Benefits of combinations of vitamin A, C and E derivatives in the stability of cosmetic formulations

Abstract

Chemically stable ester derivatives of vitamins A, C and E have become a focus of interest for their role in the satisfactory results in skin aging treatments. Accordingly, the aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing 1% retinyl palmitate, ascorbyl tetraisopalmitate and tocopheryl acetate, alone or in combination. In the studies of physical stability, a Brookfield rheometer was used to determine rheological behavior of formulations containing the vitamins. Chemical stability was determined by HPLC on a Shimadzu system with UV detection. Results showed that formulations had pseudoplastic behavior and that vitamins did not alter their apparent viscosity and thixotropy. In the chemical stability studies, first-order reaction equations were used for determinations of the shelf-life of vitamins derivatives considering a remaining concentration of 85%. Combined vitamins in a single formulation had a slightly lower degradation rate as compared to different preparations containing only one of the vitamins. Considering that many cosmetic formulations contain vitamin combinations it is suggested that the present study may contribute to the development of more stable formulations containing liposoluble vitamins.

Figure 1

Rheograms of formulations supplemented (b) or not (a) with the combination of vitamins under study, when stored at 25 °C, during 0, 7, 14, 21 and 28 days after preparation. (a) formulation with vitamins in combination stored at 25 °C; (b) formulation without vitamins stored at 25 °C.

Figure 2

Alterations in the apparent viscosity (a), flow index (b), consistency index (c) and thixotropy (d) of vehicle (F V), or the vehicle supplemented with vitamin A (FA), vitamin C (FC), vitamin E (FE) or with the combination of these vitamins (F ACE) initially (0), 7, 14, 21 and 28 days after preparation, at room temperature.

Figure 3

HPLC chromatograms of vitamin E (VE), A (VA) and C (VC) derivatives extracted from the gel-cream formulation in concentration of 250 μg/mL, with Vitamin K1 (PI) as an internal standard.

Figure 4

Quantification of vitamin A palmitate (VA), vitamin C (ascorbic acid (VC)) and vitamin E acetate (VE), expressed as logs of concentration values over time, when added, alone (a) or in combination (b) to the formulation under study stored at 37 and 45 °C with 75% RH.