costunolide

Costunolide is a natural sesquiterpene lactone belonging to the germacranolide subclass. It is commonly described as having an α-methylene-γ-lactone moiety, a functional group associated with covalent reactivity toward thiol groups in proteins, which underpins many of its biological effects.

It has been isolated from several members of the Asteraceae family, notably Costus speciosus, and has also been detected in other genera such as Inula and related plants. As a plant metabolite, costunolide is typically obtained by extraction of dried material followed by purification.

Costunolide exhibits a range of biological activities in vitro, including anti-inflammatory, antimicrobial, and cytotoxic effects. In cellular assays, it can inhibit NF-κB signaling and induce apoptosis through mitochondrial pathways, with effects attributed in part to covalent modification of cellular thiols by the α-methylene-γ-lactone moiety. It has attracted interest as a lead compound for anti-cancer drug development, although clinical efficacy and safety have not been established, and the compound’s reactivity raises concerns about non-specific toxicity.

Chemically, costunolide is used in phytochemical research and as a starting point for semi-synthetic derivatives to explore structure–activity relationships and to modulate activity and selectivity. In addition to research applications, costunolide serves as a chemical probe for studying sesquiterpene lactone biology.