1,720,974 research outputs found
Complexation of the sunscreen agent, 4-methylbenzylidene camphor with cyclodextrins. Effect on photostability and human stratum corneum penetration
No full textThe interaction between the sunscreen agent, 4-methylbenzylidene camphor (4-MBC) and hydrophilic α-, p- and γ-cyclodextrin derivatives was investigated in water by phase-solubility analysis. Among the studied cyclodextrins, random methyl-β-cyclodextrin (RM-β-CD) had the greatest solubilizing activity. The complexation of the sunscreen agent with RM-p-CD was confirmed by nuclear magnetic resonance spectroscopy and powder X-ray diffractometry. The light-induced decomposition of 4-MBC in emulsion vehicles was markedly decreased by complexation with RM-p-CD (the extent of degradation, determined by HPLC, was 7.1% for the complex compared to 21.1% for free 4-MBC). The influence of RM-P-CD on the human skin penetration of the sunscreen was investigated in vivo using the tape stripping method, a useful procedure for selectively removing the outermost cutaneous layers. Considerable quantities (21.2-25.1% of the applied dose) of 4-MBC permeated in the stratum corneum. However, no significant differences in the amounts of UV filter in the 10 first strips of the horny layer were observed between the formulations containing 4-MBC free or complexed with RM-p-CD. Therefore, RM-p-CD complexation did not alter the retention of 4-MBC in the superficial layers of the stratum corneum, where its action is more desirable
Complexation of the sunscreen agent, 4-methylbenzylidene camphor with cyclodextrins: Effect on photostability and human stratum corneum penetration
No full textThe interaction between the sunscreen agent, 4-methylbenzylidene camphor (4-MBC) and hydrophilic α-, β- and γ-cyclodextrin derivatives was investigated in water by phase-solubility analysis. Among the studied cyclodextrins, random methyl-β-cyclodextrin (RM-β-CD) had the greatest solubilizing activity. The complexation of the sunscreen agent with RM-β-CD was confirmed by nuclear magnetic resonance spectroscopy and powder X-ray diffractometry. The light-induced decomposition of 4-MBC in emulsion vehicles was markedly decreased by complexation with RM-β-CD (the extent of degradation, determined by HPLC, was 7.1% for the complex compared to 21.1% for free 4-MBC). The influence of RM-β-CD on the human skin penetration of the sunscreen was investigated in vivo using the tape stripping method, a useful procedure for selectively removing the outermost cutaneous layers. Considerable quantities (21.2–25.1% of the applied dose) of 4-MBC permeated in the stratum corneum. However, no significant differences in the amounts of UV filter in the 10 first strips of the horny layer were observed between the formulations containing 4-MBC free or complexed with RM-β-CD. Therefore, RM-β-CD complexation did not alter the retention of 4-MBC in the superficial layers of the stratum corneum, where its action is more desirable
Assay of common sunscreen agents in suncare products by high-performance liquid chromatography on a cyanopropyl-bonded silica column
No full textA rapid high-performance liquid chromatographic method was developed for the simultaneous assay of eight of the most common sunscreen agents (octyl-methoxycinnamate, oxybenzone, butyl-methoxydibenzoylmethane, octyl-salicilate, methylbenzylidene camphor, octyl-dimethylamminobenzoate, phenylbenzimidazole sulphonic acid and octocrylene) in sun protection products. Evaluation of the influence of different stationary phases and eluents on the separation selectivity showed that optimal resolution was obtained on a cyanopropyl-silica column eluted with methanol–acetonitrile–tetrahydrofuran–aqueous acetic acid. A small adjustment of the proposed chromatographic system (reduction in the aqueous content of the mobile phase) permitted also the determination of the extremely hydrophobic UV filter, methylene bis-benzotriazolyl tetramethylbutylphenol along with three other sunscreen agents, octyl-methoxycinnamate, oxybenzone, butyl-methoxydibenzoylmethane. Recoveries of the UV filters from the spiked formulation were between 95.7 and 103.7% and the precision of the method was better than 6.1% relative standard deviation. The developed HPLC procedure is suitable for quality control and photostability analyses of commercial suncare products
Microparticelle lipidiche - veicolazione del butil metossidibenzoilmetano
No full textIn questo studio sono state preparate microparticelle lipidiche contenenti butil metossidibenzoilmetano, il filtro UV-A più utilizzato. I sistemi microparticellari sono stati caratterizzati dal punto di vista morfologico, dimensionale e funzionale. Le microparticelle sono state poi inserite in un'emulsione olio in acqua e sottoposte all'azione di un simulatore solare. I risultati ottenuti indicano che la veicolazione del butil metossidibenzoilmetano nelle microparticelle lipidiche permette
di ridurne in maniera significativa la decomposizione indotta dalla luce
Influence of cyclodextrin complexation on the in vitro human skin penetration and retention of the sunscreen agent, oxybenzone
No full textThe objective of this study was to investigate the influence of cyclodextrins on the cutaneous availability of the sunscreen oxybenzone. The interaction between oxybenzone and hydrophilic α-, β- and γ-cyclodextrin derivatives was studied in water by phase-solubility analysis. Among the available cyclodextrins, hydroxypropyl-β-cyclodextrin (HP-β-CD) and especially sulfobutylether-β-cyclodextrin (SBE-β-CD) had the greatest solubilizing activity. Ethanol-water solutions containing oxybenzone free or complexed with HP-β-CD or SBE-β-CD were applied to human skin in Franz diffusion cells and the amount of sunscreen permeated into the different cutaneous compartments was determined by HPLC. As much as 20.5% of the oxybenzone applied dose diffused within the skin tissue after 6 h application. Between 39.4% and 54.9% of the penetrated UV filter was localized in the stratum corneum, with no significant difference between uncomplexed oxybenzone or its complex with HP-β-CD. Conversely, the amount ..
Microparticelle lipidiche - Veicolazione del Butil metossidibenzoilmetano
No full textLa veicolazione del BMDBM in microparticelle lipidiche permette di ridurne in maniera significativa la decomposizione indotta dalla luce
Enhancement of melatonin photostability by encapsulation in lipospheres
No full textThe effect of lipid microparticle carrier systems on the light-induced degradation of melatonin was investigated. Microspheres loaded with melatonin were prepared using tristearin or tripalmitin as the lipid material and hydrogenated phosphatidylcholine or polysorbate 60 as the emulsifier. The obtained lipid microspheres were characterized by scanning-electron microscopy and differential scanning calorimetry. Free or microencapsulated melatonin was incorporated in a model cream formulation (oil-in-water emulsion) and irradiated with a solar simulator. The extent of photodegradation was measured by high-performance liquid chromatography. The photolysis experiments demonstrated that the light-induced decomposition of melatonin was markedly decreased by encapsulation into lipid microspheres based on tristearin and phosphatidylcholine (the extent of degradation was 19.6% for unencapsulated melatonin compared to 5.6% for the melatonin-loaded microparticles). Therefore, incorporation in lipid microparticles can be considered an effective system to enhance the photostability of melatonin
Enhancement of melatonin photostability by encapsulation in lipospheres
No full textThe effect of lipid microparticle carrier systems on the light-induced degradation of melatonin was investigated. Microspheres loaded with melatonin were prepared using tristearin or tripalmitin as the lipid material and hydrogenated phosphatidylcholine or polysorbate 60 as the emulsifier. The obtained lipid microspheres were characterized by scanning-electron microscopy and differential scanning calorimetry. Free or microencapsulated melatonin was incorporated in a model cream formulation (oil-in-water emulsion) and irradiated with a solar simulator. The extent of photodegradation was measured by high-performance liquid chromatography. The photolysis experiments demonstrated that the light-induced decomposition of melatonin was markedly decreased by encapsulation into lipid microspheres based on tristearin and phosphatidylcholine (the extent of degradation was 19.6% for unencapsulated melatonin compared to 5.6% for the melatonin-loaded microparticles). Therefore, incorporation in lipid microparticles can be considered an effective system to enhance the photostability of melatonin
Encapsulation in lipospheres of the complex between butyl methoxydibenzoylmethane and hydroxypropyl-b-cyclodextrin.
No full textThe aim of this study was to investigate the incorporation into lipospheres of the complex between hydroxypropyl-β-cyclodextrin (HP-β-CD) and the sunscreen agent, butyl methoxydibenzoylmethane (BMDBM) and to examine the influence of this system on the sunscreen photostability. The formation of the inclusion complex was confirmed by thermal analysis and powder X-ray diffraction. Lipid microparticles loaded with free BMDBM or its complex with HP-β-CD were prepared using tristearin as the lipid material and hydrogenated phosphatidylcholine as the emulsifier. The obtained lipospheres were characterized by scanning electron microscopy and differential scanning calorimetry. The microparticle size (15–40 μm) was not affected by the presence of the complex. Release of BMDBM from the lipospheres was lower when it was incorporated as inclusion complex rather than as free molecule. Unencapsulated BMDBM, its complex with HP-β-CD, the sunscreen-loaded lipospheres or the lipoparticles containing the BMDBM/HP-β-CD complex, were introduced into a model cream (oil-in-water emulsion) and irradiated with a solar simulator. The photodegradation studies showed that all the examined systems achieved a significant reduction of the light-induced decomposition of the free sunscreen agent (the BMDBM loss decreased from 28.9 to 17.3–15.2%). However, photolysis experiments performed during 3 months storage of the formulations, demonstrated that the photoprotective properties of the HP-β-CD complex and of BMDBM alone-loaded lipospheres decreased over time, whereas the microencapsulated HP-β-CD/BMDBM complex retained its photostabilization efficacy. Therefore, incorporation in lipid microparticles of BMDBM in the cyclodextrin complex form is more effective in enhancing the sunscreen photostability than the complex alone or the liposphere-entrapped free BMDBM
Influence of liposphere preparation on butyl-methoxydibenzoylmethane photostability
No full textThe incorporation of butyl-methoxydibenzoylmethane (BMDBM), one of the most efficient and frequently used UV-A blockers, into lipospheres was examined in order to decrease the light-induced sunscreen degradation. Lipospheres, obtained by the melt technique and using tristearin as the lipid material and hydrogenated phosphatidylcholine as the emulsifier, showed proper features in terms of size (10–40 μm), BMDBM loading level (21.63% ± 0.90%, w/w) and physical state. Photolysis studies, involving irradiation of lipospheres with simulated sunlight before and after their introduction in emulsion formulations, demonstrated a relevant enhancement of the encapsulated sunscreen photostability in comparison with unencapsulated BMDBM
- …
