Amphibian skin peptides: Diversity, biological functions, and research progress

Bioactive peptides derived from amphibian skin have attracted increasing attention due to their potent biological activities and potential toxicological and pharmacological relevance. Amphibians, particularly frogs (order Anura), possess highly specialized skin glands that secrete diverse peptides functioning in chemical defense and innate immunity. Owing to their broad-spectrum antimicrobial, antiviral, anticancer, antioxidant, and immunomodulatory properties, these peptides are regarded as promising candidates for drug development, while their biological activities also raise important considerations regarding safety and toxicity. This review focuses on skin-derived peptides in Amphibia, with an emphasis on frog peptides, reflecting their dominance in species diversity and available research data. We first summarize the diversity of amphibian skin structures and peptide-secreting glands, and then present a bibliometric analysis of frog peptide-related publications over the past two decades, identifying antimicrobial and antiviral peptides as major research hotspots. Subsequently, amphibian skin peptides are systematically categorized according to their biological functions, including antimicrobial, antioxidant, wound-healing, anticancer, immunomodulatory, and antiviral activities. By integrating structural, functional, and bibliometric perspectives, this review provides a consolidated framework for understanding the biological significance and application potential of amphibian skin peptides, thereby offering a reference for future toxicological evaluation and translational research.