What Is Depsipeptide? Definition and What Research Reports

Definition

A depsipeptide is a peptide-like molecule in which one or more of the amide (peptide) bonds of a normal peptide backbone has been replaced by an ester bond. That substitution happens because at least one residue in the chain is a hydroxy acid (contributing an –OH group) rather than a standard amino acid (contributing an –NH₂ group). The result sits between a peptide and a polyester: the sequence still reads as a chain of residues, but the linkage chemistry, conformational preferences and hydrolytic stability differ at the ester position. Many depsipeptides are macrocyclic, closing the ring through a lactone formed between a side-chain or terminal hydroxyl and a carboxyl group, and they frequently contain non-proteinogenic residues, N-methylated amides or fatty-acid tails. The term is descriptive of bond chemistry only; it says nothing about what a given molecule does, and depsipeptides span antibiotics, enzyme inhibitors, ionophores and research scaffolds. This page is for educational purposes only and is not medical advice; consult a licensed physician for any clinical question.

Depsipeptide vs. peptide in one line

• Peptide: all backbone linkages are amide bonds between amino acids.
• Depsipeptide: at least one backbone linkage is an ester bond, contributed by a hydroxy acid residue.
• Cyclic depsipeptide: a macrocycle in which ring closure occurs through that ester (a macrolactone).

Where Depsipeptides Come From

Most named depsipeptides were first described as natural products from microorganisms. Fungi are one recurring source: researchers described morinagadepsin as a depsipeptide isolated from the fungus Morinagamyces vermicularis, reporting its structure alongside the taxonomic reassignment of the producing organism (PMID 34073017). Marine cyanobacteria are another: a 2024 report described the isolation and total synthesis of PM170453, a new cyclic depsipeptide obtained from Lyngbya sp. (PMID 39057411). Marine bacteria also contribute; a survey examined didemnin depsipeptide production across Tistrella strains and reported on the distribution of that biosynthetic capacity within the genus (PMID 36827097).

Beyond isolation, the biosynthetic machinery itself has been studied. A 2026 report in Nature Communications addressed the molecular basis for combinatorial biosynthesis of depsipeptide histone deacetylase (HDAC) inhibitors, describing how the assembly-line enzymology can be recombined to generate related structures (PMID 42386723). Depsipeptides are also produced entirely by chemistry: methodological reviews have compiled solution- and solid-phase strategies for depsipeptide synthesis, including the ester-forming steps that distinguish them from ordinary peptide coupling (PMID 18604953).

How the Term Is Used in Peptide Research

In the peptide-chemistry literature, "depsipeptide" is used in three broad ways.

1. As a structural label for natural products

A compound is called a depsipeptide when its characterised structure contains an ester in the backbone — for example the cyclic marine and fungal metabolites above.

2. As a design element in synthetic scaffolds

Chemists deliberately install ester linkages to alter ring size, rigidity, solubility or degradability. A Japanese synthetic study described routes to bicyclic depsipeptides containing an intramolecular disulfide bond, using the depsipeptide framework together with the disulfide to constrain the macrocycle (PMID 36047217). Earlier work extended the motif into branched architectures, reporting the construction of depsipeptide dendrimers built from ester-linked peptide arms (PMID 11931104). Because esters hydrolyse more readily than amides, the same logic has been applied to delivery materials: a 2024 study in the Journal of Controlled Release reported that biodegradable depsipeptide nanoassemblies were used to inhibit a protein–protein interaction, with the depsipeptide chemistry providing the degradable component of the assembly (PMID 38128883).

3. As a structure–activity variable

Swapping an amide for an ester in a known bioactive peptide is a common probe of how much the backbone NH contributes to binding. Researchers examined exactly this in the antibacterial acyldepsipeptide series, reporting the consequences of depsipeptide substitution on ClpP protease activation activity (PMID 29152050).

What the Published Literature Reports

The verified literature on this page is largely chemical and preclinical. Antibacterial work has mapped depsipeptides onto specific bacterial targets: a 2025 preprint-stage report described a natural depsipeptide antibiotic that targets the E site of the bacterial ribosome, a binding site distinct from those of most established ribosome-directed antibiotics (PMID 40630547). A separate mechanism is protease dysregulation rather than inhibition, as in the acyldepsipeptide work on ClpP activation (PMID 29152050).

In cancer-cell biology, a study of the marine depsipeptide nobilamide I reported inhibition of cancer cell motility and tumorigenicity in laboratory models, with suppression of epithelial–mesenchymal transition markers and of MMP2/MMP9 expression described as the associated molecular changes (PMID 35071867). The best-known depsipeptide in oncology literature is FR901228, a bicyclic depsipeptide HDAC inhibitor that older papers referred to simply as "depsipeptide"; a nonhuman primate study characterised its plasma and cerebrospinal fluid pharmacokinetics, reporting the extent of central nervous system penetration relative to plasma exposure (PMID 15042312). Work on the biosynthetic enzymology of depsipeptide HDAC inhibitors has since addressed how such scaffolds can be diversified (PMID 42386723).

Safety and Adverse Events: What Studies Report

The verified reports collected here are isolation, synthesis, biosynthesis, materials and mechanism papers, and they did not set out to characterise human tolerability; none of them reported a human adverse-event profile for a depsipeptide. The closest exposure-related data point in this set is the nonhuman primate pharmacokinetic study of FR901228, which reported plasma and cerebrospinal fluid concentrations rather than safety outcomes (PMID 15042312). Because "depsipeptide" names a bond type and not a single substance, safety information cannot be generalised across the class: an ester-containing antibiotic that binds the bacterial ribosome (PMID 40630547) and a degradable depsipeptide nanoassembly used as a delivery material (PMID 38128883) share almost nothing beyond chemistry.

Limitations of the Evidence

• Class term, not a compound. Findings apply to the specific molecule studied, not to depsipeptides generally.
• Mostly preclinical. The cited activity data came from cell-based, microbiological or animal models, as in the cancer-cell motility report (PMID 35071867) and the nonhuman primate pharmacokinetic study (PMID 15042312).
• Publication stage varies. The ribosome E-site antibiotic report was posted as a preprint-stage record (PMID 40630547), and preprints have not completed journal peer review.
• Chemistry-first literature. Several entries, including depsipeptide synthesis methodology (PMID 18604953) and dendrimer construction (PMID 11931104), reported synthetic routes and yields rather than biological outcomes.

References

• Depsipeptide synthesis (Methods in Molecular Biology, 2007)
• Molecular basis for depsipeptide HDAC inhibitor combinatorial biosynthesis (Nature Communications, 2026)
• Synthetic Study on Bicyclic Depsipeptides Containing an Intramolecular Disulfide Bond (Yakugaku Zasshi, 2022)
• Inhibition of protein-protein interactions using biodegradable depsipeptide nanoassemblies (Journal of Controlled Release, 2024)
• Morinagadepsin, a Depsipeptide from the Fungus Morinagamyces vermicularis gen. et comb. nov (Microorganisms, 2021)
• Isolation and Total Synthesis of PM170453, a New Cyclic Depsipeptide Isolated from Lyngbya sp (Marine Drugs, 2024)
• A Natural Depsipeptide Antibiotic that Targets the E site of the Bacterial Ribosome (Research Square, 2025)
• A Survey of Didemnin Depsipeptide Production in Tistrella (Marine Drugs, 2023)
• Plasma and cerebrospinal fluid pharmacokinetics of depsipeptide (FR901228) in nonhuman primates (Cancer Chemotherapy and Pharmacology, 2004)
• Depsipeptide dendrimers (Chemistry - A European Journal, 2000)
• Consequences of Depsipeptide Substitution on the ClpP Activation Activity of Antibacterial Acyldepsipeptides (ACS Medicinal Chemistry Letters, 2017)
• Marine Depsipeptide Nobilamide I Inhibits Cancer Cell Motility and Tumorigenicity via Suppressing Epithelial-Mesenchymal Transition and MMP2/9 Expression (ACS Omega, 2022)