Bold claim: MIT chemists have achieved a milestone by synthesizing verticillin A, a complex fungal compound with promising anticancer potential, for the first time. This breakthrough revives interest in verticillin A, discovered over five decades ago, and demonstrates how modern chemistry can access and adapt such intricate molecules that previously resisted laboratory replication.
Moving beyond mere reproduction, the work also shows how subtle structural differences can dramatically alter synthetic difficulty. “We now have the technology to access verticillin A for the first time since its isolation,” explains Mohammad Movassaghi, a professor of chemistry at MIT. “More importantly, we can design and create numerous variants to enable deeper study.”
In cellular tests, a derivative of verticillin A demonstrated notable activity against diffuse midline glioma (DMG), a pediatric brain cancer. While these findings are encouraging, further studies are required to determine clinical viability and safety.
Movassaghi and Jun Qi, associate professor of medicine at the Dana-Farber Cancer Institute/Boston Children’s Hospital, and Harvard Medical School, lead the study, published in the Journal of the American Chemical Society. Lead author Walker Knauss PhD ’24 contributed to the paper, with Xiuqi Wang of Dana-Farber and Mariella Filbin of Dana-Farber/Boston Children’s also listed as authors.
A challenging synthesis, from isolation to construction
Verticillin A was first isolated from fungi in 1970, where the compound serves to defend against pathogens. Its relatives attracted attention for potential anticancer and antimicrobial properties, but their synthesis remained daunting due to extreme structural complexity.
A precursor achievement came in 2009 when Movassaghi’s lab synthesized (+)-11,11'-dideoxyverticillin A, a structurally similar fungal molecule featuring 10 rings and eight stereogenic centers—carbon atoms bonded to four different groups. Achieving the correct three-dimensional arrangement (stereochemistry) is crucial for biological activity.
Even after that milestone, verticillin A resisted synthesis. The two oxygen atoms that distinguish verticillin A from (+)-11,11'-dideoxyverticillin A severely constrained the chemical space available for transformations, making the molecule fragile and highly sensitive to reaction conditions.
Both verticillin A and its dimer partner consist of two identical fragments that must be joined, forming a dimer. In the case of (+)-11,11'-dideoxyverticillin A, dimerization occurred late in the sequence, followed by the formation of four essential carbon-sulfur bonds. But attempting the same late-stage approach for verticillin A did not yield the correct stereochemistry, prompting a strategic rethink and a radically different sequence of steps.
The key lesson: timing matters. “The order of bond-forming events had to be completely redesigned,” Movassaghi notes. This insight reshaped the entire synthetic route.
The new synthesis starts from beta-hydroxytryptophan, an amino acid derivative, and is built step by step through the careful installation of alcohol, ketone, and amide functionalities to lock in the correct stereochemistry. Early introduction of a functional group containing two carbon-sulfur bonds and a disulfide pair helped control stereochemistry, with protective masking to prevent premature disulfide breakdown. The disulfides are regenerated after dimerization.
Describing the feat, Movassaghi emphasizes the substrate complexity involved in the final dimerization, noting it brings together a dense array of functional groups and stereochemical requirements. The completed verticillin A synthesis comprises 16 steps from the beta-hydroxytryptophan starting material.
Exploring therapeutic potential
After successfully synthesizing verticillin A, researchers used the route to generate derivatives. Dana-Farber scientists then tested these compounds against several DMG models, a rare pediatric brain tumor with limited treatment options.
The most sensitive DMG cell lines were those with high EZHIP protein levels. EZHIP is implicated in DNA methylation and has emerged as a potential drug target for DMG. The team aims to clarify how these compounds act and to optimize them for selectivity and efficacy.
The data suggest the derivatives interact with EZHIP in a way that increases DNA methylation, pushing cancer cells toward programmed cell death. Among the most effective compounds were N-sulfonylated (+)-11,11'-dideoxyverticillin A and N-sulfonylated verticillin A, where N-sulfonylation adds a sulfur- and oxygen-containing group to improve stability.
Movassaghi cautions that the natural product itself isn’t the most potent form, but its synthesis enabled the creation of potent derivatives and the study of their properties. The team plans to continue validating the mechanism of action and to pursue animal studies in pediatric brain cancers.
Looking ahead, the Dana-Farber group aims to integrate chemistry, chemical biology, cancer biology, and patient-care expertise to fully assess therapeutic potential. They have already profiled lead molecules across more than 800 cancer cell lines, broadening understanding of how these compounds might perform against other cancers.
Funding and collaboration
The research was funded by the National Institute of General Medical Sciences, the Ependymoma Research Foundation, and the Curing Kids Cancer Foundation, underscoring a collaborative effort across institutions to advance potential brain cancer therapies.
