Marine Drugs

Carotenoproteins from marine sponges represent an underexplored class of pigment–protein complexes with distinctive structural and functional properties. Here, we report the isolation and biophysical characterization of a blue carotenoprotein from the sponge Tedania ignis, termed Ti-CP. The protein was purified and shown to consist of two closely related isoforms with molecular masses of approximately 27–29 kDa. Reverse-phase chromatography enabled separation of the apoprotein (ApoTi-CP) and its associated carotenoids, which were identified as oxygenated carotenoids consistent with astaxanthin and mytiloxanthin. Circular dichroism analysis revealed that both Ti-CP and ApoTi-CP are dominated by β-sheet secondary structure and display highly similar conformational profiles. In contrast, dynamic light scattering demonstrated that carotenoid binding is critical for protein stability, as the native form exhibited a compact and monodisperse organization, whereas ApoTi-CP showed pronounced aggregation. Isothermal titration calorimetry revealed that Ti-CP, but not ApoTi-CP, interacts with tetracycline, oxacillin, and streptomycin, indicating that pigment-mediated stabilization modulates ligand binding. Both Ti-CP and ApoTi-CP reduced bacterial viability and biofilm formation in a strain-dependent manner and enhanced antibiotic activity, including synergistic effects against resistant bacteria. Together, these results provide a comprehensive description of a previously uncharacterized sponge carotenoprotein and highlight the dual role of carotenoids in structural stabilization and antimicrobial modulation, reinforcing the biotechnological relevance of marine pigment–protein complexes.

Chemical investigation of the marine sponge-derived Streptomyces xiamenensis 1310KO-148 afforded six polycyclic tetramate macrolactams (PTMs), including three known compounds (1–3) and three previously undescribed chlorohydrin-containing analogues, chlokamycins B–D (4–6). Their planar structures were elucidated by extensive analysis of 1D and 2D NMR spectra and HR-ESIMS data, while the relative configurations were assigned using NOESY correlations. The absolute configurations were further confirmed by electronic circular dichroism (ECD) calculations. Compounds 3–6 exhibited significant cytotoxic activity against 14 human cancer cell lines (GI₅₀ = 2.68–24.92 μM) and antibacterial activity against Staphylococcus aureus (MIC = 16.00–32.00 μg/mL) and Micrococcus luteus (MIC = 4.00–32.00 μg/mL) among six tested bacterial strains.

Functional seafoods derived from marine organisms, including fish, shellfish and algae, are gaining increasing attention due to their high content of bioactive compounds, such as omega-3 fatty acids, peptides, polysaccharides and antioxidants, which provide health benefits beyond basic nutrition. These marine-derived compounds exhibit a wide range of biological activities and have been investigated for their potential roles in the prevention and management of chronic diseases, including cardiovascular, neurodegenerative, cancer and gastrointestinal disorders. Their effects are largely mediated through anti-inflammatory, antioxidant and immunomodulatory mechanisms. Advances in biotechnology, including genetic engineering and improved extraction of bioactive compounds, have enhanced the nutritional quality and pharmacological relevance of functional seafoods. At the same time, sustainable aquaculture practices are being developed to reduce environmental impacts. Nevertheless, challenges such as regulatory inconsistencies, scalability issues and limited understanding of bioavailability and long-term effects still persist. These constraints should be considered when interpreting mechanistic and efficacy findings presented across different study designs and exposure conditions. Future perspectives highlight innovations in precision aquaculture, waste valorisation and traceability as key strategies to improve sustainability and strengthen consumer trust. This review summarizes current knowledge on functional seafoods, with emphasis on pharmacological mechanisms, clinical applications and the need for interdisciplinary research to optimize their health benefits and commercial potential.