Summary: For the first time, chemists have completed the total synthesis of verticillin A, a structurally intricate fungal natural product with notable anticancer activity. Because the molecule is unusually fragile, researchers redesigned the entire synthetic sequence, allowing them not only to reproduce verticillin A but also to create more stable and potentially more effective derivatives.
Early laboratory studies in human cancer cell lines show particular promise against diffuse midline glioma, a devastating pediatric brain tumor that presently has very limited treatment options. With a reliable synthetic route now established, researchers can systematically explore verticillin-based compounds across wider cancer models and optimize them for therapeutic development.
Key Facts
- Breakthrough Synthesis: Verticillin A has been synthesized in the laboratory for the first time since its original isolation more than 50 years ago.
- Therapeutic Potential: A chemically stabilized derivative demonstrated strong activity against pediatric diffuse midline glioma cells in vitro.
- Structural Insight: Changing the order of key bond-forming steps was essential to control the molecule’s delicate stereochemistry and to avoid unwanted rearrangements.
Source: MIT
MIT chemists report the first total synthesis of verticillin A, a complex fungal metabolite discovered over five decades ago that has shown anticancer promise.
Although verticillin A differs from similar compounds by only a few atoms, those differences make the molecule far more challenging to assemble. Its densely functionalized framework and sensitive chemical features required the team to rethink conventional synthetic tactics.
“We now have a much clearer view of how small structural changes can dramatically increase synthetic difficulty,” says Mohammad Movassaghi, professor of chemistry at MIT. “With this new strategy, we can access verticillin A for the first time in decades and also prepare designed analogs for detailed biological study.”
Tests carried out in cultured human cancer cells indicate that one verticillin derivative is especially active against diffuse midline glioma (DMG), a rare and aggressive childhood brain tumor. The researchers caution that additional studies are required to determine whether these compounds have clinical potential.
The study’s senior authors are Mohammad Movassaghi and Jun Qi, associate professor of medicine at Dana‑Farber Cancer Institute/Boston Children’s Cancer and Blood Disorders Center and Harvard Medical School. The paper appears in the Journal of the American Chemical Society. Walker Knauss (PhD ’24) is the lead author, and other contributors include Xiuqi Wang and Mariella Filbin from Dana‑Farber/Boston Children’s.
A complex synthesis
Verticillin A was first isolated from fungi in 1970; these organisms likely produce the compound as a defensive metabolite. Over the years, verticillin A and related epidithiodiketopiperazine (ETP) alkaloids have attracted interest for their antimicrobial and anticancer activities, but their chemical complexity made total synthesis elusive.
In 2009, Movassaghi’s group synthesized a related molecule, (+)-11,11′-dideoxyverticillin A, which contains ten rings and eight stereogenic centers. Despite that earlier achievement, verticillin A posed new obstacles: the addition of two oxygen atoms in verticillin A dramatically reduced the tolerance for many chemical transformations and made the molecule far more sensitive to reaction conditions.
“Those two oxygen atoms shrink the margin for error,” Movassaghi explains. “They render the molecule more fragile and limit the scope of manipulations we can perform without damaging key features.”
Both verticillin A and the earlier dideoxy derivative are dimers formed by joining two identical subunits. For the dideoxy compound, the team performed dimerization late in the sequence and then installed critical carbon–sulfur bonds. But applying the same order of steps to verticillin A produced the wrong stereochemical outcomes.
To overcome that problem, the researchers devised a new sequence in which particular sulfur-containing groups and the disulfide motif are introduced earlier, then temporarily masked to survive subsequent steps. After the dimerization step, the team unmasked those groups and completed the final transformations to reveal the epidithiodiketopiperazine substructures with the correct relative stereochemistry.
“The timing of each bond-forming event proved decisive,” Movassaghi says. “We had to rearrange the order of operations to gain stereochemical control over a very sensitive molecular architecture.”
The synthesis begins from a beta-hydroxytryptophan derivative and proceeds through a carefully planned sequence of functional-group installations—alcohols, ketones, amides, and sulfide motifs—designed to preserve and control stereochemistry throughout. In total, the route from the starting amino-acid derivative to verticillin A requires 16 steps.
Killing cancer cells
With a reliable synthetic route in hand, the chemists produced various verticillin derivatives and provided these to collaborators at Dana‑Farber for biological testing. The team evaluated the compounds against multiple diffuse midline glioma cell lines, seeking sensitivity patterns and potential molecular targets.
Cells that proved most vulnerable were those expressing high levels of EZHIP, a protein known to influence histone H3 lysine 27 trimethylation (H3K27me3). Prior studies had implicated EZHIP in altering chromatin methylation, making it a plausible target for these compounds.
According to Jun Qi, “Pinpointing the cellular targets of these molecules is essential for understanding how they work and for guiding chemical modifications that improve target specificity and therapeutic potential.”
The verticillin derivatives appear to interact with EZHIP and increase H3K27me3 levels in susceptible cells, which in turn promotes programmed cell death (apoptosis). The most effective molecules in the cell assays were N‑sulfonylated forms of (+)-11,11′-dideoxyverticillin A and N‑sulfonylated verticillin A. N‑sulfonylation introduces a sulfonyl group that enhances molecular stability under biological conditions.
“The native natural product is a valuable starting point, but the synthetic route is what enabled us to derive and evaluate more stable, biologically active analogs,” Movassaghi notes.
Dana‑Farber researchers are continuing to validate the compounds’ mechanism of action and hope to advance the most promising candidates into animal studies of pediatric brain tumors. In parallel, the team has profiled lead molecules across more than 800 cancer cell lines to assess broader activity patterns and potential applications beyond DMG.
“Natural products remain a rich resource for drug discovery,” Qi says. “By combining chemistry, chemical biology, cancer biology, and clinical insight, we aim to evaluate these compounds thoroughly and advance the most promising candidates toward therapeutic development.”
Funding:
This research was supported by the National Institute of General Medical Sciences, the Ependymoma Research Foundation, and the Curing Kids Cancer Foundation.
Key Questions Answered:
A: Verticillin A’s densely functionalized and chemically sensitive structure made it effectively inaccessible for more than five decades. Achieving total synthesis enables controlled production, the creation of structural variants, and systematic exploration of therapeutic uses.
A: The derivatives appear to engage EZHIP, a protein linked to regulation of H3K27me3, increasing DNA/histone methylation in susceptible cells and promoting programmed cell death.
A: Researchers are validating the mechanism in detail, profiling lead derivatives across hundreds of cancer cell lines, and planning animal studies to assess safety and efficacy in models of pediatric brain cancer.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by the editorial team.
- Additional context was provided by staff to clarify background and implications.
About this brain cancer research news
Author: Sarah McDonnell
Source: MIT
Contact: Sarah McDonnell – MIT
Image: Image credited to Neuroscience News
Original Research: Closed access.
“Total Synthesis and Anticancer Study of (+)-Verticillin A” by Mohammad Movassaghi et al., Journal of the American Chemical Society.
Abstract
Total Synthesis and Anticancer Study of (+)-Verticillin A
This work reports the first total synthesis of (+)-verticillin A, achieved more than 50 years after the natural product was isolated. An initial plan to install sulfidic functionality on a dimeric diketopiperazine (DKP) produced undesired stereochemistry in the ETP substructures. The team therefore developed a protocol to introduce the disulfide with correct relative stereochemistry using benzhydryl hydrodisulfide on a complex DKP prior to dimerization.
Because ETP frameworks are sensitive to carbon-centered radicals and UV light, the researchers masked the disulfide as a pair of alkyl sulfides before undertaking a radical dimerization that joined two bis-sulfide DKPs at the C3–C3′ linkage. Subsequent photochemical N1 desulfonylation and a final-stage unveiling of the ETP elements furnished (+)-verticillin A, representing the first total synthesis of a dimeric ETP natural product with C12 oxygenation.
Both (+)-verticillin A and its N1-sulfonylated derivatives showed potent activity in cancer cell assays and modulated histone H3K27 trimethylation levels, leading to apoptosis in sensitive cells. Treatment of cell lines with high expression of EZH inhibitory protein (EZHIP) led to upregulation of H3K27me3, consistent with interaction between verticillin derivatives and EZHIP.
A thermal shift assay using cell lysates confirmed binding of N1-sulfonylated (+)-dideoxyverticillin A to EZHIP; a related ETP, (+)-chaetocin A, did not show measurable engagement with EZHIP under the same conditions. The observed interaction between verticillin A derivatives and EZHIP suggests a potential avenue for treating pediatric cancers that are sensitive to alterations in H3K27me3.