32 SKIN PROTECTION
through a solution of 0.3% carotenoid active and transmitted light projected onto a white screen (Fig 6 B). To test the carotenoid active in cosmetic formulations, blue light protection was determined in o/w emulsions with different concentrations of the carotenoid active (0% (control), 0.25%, 0.5%, 1% or 2%), which were spread over a transparent, roughened slide (4 mg/cm2
). Incident visible light was
passed through the emulsions and transmitted light was analyzed by a photomultiplier. A selective reduction in blue light intensity is expressed as blue light protection. Blue light protection was calculated as reduction of blue light intensity in visible light. Results: The carotenoid active, as a raw material, efficiently absorbed blue light between 400 - 500 nm (Fig 6 A). Further, the carotenoid active selectively shields blue light as shown in the LED light demonstration experiment: red light and green light pass through; only blue light is filtered (Fig 6 B). Finally, in a cosmetic formulation, the carotenoid active selectively absorbs blue light, as light transmitted through a carotenoid active cream contained less blue light than incident light (Fig 6 C). The effect was dose dependent.
Reducing oxidative stress induced by visible blue light Objective: To show that topical application of the active ingredient reduces VIS blue light-induced oxidative stress in biological tissues. Technique: Test substances were applied onto the surface of a 3D tissue model (Oryzias latipes) and allowed to penetrate for 5 min. Thereafter, test substances were completely removed, and the tissues were irradiated with visible blue light for 60 min. Finally, free oxygen radicals were visualized by a fluorescent ROS sensor and quantified fluorometrically. Results: The carotenoid active reduces
Carotolino reduces blue light induced oxidative stress.
**
120 100 80 60 40 20 0
No Light
Untreated control
-29%
The pigment was exposed to high intensity visible light (LED) for 3h (inner circle in Figure 8). The outer area was not exposed (control). Melanin bleaching was quantified using a colorimeter (L* value of CIE Lab color system).
Carotene Active
Figure 7: Carotolino reduces blue light induced oxidative stress. ROS emissions diminished by 29%. N=7; Mean + SEM; Student’s unpaired t- test; ** = p<0.01.
blue light induced oxidative stress (ROS emission) in biological tissues. (Fig 7: untreated control, ROS=100%). Previous treatment with the carotenoid active reduces ROS by -29% (Fig 7: Carotolino, ROS=71%).
Carotenoids protect melanin from high intensity blue light Melanin, the skin’s dark pigment, protects skin from visible and UV light. Although melanin is a stable chromophore, it can be degraded by high intensity visible light in a process called photo-beaching.7
In this
process, incident light is absorbed by melanin, which produces oxygen radicals (by photosensitization) that finally auto-degrade the pigment (photobleaching). To test the efficacy of the carotenoid active, the photobleaching experiment was performed either in its presence or absence. Objective: To show that the active
ingredient protects melanin from photobleaching through high intensity visible light (VIS) exposure. (Experiment adapted from reference7
.)
Technique: Melanin pigment is adsorbed to an inert surface either supplemented with the carotenoid active or not (control).
Photobleaching of melanin by high intensity visible light a
Control Carotolino
How to create a vivid skin color - a consumer self-assessment test Objective: To show that a carotenoid active formulation perceptively changes skin color by adding an expression of liveliness and vividness and by compensating pale and sallow skin tones, without being perceived as too orange. Further, to show that the application of a carotenoid active cream changes the general appearance of skin, including its overall beauty, healthiness and attractiveness. And finally, to show that the carotenoid active adds value to a cosmetic formulation that convinces consumers to recommend and buy a cosmetic product. Technique: In a placebo-controlled consumer test, two groups of 20 female volunteers each applied a test cream with the carotenoid active (group A) or a placebo cream (group B) for 7 days, twice a day. The volunteers rated skin parameters according to a questionnaire before the first application and after 7 days of application. Results: Consumer ratings confirmed
improvements in skin color (Fig 9). Consumers were more satisfied with their skin color and they perceived their skin as healthier and more attractive. Further, pale and sallow skin tones were reduced, and skin color was more vibrant. Nevertheless, color changes were not perceived as too orange.
The observed color changes also influenced the general appearance of skin. Volunteers judged their skin as livelier, healthier, younger and more attractive (Fig 10).
As part of the same study, volunteers
were asked to estimate the purchase price of the test product. Remarkably, consumers believed that a cream containing the
b Light exposed area (center-melanin bleaching)
Shadowed area (outer circle)
100 95 90 85 80
exposed Not ** -7%
Control Carotolino
Figure 8: Carotolino protects melanin from photodegradation by visible light. The inner circles of both supports were exposed to high intensity visible light. The outer circles were covered and not exposed to light. The control (left) was photo-beached, reducing melanin content by -8%. Carotolino protected melanin (right); almost no photobleaching was detected (-1%). N = 3; Mean +/- SEM; Student’s paired t-test; ** = p< 0.01.
PERSONAL CARE NORTH AMERICA May 2019
Generation of ROS
Melanin content in %
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