RESUMEN
Broccoli sprouts contain health-promoting glucosinolate and phenolic compounds that can be enhanced by applying ultraviolet light (UV). Here, the effect of UVA or UVB radiation on glucosinolate and phenolic profiles was assessed in broccoli sprouts. Sprouts were exposed for 120 min to low intensity and high intensity UVA (UVAL, UVAH) or UVB (UVBL, UVBH) with UV intensity values of 3.16, 4.05, 2.28 and 3.34 W/m², respectively. Harvest occurred 2 or 24 h post-treatment; and methanol/water or ethanol/water (70%, v/v) extracts were prepared. Seven glucosinolates and 22 phenolics were identified. Ethanol extracts showed higher levels of certain glucosinolates such as glucoraphanin, whereas methanol extracts showed slight higher levels of phenolics. The highest glucosinolate accumulation occurred 24 h after UVBH treatment, increasing 4-methoxy-glucobrassicin, glucobrassicin and glucoraphanin by ~170, 78 and 73%, respectively. Furthermore, UVAL radiation and harvest 2 h afterwards accumulated gallic acid hexoside I (~14%), 4-O-caffeoylquinic acid (~42%), gallic acid derivative (~48%) and 1-sinapoyl-2,2-diferulolyl-gentiobiose (~61%). Increases in sinapoyl malate (~12%), gallotannic acid (~48%) and 5-sinapoyl-quinic acid (~121%) were observed with UVBH Results indicate that UV-irradiated broccoli sprouts could be exploited as a functional food for fresh consumption or as a source of bioactive phytochemicals with potential industrial applications.
Asunto(s)
Brassica/efectos de la radiación , Glucosinolatos/análisis , Fenoles/análisis , Brassica/química , Alimentos Funcionales , Glucosinolatos/química , Glucosinolatos/efectos de la radiación , Estructura Molecular , Fenoles/química , Fenoles/efectos de la radiación , Plantones/química , Plantones/efectos de la radiación , Factores de Tiempo , Rayos UltravioletaRESUMEN
This study focuses on the feasibility of a spectroscopic multivariate method for monitoring the concentration of phenol and its main degradation products during heterogeneous photocatalysis. Phenolic compounds were chosen as model to evaluate the degradation process due to their toxicity and persistence in the environment and also their well-known degradation pathway. The predictive capability of the multivariate method developed by partial least squares regression (PLSR) over the spectral range of 200-350 nm was satisfactory, allowing mean predicted errors below 5.0 % in the simultaneous determination of the target compounds using six latent variables and smoothing spectra. Suitable results were reported for the simultaneous determination of hydroquinone, resorcinol, pyrocatechol, and p-benzoquinone in accordance to the chromatographic method. Characteristics such as simplicity, low cost, and fast data acquisition are remarkable in this procedure, which makes it appropriate for this type of analytical control.
Asunto(s)
Modelos Químicos , Fenoles , Titanio/química , Fenoles/análisis , Fenoles/química , Fenoles/efectos de la radiación , FotólisisRESUMEN
The photoelectrocatalytic (PEC) degradation of 4-nonylphenol ethoxylate (NP4EO) using a low, moderate, or high UV photon flux in different treatment times was investigated. The byproducts were verified using gas chromatography with flame ionization detection (GC-FID) and gas chromatography with quadrupole mass analyzer (GC-qMS). The GC results showed that the use of a low (2.89 µmol m(-2)s(-1)) or a high (36.16 µmol m(-2)s(-1)) UV photon flux reaching the anode surface was associated to the production of alcohols and the toxic byproduct nonylphenol (NP), leading to the same degradation pathway. Meanwhile, the use of a moderate UV photon flux (14.19 µmol m(-2)s(-1)) reaching the anode surface did not produce alcohols or the NP toxic byproduct. This study demonstrates that different UV photon fluxes will have an influence in the degradation of NP4EO with or without generation of toxic byproducts. Furthermore, it is concluded that, after the determination of the UV photon flux able to degrade NP4EO without NP formation, the treatment time is essential in removal of NP4EO, since increasing the treatment time of 4 to 10 h, when using the PEC best conditions (moderate UV photon flux), implies in a higher treatment efficiency.
Asunto(s)
Disruptores Endocrinos/química , Fenoles/química , Fotones , Rayos Ultravioleta , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Electrólisis , Disruptores Endocrinos/efectos de la radiación , Ionización de Llama , Cromatografía de Gases y Espectrometría de Masas , Fenoles/efectos de la radiación , Fotólisis , Factores de Tiempo , Contaminantes Químicos del Agua/efectos de la radiaciónRESUMEN
Trans-resveratrol (RES) is used in cosmetic formulations and beta-carotene (BTC) is a classical sunscreen antioxidant, but their photostability in sunscreens, a property directly correlated to performance and safety has not been addressed in the literature. This paper reports the assessment of RES and/or BTC influence on the photostability of five UV-filters (octyl methoxycinnamate - OMC, avobenzone -AVO, octocrylene - OCT, bemotrizinole - BMZ, octyltriazone - OTZ) in three different combinations after UVA exposure followed by the identification of degradation products and the assessment of photoreactivity. The evaluation of sunscreen photostability was performed by HPLC and spectrophotometric analysis, and degradation products were identified by GC-MS analysis. Components RES, BTC, OMC and AVO were significantly degraded after UV exposure (reduction of around 16% in recovery). According to HPLC analysis, all formulations presented similar photostability profiles. Eleven degradation products were identified in GC-MS analysis, among them products of RES, BTC, OMC and AVO photodegradation. All evaluated formulations were considered photoreactive, as well as the isolated compounds RES and AVO. Considering HPLC, spectrophotometric and GC-MS results, it is suggested that formulations containing BMZ were considered the most photostable. The combination RES+BTC in a sunscreen improved the photostability of AVO. The benefits of using a combination of antioxidants in sunscreens was demonstrated by showing that using RES+BTC+studied UV-filters led to more photostable formulations, which in turn implies in better safety and efficacy.
Asunto(s)
Estilbenos/efectos de la radiación , Protectores Solares/efectos de la radiación , Rayos Ultravioleta , beta Caroteno/efectos de la radiación , Acrilatos/efectos de la radiación , Benzoatos/efectos de la radiación , Cromatografía Líquida de Alta Presión , Cinamatos/efectos de la radiación , Estabilidad de Medicamentos , Cromatografía de Gases y Espectrometría de Masas , Fenoles/efectos de la radiación , Fotólisis , Propiofenonas/efectos de la radiación , Resveratrol , Oxígeno Singlete/química , Espectrofotometría Ultravioleta , Superóxidos/química , Triazinas/efectos de la radiaciónRESUMEN
This study aimed to assess the phototoxic potential of combined UV-filters and retinyl palmitate (RP) in the presence or not of bemotrizinol (BMTZ), employing photostability and in vitro and in vivo phototoxicity assays. The formulations tested contained octocrylene (OCT), octyl methoxycinnamate (OMC), benzophenone-3 (BZP-3) and RP (photostable) or octocrylene (OCT), octyl methoxycinnamate (OMC), avobenzone (AVO) and RP (less photostable). Both formulations were supplemented with bemotrizinol. Photostability was evaluated by exposing, or not, formulations spread on a glass plate to UVA/UVB irradiation. The resulting products were quantified by HPLC analysis. In vitro phototoxicity of UV-filters and combinations were evaluated using 3T3 viable monolayer fibroblast cultures submitted, or not, to irradiation according to OECD TG 432. In vivo photoallergy and photoxicity were assessed by clinical studies (photopatch test). Photostability assays showed that UV-filter bemotrizinol was a better photostabilizer for RP/benzophenone-3 than for RP/avobenzone. The in vitro phototoxicity of the combination RP/avobenzone was reduced by bemotrizinol. Clinical studies did not indicate phototoxic or photoallergenic potentials in all formulations tested. It is concluded that the 3T3 NRU phototoxicity test may be considered a supplementary assay in formulation developments, since it can detect chemically unstable and potentially phototoxic combinations. However, extrapolation of in vitro positive results to human photopatch tests may be performed only to a limited extent.
Asunto(s)
Dermatitis Fotoalérgica/etiología , Dermatitis Fototóxica/etiología , Fenoles/efectos adversos , Protectores Solares/efectos adversos , Triazinas/efectos adversos , Vitamina A/análogos & derivados , Células 3T3 , Acrilatos/efectos adversos , Acrilatos/farmacología , Acrilatos/efectos de la radiación , Adolescente , Adulto , Anciano , Animales , Benzofenonas/efectos adversos , Benzofenonas/farmacología , Benzofenonas/efectos de la radiación , Cinamatos/efectos adversos , Cinamatos/farmacología , Cinamatos/efectos de la radiación , Diterpenos , Método Doble Ciego , Interacciones Farmacológicas , Estabilidad de Medicamentos , Humanos , Ratones , Persona de Mediana Edad , Rojo Neutro/metabolismo , Fenoles/farmacología , Fenoles/efectos de la radiación , Ésteres de Retinilo , Medición de Riesgo , Protectores Solares/farmacología , Protectores Solares/efectos de la radiación , Triazinas/farmacología , Triazinas/efectos de la radiación , Rayos Ultravioleta , Vitamina A/efectos adversos , Vitamina A/farmacología , Vitamina A/efectos de la radiación , Adulto JovenRESUMEN
In this work, a saline aqueous solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a falling-film solar reactor. The influence of the parameters such as initial pH (5-7), initial concentration of Fe2+ (1-2.5mM) and rate of H202 addition (1.87-3.74mmol min-1) was investigated. The efficiency of photodegradation was determined from the removal of dissolved organic carbon (DOC), described by the species degradation of phenol, 2,4-D and 2,4-DCP. Response surface methodology was employed to assess the effects of the variables investigated, i.e. [Fe2+], [H202] and pH, in the photo-Fenton process with solar irradiation. The results reveal that the variables' initial concentration of Fe2+ and H202 presents predominant effect on pollutants' degradation in terms of DOC removal, while pH showed no influence. Under the most adequate experimental conditions, about 85% DOC removal was obtained in 180 min by using a reaction system employed here, and total removal of phenol, 2,4- and 2,4-DCP mixture in about 30min.
Asunto(s)
Ácido 2,4-Diclorofenoxiacético/química , Peróxido de Hidrógeno/química , Hierro/química , Fenoles/química , Fotoquímica/instrumentación , Cloruro de Sodio/química , Energía Solar , Purificación del Agua/instrumentación , Ácido 2,4-Diclorofenoxiacético/aislamiento & purificación , Ácido 2,4-Diclorofenoxiacético/efectos de la radiación , Mezclas Complejas/química , Mezclas Complejas/aislamiento & purificación , Mezclas Complejas/efectos de la radiación , Suministros de Energía Eléctrica , Diseño de Equipo , Análisis de Falla de Equipo , Peróxido de Hidrógeno/efectos de la radiación , Hierro/efectos de la radiación , Fenoles/aislamiento & purificación , Fenoles/efectos de la radiación , Fotoquímica/métodos , Cloruro de Sodio/efectos de la radiaciónRESUMEN
A new chemical structure, the 4,2',4",2'''-tetrahydroxy-6',6'''-dimethoxy-4'-O-4'''- bichalcone, named achyrobichalcone was isolated and identified from an Achyrocline satureioides spray-dried powder (SDP80). The thermal and photo stability of this new compound as well as that of the main polyphenols present in the spray dried powder, quercetin, luteolin, 3-O-metylquercetin and the corresponding kinetics of degradation are reported. In the long-term testing (30 +/- 2 degrees C/75 +/- 5% RH, 12 months), the total polyphenols contained in SDP80 demonstrated to be stable, remaining higher than 90% after a 12 month exposure. The photo stability testing revealed that all polyphenols were stable for 48 h when SDP80 was conditioned in amber or transparent flasks and exposed to UV-C radiation (light express LE UV, 254 nm, 30W). In contrast, when unprotected, the polyphenols demonstrated to be sensitive to both, thermal stress testing (80 +/- 2 degrees C), for 14 days and to UV-C radiation. Luteolin showed to be the most stable against UVC light and 3-O-methylquercetin against temperature. The achyrobichalcone demonstrated to be the more unstable against both, temperature and light. The kinetics of polyphenol thermal degradation (80 +/- 2 degrees C, 49 days) and photodegradation (UV-C radiation, 96 h) followed, 2nd and 1st order reaction, respectively.
Asunto(s)
Achyrocline/química , Chalconas/análisis , Chalconas/efectos de la radiación , Cromatografía Líquida de Alta Presión , Desecación , Estabilidad de Medicamentos , Etanol , Calor , Cinética , Luz , Espectroscopía de Resonancia Magnética , Fenoles/análisis , Fenoles/efectos de la radiación , Extractos Vegetales/análisis , Polvos , Estándares de Referencia , SolventesRESUMEN
Bisphenol A (BPA), a chemical compound largely used in the plastics industry, can end up in aquatic systems, which it disturbs by its endocrine disrupting effect (EDE). This study investigated the BPA degradation upon ultrasonic action under different experimental conditions. The effect of saturating gas (oxygen, argon and air), BPA concentration (0.15-460 micromol L(-1)), ultrasonic frequency (300-800 kHz) and power (20-80 W) were evaluated. For a 118 micromol L(-1)-BPA solution, with the best performance obtained at 300 kHz, 80 W, with oxygen as saturating gas. In these conditions, BPA can be readily eliminated by the ultrasound process (approximately 90 min). However, even after long ultrasound irradiation times (9 h), more than 50% of chemical oxygen demand (COD) and 80% of total organic carbon (TOC) remained in the solution. Analyses of intermediates using HPLC-MS investigation identified several products: monohydroxylated bisphenol A, 4-isopropenylphenol, quinone of monohydroxylated bisphenol A, dihydroxylated bisphenol A, quinone of dihydroxylated bisphenol A, monohydroxylated-4-isopropenylphenol and 4-hydroxyacetophenone. The presence of these hydroxylated aromatic structures showed that the main ultrasonic BPA degradation pathway is related to the reaction of BPA with the *OH radical. After 2h, these early products were converted into biodegradable aliphatic acids.
Asunto(s)
Fenoles/química , Fenoles/efectos de la radiación , Compuestos de Bencidrilo , Catálisis , Cromatografía Líquida de Alta Presión , Gases , Peróxido de Hidrógeno/química , Hierro , Cinética , Espectrometría de Masas , Fenoles/análisis , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría Ultravioleta , UltrasonidoRESUMEN
Advanced oxidation processes are an emerging option to treatment of the painting industry effluents. The aim of this study was to compare the effectiveness of the Fenton and photo-Fenton processes in chemical oxygen demand (COD), total organic carbon (TOC) and phenolic compounds removal from wastewaters generated during alkydic resins manufacture. The optimized treatment conditions are the following: pH 3.0, 15.15x10(-3)molL(-1) FeSO(4) and 0.30molL(-1) H(2)O(2) for a reaction time of 6h. photo-Fenton experiments were carried out in the presence of sunlight or artificial radiation and complementary additions of H(2)O(2) were made for all experiments. The best results were obtained with photo-Fenton process assisted with solar radiation, with reductions of 99.5 and 99.1% of COD and TOC levels, respectively. Fenton and photo-Fenton (with artificial irradiation) processes presented lower but not insignificant removals, within 60-80% reduction for both COD and TOC. In addition, an excellent removal (95%) of total phenols was obtained using photo-Fenton process assisted with artificial irradiation. This study demonstrated that the use of photo-Fenton process on alkydic resins wastewater treatment is very promising especially when solar light is used.
Asunto(s)
Fenoles/química , Fenoles/efectos de la radiación , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/efectos de la radiación , Carbono/análisis , Peróxido de Hidrógeno/química , Residuos Industriales , Hierro/química , Oxidantes/química , Oxidación-Reducción , Oxígeno/química , Pintura , Rayos UltravioletaRESUMEN
Laser flash photolysis (LFP) studies, atoms in molecules (AIM) studies, and density functional theory (DFT) calculations have been performed in order to study the mechanism of the hydrogen abstraction by alpha-diketones in the presence of phenols. Laser irradiation of a degassed solution of 1,2-diketopyracene in acetonitrile resulted in the formation of a readily detectable transient with absorption at 610 nm, but with very low absorptivity. This transient decays with a lifetime of around 2 micros. The quenching rate constant for substituted phenols, kq, ranged from 1.10x10(8) L mol-1 s-1 (4-cyanophenol) to 3.87x10(9) L mol-1 s-1 (4-hydroxyphenol). The Hammett plot for the reaction of the triplet of 1,2-diketopyracene with phenols gave a reaction constant rho=-0.9. DFT calculations (UB3LYP/6-311++G**//UB3LYP/6-31G*) of the triplet complex ketone-phenol revealed that hydrogen transfer has predominantly occurred and that the reaction with alpha-diketones are generally 7 kcal/mol less endothermic than the respective reactions of the monoketones. These results together with the geometries obtained from the DFT calculations, natural bond order (NBO) analysis, and AIM results indicate that hydrogen abstraction for alpha-diketones is facilitated by the electrophilicity of the ketone, instead of neighboring group participation by the second carbonyl group.
Asunto(s)
Cetonas/química , Cetonas/efectos de la radiación , Rayos Láser , Modelos Químicos , Fenoles/química , Fenoles/efectos de la radiación , Compuestos Policíclicos/química , Compuestos Policíclicos/efectos de la radiación , Modelos Moleculares , Estructura Molecular , Fotólisis , Rayos UltravioletaRESUMEN
Thermal and the photo stabilities of an Achyrocline satureioides powder (SDP40) were evaluated in particular concerning the total polyphenol content as well as the main identified constituents quercetin, luteolin, 3-O-methylquercetin and caffeic acid. SDP40 presented good stability for nine months under normal storage conditions of 25 degrees C temperature and 60% relative humidity (RH). In accelerated term testing, 50 degrees C temperature and 90% RH and also in stress testing, 80 degrees C, caffeic acid and a non-identified constituent P3 were the most instable constituents. Luteolin and 3-O-methylquercetin were the most stable constituents. Quercetin presented an unusual behavior, improving its concentration after 1 month at 50 degrees C or 2 days at 80 degrees C exposition, followed by a decrease in its concentration. The hypothesis that this observation is related to the simultaneous decreasing of a non-identified peak P3 or to the hydrolysis of a non-identified precursor as a quercetin heteroside is being investigated. The SDP40 presented good stability against UV-C light when conditioned in amber or transparent containers, but it suffered degradation when stored in open-dishes. In summary, the total polyphenol content remains within acceptable limits of 10% under normal storage conditions for nine months. However, the LC polyphenol analysis demonstrated that the behavior of individual constituents has still to be enlightened.