Marine mollusks comprise a group of shelled and shell-less soft-bodied animals. The shell-less eterobranchs are often colorful, slow-moving animals that rely extensively on chemical defenses for their survival, and many of these agents are transformed dietary derivates, resulting from selective feeding and accumulation. This phenomenon provides researchers with a screening model that is different from traditional methods to find leading compounds of physiologically active drugs from nature.
In recent years, the chemical ecological relationship (prey-predator relationship) between mollusks and their upstream and downstream food chain organisms has become a frontier hotspot in marine natural product research. The marine mollusk-derived secondary metabolites have been found to have important ecological significance and special therapeutical potential, which has led to the elucidation of the chemical ecological relationship between them and their preys or predators. At the same time, small-molecule compounds with chemical defense functions also show novel chemical diversity and a wide range of biological activities and are being studied for drug-related development. Mollusks have become an important class of drug source organisms in the research of new marine drugs.
On August 9, the marine drug research group led by Professor Guo Yuewei from the Shanghai Institute of Materia Medica (SIMM) of the Chinese Academy of Sciences, published a review paper in Nat. Prod. Rep., summarizing the recent advances in study of the interesting secondary metabolites from marine mollusks, which focuses on their structural features, possible chemo-ecological significance, and promising biological activities.
The research team first summarized the taxonomy of different species of mollusks reported in the past decade and found that they can be traced back to five subclasses (Autobranchia, Caenogastropoda, Heterobranchia, Patellogastropoda and Vetigastropoda). Then, the team aggregated the global distribution of mollusks studied in the last decade according to the collection place. Next, the researchers classified more than 300 secondary metabolites from mollusks according to their structural types, including 33 peptides, 38 alkaloids, 192 terpenes, 54 polyketides, 20 steroids and 20 miscellaneous, and clarified their probable origin (prey-predator relationship with mollusks), structural identification, and reported therapeutical potential. Among all the metabolites, peptides showed significant cytotoxicity and neuroregulatory activity, and some alkaloids and macrolides showed potent cytotoxicity. These results provide an important reference for finding compounds with drug potential from the ocean.
The researchers also discussed the ecological significance of each type of compound from the perspective of the different types of structure. Among them, most compounds could be recognized as chemical markers of the “predator-prey” chemical ecological relationship between mollusks and their food sources (such as algae, sponges, corals, etc.), and a few compounds could be recognized as markers of symbiotic/parasitic relationship between mollusks and bacteria. Interestingly, many sacoglossans (such as Plakobranchus ocellatus) could sequester the algae chloroplasts to photo-biosynthesize γ-pyrone polypropionates, which is a phenomenon known as “kleptoplasty”.
The research of chemical ecology provides important clues for finding molecular types with pharmacological activity from mollusks more quickly, which has offered a new insight into the research of marine natural medicines and provides a new idea for multi-dimensionally revealing the capacity of natural products for conversion to pharmaceutical compounds.
For more information, please contact:
Diao Wentong
E-mail: diaowentong@simm.ac.cn
Shanghai Institute of Materia Medica (SIMM),
Chinese Academy of Sciences
Source: Shanghai Institute of Materia Medica (SIMM),
Chinese Academy of Sciences