48 FORMULATING FOR MILDNESS
volunteers were selected and a patch was applied on forearms for 24 hours. POHOP was tested in several aqueous solutions: in detail all solutions were concentrated at 10% active matter. Among the systems analyzed, POHOP was used alone, in combination to Sodium Laureth Sulfate (SLES) with the ratio (9.5 SLES: 0.5 POHOP) and compared to a solution only containing SLES as control. The aim of this specific study is to evaluate the mildness of the POHOP molecule and how it impacts the mildness of formulations containing significant amounts of aggressive ingredients like SLES indeed. SOG samples were instead applied as a 5% aqueous solution; additional solutions were applied to the volunteers, in particular: 5% aqueous solution of SLES as positive control, physiological water as negative control and a 5% aqueous solution of decyl glucoside as competitor. The irritant effect was detected by measuring the transepidermal water loss (TEWL) and erythema index in the areas of interest before the start of treatment (T0), and after 60 minutes after removal of the patch (T24 hours). All the data obtained were interpreted by an appropriate statistical analysis. The patch contained six cells in which the aqueous solutions of the molecules to be tested have been loaded. A DermaLab Combo skin analysis system
made by Cortex was used to measure the reddening of the skin caused by the application of the molecules under analysis. The instrument used is equipped with a probe with a microchip able to measure the colour of the skin in standardized conditions. The colour is detected and expressed
according to the coordinates CIE-L * a * b * and, through a mathematical function that combines different parameters, the software calculates the erythema index, which represents a measure of redness level of the skin. By measuring the redness index variations in the area under examination at times T0 and T24 hours it is possible to evaluate the irritating effect of the applied products: the higher the redness value after treatment compared to T0, the greater the irritating potential of the applied substance.
120 90 60 30 0 BASAL
10% SLES
9.5% SLES+
0.5% Potassium Olivoyl Hydrolyzed Oat Protein
10% Potassium
Olivoyl Hydrolyzed Oat Protein
Water
Figure 1: TEWL of Olivoil Avenate Emulsifier lipo-polypeptide (Potassium Olivoyl Hydrolyzed Oat Protein) The DermaLab Combo system was also
used to measure TEWL through the skin. A high level of TEWL may indicate a damage to the skin barrier which can be caused by chemicals, physical insult or pathological conditions. The rates of TEWL increase in proportion to the level of damage. By measuring the water loss variations in
the area under examination at times T0 and T24 hours, it is possible to evaluate the ability of a substance to damage the skin barrier and therefore to exert an irritating action on the skin.
Results The data collected in Figure 1, expressed in percentages, demonstrate that the Avenate emulsifier lipo-polypetide (POHOP), when used alone, shows a TEWL value matching the score of physiological water and inferior by almost 100% when compared to the values detected with the same amounts of SLES. When used at 0.5% a.m., in presence of SLES @ 9.5%, it reduces the SLES related water transpiration more than 50%. For the Glutamate emulsifier lipo- aminoacid (DOG) performances, the mean TEWL values before and after the application of the occlusive patch test (T0 and T24h)
Physiological Water ■ Sodium Lauryl Sulfate ■ Decyl Glucoside ■ Sodium Olivoyl Glutamate ■ 18
13.5 9 4.5 0
Figure 3: Eryhtema index of Olivoil Glutamate lipo-aminoacid (Sodium Olivoyl Glutamate)
PERSONAL CARE April 2023
are summarized in Figure 2. The values are expressed as mass of water vapour per area and time (g/m2 h). SOG proved to be non- aggressive, showing the best score among the substances object of the study, including a benchmark with well-known mildness. The same results pattern was observed for the erythema index value (Figure 3).
Applications and formulations examples Olivoil emulsifiers enable to formulate dermo- compatible and extremely mild emulsions on a wide variety of cosmetic applications according to the concentrations of use and the excipients used, showing a totally unusual versatility of use for vegetable derived self- emulsifying bases. By using low dosages (1-2%) it is possible to
develop low viscosity products such as serums, sprayable emulsions, roll-on deodorants and cleansing milks. By increasing the dosage up to a maximum of 10%, high viscosity formulas such as rich night creams or body butters can be developed. In between these extremes, further
applications can be considered, such as make-up formulations, including mascara,
Physiological Water ■ Sodium Lauryl Sulfate ■ Decyl Glucoside ■ Sodium Olivoyl Glutamate ■ 2.2
1.65 1.1 0.55 0
Figure 4: TEWL of Olivoil Glutamate lipo-aminoacid (Sodium Olivoyl Glutamate)
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Water vapour mass (g/m2
h)
TEWL %
Erythema index
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