated compounds formed from parabens during wastewater disinfection are a potential environmental concern. In order to identify these transformation products and investigate their mechanism of formation, a synthetic route to ethyl parabens labeled with the stable isotope carbon-13 at specific positions within the benzene ring was developed. This efficient two-step procedure starts from commercially available ¹³C-labeled phenols and involves (1) initial acylation of the phenol via a Houben–Hoesch reaction with trichloroacetonitrile followed by (2) a modified haloform reaction of the resulting trichloromethyl ketone to afford the corresponding ¹³C-labeled ethyl parabens in 65%–80% overall yield. The scope of the modified haloform reaction was also investigated, allowing for the synthesis of other parabens derived from primary or secondary alcohols, including ¹³C- and deuterium-labeled esters. In addition, 4-hydroxybenzoic acid can be formed directly from the common trichloromethyl ketone intermediate upon treatment with lithium hydroxide. This protocol complements existing methods for preparing ¹³C-labeled paraben derivatives and offers the specific advantages of exhibiting complete regioselectivity in the Houben–Hoesch reaction (to form the para-disubstituted product) and avoiding the need for protecting groups in the modified haloform reaction that forms the paraben esters.     

反相高效液相色谱法同时测定水杨酸原料中水杨酸和微量杂质苯酚含量

本文采用反相高效液相色谱法同时测定水杨酸原料中水杨酸及微量杂质苯酚含量。该法简便、快速、样品测定在１０ｍｉｎ内完成，其中水杨酸平均回收率为１００．４２％（ＲＳＤ１．４５％），苯酚平均回收率为１０２．２７％（ＲＳＤ２．１２％）。     

Effect of the phenol antioxidant katavidan on autooxidation of microsomes exposed to visible light

A study is performed of the effect of the phenol antioxidant katavidan on autooxidation of microsomes from rat liver exposed to visible light. It is shown that katavidan in a concentration of 10⁻³ M inhibits but in concentrations of 10⁻⁵–10⁻⁷ M stimulates autooxidation of microsomes. No stimulation is observed under conditions of dark incubation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, № 10, pp. 393–394, October, 1994 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Chemical Characterization of Macrophage Cytotoxicity Factor,Macrophage Migration Inhibitory Factor,T-Helper Cell-Replacing Factor and Colony-Stimulating Factor from Culture Supernatants of Concanavalin A-Stimulated Murine Spleen Cells

Supernatants from Concanavalin A-stimulated murine spleen cells were subjected to hydrophobic interaction chromatography on phenyl-Sepharose. Macrophage cytotoxicity factor (MCF), macrophage migration inhibitory factor (MIF), T-helper cell-replacing factor (TRF) and colony-stimulating factor (CSF) were bound at high ionic strength and were released stepwise at low ionic strength. CSF thus could be separated from MCF, MIF and TRF and the bulk of other proteins. Chromatography of pools containing MCF, MIF and TRF on Sephadex did not lead to a separation of the three activities which were all found in a molecular weight range of 25.000-55.000. Isoelectric focusing of these pools in pH range from 4 to 9 gave two peaks for MCF at pH 8.2 and 7.2, whereas MIF activity focused from pH 4.5 to 5.5. TRF activity was found in a single sharp peak at pH 5.3. The results demonstrate that the four biological activities can be distinguished on a chemical basis and are accessible for purification and chemical characterization.     

Chemical and statistical considerations in the determination of partition coefficients of weakly ionizable drugs and poisons

Equations have been developed that relate the concentration (or a parameter directly proportional to concentration, such as optical absorbance) of a weakly ionizable solute in a water-immiscible phase, in equilibrium with an aqueous phase, to the pH of the aqueous phase, the partition coefficient of the unionized solute and the phase volume ratio. These relationships have been used in the design of experimental methods for determining partition coefficients, which require measurement of solute concentration in only one phase. Data obtained in this way permit ready recognition of deviations from assumptions made in the development of the model; these assumptions include insolubility of the ionized solute in the water-immiscible phase and lack of interaction between buffer components and solute. Conditions for optimal liquid—liquid extraction of weakly ionizable solutes are more easily recognized. With these techniques, the negative logarithm of the acid dissociation constant (pK′_a) and the logarithm of the octanol—water partition coefficient (log P) have been measured for warfarin (pK′_a = 5.15 ± 0.04; log P = 2.82 ± 0.06), strychnine (pK′_a = 8.29 ± 0.02; log P = 2.23 ± 0.04), phenol (pK′_a = 9.88 ± 0.02; log P = 1.75 ± 0.05), procaine (pK′_a = 8.11 ± 0.04; log P = 1.10 ± 0.08), and ephedrine (pK′_a = 9.92 ± 0.01; log P = 1.65 ± 0.04) at 21°C.     

Exposure to formaldehyde and phenol during an anatomy dissecting course: sensitizing potency of formaldehyde in medical students

BACKGROUND: The sensitizing potency of formaldehyde and phenol during anatomy dissecting was investigated. The objective was to determine whether exposure induces specific IgE or IgG against formaldehyde-albumin or phenol-albumin. METHODS: In 27 medical students, specific IgE against formaldehyde-albumin by RAST plus ELISA and specific IgE against phenol-albumin by ELISA were assessed. In addition, specific IgG against formaldehyde-albumin was assessed in 23 students. Symptoms before and during dissecting were assessed, and indoor formaldehyde and phenol were measured. RESULTS: Mean indoor formaldehyde was 0.265 +/- 0.07 mg/m3, and mean indoor phenol was 4.65 +/- 2.96 mg/m3. Specific IgE/IgG against formaldehyde-albumin was not found at the beginning. Four students developed specific IgE against formaldehyde-albumin (RAST classes of > or =2.0), and all four also had specific IgE in the ELISA, but IgG against formaldehyde-albumin was not found. Specific IgE against phenol-albumin was not seen. Itch and paresthesia of the hands (P<0.00001), dizziness (P<0.008), burning eyes (P<0.01), headache, sneezing, epistaxis, gingival bleeding, oral or pharyngeal itch, and shortness of breath were experienced. CONCLUSIONS: Formaldehyde exposure during dissecting may induce specific IgE, but not IgG, against formaldehyde-albumin. Sensitization did not correlate with symptoms.     

Actions of 4-chloro-3-ethyl phenol on internal Ca2+ stores in vascular smooth muscle and endothelial cells

1. Recently, 4-chloro-3-ethyl phenol (CEP) has been shown to cause the release of internally stored Ca²⁺, apparently through ryanodine-sensitive Ca²⁺ channels, in fractionated skeletal muscle terminal cisternae and in a variety of non-excitable cell types. Its action on smooth muscle is unknown. In this study, we characterized the actions of CEP on vascular contraction in endothelium-denuded dog mesenteric artery. We also determined its ability to release Ca²⁺, by use of Ca²⁺ imaging techniques, on dog isolated mesenteric artery smooth muscle cells and on bovine cultured pulmonary artery endothelial cells.
2. After phenylephrine-(PE, 10 μM) sensitive Ca²⁺ stores were depleted by maximal PE stimulation in Ca²⁺-free medium, the action of CEP on refilling of the emptied PE stores was tested, by first pre-incubating the endothelium-denuded artery in CEP for 15 min before Ca²⁺ was restored for a 30 min refilling period. At the end of this period, Ca²⁺ and CEP were removed, and the arterial ring was tested again with PE to assess the degree of refilling of the internal Ca²⁺ store.
3. In a concentration-dependent manner (30, 100 and 300 μM), CEP significantly reduced the size of the post-refilling PE contraction (49.4, 28.9 and 5.7% of control, respectively) in Ca²⁺-free media. This suggests that Ca²⁺ levels are reduced in the internal stores by CEP treatment. CEP alone did not cause any contraction either in Ca²⁺-containing or Ca²⁺-free Krebs solution.
4. Restoring Ca²⁺ in the presence of PE caused a large contraction, which reflects PE-induced influx of extracellular Ca²⁺. The contraction of tissues pretreated with 300 μM CEP was significantly less compared with controls. However, tissues pretreated with 30 and 100 μM CEP were unaffected. Washout of CEP over 30 min produced complete recovery of responses to PE in Ca²⁺-free and Ca²⁺-containing medium suggesting a rapid reversal of CEP effects.
5. Concentration-response curves were constructed for PE, 5-hydroxytryptamine (5-HT) and K⁺ in the absence of and after 30 min pre-incubation with 30, 100 and 300 μM CEP. In all cases, CEP caused a concentration-dependent depression of the maximum response to PE (84.8, 43.4 and 11.6% of control), 5-HT (65.4, 25.7 and 6.9% of control) and K⁺ (77.6, 41.1 and 10.8% of control).
6. Some arterial rings were pre-incubated with ryanodine (30 μM) for 30 min before the construction of PE concentration-response curves. In Ca²⁺-free Krebs solution, ryanodine alone did not cause any contraction. However, 58% (11 out of 19) of the tissues tested with ryanodine developed contraction (6.9±1.2% of 100 mM K⁺ contraction, n=11) in the presence of external Ca²⁺. EC₅₀ values for PE in ryanodine-treated tissues (1.7±0.25 μM, n=16) were not significantly different from controls (2.5±0.41 μM, n=22). Maximum contractions to PE (118.5±4.4% of 100 mM K⁺ contraction, n=16) were also unaffected by ryanodine when compared to controls (129±4.2%, n=23).
7. When fura-2 loaded smooth muscle cells (n=13) and endothelial cells (n=27) were imaged for Ca²⁺ distribution, it was observed that 100 and 300 μM CEP in Ca²⁺-free medium caused Ca²⁺ release in both cell types. Smooth muscle cells showed a small decrease in cell length. Addition of EGTA (5 mM) reversed the effect of CEP on intracellular Ca²⁺ to control values.
8. These data show, for the first time in vascular smooth muscle and endothelial cells, that CEP releases Ca²⁺ more rapidly than ryanodine. Unlike ryanodine, CEP caused no basal contraction but depressed contractions to PE, 5-HT and K⁺. The lack of basal contraction may result from altered responsiveness of the contractile system to intracellular Ca²⁺ elevation.

     

荧光分光光度法测定饮用水中挥发酚类的研究

〔目的〕分析 4-氨基安替比林氯仿萃取分光光度法、直接荧光分光光度法、正丁醇萃取荧光分光光度法三种方法测定水中挥发酚的优缺点及适用范围 ,旨在找出一个更好的检测方法测定饮用水中挥发酚。〔方法〕使用此三种方法分别测定样品及标准中的挥发酚的含量 ,比较其相关系数、线性范围、灵敏度、回收率与检出限。〔结果〕以上三种方法的相关系数分别为 0 .9988、0 .9998、0 .9994,线性范围分别为 0 -0 .0 40mg L、0 -0 .0 40mg L、0 -0 .0 2 0mg L ,平均回收率分别为 95 .9%、10 0 .2 %、96.9% ,检出限分别为 0 .0 0 2mg L、0 .0 0 10 7mg L、0 .0 0 0 3 3mg L ,灵敏度分别为 11.177、3 2 61.9、3 745 6。〔结论〕正丁醇萃取荧光分光光度法有很好的灵敏度、回收率、检出限和相关系数 ,方法较简单且试剂毒性小 ,适合饮用水中挥发酚测定的国家标准要求 ,可以取代 4-氨基安替比林氯仿萃取分光光度法成为国家标准方法。     

骨肽注射液中苯酚含量的RP—HPLC法测定

目的:建立高效液相色谱法测定骨肽注射液中苯酚的含量。方法:采用 ZORBAX C_(18)柱(4.6mm×250mm,5μm);流动相为甲醇-水(25:75);流速1.0 mL·mm~(-1);检测波长:270nm;进样量:10μL。结果:方法的线性范围为0.001-1.0mg·mL~(-1)(r=0.9998);检测限为0.2μg·mL~(-1);精密度 RSD 为0.23%(n=7);高、中、低浓度回收率(n=3)分别为98.8%(RSD为0.5%)、99.2%(RSD 为0.2%,)、99.0%(RSD 为0.3%)。结论:本法具有专属、灵敏、快速、准确的特点,可用于骨肽注射液中的苯酚测定。     

明目地黄丸中牡丹皮、白芍的含量测定

目的:建立紫外分光光度法测定明目地黄丸中牡丹皮、白芍两味中药总丹皮酚含量.方法:按<中国药典>2000年版一部收载六味地黄丸中牡丹皮含量测定方法,以水蒸气蒸馏丹皮酚,通过测定274nm最大吸收波长处紫外吸收进行含量测定.结果:该方法的线性范围2.00～10.00μg/ml(r=0.9996,n=5),平均回收率为99.7%RSD=0.8%(n=5).结论:本法简便,准确,灵敏度高,重现性好,结果稳定可靠.