DECODING THE VIBRANT CHEMISTRY: LINKING STRUCTURE AND PROPERTIES OF AMPHIBIAN CAROTENOIDS TO THEIR FUNCTIONAL ROLES

Carotenoids are a category of bioactive compounds widely found, not only in the plant kingdom but also in some animal products. They form a group of more than 700 fat-soluble compounds, which generally contribute to the yellow to red colours of many foods, although colourless carotenoids such as phytoene have also been identified. These molecules are divided into hydrocarbon carotenes, i.e., containing only carbon and hydrogen (e.g., α- and ß-carotene), and xanthophylls (e.g., lutein) characterized by the presence of oxygen atoms. Numerous studies and systematic reviews have been performed to analyze the determinants of carotenoid bioavailability, concluding that the efficiency of their absorption can be affected by numerous intrinsic and extrinsic factors. In amphibians, carotenoids are implicated in aposematic and sexual signalling, photoprotection, antioxidant buffering and interactions with pathogens and symbiotic microbes. Carotenoid research in amphibians has matured but progress will require integrative, multi-disciplinary studies that move beyond single-factor experiments and into the ecological and evolutionary contexts that shape how amphibians use these versatile pigments.