A Stereospecific Synthesis and In Vitro Anti-Influenza H1N1 Properties of Lithocholic Acid-Based Spiro-1,2,4-trioxolane

Bile acids provide a versatile platform for the design of biologically active compounds due to their amphiphilic structure, biocompatibility, and capacity for diverse chemical modifications. Among them, lithocholic acid is a promising scaffold for designing and revealing new antiviral agents. A novel lithocholic acid-based 3-<i>spiro</i>-1,2,4-trioxolane was synthesized by Griesbaum co-ozonolysis of methyl 3-<i>O</i>-methyl-oximino-lithocholate and 4-(trifluoromethyl)-cyclohexanone, and its structure was confirmed by 2D NMR and X-ray crystallographic analysis. Lithocholic acid derivatives were evaluated for cytotoxicity and anti-influenza activity against A/Puerto Rico/8/34 (H1N1), showing that steroid 1,2,4-trioxolane <b>3</b> exhibited the highest potency (IC₅₀ 4.3 µM, SI 11) compared to the parent methyl-3-oxo-lithocholate <b>1</b> (IC₅₀ > 84 µM, SI 1). In silico ADME predictions revealed several favorable drug-like properties, including a highly three-dimensional structure (Fsp³ = 0.97), significant lipophilicity (LogP = 7.54), and the presence of key pharmacophores such as a peroxide moiety and a trifluoromethyl group. Taken together, a stereospecific synthesis of a lithocholic acid 3-<i>spiro</i>-1,2,4-trioxolane by Griesbaum co-ozonolysis was realized and the first evidence of anti-influenza activity in the steroid-1,2,4-trioxolane series was found.