Protein Composition and Biomedical Potential of the Skin Secretion of Hylarana erythraea (Schlegel, 1837) (Anura: Ranidae) from Langkawi Archipelago, Kedah, Peninsular Malaysia

The skin secretion of amphibians is known for its high content of bioactive compounds. These bioactive compounds are essential for the advancement of biomedical industries. Four wild green paddy frogs, Hylarana erythraea, were collected from various habitat types within the Langkawi Archipelago. These frogs’ skin secretions were collected, extracted, and analysed for their protein compounds together with biomedical potentials using liquid chromatography–mass spectrometry (LC–MS). The total protein concentration of H. erythraea skin secretions was determined as 0.269 mg/mL. Based on the UniProt (Anura) database, we identified 29 proteins. These proteins were categorised as antimicrobial (AMP) (38%), followed by hormone (17%), enzyme (17%), unreviewed proteins (17%), structural proteins (7%), and regulatory proteins (4%). The AMPs identified were from the family of esculentin-1, esculentin-2, brevinin-1, and frenatin-4, while the hormones belonged to the cholecystokinin group. The enzymes detected were adenylate cyclase 9, the suppressor of tumorigenicity 14 protein homolog, and the HGF activator. The structural proteins belonged to toe pad keratin 2 and Krt5.7 proteins, while the single regulatory protein is CCR4-NOT transcription complex subunit 6-like. These proteins have a wide range of biomedical importance, such as wound healings, facilitate digestions, anti-tumours, and anti-cancer effect.