From ocean to pharmacy: marine sugars emerge as next-generation drug candidates

The ocean has long been regarded as a vast reservoir of chemical novelty, but one of its most abundant and least celebrated classes of molecules is now stepping into the pharmaceutical spotlight. Carbohydrates produced by algae, marine invertebrates and microorganisms display structural features that are rarely encountered in land-based organisms, and a new review published in Glycoscience & Therapy argues that these distinctive architectures could underpin a new generation of medicines. The work, led by researchers at the Key Laboratory of Marine Drugs at the Ocean University of China, brings together decades of scattered findings on the sources, structures and biological activities of marine carbohydrates, and maps out what it actually takes to convert a complex natural sugar into a reproducible, clinically approved drug.

What makes marine carbohydrates so chemically interesting is their structural diversity. Polysaccharides extracted from seaweeds, sponges, shellfish and marine bacteria can carry sulfate groups in patterns that differ from species to species, form glycosidic linkages that are uncommon in terrestrial plants, and adopt branched architectures that change how they interact with biological targets. Fucoidans from brown algae, carrageenans from red algae, chitin and chitosan derivatives from crustacean shells, and sulfated glycosaminoglycan-like molecules from marine animals all fall into this category. Because the precise arrangement of sulfate groups and sugar units determines how these molecules bind to proteins, enzymes and cell surfaces, even subtle structural differences can translate into dramatically different biological effects.

That sensitivity to structure is precisely why these molecules have attracted attention across so many therapeutic areas. The review documents reported antiviral, anticoagulant, immunomodulatory and antitumor activities for marine-derived carbohydrates and their derivatives, alongside material properties that make them useful in drug delivery systems, wound dressings and tissue engineering scaffolds. Sulfated polysaccharides, for example, can interfere with viral attachment and entry by mimicking the charged surfaces that viruses normally latch onto, while alginate-based materials have become mainstays in encapsulation and wound-care applications because of their gentle gelling behavior and biocompatibility.

The clinical story of marine-inspired drugs is older than many readers might expect. The review’s authors anchor their timeline to cytarabine, an antileukemia drug approved in the United States in 1969, which traces its chemical inspiration to nucleosides originally isolated from a Caribbean sponge. Although cytarabine is not itself a carbohydrate in the polysaccharide sense, it established a crucial precedent: molecules derived from marine organisms could survive the full gauntlet of preclinical testing, regulatory scrutiny and clinical use. Later products built on alginate, carrageenan and other marine raw materials followed, extending the family of carbohydrate-based medicines into areas such as wound management, drug formulation and symptomatic treatment.

Today, the pipeline is broader than ever. The review surveys clinical-stage candidates derived from marine carbohydrates currently being evaluated for viral infections, cancer, metabolic disorders, tissue repair, cystic fibrosis and neurological disease. This breadth reflects both the versatility of the molecules and the maturity of the field: what was once a collection of exploratory extracts has become a portfolio of defined candidates moving through controlled trials. Yet the authors are careful to note that the distance between a promising laboratory result and an approved product remains substantial, and that the obstacles are not primarily about discovering new activities.

The central challenge, according to the review, is reproducibility. The biological activity of a marine polysaccharide depends on its molecular weight, its sulfation pattern and its monosaccharide composition, but all three of these parameters can vary with the species from which the material is harvested, the season in which it is collected, and the extraction and processing methods used to isolate it. A batch of fucoidan gathered from one coastline in spring may differ measurably from a batch of the nominally same polymer collected elsewhere in autumn. For a regulatory agency, such variability is a serious problem, because a drug must deliver the same molecule, with the same quality attributes, every single time.

Solving that problem requires the kind of systematic thinking that the review tries to encourage. The authors argue that marine carbohydrates have too often been studied in terms of individual biological activities, with each research group reporting a single effect in isolation, while clinical development demands an integrated understanding of how structure, production, quality control and mechanism of action fit together. A candidate cannot advance if researchers cannot define its composition precisely, manufacture it consistently and explain how it works at the molecular level. The review therefore treats approved drugs and clinical candidates not just as success stories, but as case studies in how these elements can be aligned.

The priorities for future development that the authors identify are correspondingly practical. They call for reliable production methods based on cultivation, fermentation or enzymatic processing, which would decouple drug supply from wild harvesting and reduce batch-to-batch variation. They emphasize the need for improved quality control that combines structural characterization with activity-based assays, so that manufacturers can verify not only what a batch contains but what it does. They also stress the importance of validating molecular targets and mechanisms of action, and of conducting more rigorous pharmacokinetic and safety studies, areas in which complex carbohydrates have historically lagged behind small-molecule drugs because of their size, heterogeneity and analytical difficulty.

Achieving these goals, the review concludes, will require collaboration across disciplines that do not always work together. Senior and co-corresponding author Guangli Yu of the Ocean University of China notes that progress will depend on close cooperation among researchers in glycoscience, analytical chemistry, synthetic biology, materials science and clinical research. Co-corresponding author Chao Cai, also of the Ocean University of China, shares responsibility for the work, which was conducted within the Key Laboratory of Marine Drugs under the Ministry of Education and the Shandong Key Laboratory of Glycoscience and Glycotherapeutics. The interdisciplinary framing is deliberate: no single field currently possesses all the tools needed to characterize, manufacture and clinically validate a heterogeneous natural polymer.

The significance of the review lies less in any single discovery than in its synthesis. By following a clinical timeline that stretches from a 1969 leukemia drug to today’s trials in virology, oncology, metabolic disease and neurology, it demonstrates that marine carbohydrate therapeutics are not a speculative frontier but an evolving branch of pharmacology with a documented track record. The structural uniqueness of ocean-derived sugars, once a curiosity, is now understood as a design resource, and the field’s remaining challenges are the familiar ones of manufacturing, characterization and clinical evidence. If the collaborative agenda the authors describe takes hold, the next chapters of this timeline may be written not by chance discoveries in tide pools, but by engineered production systems capable of delivering the ocean’s chemistry with pharmaceutical precision.

Subject of Research: Marine carbohydrate-based drug development and clinical translation

Article Title: Marine carbohydrate therapeutics: from structural diversity to clinical translation

Article References: Marine carbohydrate therapeutics: from structural diversity to clinical translation. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: marine carbohydrates, polysaccharides, fucoidan, alginate, carrageenan, drug development, clinical trials, glycoscience, sulfation, antiviral, anticoagulant, Ocean University of China