The test formulations consisted of a placebo formulation and an active formulation of 4% of a commercial product containing 2500 ppm of DABBA (Trade name SYN®-AKE, DSM Nutritional Products, Switzerland). The composition of both placebo and active formulation is outlined in Table 1.
Study Outline and Volunteers
This human study was conducted at SGS Stephens Inc. (formerly Thomas J. Stephens & Associates Inc.), Richardson, TX, United States. The study took place between 8th July and 22nd September 2019. This was a single centre, placebo-controlled, randomized, and double-blind study. This study adhered to the guidelines of the declaration of Helsinki. Volunteers gave their informed consent to participate in the study. The study was approved by the local ethics committee, IntegReview Institutional Review Board (IRB) on 25th June 2019. IntegReview IRB, located in Austin, Texas, is a duly constituted IRB under Title 21 CFR Parts 50 and 56. Volunteers were female: 54 Caucasian, 2 Asian, and 1 mixed race, ages 50 to 65 years. For the wrinkle pattern analysis, we recruited eight additional volunteers (7 Caucasian, 1 Asian) who were biologically related daughters to eight of the volunteers. Subjects were in good general health (physical, mental, and social well-being, not merely the absence of disease/infirmity), according to a self-report, and had Fitzpatrick skin type I–IV. The 8 daughters were 21–35 years old and had no to a mild score for wrinkles on the overall face (score of 0–3 according to a modified Griffiths scale, where 0 = none and 9 = severe). Volunteers in the 50–65 age group had mild to moderate scores (score of 3–6 according to a modified Griffiths scale, where 0 = none and 9 = severe) for wrinkles in at least 3 of the following locations: Forehead, Crow’s feet, Nasolabial (nose to corners of mouth), Marionette (corners of mouth down to chin). Subjects were willing not to use any foundation during the course of the 4-week study (lip and eye color cosmetics were allowed), not had any facial treatments in the past 6 months, and were willing to withhold all facial treatments during the course of the study.
Exclusion criteria: Standard exclusion criteria were applied. In brief: having known allergies to facial skin care products; to be nursing, pregnant, or planning to become pregnant according to self-report; a history of skin cancer within the past 5 years; to be taking or have taken anti-aging or skin lightening products, or other products or topical or systemic medication known to affect skin aging or dyschromia, during the two weeks before the study.
Assignment and Application of Test Formulations
Randomization: Validated software (RITA, Randomization in Treatment Arms) was used to assign the test products to the subgroups in a way that minimized potential imbalance regarding age, phototype and ethnicity. Product A received 28 subjects. Product B received 29 subjects. Application: Twice per day (morning and evening), after facial cleansing, a nickel-sized amount (2 mg cm−2) of test material was applied over the entire face and allowed to absorb.
Subjects had images taken at the baseline and week 4. Subjects acclimatized to ambient conditions within the clinic for at least 15 min before any photographs were taken. Digital images of each subject’s face were taken using VISIA CR photo station (Canfield Imaging Systems, Fairfield, NJ, USA) with a Canon Mark II digital SLR camera (Canon Incorporated, Tokyo, Japan). Subjects adopted a neutral, unsmiling expression for images taken from left, center, and right views. At the baseline and week 4, an additional center view image was taken with an “angry” frowning expression, and an additional left view image was taken with a wide smiling expression. In order to standardize this procedure as much as possible, subjects were asked to assume as angry an expression as possible and to assume as wide a smile as possible at both timepoints. A 48 patches color chart (Newtone Technologies, Princeton, NJ, USA) was added to the system and present on each image.
Primoslite Imaging Procedures
Primoslite imaging was performed on crow’s feet area. The Primoslite 45 × 30 mm system (GFMesstechnik GmbH, Teltow, Germany) is a hand-held 3D imaging device for assessing the microtopography of skin. The field of view is 45 × 30 × 20 mm with resolution of 61 × 61 × 6 µm. Primoslite images were analyzed using the Primoslite wrinkle analysis software built-in function (Widgerow, Jiang, and Calame 2018).
Clinical Grading of Efficacy Parameters
At the baseline and week 4, subjects were evaluated for wrinkles on the forehead, crow’s feet, nasolabial folds, marionette area, and upper lip according to a modified Griffiths scale (Griffiths et al. 1992).
Wrinkle Analysis of Angry and Smiling Faces and Visual Enhancement
In order to study the evolution of wrinkles over time, the wrinkles were segmented using specific image processing algorithms. Then the wrinkles were characterized by computing their conspicuous surface area, length, and volume (Campiche et al. 2019). In addition to the analysis, two types of illustration were created to visualize the product effect. First, a visual enhancement was performed to highlight wrinkles using an image processing pretreatment. Then, delta values of expert grading scores between the baseline and week 4 were mapped on a 3D face using a pink facial colour map (Newtone Technologies, Lyon, France) (Voegeli et al. 2015, 2019).