Thiohydantoin and Hydantoin Derivatives from the Roots of <i>Armoracia rusticana</i> and Their Neurotrophic and Anti-neuroinflammatory Activities

Abstract

Two new thiohydantoins (<b>1</b> and <b>3</b>) and three new hydantoins (<b>2</b>, <b>4</b>, and <b>5</b>) along with three known compounds (<b>6</b>-<b>8</b>) were isolated from roots of horseradish. Physical data analysis including NMR (¹H and ¹³C NMR, ¹H-¹H COSY, HSQC, and HMBC), HRESIMS, and ECD were employed for structure elucidation of the new compounds <b>1</b>-<b>5</b>. Potential neuroprotective effects of all compounds (<b>1</b>-<b>8</b>) on nerve growth factor (NGF) induction in C6 glioma were also evaluated. Among these compounds, <b>1b</b> and <b>2a</b> exhibited potent NGF secretion stimulation activities (NGF secretion levels: 153.59 ± 5.44% and 141.99 ± 5.21%, respectively). Their anti-neuroinflammatory activities were also assessed based on their inhibitory effects on nitric oxide (NO) production in lipopolysaccharide-stimulated murine microglia. Compound <b>7</b> marginally inhibited NO production with an IC₅₀ value of 32.6 μM.