We investigated the tumor necrosis factor-alpha (TNF-) inhibitory activity of sesquiterpenes from root extracts. According to the hexane and EtOAc extracts showing significant activity with IC values of 0.5 and 1.0 µg/mL, respectively, chromatographic fractionation of the extracts was performed and led to the isolation of 10 sesquiterpenes (1: -10: ). Costunolide (1: ), a major compound, and dehydrocostus lactone (4: ) exhibited high efficiency in decreasing TNF- levels, with IC values of 2.05 and 2.06 µM, respectively. In addition, sesquiterpene analogues were synthesized to establish their structure-activity relationship (SAR) profile. Among the semi-synthetic analogues, compounds 6A: and 16: showed the most potent activity with IC values of 1.84 and 1.97 µM, respectively. More importantly, compound 6A: showed less toxicity than costunolide and 16: . These results provided the first SAR profile of sesquiterpene lactones and indicated that the -methylene--lactone moiety plays a crucial role in TNF- inhibition. Additionally, the epoxide derivative 6A: might represent a lead compound for further anti-TNF- therapies, owing to its potent activity and reduced toxicity.

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Six new chamigrane sesquiterpenes, merulinols A‒F (1‒6), and four known metabolites (7‒10) were isolated from the culture of the basidiomycetous fungus XG8D, a mangrove-derived endophyte. Their structures were elucidated mainly by 1D and 2D NMR, while the structures of 1 and 2 were further confirmed by single-crystal X-ray diffraction analysis. The in vitro cytotoxicity of all compounds was evaluated against three human cancer cell lines, MCF-7, Hep-G2, and KATO-3. Compounds 3 and 4 selectively displayed cytotoxicity against KATO-3 cells with IC50 values of 35.0 and 25.3 μM, respectively.

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