Photoprotective Effects of Oral Pterostilbene in UVB-Induced Skin Photoaging BALB/c Mouse Model

Abstract

Background: Photoaging results from prolonged and repeated exposure to solar ultraviolet-B (UVB) radiation. While sunscreen is effective in preventing ultraviolet (UV)-induced skin damage, oral antioxidants may offer additional protective benefits. Pterostilbene (PS), a compound found in blueberries and Pterocarpus marsupium heartwood, is recognized for its anti-aging and anti-photocarcinogenic properties. However, its photoprotective effects on photoaging have not been extensively studied. Objectives: This study investigates the photoprotective effects of oral PS in a UVB-induced skin photoaging BALB/c mouse model. Methods: Sixteen 7-week-old female BALB/c mice were randomly assigned to groups using an online random number generator. The mice received daily oral doses of corn oil or PS at 30 and 60 mg/kg in corn oil. After a 2-week period without UVB exposure, the UVB (-) group remained unexposed, while the UVB (+), UVB (+) PS30, and UVB (+) PS60 groups were subjected to increasing UVB doses three times a week for eight weeks, resulting in a cumulative exposure of 3.7 J/cm2. Weekly pinch tests were conducted throughout the 8-week exposure period. Photographs of the mice skin were taken before culling, and skin samples were collected for Hematoxylin & Eosin (H&E) staining, Masson's trichrome staining, reduced glutathione (GSH) assay, and melanin content assay. Results: The UVB (+) PS30 group showed reduced erythema and wrinkles, while the PS60 group exhibited the most significant improvement in photoaged skin, with eliminated erythema, reduced wrinkles, and smoother skin. The PS30 (4.05 ± 0.11 seconds) and PS60 (3.65 ± 0.06 seconds) groups significantly reduced pinch test times compared to the UVB (+) group (4.96 ± 0.12 seconds), indicating improved skin elasticity. Additionally, PS30 (61.87 ± 3.58 µm) and PS60 (43.64 ± 2.08 µm) significantly reduced epidermal thickness compared to the UVB (+) group (67.39 ± 1.69 µm). Collagen content significantly increased in the PS30 (1.41 ± 0.04) and PS60 (1.27 ± 0.02) groups compared to the UVB (+) group (1.11 ± 0.01). The GSH levels (µmoL/mg) were significantly higher in the PS30 (0.56 ± 0.01) and PS60 (0.56 ± 0.02) groups compared to the UVB (+) group (0.48 ± 0.01), with no significant difference between the PS doses. Melanin content (µmoL/mg) in the PS30 (0.34 ± 0.01) and PS60 (0.35 ± 0.01) groups showed no significant difference compared to the UVB (+) group (0.387 ± 0.04). Conclusions: Oral PS demonstrated significant photoprotective effects in UVB-induced skin photoaging, suggesting its potential as an anti-photoaging agent in the cosmeceutical and nutraceutical industries.