The Scandinavian region is home to a unique biome with endemic plant species. The aim of this study was to explore this natural diversity and identify plant extracts providing positive skin barrier effects. Six plant extracts were identified as starting material. Following biochemical screening, two candidates outperformed the rest: Betula alba (BA) and Empetrum nigrum (EN). Quantitative PCR analysis showed that BA and EN upregulated barrier genes, when used individually and in combination. Betula alba increased AQP3 and OCLN protein expression, something niacinamide was incapable of. Additionally, the skin barrier was strengthened, evidenced by inhibition of KLK5 and hyaluronidase and showed strong antioxidant and anti-inflammatory activity through DPPH and COX2 inhibition, respectively. A first split-face clinical study was conducted using the combination of extracts versus placebo. There was a significantly better skin restructuring effect and corneocyte cohesion on the side treated with combined extracts. A second split-face clinical study assessed the combined extracts versus 3% niacinamide. Significant variations in skin hydration and TEWL were observed in favor of the extract treated side. In conclusion, we identified a natural alternative to niacinamide for improving skin barrier health, in Scandinavian plant extracts, which yield strong performance, but at a lower concentration.

Both UVB irradiation and air pollution are major extrinsic factors causing premature aging of the skin, including sagging, wrinkles, and pigmentation spots. Naringenin, a naturally occurring flavanone, found in citrus fruits, and known for its good antioxidant and anti-inflammatory effects, was investigated for protective effects in human skin cells and reconstructed epidermis. The results showed that naringenin inhibits UVB-induced inflammation markers MMP1, MMP3, IL6, and GM-CSF, as well as pollution-induced MMP1 in human skin fibroblasts. Furthermore, naringenin inhibited the pollution-induced expression of the CYP1A1 gene in human skin keratinocytes. In melanocytes and pigmented reconstructed epidermis, naringenin significantly downregulated several genes involved in melanogenesis, such as MITF, MLPH, and MYO5A. Additionally topical treatment with naringenin on pigmented reconstructed epidermis significantly decreased melanin production. In conclusion, this study demonstrates that naringenin could be a valuable ingredient in skincare products, protecting against the detrimental effects of both UVB and pollution on the skin.