A study on 2-(2'-hydroxyphenyl) benzoxazoles derivatives as potential organic UV filters, Part I

Abstract Damage resulting from the incidence of ultraviolet (UV) radiation on the skin is common nowadays, with UVB (290-320 nm) and UVA (320-400 nm) radiation responsible for photoaging, sunburn and carcinogenesis. For this reason, sunscreens represent products of growing interest to prevent such damage. However, there are few organic filters marketed worldwide with photostability and effectiveness at wavelengths greater than 340 nm (long UVA), which justifies the exploration for new compounds. In this work, we determined the photostability and sun protection factor (SPF) of three 2-(2'-hydroxyphenyl)benzoxazole derivative dyes in order to develop new organic UV filters. UV-vis spectrophotometry has high level of reproducibility when compared with in vivo human clinical methods. Solubility determinations were performed in different solvents. The compounds absorbed UVA and UVB radiation, with maximum absorption wavelengths ranging from 336 to 374 nm. Photostability was evaluated using a solar simulator (3 J.m2.s-1 UVA radiation) for a maximum of 3 h. The 2-(amino-2'-hydroxyphenyl) benzoxazoles showed higher photostability than the acetylated derivative under the evaluated conditions. The three benzoxazoles presented SPF values of around 40 and preliminary results indicate that they show suitable properties to act as good chemical filters in photoprotective formulations.

Enhancing The Sunscreen Efficacy Of Bemotrizinol Micropigment By Using O/W Nanoemulsion Topical Preparations

Objective: Bemotrizinol (BEMT) is the most efficient broad-spectrum UV-absorber having a dual mechanism of action in absorbing and reflecting photons. The main objective of this work was to develop successful oil in water (o/w) nanoemulsion for improving the solubility of BEMT and its protective characteristics. Methods: Pseudo-ternary phase diagrams were constructed using labrafac PG and isopropyl myristate as oil phase, tween 80 as surfactant (S) and cremophor EL as cosurfactant (CoS) the ratio of S/CoS was determined according to highest percent of water incorporation to the system. Full factorial study design (24) using Design-Expert® software was adopted to study the effect of four independent variables namely: oil type, oil concentration, S/CoSmix (3:1) concentrations and BEMT concentration on the particle size and the in vitro release at 2 h (Q2h) of the prepared nanoemulsion formulae. Two systems each of eight formulae were developed and evaluated through droplet size analysis, zeta potential measurement, refractive index, in vitro drug release and according to the desirability value two formulae (F6 and F14) were used for further evaluations including in vitro sun protection factor (SPF), ex-vivo deposition by tape stripping technique, permeation test and photostability study. Results: Formula (F14) was chosen as the optimum formula having an in vitro SPF of 16.08±0.39, lowest permeation of 140±0.06 μg/cm2after six h and highest photostability (t90% = 168.02) after 120 min. Conclusion: Despite the poor solubility of bemotrizinol, it could be enhanced by novel drug delivery systems with good SPF value while maintaining its photostability.

Desenvolvimento, caracterização e avaliação da formação de complexos de inclusão de rutina, avobenzona e ρ-metoxicinamato de octila na presença de ciclodextrinas / Development, characterization and evaluation of inclusion complexes between rutin, avobenzone and octyl ρ-methoxycinnamate with cyclodextrins

A radiação UV pode causar danos à pele humana, e, evitar estes danos, é uma preocupação crescente para a população e um desafio à comunidade científica. Para uma ação efetiva de fotoproteção, a associação de filtros, como avobenzona (BMBM) e ρ-metoxicinamato de octila (EHMC), são empregados. Devido à semelhança estrutural com os filtros solares químicos, a rutina (RUT), tal como outros flavonoides, apresenta atividade fotoprotetora. Apesar da disponibilidade de diferentes classes de filtros solares, o desenvolvimento de fotoprotetores contendo filtros químicos é um desafio, devido à instabilidade inerente a certos filtros orgânicos. As ciclodextrinas (CDs) são oligossacarídeos cíclicos, de formato tronco-cônico, cuja estrutura externa é hidrófilica e sua cavidade interna central hidrofóbica, com a capacidade de acomodar substâncias lipofílicas, formando complexos de inclusão. A formação dos complexos de inclusão pode levar à alterações de propriedades físico-químicas da molécula hóspede, tais como, solubilidade, fotoestabilidade e biodisponibilidade. O objetivo deste trabalho foi desenvolver, caracterizar e avaliar a formação de complexos de inclusão entre RUT, BMBM e EHMC e as CDs (HPßCD e SBEßCD). Os complexos de inclusão (RUT:HPßCD, RUT:SBEßCD, BMBM:HPßCD, BMBM:SBEßCD, EHMC:HPßCD e EHMC:SBEßCD) foram obtidos pelo método de liofilização e quantificados por cromatografia líquida de alta eficiência (CLAE). Os sistemas binários foram caracterizados em solução, pelo método de equilíbrio de solubilidade, e, no estado sólido, empregando calorimetria exploratória diferencial (DSC), termogravimetria (TG/DTG) e difração de raios-X de pó (PDRX). As substâncias isoladas e os complexos binários foram avaliados quanto à fotoestabilidade em estado sólido, e, em solução. Incremento na solubilidade (X mcg mL-1) foi observado para os complexo RUT:HPßCD (4,13x); RUT:SBEßCD (4,38x); BMBM:HPßCD (43,3x); BMBM:SBEßCD (53,3x); EHMC:HPßCD (12,7x); e EHMC:SBEßCD (70,0x). Os ensaios de DSC, TG/DTG, e P-DRX indicaram a formação de complexos de inclusão para os todos os sistemas, onde a supressão dos eventos endotérmicos característicos das substâncias isoladas foram observados; porém, nos complexos de BMBM, a presença de avobenzona livre no meio foi detectada, sugerindo, que a complexação não foi completa. A formação dos complexos de inclusão promoveu o aumento da fotoestabilidade em todos os sistemas avaliados, tanto no estado sólido, como em solução. Os resultados reportados neste estudo, indicaram que a complexação de substâncias fotoprotetoras com HPßCD e SBEßCD, pode representar, uma estratégia promissora quanto ao aumento da solubilidade e da fotoestabilidade

UV radiation may cause demage on human skin, and preventing it, is an increasing worry for the population and a challenge to the scientific community. For an effective action of photoprotection, the association of filters, like avobention (BMBM) and octyl ρ-methoxycinnamate (EHMC), are used. Due to the structural similarity with the chemical solar filters, the rutin (RUT), like other flavonoids, shows photoprotective activity. Despite the availability of different classes of sunscreens, the development of photoprotectors containing chemical filters is a challenge, due to the inherent instability of certain organic filters. The cyclodextrins (CD) are cyclic oligosaccharides of truncated conical structure, which external structure is hydrophilic and its internal central hydrophobic cavity, with capacity to accommodate lipophilic substances, forming inclusion complexes. The formation of the inclusion complexes can lead to changes in physicalchemical properties of the host molecule, such as, solubility, photostability and bioavailability. The objective of this work was to develop, characterize and evaluate the formation of the inclusion complexes between RUT, BMBM and EHMC and the CDs (HPßCD and SBEßCD). The inclusion complexes (RUT:HPßCD, RUT:SBEßCD, BMBM:HPßCD, BMBM:SBEßCD, EHMC:HPßCD and EHMC:SBEßCD) were obtained by the lyophilization method and quantified by high performance liquid chromatography (HPLC). The binary systems were characterized in solution, by solubility equilibrium method and in solid state, using differential scanning calorimetry (DSC), thermogravimetry (TG/DTG) and powder X-ray diffraction (P-XRD). The isolated substances and binary complexes were evaluated the photostability in solid state, and in solution. The increase in solubility (X mcg mL-1) was observed for the complexes RUT:HPßCD (4.13x); RUT:SBEßCD (4.38x); BMBM:HPßCD (43.3x); BMBM:SBEßCD (53.3x); EHMC:HPßCD (12.7x); and EHMC:SBEßCD (70.0x). The analysis of DSC, TG/DTG, and P-DRX indicated the formation of inclusion complexes for all systems, where the suppression of the endothermic events characteristic of the isolated substances were observed; however, in the BMBM complexes, the presence of free avobenzone was detected, suggesting that the complexation was not complete. The formation of inclusion complexes promoted the increase of photostability in all evaluated systems, as in solid state as in solution. The results reported in this study indicated that the complexation of photoprotective substances with (HPßCD e SBEßCD). may represent a promising strategy for increasing solubility and photostability

Evaluation and effects on HaCaT cells in vitro of tanshinone IIA-loaded nanostructured lipid carrier / 中草药

Objective: To evaluate TIIA-NLC's quality in vitro and study its effects on the HaCaT cells. Methods: Its particle size, polydispersity index (PDI) and photostability were investigated by Zetasizer analyzer and high-performance liquid chromatography (HPLC). The in vitro release of TIIA-NLC within 72 h was measured by dialysis method; Meanwhile MTT assay was used to detect proliferation activity on HaCaT cells. Results: The average particle size, PDI and Zeta potential of TIIA-NLC was: (178 ± 9) nm, 0.183 ± 0.017 and (−27.5 ± 5.6) mV. The 72 h in vitro accumulative release rate was 52.28%, and the degradation velocity of TIIA was significantly slowed down. The TIIA-NLC inhibited the proliferation of HaCaT cells in concentration-dependent mode within a certain range. Compared with TIIA group, TIIA-NLC had more effects on the HaCaT cells. Conclusion: The prepared TIIA-NLC showed good stability, sustained release of interest, good cell biology intermiscibility, and could obviously increase the effects on the HaCaT cells.

Microencapsulation of a Colombian Spodoptera frugiperda Nucleopolyhedrovirus with Eudragit® S100 by spray drying

A Colombian Spodoptera frugiperda nucleopolyhedrovirus NPV003 with high potential for the development of an efficient biopesticide was microencapsulated by spray drying with a pH dependent polymer (Eudragit® S100). Conditions for microparticles production were standardized and microencapsulation process was validated. Physical properties, insecticide activity and photo-stability of microencapsulated virus were determined. The microparticles were spherical and irregular shaped, with sizes between 17.64 and 19.47 µm. Moisture content was 10.38 ± 0.87%; encapsulation efficiency 84.61± 13.09% and process yield was 91.20 ± 6.40%. Microencapsulation process did not affect viral insecticidal activity and provided efficient protection against UVB radiation. Results demonstrated technological feasibility of spray drying process to be used in formulating a biopesticide based on NPV003.

Photostability of nifedipine in monolaurin solid matrix and micellar solution.

The purpose of this study is to evaluate the photostability of nifedipine (NIF) in solid monolaurin (ML)-based matrix and the micellar solutions thereof. NIF loaded-ML matrices at concentrations of 1:1, 1:4 and 1:9 w/w were prepared using a fusion-high shear homogenization method and characterized using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The absence of an endothermic melting peak at 173° C in the 1:4 and 1:9 w/w NIF-ML matrices indicates that NIF is in an amorphous state. The 1:1 w/w NIFML matrix showed an endothermic peak at 154° C indicating the transformation of NIF into polymorph III. Stability-indicating HPLC method was developed and validated to quantify NIF and its degradation product. Photoexposed 1:1, 1:4 and 1:9 w/w NIF-ML matrices exhibited 2.1, 4.6 and 17 fold slower first-order degradation rates as compared to the NIF powder. After 24 days of exposure, the percent drug remaining in the 1:9 w/w NIF-ML matrix was 85% as compared to only 5% in pure NIF powder. The micellar solutions exhibited 7-fold slower degradation kinetics than the aqueous solution. The results of this study indicate that the stability of nifedipine can be improved by formulation into monoglycerides matrix.

Light-induced fluorescence enhancement in cells stained with Ca2+ indicators / 医用生物力学

Objective As the photostability of calcium ions (Ca2+) indicators is an important property for indicating the temporal features of cytosolic Ca2+ in cells, this study aims to quantitatively measure the light-induced fluorescence enhancement in cells stained with Ca2+ indicators. Methods Five cell lines, MC3T3-E1, RAW264.7, MLO-Y4, MEF3T3 and HEK293, were exposed to the light with five levels of optical power, respectively, so as to investigate the light induced responses of two commonly-used Ca2+ indicators, Fluo-4 AM and Oregon green. The light-induced fluorescence enhancement, the succeeding photobleaching and the thapsigargin (TG)-induced responsive peak followed by were observed. The characteristic parameters of responsive peaks were further analyzed. Results Light with higher power level would induce the fluorescence enhancement for both Fluo-4 AM or Oregon green, while the responsive percentage as well as the magnitude and time span of light-induced peak of Oregon green-stained cells were significantly lower than those of Fluo-4 AM-stained cells. Conclusions The use of Oregon green with low power level light shows better photostability to indicate the intracellular Ca2+.

Influência da rutina na fotoestabilização da avobenzona (filtro UVA) e do ρ-metoxicinamato de octila (filtro UVB) / Influence of rutin in photostabilization of avobenzone (UVA filter) and octyl methoxycinnamate (UVB filter)

Com o intuito de promover proteção de amplo espectro, na maioria dos protetores solares estão associados pelo menos dois filtros orgânicos (UVA e UVB). A combinação da avobenzona (BMBM), filtro UVA, e do p--metoxicinamato de octila (EHMC), filtro UVB, é conhecida e muito utilizada em formulações manipulas e industrializadas, porém apresenta alteração na absorção espectral após exposição à radiação UV. A estratégia empregada com maior frequência para reduzir a instabilidade da combinação é baseada na adição de agentes fotoestabilizadores. A adição de substâncias naturais em formulações fotoprotetoras vem sendo explorada, especialmente o grupo dos flavonoides, como a rutina, que apresenta resultados positivos em relação à eficácia fotoprotetora. O objetivo principal desta pesquisa foi avaliar o potencial da rutina como substância fotoestabilizadora dos filtros EHMC e BMBM. Foram desenvolvidas formulações contendo os dois filtros associados ou não com rutina de acordo planejamento fatorial em três níveis. As formulações foram avaliadas quanto a eficácia fotoprotetora in vitro aplicadas em placas de PMMA e analisadas por espectrofotometria de refletância com esfera de integração antes e após a exposição à radiação UV. As interações moleculares dos filtros com a rutina foram avaliadas por 1H RMN, DSC, TG e análise qualitativa da supressão do estado energético singleto. A adição de rutina nas formulações contendo 5,0% (p/p) de BMBM e 10,0% (p/p) de EHMC promoveu elevação na conservação do FPS in vitro de 53,9% para 65,8 (0,1% de rutina) e 70,8% (1,0% de rutina). As curvas DSC e TG da rutina apresentaram alterações promovidas pela presença dos filtros BMBM e EHMC, indicando interação entre o flavonoide e os filtros. Após dose de 5760 J cm-2 de radiação UV o valor da razão trans/cis para o filtro EHMC em solução adicionado do filtro BMBM foi elevado de 5,5±0,1, sem adição de rutina, para 12,6±0,4, com adição da rutina. A análise qualitativa da supressão do estado singleto indicou que um dos mecanismos envolvidos na fotoestabilização dos filtros BMBM e EHMC é a supressão do estado energético singleto. Os resultados reportados neste estudo indicaram que a adição da rutina em formulações fotoprotetoras representa um caminho simples e efetivo para elevar a fotoestabilidade da combinação dos filtros BMBM e EHMC. A adição da rutina em formulações fotoprotetoras representa uma estratégia promissora, pois aliada a ação fotoestabilizadora, verificada nesse estudo, esse flavonoide possui propriedades antioxidante e quelante de metais que podem colaborar para o desenvolvimento de formulações fotoprotetoras de amplo espectro com aumento da segurança e eficácia

In order to promote broad-spectrum protection, most sunscreens are associated with at least two organic filters (UVA and UVB). The combination of avobenzone (BMBM), UVA filter, and octyl methoxycinnamate (EHMC), UVB filter, is well known and widely used in industrial formulations and pharmaceutical compounding, but shows alteration in spectral absorption after UV radiation exposure. The most commonly used strategy to reduce the instability of the combination is based on the addition of photostabilizer agents. The addition of natural substances in sunscreen formulations has been explored, especially the group of flavonoids such as rutin, which shows positive results regarding photoprotective efficacy. The main objective of this research was to evaluate the potential of rutin as a photostabilizer substance of EHMC and BMBM. Formulations were developed containing the two filters associated or not with rutin, according to factorial design at three levels. The formulations were evaluated for in vitro photoprotective efficacy applied on PMMA plates and analyzed by spectrophotometer with integrating sphere reflectance before and after exposure to UV radiation. Molecular interactions of filters with rutin were evaluated by 1H NMR, DSC, TG and qualitative analysis of the suppression of singlet energy state. The addition of rutin in the formulations containing 5.0 % (w/w) BMBM and 10.0 % (w/w) EHMC promoted an increase in the preservation of in vitro SPF of 53.9% to 65.8 (0.1 % rutin) and 70.8 % (1.0% rutin). The DSC and TG curves of rutin showed changes promoted by the presence of BMBM and EHMC filters, indicating interaction between the flavonoid and filters. After 5760 J cm-2 of UV radiation the value of the trans/cis ratio for the EHMC filter added from the BMBM filter was increased from 5.5 ± 0.1 without addition of rutin, to 12.6 ± 0 4,with the addition of rutin. Qualitative analysis of the suppression of the singlet state indicated that one of the mechanisms involved in the photostabilization BMBM and EHMC filters is suppression of singlet excited state.The results reported in this study indicate that the addition of rutin in sunscreen formulations is a simple and effective way to increase the photostability of the combination of BMBM and EHMC. The addition of rutin in sunscreen formulations represents a promising strategy, for allied with the photostabilization action, observed in this study, this flavonoid has antioxidant and chelating properties of metals that can contribute to the development of broad-spectrum sunscreens formulations with increased safety and efficacy

Preparation of pellets containing Pothomorphe umbellata extracts by extrusion-spheronization: improvement of 4-nerolidylcatechol photostability

Pothomorphe umbellata (L.) Miq., Piperaceae, has been extensively used in Brazilian folk medicine and it is well known for its strong antioxidant properties. However, its main active constituent, 4-nerolydilcatechol (4-NC), is sensitive to ultraviolet and visible light, which can limit the use of intermediate and final herbal preparations of this species. In the present work, coated multiparticulate solid dosage forms of P. umbellata were obtained with the purpose of increasing the stability of 4-NC. P. umbellata extract was used as a wetting liquid for the preparation of pellets by extrusion-spheronization. Pellets were coated in a fluidized bed by three different polymers (hydroxypropylmethylcellulose (HPMC), polyvynilpirrolidone K-30 (PVP-K30), and polyvinyl alcohol-polyethylene glycol graft-copolymer (PVAPEG)). 4-NC photostability was evaluated by an accelerated photostability protocol. Pellets showed a narrow size distribution and low friability. 4-NC photodegradation followed a second order degradation kinetics with similar k values for the percolate, uncoated pellets and HPMC coated pellets. Photoprotection was higher in pellets coated with PVP-K30 and PVA-PEG. PVA-PEG coated pellets with 6 and 9% weight gain resulted in a final concentration of 4-NC approximately cinco times higher than uncoated pellets or liquid extracts, suggesting the potential of this formulation as a multiparticulate solid dosage form for P. umbellata extracts.

Photostability of curcumine, demethoxycurcumin, and bisdemethoxycurcumin in rhizomes of Curcuma longa / 中草药

Objective: To study the photostability of curcumin (Cur), demethoxycurcumin (DMCur), and bisdemethoxycurcumin (BDMCur) in the rhizomes of Curcuma longa, and to investigate the photochemical conversion product of BDMCur. Methods: The stock solution of the extracts from the rhizomes of C. longa was kept in brown volumetric flasks. Then the absorbances of Cur, DMCur, and BDMCur were determined by HPLC analysis, and the solutions were placed in the daylight or daylight/dark conditions for 0, 1, 2, 4, 6, and 8 h. The photochemical conversion products of BCMCur were detected by LC-MS analysis. Results: Both Cur and DMCur were stable in the daylight and daylight/dark conditions. BDMCur was liable to photochemical reaction in the daylight condition. Conclusion: Both Cur and DMCur have good photostabilities, but BDMCur is not stable in daylight condition. As a result, the sample solution of the rhizomes of C. longa should be conserved in dark.

The development of efficient sunscreens.

Skin exposure to acute or repetitive ultraviolet light induces risks which are now well identified. An efficient photoprotection is thus required for both UVB and UVA radiation. In particular, increasing evidence of the detrimental effects of UVA on skin has led to the development of a new generation of sunscreens that provide effective protection throughout the whole UV radiation spectrum. Many new UV filters have been introduced in the last decade, particularly UVA filters, with improved efficacy and safety. Sunscreen filters must be carefully combined to achieve esthetically pleasing products offering photostable and well-balanced photoprotection.

Avaliação da fotoestabilidade de acetazolamida e loratadina e da capacidade de fotoproteção de seus complexos com ciclodextrinas / Assessing the photostability of acetazolamide and loratadine and the photoprotection capacity of its complexes with cyclodextrins

A fotoestabilidade é uma propriedade das moléculas que, quando utilizada como parâmetro farmacêutico, descreve como um fármaco responde à exposição à luz (solar ou artificial). No presente trabalho, foi avaliada a fotoestabilidade dos fármacos loratadina (LORA) e acetazolamida (ACZ) e de complexos LORA-ciclodextrinas. O estudo de fotoestabilidade de LORA (Capítulo 2) indicou que o fármaco é estável quando no estado sólido, porém, ocorre surgimento de coloração intensa. Por outro lado, quando em solução, observou-se degradação do fármaco, com surgimento de vários fotoprodutos denominados F1 a F15, dentre os quais foi possível identificar cinco compostos: F4 (C13H10N), F10 (C14H10CIN), F8 (C20H18CIN2O), F9 (C19H18CIN2) e F14 (C17H14CIN). A validação do método analítico CLAE, utilizado para quantificação de LORA em especialidades farmacêuticas (comprimidos e xaropes) é descrita no Capítulo 3. Na avaliação da fotodegradação forçada de formulações líquidas contendo LORA, foram degradados até 50% do fármaco. As formulações sólidas apresentaram-se fotoestáveis, observando-se perda de menos de 5% do fármaco. Não foram encontrados produtos de fotodegradação nas formulações, quando analisadas tal qual, obtidas do mercado. Dessa forma, as embalagens primárias garantiram sua estabilidade. A complexação de LORA com ciclodextrinas (Capítulo 4) mostrou-se um recurso bastante interessante para melhorar a fotoestabilidade do fármaco, uma vez que, após 12 horas de irradiação luminosa, é possível recuperar até 99% deste, quando na forma de complexo com γ-CD na proporção 1:1. Finalmente, o Capítulo 5 traz o método CLAE desenvolvido e validado para avaliação da acetazolamida (ACZ), o qual mostrou-se adequado para a quantificação do fármaco, obtendo-se ótima linearidade, precisão, exatidão e seletividade. Segundo as condições do guia Q1B, a ACZ se manteve estável quando submetida à radiação luminosa utilizando meios aquosos e no estado sólido. No entanto, a fotoestabilidade da ACZ foi afetada na presença de metanol, sendo possível quantificar três impurezas

Photostability is a property of molecules that, when used as a pharmaceutical parameter, can describe how a drug responds to exposure to light (either solar or artificial). In this study, the photostability of the drugs loratadine (LORA) and acetazolamide (ACZ), as well as LORA-cyclodextrin complexes, was evaluated. A study of the photostability of LORA (Chapter 2) indicated that the drug is stable in its solid form, however intense coloring does occur. On the other hand, when in solution form, degradation of the drug was observed, with the appearance of several photoproducts that we labled F1 to F15, among which it was possible to identify five compounds: F4 (C13H10N), F10 (C14H10CIN), F8 (C20H18CIN2O), F9 (C19H18CIN2) and F14 (C17H14CIN). The validation of the analytical method by HPLC, used for the quantification of LORA in pharmaceutical products (tablets and syrups) is detailed in Chapter 3. In the evaluation of forced photodegradation of liquid formulations containing LORA, up to 50% of the drug was degraded. The solid formulations proved to be photostable, with a loss of less than 5% of the drug. No photodegradation products were found in the formulations when they were analyzed "as is" (the way they were obtained from the commercial market). Accordingly, their primary packaging protected their stability. The complexation of LORA with cyclodextrins (Chapter 4) proved to be an effective resource for improving the photostability of the drug, since, after 12 hours of luminous radiation, it was possible to recover up to 99% of the drug, when in the complex form with γ-CD, in the proportion 1:1. Finally, Chapter 5 describes the HPLC method developed and validated for the evaluation of acetazolamide (ACZ), which proved to be adequate for the quantification of the drug, with the attainment of optimal linearity, precision, exactness and selectivity. According to the conditions of the Q1B guideline, ACZ was stable when subjected to luminous radiation using aqueous means and in its solid state. However, the photostability of ACZ was affected by the presence of methanol, and we were able to quantify three impurities

Estudio de la fotodegradación de ácido fólico encapsulado en microesferas de goma arábiga y maltodextrina / Study of photodegradation of folic acid encapsulated in microspheres of gum arabic and maltdextrin

En este estudio se adaptó un método HPLC de par iónico que permitió medir de forma selectiva el ácido fólico y sus 2 productos de degradación formados en las condiciones de irradiación usadas (lámpara de xenón a 250 Wm-2). Los tiempos de retención fueron: ácido fólico 10,2 min, formilpterina 4,4 min y p-aminobenzoil-L-ácido glutámico 6,1 min. El método se aplicó para determinar la longitud de onda responsable de la fotodegradación y para cuantificar el porcentaje de degradación que sufre el ácido fólico incorporado en microesferas obtenidas por secado por aspersión y con proporciones diferentes de goma arábiga-maltodextrina: 100-0, 80-20, 70-30 y 50-50, como materiales de cubierta. Se encontró como responsable de la fotodegradación la radiación de 350 nm, y las microesferas con mayor contenido de goma arábiga fueron las que presentaron mayor capacidad de proteger el ácido fólico, en estas el porcentaje de degradación fue de 20,1 por ciento mientras que en el control fue de 49,2 por ciento.

In present paper a par ionic HPLC method was adapted to measure in a selective way the folic acid and its two degradation products formed under the irradiation conditions used (250 Wm²). The retention times were: folic acid (10.2 min; formylpterin (4,4 min) and p-aminobenzoil-glutamic acid (6,1 min). Method was applied to determine the wavelength accounting for photodegradation and also to quantify the degradation percentage suffering ty the folic acid added in microspheres obtained by aspersion driying and with different ratios of gum arabic and maltodextrin: 100-0, 80-20, 70-30 and 50-50 as covering materials. The responsible of photodegradation was the 350 nm radiacion and the microspheres with a great content of gum arabic had the greater ability to protect the folic acid, in these ones el degradation percentage was of 20.1 percent whereas in the control it was of 49.2 percent.

Effects of the Photostability of Sunscreens on the in vivo Photoprotection / 대한피부과학회지

BACKGROUND: Solar ultraviolet (UV) radiation induces sunburn, immune suppression, and various pigmentary disorders. Sunscreens are widely used to protect those untoward effects by UV but there are reports of phototoxicity or stability problems of sunscreens after exposure to UV. OBJECTIVE: We tried to compare sunscreens with different photostability in terms of their protection against various biologic responses like sunburn, immune suppression or pigmentation. METHODS: Three different sunscreens with SPF around 30 were used; Sunscreen-A (Sc-A) was photochemically inert, sunscreen-B (Sc-B) showed intermediate level of photostability, and sunscreen-C (Sc-C) was the least stable. To observe their in vivo effects, we measured sunscreen-protection against sunburn by back-skin swelling and sunburn cell formation, against immune suppression measured by depletion of Langerhans cells, local and systemic suppression of contact hypersensitivity (CHS), and against pigmentation by irradiation with mixed light source with UVA and UVB lamps that mimic solar UV spectrum. RESULTS: Back skin swellings by 5 kJ/m2 of UVB were protected well by sunscreens, but protection of Sc-C against 50 kJ/m2 of UVB was worse than Sc-A or Sc-B. Sunburn cells were increased significantly in mice irradiated with 5 kJ/m2 of UVB and it was protected by sunscreens, and the effect of photostability was minimal. Depletion of epidermal Langerhans cells by 5 kJ/m2 of UVB was protected completely by sunscreens. Local suppression of CHS by 5 kJ/m2 of UVB was protected by sunscreens, and Sc-A had better protection. But, in the experiment with 50 kJ/m2 of UVB, the protective efficacy was reversed; Sc-A showed worse protection. Systemic suppression of CHS by 10 kJ/m2 of UVB was protected well by sunscreens, and Sc-A had better protection and Sc-C had worse protection. In the experiment irradiated with 100 kJ/m2 of UVB, the protection of sunscreens was decreased, and Sc-B showed better protection, whereas Sc-C showed worse protection. In UV-induced pigmentation, all three sunscreens showed significant protection both by L* value and individual topographic angle (ITA) with the best protection by Sc-A and the worst protection by Sc-B. CONCLUSION: These data showed sunscreens can protect various in vivo responses and photostability of sunscreens played important roles particularly in the back-skin swelling and systemic suppression of CHS by high dose of UVB.

Comparative Study on Function and Stability of Sunscreening Products / 대한피부과학회지

BACKGROUND: A lot of protective tools such as sunshades (sun-cap), sun-shielding tints and various sunscreens are widely used to protect solar ultraviolet (UV) radiation. Although dermatologists are aware of these products, they do not know the exact protective efficacy or their stability after strong UV irradiation. OBJECTIVE: We tried to measure the spectal absorbance and transmittance of various sunscreening products. In addition, we measured change of sunscreens's absorbance or transmittance after strong UV irradiation for 30, 60 and 90 minutes. METHODS: We purchased five commercially available sunshades (product A-E), five sun-tinting films (product A-E), and eight sunsceens (product A-H) with similar sun-protection factor (SPF) around 30, and measured spectral absorbance and transmittance of those agents. For the sunscreens, they were irradiated with 250 watt Xenon-Arc lamp and change of spectral responses were evaluated. RESULTS: In absorption and transmission spectra of five different sun-caps, sun-cap C showed very good protection in entire UV range whereas all others protected UV only partially. Absorption and transmission spectra of six different sun-shielding tints showed all of them protected UV fairly well and tint C showed the best protection. Eight different sunscreens showed profound differences in spectal absorbances or transmittances. Sunscreen-A showed the best protection and there was no relationship between price and spectral-protection of sunscreens. In the photo-stability of eight sunscreens after UV-irradiation, there were big differences. Only sunscreen-A showed the least change after UV irradiation, and all other sunscreens showed a change of specta by increased UV-irradiation time. CONCLUSION: Protection efficacies of sunscreening products were variable, and most sunscreens were unstable to strong UV irradiation. Further studies would be necessary to give proper information for protecting UV effectively to dermatologists and consumers.