两种荧光染料的光稳定性研究

采用标准氙灯分别光照自制的苯乙烯吡啶盐阳离子荧光橘红DHEASPBr-C2和市售的阳离子荧光黄X-10GFF染色腈纶织物,探究两种染料光稳定性。在染料0.05%（omf）条件下,阳离子荧光黄X-10GFF染色腈纶织物的荧光强度大于阳离子荧光橘红DHEASPBr-C2;在标准氙灯光照条件下,两只染料均发生不同程度的光褪色,前者略好于后者。采用量子化学中的密度泛函方法(DFT),揭示两种染料光降解机理。阳离子荧光橘红DHEASPBr-C2因具有较多的活泼位点,更易在空气中发生光褪色。     

Monoammonium glycyrrhizinate stability in aqueous buffer solutions

The objective of this research is to evaluate the thermal stability of monoammonium glycyrrhizinate. Thermodegradation of solutions of monoammonium glycyrrhizinate at various temperatures (50, 70 and 90°C) was studied. This degradation appeared to follow first-order kinetics independently of temperature and was found to be pH dependent. The experiments revealed an activation energy (E_a) of about 33 kJ mol⁻¹ and a t_90% of about 3 years at 20°C in a pH range from 7 to 9. So it can be concluded that monoammonium glycyrrhizinate is stable in a pH range from 7 to 9. It can be interesting for use in oral care or in food industry. © 1998 SCI.     

酶处理异槲皮苷对辣椒红素光稳定性的影响

目的考察酶处理异槲皮苷(enzymatically modified isoquercitrin,EMIQ)对辣椒红素光稳定性的影响。方法使用氙灯光照老化箱对pH 3、4和5(柠檬酸-柠檬酸钠缓冲体系)下的EMIQ和辣椒红素混合溶液进行光照实验(340 nm,0.4±0.1 W/m~2,(55±5)℃),检测光照4 h中连续取得样品的Lab值和OD464。根据计算得到的总色差△E*和色素分解率评价色素的光稳定性,通过250~800 nm的光谱扫描图分析EMIQ能作为辣椒红素护色剂的原因。结果在排除温度对辣椒红素的稳定性影响后,氙灯老化箱的光照实验表明光是引起辣椒红素褪色的主要原因,溶液p H对辣椒红素的稳定性影响不大,EMIQ能够提高辣椒红素的光稳定性,用量越高效果越好。结论 EMIQ不能对辣椒红素的热稳定性造成影响,但能够显著提高辣椒红素的光稳定性,与以辅色苷的形式提高花青素的光稳定性不同,EMIQ主要通过吸收UV-A对辣椒红素进行保护。     

抗紫外线整理改善漂白羊绒的耐光稳定性

为改善漂白羊绒织物的耐光稳定性,对其进行抗紫外线整理,优化的工艺为:整理剂质量分数5％、整理温度60℃、整理时间30 min.整理后羊绒织物的UPF值达90以上,白度略有下降.在人造光源下连续辐照40 h,或者UVA光源下连续辐照168 h,羊绒织物白度变化很小,表明抗紫外线整理可以明显改善漂白羊绒的耐光稳定性.     

苯并三唑结构紫外线吸收剂对蚕丝耐光稳定性能的影响

为提升蚕丝织物的耐光稳定性能,采用苯并三唑结构紫外线吸收剂UV-FAST W（简称UVFW）对其进行处理,并将处理蚕丝进行紫外光照实验,测试了蚕丝的光照黄变历程,分析了UVFW浓度对蚕丝光黄变与光脆损的影响,探讨了UVFW处理蚕丝的湿牢度问题,同时还研究了UVFW对染色蚕丝颜色指标与光色牢度的影响。结果表明：经1%浓度UVFW处理的蚕丝,光稳定性能得到较大程度的提升,继续增加UVFW浓度,蚕丝的光稳定性能提升不明显,且UVFW浓度增加将降低蚕丝的初始白度;UVFW处理蚕丝的湿处理牢度需进一步提升,水洗后蚕丝光稳定性能明显下降;UVFW对染色蚕丝的颜色指标与光色牢度均产生影响,但影响程度与染料有关。     

Technological strategies to improve photostability of a sunscreen agent

Due to the reduction of the ozone layer, there is an increasing need of effective UV protection systems with minimized side-effects. Trans-2-ethylhexyl- p -methoxycinnamate ( trans -EHMC) represents one of the most widely used sunscreen compound. Several studies demonstrated that trans -EHMC is unstable following UV irradiation both in solution and in emulsion formulations. Moreover, various reports of photocontact sensitization induced by trans -EHMC have appeared in the literature. Consequently, in order to ensure adequate efficacy and safety for this sunscreen agent, there is a need for new carrier systems to enhance trans -EHMC photostability. In the present study the photostability of the filter in different formulation types (emulsion–gel, gel and emulsion) with various ingredients is evaluated. In addition, nanoparticles based on poly- D , L -lactide-co-glycolide (PLGA) as carrier for trans -EHMC are investigated. The influence of nanoparticle matrix on the photochemical stability of the sunscreen agent is also presented. The results obtained demonstrated that PLGA nanoparticles are effective in reducing the light-induced degradation of the sunscreen agent. Moreover, the choice of formulation type and the excipients used play an important role in order to obtain a stable cosmetic product containing trans -EHMC.     

Vitamin A palmitate photostability and stability over time

Vitamin A palmitate photostability in relation to ultravoilet A (UVA) and ultravoilet B (UVB) was tested in hydroxy ethyl cellulose hydrogels at pH 4.0, 5.6, 7.0, and 8.0, alone and with the addition of sunscreens (3,4‐methylbenzilidencamphor or butyl methoxy dibenzoylmethane) or an antioxidant (butylated hydroxy toluene). The photostability of vitamin A palmitate was also tested in encapsulated systems (Tagravit_A1 microcapsules, Lipotec_liposomes, phosphatidylcholine liposomes, and Lipotec_nanocapsules) dispersed in gels at pH 5.6 and 7.0. The stability of retinyl palmitate over time in hydroxy ethyl cellulose hydrogels at pH 5.6 and 7.0 (stored 1 month at 25 or 40 °C), alone or with butylated hydroxy toluene, was also tested. The stability of retinyl palmitate over time in encapsulated systems, dispersed in gels at pH 5.6 and 7.0, was also studied. O/W emulsions were also prepared to compare the stability of vitamin A palmitate introduced in a lipophilic/hydrophilic medium (O/W emulsions) and a hydrophilic medium (hydrogels). HPLC analysis showed that encapsulated systems such as Lipotec_nanocapsules, Tagravit_A1 microcapsules, phosphatidylcholine liposomes, and Lipotec_liposomes protect the vitamin A ester over time from hydrolysis and from oxidation to retinaldeide and retinoic acid, and that Lipotec_nanocapsules and phosphatidylcholine liposomes also improve the vitamin's photostability. A change in pH (5.6–7.0) of the gels did not influence the vitamin ester's stability. pH levels of 4.0 and 8.0 determined a decrease in the stability of retinyl palmitate in the gels. A high concentration of sunscreens improved the photostability of retinyl palmitate in the gels at pH 5.6 and 7.0. Butylated hydroxy toluene protected retinyl palmitate from degradation induced by light at all the pH levels studied and by heat at pH 5.6 and 7.0, as can be seen from the study of the photostability of vitamin A palmitate under UVB and UVA and of stability over time. Rheological studies showed a slight decrease in the viscosity of the gels after UVB–UVA irradiation and a higher decrease in the viscosity of the gels and the emulsions after storage at 25 and 40°C. This decrease can be attributed to a partial degradation of hydroxy ethyl cellulose and of emulsifier, as can be seen from the decrease in shear stress versus shear rate values under these conditions of storage, denoting a depolymerization of the rheological modifier.     

电渗析法从谷氨酸发酵液中提取谷氨酸铵的研究

探讨了利用电渗析法从谷氨酸发酵液中直接分离提取谷氨酸铵。通过模拟谷氨酸发酵液对提取工艺进行了单因素优化实验,获得了如电流密度、料液与浓缩液体积比、循环流量等优化操作条件。采用优化条件对真实谷氨酸发酵液进行电渗析分离提取谷氨酸铵,当料室pH4.7左右可观察到结晶现象。通过补加氨水调节料室pH,可明显改善电渗析的整体效果,其中浓室谷氨酸浓度达到120g/L,回收率为78.8%。     

红曲色素光稳定性评价方法的研究

以红曲色素中红色素为研究对象，研究光源、照射距离、初始吸光度、色素液厚度和光照时间对红曲红色素光稳定性测定结果的影响，确定出较佳的评价方法，光照光源紫外光，色素液的起始吸光度选1．0，色素液厚度选4．5mm，照射距离选15cm，照射时间选1h。     

各类载体对红曲红色素光稳定性的影响

水溶性蛋白类载体为目前市场销售红曲红产品中主要载体，可使红曲红色素光稳定性由35．6％提高到54．6％，海藻酸钠、明胶和β-环状糊精作载体可使红曲红色素光稳定性由35．6％分别提高到66．5％、66．3％和60．6％。     

溶胶-凝胶改善芳纶织物的耐光性

 针对高性能纤维耐光性较差的现状,采用TiO2溶胶－凝胶涂层方法改善芳纶织物的耐光性。利用动态光散射激光粒度分析仪Nano ZS分析发现,制备的TiO2水溶胶粒子尺寸和分布都很均匀。利用U-4100紫外/可见/近红外分光光度计表征,对比涂层前后织物对光的透射、反射和吸收量,发现涂层后织物耐光性提高。同时,通过扫描电镜观察,涂层后在织物表面形成TiO2水溶胶－凝胶的连续膜结构,对光辐照有较好的屏蔽作用。     

溶胶-凝胶法改善芳纶织物的耐光性

针对高性能纤维耐光性较差的现状,采用TiO2溶胶-凝胶涂层方法改善芳纶织物的耐光性.利用动态光散射激光粒度分析仪Nano ZS分析发现,制备的TiO2水溶胶粒子尺寸和分布都很均匀.利用U-4100紫外/可见/近红外分光光度计表征,对比涂层前后织物对光的透射、反射和吸收量,发现涂层后织物耐光性提高.同时,通过扫描电镜观察,涂层后在织物表面形成TiO2水溶胶一凝胶的连续膜结构,对光辐照有较好的屏蔽作用.     

半花菁荧光染料光稳定性的量子化学计算

针对纺织品用荧光染料光稳定性较差的问题,应用已合成的2种半花菁荧光染料进行研究。对染料染色腈纶织物进行光老化试验,比较2种染料的日晒牢度;进行染料水溶液的光降解试验,得到量化的染料降解速率常数。采用量子化学理论中的密度泛函方法,对2种染料阳离子进行构型优化和频率计算,并对得到的稳定构型进行分子轨道计算;通过研究各形态氧与染料阳离子前线分子轨道的相互作用,在理论上比较2种染料阳离子的活泼位点及其稳定性差异。结果表明,半花菁荧光染料1,3,3-三甲基-反式-2-[对-（N,N-二乙基）-氨基-苯乙烯基]-N-甲基吲哚氯化盐的光稳定性优于反式-4-[对-（N,N-二乙基）-氨基-苯乙烯基]-N-乙基吡啶溴化盐,计算结果与实验结果有很好的一致性,可作为判断此类染料光稳定性的理论参考。     

Proposed protocol for determination of photostability Part I: cosmetic UV filters

The protocol described here has been developed to measure the stability of UV-B filters; a modified version is recommended for UV-A filters. It should be considered as a tool to predict the effectiveness remaining after exposure to UV-A and UV-B light. It is a simple and reliable in vitro model simulating conditions of actual use. The results show that each filter requires an appropriate choice and fine tuning of reproducible analytical conditions. While absolute values are directly influenced by uncertainties in irradiance (dosimetry), comparative measurements with respect to a known standard are very reliable.     

Quartz plates for determining sun protection in vitro and testing photostability of commercial sunscreens

Testing plate made of optical quartz has been developed for the purpose of determination of sun protection factor (SPF) _in vitro by the method of diffusion transmission spectroscopy; the plates were coarsened by sanding and grinding to surface roughness values (Ra) of 18 μm. The plate was coated with a film of sunscreen by an application of 2 mg cm⁻² as that used for determination of SPF _in vivo by the COLIPA method. The transmission values measured were converted into the SPF _in vitro and the protection factor in ultraviolet A light, UVAPF _{in vitro} . The testing plate was tested with commercial sunscreens. The found values of SPF _in vitro fit well with the values determined by means of the COLIPA method in vivo . The plates coated with sunscreen film were irradiated with light simulating the sun radiation. The values of protection factors obtained before and after irradiation were compared, and the differences were used for estimation of photostability of the UV filters included.     

In vitro assessment of sunscreen photostability: the effect of radiation source, sunscreen application thickness and substrate

The photostabilities of four sunscreen products have been assessed in vitro by applying sunscreen to a substrate and measuring the spectral transmission prior to, and after exposure to a source of ultraviolet (UV) radiation. Results were independent of whether an application thickness of 1 or 2 mg/cm ; 2 was used, and whether the UV source was natural sunlight or a xenon arc solar-simulator. There were significant differences, however, between results obtained on a roughened quartz substrate and those obtained on excised human epidermis. It is unlikely that any substrate will give an exact representation of the in vivo situation and, indeed, both quartz and excised human epidermis have disadvantages associated with their use. However, the ranking of the four products in terms of their photostability was the same for both substrates. This implies that transmission spectroscopy, with either a quartz or a human epidermis substrate, can be used successfully to compare the photostabilities of different sunscreen products.     

Comparative evaluation of different substrates for the in vitro determination of sunscreen photostability: spectrophotometric and HPLC analyses

Polymethylmethacrylate (PMMA) plates and Transpore^TM tapes were compared as substrates for the in vitro evaluation of photostability of commercial sunscreen products. The sun care preparations were applied respectively on Transpore^TM tapes and PMMA plates and their sun protection factors (SPF) and UVA protection parameters [UVA/UVB ratio, critical wavelength, UVA protection factor (UVA‐PF)] were measured by transmission spectroscopy, before and after irradiation with simulated sunlight. No significant differences were observed in the UV protection parameters measured on Transpore^TM tapes or PMMA plates, before exposure to the solar simulator. Conversely, after irradiation, the SPF values of the sun care products exhibited marked variations between the two substrates, the decrease in SPF being greater on PMMA plates (31.3–63.1%) than on Transpore^TM tapes (10.4–23.8%). Differences between the two substrates were detected also for the UVA protection parameters, although they were significant only for the UVA‐PF. The tested samples were assayed also by high‐performance liquid chromatography (HPLC) to assess the extent of photodegradation of the UV filters present in the examined formulations. The results showed that for the PMMA plates, the light‐induced decrease in SPF, as determined by spectrophotometry, fitted well with the percentage loss of ethyl hexyl methoxycinnamate (the only photounstable UVB filter present) measured by HPLC. Moreover, for the PMMA substrate, the UVA‐PF percentage reduction was consistent with the percentage degradation of butyl methoxydibenzoylmethane (the only photounstable UVA filter present) determined by HPLC. On the other hand, poor correlation between spectrophotometric and HPLC analyses was observed on Transpore^TM tapes. Therefore, PMMA plates are more reliable than Transpore^TM tapes as substrates for in vitro photodegradation tests of sunscreen products by transmission spectroscopy.     

反相高效液相色谱法测定不同品种花生白藜芦醇含量

研究了超声波辅助乙醇提取及大孔树脂初步纯化花生根中白藜芦醇的工艺条件。以花生根白藜芦醇的提取率为指标,考查了乙醇浓度、超声功率、超声时间和料液比对提取率的影响。结果表明,通过单因素实验和响应面法优化的最佳条件如下：乙醇浓度90%、超声功率290 W、超声时间12 min、料液比1:38（g/mL）,白藜芦醇的含量为175.53±1.57 μg/g。通过方差分析发现：超声时间、超声功率和乙醇浓度对白藜芦醇含量的影响达到显著水平（P<0.05）。最佳条件下为树脂H103,上样浓度201.13 μg/mL,上样速率为1.0 mL/min,上样量为120 mL,洗脱溶剂为90%乙醇,洗脱流速为1.0 mL/min,洗脱量为160 mL,一次处理后,粗产品中白藜芦醇的含量为49.19%±0.81%,RSD为1.65%。超声辅助提取白藜芦醇和大孔树脂初步纯化白藜芦醇是可行的。