ANHYDROXYLITOL

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of 7 saccharides/saccharide derivatives as used in cosmetic products; all of these ingredients are reported to function as skin-conditioning agents-humectant in cosmetics. The Panel reviewed data relevant to the safety of these ingredients in cosmetic formulations and concluded that Anhydrogalactose, Anhydroglucitol, Anhydroxylitol, Arabinose, Psicose, Saccharide Hydrolysate, and Saccharide Isomerate are safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Silicone replicas and non-contact methods are effective methods to analyse the micrometric scale of the skin microrelief. Yet, they imply data capture in research facilities. The capabilities of a new connected portable camera were evaluated to analyse microrelief under nomadic conditions, also studying the effect of moisturisers. 3D depth maps were constructed using shape-from-shading algorithms. Roughness heterogeneity (Spa) was computed, and skin profiles were extracted to calculate roughness amplitude (Ra, Rq), as well as furrows/plateaus characteristics. Validation of the connected camera was performed on tanned cowhide leather and on the inner forearm skin of a single subject. The forearms of 18 subjects (23-60 years old) were also evaluated. While living their regular life, they self-performed triplicate acquisitions at various times. The effects of a placebo and of cream containing moisturisers-saccharide isomerate, urea or xylitylglucoside-anhydroxylitol-xylitol-were investigated, using untreated control skin as a reference. Validation of the device on leather and forearm skin shows high repeatability. The 18 subjects show the known correlation between age and changes in microrelief. While testing formulas, 8 h after a single application, all decreased Spa (-1.6/-2.1 folds). Only saccharide isomerate and xylitylglucoside-anhydroxylitol-xylitol decreased Ra (-2.4/-2.8 folds). The sectional area of plateaus was reduced from -1.5 (urea) to -2.1 folds (xylitylglucoside-anhydroxylitol-xylitol). The height of plateaus is also decreased by all moisturisers, from -1.5 (urea) to -2.1 folds (xylitylglucoside-anhydroxylitol-xylitol). This novel camera device enables microrelief analysis under nomadic conditions, allowing monitoring its changes along the day and upon moisturisers' application.

Water is an important factor on the appearance and function of the skin and, when dehydrated, it becomes rough and flaky. The measurement of stratum corneum hydration is widely employed to verify the moisture effect of topical products. This study has evaluated in vivo the stratum corneum hydration, by the electrical measurements of skin, after treatment with different moisturizers presented in gel base. MoistureMeter and Corneometer were used as bio-instruments. Urea, the herbal extract (Imperata cylindrical), the NMF components and the carbohydrate derivate compound (xylityglucoside, anhydroxylitol, and xylitol) were used as the active substances. The study protocol was carried out according to the three-factor factorial design. The gels were applied on both forearms of eight female volunteers. However, each volunteer had one untreated skin area as the skin moisture control. The electrical capacitance of the skin was measured by both instruments in different times: after application (0 time), 30, 60, 120, 240 and 360 min. Gel base, gel containing herbal extract, and gel containing NMF components statistically have equal moisture effect measurements, according to both bio-instruments. However, the values obtained for urea, carbohydrate derivate compound, and untreated skin (control) have statically different results in both devices. The gel containing urea and the carbohydrate derivate compound gel have promoted the most intense moisture effect compared with the other formulations. The measurements of hydration between the devices generated different absolute values; however, the statistical analysis has shown similar precision among the measurements.

The kinetic parameters for the interconverting substrates D-xylose in equilibrium D-xylulose and D-glucose in equilibrium D-fructose were determined for several D-xylose isomerases, with Mg2+, Co2+ and Mn2+ as metal ion activators. The Km, kcat. and kcat./Km values are tabulated for the anomeric mixtures (observed parameters) as well as for the respective reactive species, i.e. the alpha-pyranose anomers of D-xylose and D-glucose and the alpha-furanose forms of D-xylulose and D-fructose (real parameters). The real Km values and catalytic efficiencies are more favourable for the ketose sugars (reverse reaction) than for the aldose sugars (forward reaction). Comparisons of the kinetic parameters further support the existence of two distinct groups of D-xylose isomerases. Inhibition constants for the cyclic substrate analogues 5-thio-alpha-D-xylopyranose and alpha-D-xylopyranosyl fluoride and for the acyclic substrate analogue xylitol and its dehydrated form 1,5-anhydroxylitol were determined and are discussed.