| Titre : |
Photochemical interaction of ascorbic acid with riboflavin, nicotinamide and alpha-tocopherol in cream formulations |
| Type de document : |
texte imprimé |
| Auteurs : |
I. Ahmad, Auteur ; M. A. Sheraz, Auteur ; S. Ahmed, Auteur ; F. H. M. Vaid, Auteur |
| Année de publication : |
2012 |
| Article en page(s) : |
p. 123-131 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Ascorbique, Acide
Cosmétiques
Dynamique moléculaire
Formulation (Génie chimique)
Photochimie
Produits hydratants
Vitamine B
Vitamine B2
Vitamine E
|
| Index. décimale : |
668.5 Parfums et cosmétiques |
| Résumé : |
The present work is based on a study of the effect of some vitamins such as riboflavin (RF), nicotinamide (NA) and alpha-tocopherol (TP) on the photodegradation of ascorbic acid (vitamin C) (AH2) in oil-in-water cream formulations using a UV irradiation source. A UV spectrophotometric and the official iodimetric methods have been used for the assay of AH2 in cream formulations. These methods have been validated in the presence of RF, NA and TP before their application to the creams. The recoveries of AH2 in the creams are in the range of 90–95% and the reproducibility of the method is within ±5%. The apparent first-order rate constants (kobs) for the photodegradation of AH2 in the presence of RF, NA and TP, individually, in the creams have been obtained. The second-order rate constants for the photochemical interaction of AH2 and the vitamins RF, NA and TP have been determined from the plots of kobs for AH2 photolysis versus the individual vitamin concentration along with the values of k0 from the intercept on the vertical axis. The values of k0 in the presence of RF and NA are lower than those of the kobs, indicating that these vitamins act as photosensitizers for the degradation of AH2 in creams. On the contrary, the value of k0 in the presence of TP is higher than that of the kobs, suggesting a stabilizing effect of this vitamin on the degradation of AH2 in creams. The mode of interaction of the individual vitamins with AH2 on photolysis has been discussed. |
| Note de contenu : |
- MATERIALS AND METHODS : Cream formulations - Preparation of cream formulations - Measurement of pH - Measurement of light intensity - Photolysis of cream formulations - Measurement of absorption spectra - Thin-layer chromatography - RF and photoproducts
- RESULTS AND DISCUSSION : Absorption characteristics of photolysed creams - Photoproducts of ascorbic acid and other vitamins - Assay method - Kinetics of photodegradation of ascorbic acid - Interaction of riboflavin with ascorbic acid - Interaction of nicotinamide with ascorbic acid - Interaction of ?-tocopherol with ascorbic acid - Effect of physicochemical factors |
| DOI : |
10.1111/j.1468-2494.2011.00690.x |
| En ligne : |
https://onlinelibrary.wiley.com/doi/10.1111/j.1468-2494.2011.00690.x |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=14382 |
in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 34, N° 2 (04/2012) . - p. 123-131
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