Valorization of Jellyfish (Rhopilema hispidum) By-Products for Bioactive Peptides with Antibacterial, Enzyme Inhibitory, and Low Cytotoxic Activities

The escalating concern regarding antibiotic resistance and metabolic disorders has catalyzed the search for natural compounds with multifunctional bioactivities. Marine-derived peptides have surfaced as promising candidates due to their diverse structures and bioactive properties. This study investigates the enzymatic hydrolysis of low-cost salted jellyfish (Rhopilema hispidum) by-products using pepsin to produce bioactive peptides with multifunctional attributes. The resulting hydrolysates were purified through reverse-phase and ion exchange chromatography and assessed for their antibacterial activity against Escherichia coli, Vibrio parahaemolyticus, and Staphylococcus aureus. Among the synthesized peptides, NQKAMQELNE exhibited significant antibacterial effects against E. coli (28.95%) and S. aureus (51.93%) and demonstrated substantial inhibitory actions on α-amylase (100.00%) and α-glucosidase (46.99%). Additionally, PFTMYFLL displayed remarkable inhibitory activity against V. parahaemolyticus (42.88%). Importantly, all five synthesized peptides—NQKAMQELNE, TDSPAPSETTD, EQIYPMGEGDEL, PFTMYFLL, and PMETDDQPNN—exhibited low hemolytic activity (4.14–7.12%), indicating minimal cytotoxicity and a favorable safety profile. Mechanistic insights suggest that the antibacterial effects of these peptides may arise from their capacity to disrupt vital intracellular microbial processes. This research addresses environmental and economic challenges by valorizing underutilized marine by-products, thereby contributing to developing safe, natural, and multifunctional bioactive compounds. These findings highlight the potential of jellyfish-derived peptides as functional ingredients in the food and pharmaceutical industries.