Protein composition of the foam nest of Rhacophorus reinwardtii (Schlegel, 1840) (Anura: Rhacophoridae), with notes on breeding sites characteristics and biomedical applications

Rhacophorus reinwardtii is endemic to Java Island and is currently experiencing a population decline. Therefore, the sustainability of its offspring is important to prevent species extinction. Foam nest as a biosurfactant structure plays a crucial role as egg protection through major protein components function. However, studies on the functional proteins of rhacophoridae foam nests are limited. Thus, this study aims to uncover the protein-specific components and functions of the R. reinwardtii foam nest. Additionally, the characteristics of breeding sites, including abiotic factors, were also assessed. Total protein concentration of the R. reinwardtii foam nest was determined to be 747.7 μg/mL and foam nest protein consistently ranged from 130 kDa to >270 kDa, with prominent bands at >270 kDa. Based on UniProt and NCBI (amphibian) database, 17 proteins were identified. These proteins were categorised into enzymes (41%), regulatory proteins (29%), structural proteins (12%), and antimicrobial peptides (12%). The findings suggest promising potential biomedical applications, such as neurodegenerative disease therapy, diagnostic markers, and antimicrobial agents.