Stability, antioxidant activity, in vivo safety and efficacy of creams with standardized wild apple fruit extract: a comparison of conventional and biodegradable emulsifiers.

OBJECTIVE: The aim of the study was in vitro and in vivo characterization of cosmetic cream with 6% of standardized wild apple fruit extract, stabilized by conventional non-ionic emulsifier-CEW, in order to determine the influence of emulsifiers (conventional vs. biodegradable) on the characteristics of creams and their effects on the skin. METHODS: Organoleptic and physico-chemical (pH values and electrical conductivity) analysis was performed, determination of fruit acids-FAs content (using HPLC analysis) and estimation of its antioxidant activity-AA (using DPPH test) during 180 days. In vivo study included following examinations: screening of safety profile (after creams application under occlusion during 24 h at human skin); skin moisturizing potential, transepidermal water loss-TEWL, skin pH after 28 days of cream application and hypopigmentation efficacy 7 days of cream application at artificially induced skin hyperpigmentation. RESULTS: Investigated cosmetic cream-CEW showed satisfactory organoleptic, physico-chemical characteristics, stability, FAs content (0.13%) and AA (19.25 ± 0.67 %RSC) after preparation, which remained unchanged over the study period. In vivo investigation revealed absence of skin irritation after CEW's application under occlusion. An increase of skin moisturization (after 14 days ΔEC was 18.52 ± 11.51 and after 28 days of applications 16.52 ± 9.36) during 28 day-study, with unchanged TEWL and skin pH values was shown. Decrease of melanin index was revealed, too (after 7 days ΔMI was -31.40 ± 16.50). CONCLUSION: Cosmetic cream stabilized by conventional emulsifier showed better antioxidant potential and weaker moisturizing and hypopigmentation effects related to the cream with same composition but stabilized by biodegradable emulsifiers. Based on all mentioned above, investigated cosmetic cream might be considered for potential use as modern, stable, safe and efficient cosmetic product in the prevention and/or treatment of oxidative stress-related skin changes and/or damages, for moisturization of dry, even irritated skin as well as for lightening of hyperpigmented skin. RÉSUMÉ: OBJECTIF Le but de l'étude était la caractérisation in vitro et in vivo d'une crème cosmétique contenant 6 % d'extrait normalisé de pomme sauvage, stabilisée par un émulsifiant non ionique conventionnel-CEW, afin de déterminer l'influence des émulsifiants (conventionnels vs biodégradables) sur les caractéristiques des crèmes et les effets sur la peau. MÉTHODES: Des analyses organoleptiques et physico-chimiques (pH et conductivité électrique) ont été effectuées, la détermination de la teneur en acides de fruits et en acides gras polyinsaturés (par CLHP), et l'estimation de sa teneur en activité antioxydante (AA) (à l'aide du test DPPH) pendant 180 jours. L'étude in vivo comprenait les examens suivants : dépistage du profil d'innocuité (après application de crèmes sous occlusion pendant 24 h sur la peau humaine); potentiel d'hydratation de la peau, perte d'eau transépidermique (PETE), pH de la peau après 28 jours d'application de la crème et efficacité de l'hypopigmentation après 7 jours d'application de la crème sur une hyperpigmentation de la peau induite artificiellement. RÉSULTATS: La crème cosmétique-CEW étudiée a montré des caractéristiques organoleptiques, physico-chimiques, une stabilité, une teneur en AG (0,13 %) et en AA (19,25 ± 0,67 % RSC) satisfaisantes après préparation, qui sont demeurées inchangées au cours de la période de l'étude. L'étude in vivo a révélé l'absence d'irritation cutanée après l'application de CEW sous occlusion. Une augmentation de l'hydratation de la peau (après 14 jours de DEC était de 18,52 ± 11,51 et après 28 jours d'applications de 16,52 ± 9,36) pendant l'étude de 28 jours, avec une PETE et des valeurs de pH cutané inchangées, a été démontrée. Une diminution de l'indice de mélanine a été mise en évidence également (après 7 jours, ΔMI était de 31,40 ± 16,50). CONCLUSION: La crème cosmétique stabilisée par un émulsifiant conventionnel a montré un meilleur potentiel antioxydant et des effets d'hydratation et d'hypopigmentation plus faibles par rapport à la crème de même composition mais stabilisée par des émulsifiants biodégradables. D'après les données précédentes, la crème cosmétique étudiée pourrait être considérée comme un produit cosmétique moderne, stable, sûr et efficace dans la prévention et/ou le traitement des changements et/ou dommages cutanés liés au stress oxydatif, pour l'hydratation de la peau sèche, voire irritée, ainsi que pour éclaircir la peau hyperpigmentée.

Lactobionic acid as antioxidant and moisturizing active in alkyl polyglucoside-based topical emulsions: the colloidal structure, stability and efficacy evaluation.

Cosmeceutical antioxidants may protect the skin against oxidative injury, involved in the pathogenesis of many skin disorders. However, an unsuitable topical delivery system with compromising safety profile can affect the efficacy of an antioxidant active. This study investigated the antioxidant potential of lactobionic acid (LA), a newer cosmeceutical active, per se (in solution) and incorporated into natural alkyl polyglucoside (APG) emulsifier-based system using 1,1-diphenyl-2-picrylhydrazyl free radical scavenging and lipid peroxidation inhibition assays. The α-tocopherol was used as a reference compound. The physical stability (using rheology, polarization microscopy, pH and conductivity measurements) of an Alkyl glucoside-based emulsion was evaluated with and without the active (LA); colloidal structure was assessed using polarization and transmission electron microscopy, rheology, thermal and texture analysis. Additionally, the safety profile and moisturizing potential were investigated using the methods of skin bioengineering. Good physical stability and applicative characteristics were obtained although LA strongly influenced the colloidal structure of the vehicle. LA per se and in APG-based emulsion showed satisfying antioxidant activity that promotes it as mild multifunctional cosmeceutical efficient in the treatment and prevention of the photoaged skin. Employed assays were shown as suitable for the antioxidant activity evaluation of LA in APG-based emulsions, but not for α-tocopherol in the same vehicle.

Does lactobionic acid affect the colloidal structure and skin moisturizing potential of the alkyl polyglucoside-based emulsion systems?

Moisturizing creams are the most prescribed products in dermatology, essential in maintaining healthy skin as well as in the topical treatment of some diseases. The irritation potential of commonly used emulsifiers and moisturizing ingredients, but also their mutual interactions, could affect the functionality and safety of those dermopharmaceutics. The aim of this study was to promote moisturizing alkyl polyglucoside (APG)-based emulsion as vehicle for lactobionic acid (LA), advantageous representative of the alphahydroxyacids (AHAs)-multifunctional moisturizers, assessing the safety for use (in vitro acute skin irritation test using cytotoxicity assay compared with in vivo data obtained using skin bioengineering methods) and in vivo moisturizing capacity (bioengineering of the skin). In order to investigate possible interactions between APG mild natural emulsifier-based emulsion and LA, a deeper insight into the colloidal structure of the placebo and the emulsion with LA was given using polarization and transmission electron microscopy, rheology, thermal and texture analysis. This study showed that APG-based emulsions could be promoted as safe cosmetic/dermopharmaceutical vehicles and carriers for extremely acidic and hygroscopic AHA class of actives (specifically LA); prospective safety for human use of both APG and LA with the correlation between in vivo and in vitro findings was shown. However, it was revealed that LA strongly influenced the colloidal structure of the emulsion based on APGs and promoted the formation of lamellar structures which reflects onto the mode of water distribution within the cream. The advantageous skin hydrating potential of LA-containing emulsion vs. placebo was unlikely to be achieved, pointing that emulsions stabilized by lamellar liquid crystalline structures probably are not satisfying carriers for highly hygroscopic actives in order to reach the full moisturizing potential. Safe and effective use on dry skin is presumed.