In vivo evaluation of topical ascorbic acid application on skin aging by 50 MHz ultrasound

Ascorbic acid (AA) is a powerful antioxidant capable of acting significantly both in the prevention and treatment of the skin aging process. One way to assess the in vivo efficacy of anti-aging treatments is by using the high-frequency ultrasound (HFUS) skin image analysis technique, a non-invasive approach that allows for a new level of evaluating the effectiveness of dermatological and cosmetic products. The aim of the present study was to assess the performance of a topical emulsion of liquid crystalline structures containing AA using the 50 MHz HFUS skin image analysis method.Twenty-five healthy female participants between 35 and 60 years were included, all of whom randomly applied a placebo formulation and an AA-containing formulation to each forearm, once a day, for 30 days. HFUS measurements were performed before using the products (T0), 2 h later (T2h), and after 30 days of use (T30d). The analyzed parameters included total skin, dermal, and epidermal echogenicity; variation and mean thickness of total skin, the epidermis and dermis; and surface roughness. Statistical analyses were performed using the Friedman test, followed by Dunn's test for comparisons of multiple means (α = 0.05).A significant increase in total skin and dermal echogenicity was observed after topical AA application.Our findings suggest that collagen synthesis significantly increased after topical therapy with AA, which was responsible for the increment in dermal echogenicity. This study showed, through the HFUS technique, that the topical use of AA promoted dermal redensification after 30 days of application.