Didemnin B

Marine organisms produce a diverse array of secondary metabolites with significant pharmacological potential, particularly in the development of anti-cancer, anti-microbial, antifungal, and anti-viral therapies. Despite challenges in isolation and cultivation, marine-derived compounds, such as Didemnin B, Psammaplin A, and Dolastatin, have shown promise in cancer treatment, while other metabolites exhibit potent activity against drug-resistant bacteria, fungi, and viruses. These compounds have excellent potential for treating various infections, for example, MRSA (eicosapentaenoic acid and fridamycin), Candida albicans (aurantoside K), and HIV-1 and HIV-2 (sulfoquinovosyl diacylglycerol). These unique compounds offer new avenues in drug discovery, addressing current limitations in traditional therapies. This review provides an overview of the pharmacological potential of marine organisms, focusing on their applications in overcoming drug resistance and developing novel treatments for cancer, infections, and viral diseases. Sustainable approaches for harvesting these compounds are essential for future research.

Didemnins are a class of cyclic depsipeptides derived from sea tunicates that exhibit potent anticancer, antiviral, and immunosuppressive properties. Although certain Tistrella species can produce didemnins, their complete biosynthetic potential remains largely unexplored. In this study, we utilize feature-based molecular networking to analyze the metabolomics of Tistrella mobilis and Tistrella bauzanensis, focusing on the production of didemnin natural products. In addition to didemnin B, we identify nordidemnin B and [hysp²]didemnin B, as well as several minor didemnin analogs. Heterologous expression of the didemnin biosynthetic gene cluster in a Streptomyces host results in the production of only didemnin B and nordidemnin B in limited quantities. Isotope-labeling studies reveal that the substrate promiscuity of the adenylation domains during biosynthesis leads to the accumulation of nordidemnin B and [hysp²]didemnin B. Additionally, precursor-directed biosynthesis is applied to generate eight novel didemnin derivatives by supplementing the culture with structurally related amino acids. Furthermore, we increased the titers of nordidemnin B and [hysp²]didemnin B by supplementing the fermentation medium with l-valine and l-isoleucine, respectively. Finally, both compounds undergo side-chain oxidation to enhance their biological activity, with their anticancer properties found to be as potent as plitidepsin.