| Summary: | Phytochemical investigation of the whole plant of <i>Tradescantia albiflora</i> Kunth led to the isolation and characterization of a butanolide, rosmarinosin B (<b>1</b>), that was isolated from natural sources for the first time, a new butenolide, 5-<i>O</i>-acetyl bracteanolide A (<b>2</b>), and a new apocarotenoid, 2<i>β</i>-hydroxyisololiolide (<b>11</b>), together with 25 known compounds (compounds <b>3</b>−<b>10</b> and <b>12</b>−<b>28</b>). The structures of the new compounds were elucidated by analysis of their spectroscopic data, including MS, 1D, and 2D NMR experiments, and comparison with literature data of known compounds. Furthermore, four butenolides <b>4a</b>−<b>4d</b> were synthesized as novel derivatives of bracteanolide A. The isolates and the synthesized derivatives were evaluated for their preliminary anti-inflammatory activity against lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production in RAW 264.7 cells. Among them, the synthesized butenolide derivative <i>n</i>-butyl bracteanolide A (<b>4d</b>) showed enhanced NO inhibitory activity compared to the original compound, with an IC<sub>50</sub> value of 4.32 ± 0.09 μg/mL.
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