Marine Drugs

Microalgae and cyanobacteria are valuable sources of bioactive ingredients and innovative biological systems for skin applications. Their metabolites include exopolysaccharides (EPS), mycosporine-like amino acids (MAAs), carotenoids, phycobiliproteins, peptides and lipopeptides, polyunsaturated lipids, chlorophyll derivatives, and distinctive secondary metabolites such as scytonemin. Cyanobacteria additionally provide defined molecular candidates, including sacran, C-phycocyanin, MAAs, scytonemin-related compounds, and specialized peptide scaffolds. These compounds may support hydration and barrier function, photoprotection, control of oxidative stress and inflammation, pigmentation, antimicrobial and antibiofilm activity, extracellular-matrix preservation, and wound repair. This review examines major bioactive families, their sources and mechanisms, with particular emphasis on the strength of evidence supporting skin applications. Recent developments from 2024 to 2026 are highlighted, including microalgal extracellular vesicles (nanoalgosomes), photoactivated antimicrobial systems, photosynthetic hydrogels and microneedle patches, green extraction and biorefinery strategies, reconstructed human skin and skin-on-chip models, and artificial-intelligence-assisted formulation. Most reported effects remain supported mainly by biochemical, cellular, or preclinical evidence, whereas human validation is still limited. Translation will, therefore, depend on rigorous chemical standardization, effective cutaneous delivery, demonstrated stability and safety, scalable manufacturing, and validation in human-relevant models. Microalgae and cyanobacteria thus extend beyond conventional natural extracts toward next-generation dermocosmetic and cutaneous-delivery platforms.

Marine-derived natural compounds have been investigated across respiratory diseases, but evidence remains fragmented across heterogeneous interventions, models, and outcomes. We mapped the evidence, examined biological convergence, and quantitatively synthesized comparable preclinical data. PubMed/MEDLINE, Scopus, and Web of Science were searched for studies published from 2000 to 2025; random-effects meta-analyses (Hedges’ g) were conducted for model–outcome combinations reported by at least three independent studies, with risk of bias and certainty assessed using design-specific tools and an adapted GRADE approach. Sixty-five studies were included (44 in vivo, 15 in vitro, 5 randomized trials, 1 non-randomized clinical study), with recurrent effects on inflammatory signalling, oxidative stress, immune regulation, tissue injury, and remodelling. Meta-analysis of 17 preclinical studies (60 comparisons, 11 outcomes) favoured marine-derived interventions for eosinophils, IgE-related outcomes, and type 2 cytokines in allergic airway models and for inflammatory/lung-injury markers in acute lung injury models, although heterogeneity was frequent and certainty was very low for all outcomes; clinical evidence was limited and heterogeneous. Marine-derived natural compounds show recurrent biological and directional convergence in selected preclinical respiratory models, but the evidence does not establish a therapeutic class effect or support direct clinical inference; translation requires standardized compound characterization, independent replication, and rigorous candidate prioritization.

Alzheimer’s disease (AD) is an irreversible neurodegenerative disorder with complex multifactorial pathological cascades, including amyloid-β (Aβ) aggregation, tau hyperphosphorylation, sustained neuroinflammation, oxidative stress, cholinergic dysfunction and gut–brain axis imbalance. Current marketed anti-AD drugs merely relieve symptomatic cognitive impairment without halting or reversing disease progression, highlighting an urgent demand for novel multi-target therapeutic candidates. Marine ecosystems, covering 71% of the Earth’s surface, generate structurally unique, low-toxicity secondary metabolites via adaptive metabolic pathways of marine algae, invertebrates and microorganisms, which represent promising lead compounds for developing marine anti-AD therapeutics with synergistic multitarget neuroprotective activities. This systematic review comprehensively summarizes the anti-AD bioactivities and underlying molecular mechanisms of seven major categories of marine natural products, including marine polysaccharides, terpenoids, macrolides, alkaloids, polyphenols and carotenoids, sterols/lipids, and aminosulfonates. We further perform an integrated ADMET druggability assessment of representative marine bioactive molecules to evaluate their blood–brain barrier penetration, oral absorption, physicochemical properties and toxicological risks, identifying homotaurine as the most balanced candidate with favorable central nervous system delivery and safety profiles. We also elaborate the core bottlenecks restricting clinical translation, including insufficient blood–brain barrier permeability and unsatisfactory in vivo pharmacokinetic behaviors of most marine-derived compounds. Finally, we outline future research directions, covering structural modification, nanocarrier delivery, gut–brain axis-targeted intervention and cross-disciplinary translational research. This work aims to provide a comprehensive theoretical reference for the discovery, optimization and clinical transformation of marine anti-Alzheimer drugs, and facilitate high-value exploitation of marine bioactive resources for neurodegenerative disease treatment.