The skin of amphibians is a tissue with biological functions, such as defense, respiration, and excretion. In recent years, researchers have discovered a large number of peptides in the skin secretions of amphibians, including antimicrobial peptides, antioxidant peptides, bradykinins, insulin-releasing peptides, and other peptides. This review focuses on the origin, primary structure, secondary structure, length, and functions of peptides secreted from amphibians’ skin. We hope that this review will provide further information and promote the further study of amphibian skin secretions, in order to provide reference for expanding the research and application of amphibian bioactive peptides.

Deer antler is widely used as a nutraceutical in Asian countries. In the past decades, deer antler peptides (DAPs) have received considerable attention because of their various biological properties such as antioxidant, anti-inflammatory, anti-bone damage, anti-neurological disease, anti-tumor and immunomodulatory properties. This review describes the production methods of DAPs and the recent progress of research on DAPs, focusing on the physiological functions and their regulatory mechanisms.

Antler bone calcium (AB−Ca) and bioactive peptides (ABPs) were extracted from antler bones (Cervus elaphus) to maximize their value. In this study, 0.14 g calcium was obtained from 1 g antler bone. The peptide−calcium chelate rate was 53.68 ± 1.80%, and the Gly, Pro, and Glu in ABPs were identified to donate most to the increased calcium affinity through the mass spectrometry. Fourier transform infrared spectroscopy showed that calcium predominantly interacted with amino nitrogen atoms and carboxyl oxygen atoms, thereby generating a peptide–calcium chelate. The peptide−calcium chelates were characterized using scanning electron microscopy. A Caco-2 cell monolayer model showed that ABPs significantly increased calcium transport. Furthermore, the D-gal-induced aging mouse model indicated that the ABPs + AB−Ca group showed higher Ca and PINP levels, lower P, ALP, and CTX-1content in serum, and considerably higher tibia index and tibia calcium content. Results showed that ABPs + AB-Ca increased bone formation and inhibited bone resorption, thereby providing calcium supplements for ameliorating senile osteoporosis (SOP).