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1.
Acta Crystallogr E Crystallogr Commun ; 74(Pt 2): 212-216, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29850056

RESUMO

Two new crystal structures of eight- and ten-membered cyclic bis-anisyl-phosphono-thioyl disulfanes, namely 2,5-bis-(4-meth-oxy-phen-yl)-1,6,3,4,2λ5,5λ5-dioxadi-thiadi-phospho-cane-2,5-di-thione, C16H18O4P2S4, and 2,5-bis-(4-meth-oxy-phen-yl)-1,6,3,4,2λ5,5λ5-dioxadi-thia-diphosphecane-2,5-di-thione, C18H22O4P2S4, have been determined and compared to structures of the ferrocenyl analogues. The eight-membered rings have similar conformations (TBC) but the ten-membered macrocycles are differently puckered. Structural parameters of the relevant SPSSPS motif have been analysed and are discussed in detail. Compound 1 was refined as an inversion twin and 2 was refined as a two-component rotational twin.

2.
Food Chem ; 214: 587-596, 2017 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-27507514

RESUMO

The procedure for the isothiocyanates (ITCs) determination that involves derivatization with N-acetyl-l-cysteine (NAC) and separation by HPLC was developed. Prior to derivatization, plant ITCs were isolated and purified using solid-phase extraction (SPE). The optimum conditions of derivatization are: 500µL of isopropanolic eluate obtained by SPE combined with 500µL of derivatizing reagent (0.2M NAC and 0.2M NaHCO3 in water) and reaction time of 1h at 50°C. The formed dithiocarbamates are directly analyzed by HPLC coupled with diode array detector and mass spectrometer if required. The method was validated for nine common natural ITCs. Calibration curves were linear (R(2)⩾0.991) within a wide range of concentrations and limits of detection were below 4.9nmol/mL. The recoveries were in the range of 83.3-103.7%, with relative standard deviations <5.4%. The developed method has been successfully applied to determine ITCs in broccoli, white cabbage, garden cress, radish, horseradish and papaya.


Assuntos
Acetilcisteína/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida/métodos , Isotiocianatos/química , Espectrometria de Massas/métodos , Plantas/química , Extração em Fase Sólida/métodos
3.
Food Chem ; 157: 105-10, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-24679758

RESUMO

Meat consumption represents a dietary risk factor increasing the incidence of common cancers, probably due to carcinogenic amines (HAAs) formed upon meat heating. Interestingly, cancers whose incidence is increased by meat consumption, are decreased in populations consuming brassica vegetables regularly. This inverse correlation is attributed to brassica anticarcinogenic components, especially isothiocyanates (ITCs) that stimulate detoxification of food carcinogens. However, ITC reactivity towards amines generating stable thioureas, may also decrease mutagenicity of processed meat. We confirmed here that combining meat with cabbage (fresh or lyophilized), in proportions found in culinary recipes, limited by 17-20% formation of HAAs and significantly lowered mutagenic activity of fried burgers. Moreover, MeIQx mutagenicity was lowered in the presence of ITCs, as well as for synthetic ITC-MeIQx conjugates. This suggests that formation of thioureas could lead to chemical detoxification of food carcinogens, reducing the cancer risk associated with meat consumption.


Assuntos
Brassica/química , Carne/análise , Mutagênicos/análise , Carcinógenos/análise , Compostos Heterocíclicos , Humanos , Incidência , Isotiocianatos , Fatores de Risco
4.
Magn Reson Chem ; 43(1): 27-30, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15390022

RESUMO

The 15N NMR spectra of three N-alkyl-delta-carbomethoxyvalerothiohydroxamic acids (2) and six synthesized N-isopropylbenzothiohydroxamic acids (3) were measured and compared with appropriate spectra of structurally similar hydroxylamines (1), benzohydroxamic acids (4), benzamides (5) and thiobenzamides (6). The analysis of the chemical shifts of the thiohydroxamic acids under investigation indicates that the inductive effect of the hydroxyl group rather than steric hindrance is responsible for non-additivity of the effect of substituents. Additionally, N-hydroxyl diminishes the effect of aromatic ring substituents on the 15N chemical shifts in the thiohydroxamic acids 3 which is approximately half that in the respective thiobenzamides 6. The chemical shift values correlate best with Brown's sigma+ parameter.


Assuntos
Ácidos Hidroxâmicos/química , Hidroxilaminas/química , Espectroscopia de Ressonância Magnética/métodos , Alquilação , Conformação Molecular , Isótopos de Nitrogênio , Compostos de Sulfidrila/química
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