New acylphloroglucinol-sesquiterpenoid adducts with antiviral activities from Dryopteris atrata

Abstract

Seven novel acylphloroglucinol-sesquiterpenoid adducts, designated as dryatraols J-P (1-7), were isolated from the rhizomes of Dryopteris atrata (Wall. ex Kunze) Ching. The structures, including absolute configurations, were elucidated using comprehensive spectroscopic data, calculated ¹³C Nuclear Magnetic Resonance-Diastereotopic Probability Assignment Plus (¹³C NMR-DP4+) probability analysis, and ECD calculations. These structures represent a rare subclass of carbon skeleton of acylphloroglucinol-sesquiterpenoid adducts with a furan ring connecting the acylphloroglucinol and sesquiterpenoid moieties. Notably, compounds 1-6 are the first reported examples of acylphloroglucinol-sesquiterpenoid adducts with dimeric acylphloroglucinol incorporated into the aristolane- or rulepidanol-type sesquiterpene, while compound 7 features a hydroxylated monomeric acylphloroglucinol motif. A preliminary evaluation of their antiviral activities revealed that compounds 1-6 exhibited more potent activities against respiratory syncytial virus (RSV) with IC₅₀ values ranging from 0.75 to 3.12 μmol·L⁻¹ compared to the positive control (ribavirin).

Keywords

Dryopteris atrata / Acylphloroglucinol-sesquiterpenoid adducts / Structural elucidation / Antiviral activities

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