Microscopic Fungi as Sources of Natural UV-Protective Compounds

The search for sustainable and biocompatible alternatives to synthetic sunscreens has intensified due to concerns about the safety and environmental persistence of conventional UV filters. Although algae and bacteria have been extensively explored as sources of photoprotective metabolites, microscopic fungi remain comparatively neglected despite remarkable metabolic diversity and ecological adaptability. This review synthesizes research from 2014 to 2025 on fungal metabolites with photoprotective potential, including melanins, mycosporine-like amino acids (MAAs), carotenoids, quinones, xanthones, and alkaloids. These compounds absorb UV radiation and display complementary antioxidants, antimicrobial, and anti-inflammatory properties. Experimental evidence indicates that fungal metabolites can protect keratinocytes, fibroblasts, and reconstructed skin models from UV-induced oxidative stress and DNA damage, achieving sun protection factor (SPF) values comparable to commercial formulations. Advances in extraction, fermentation, and synthetic biology are enhancing production efficiency, while innovative delivery systems, such as nanoparticles, improve stability and dermal penetration. Extremophilic fungi and engineered yeasts stand out as promising biotechnological platforms for scalable biosynthesis. Despite remaining challenges in yield optimization, formulation stability, and regulatory validation, microscopic fungi represent a largely untapped resource for developing multifunctional, eco-friendly sunscreens and cosmeceuticals that integrate UV protection with broader skin health benefits.