Withanolide derivatives from the roots of Withania somnifera and their neurite outgrowth activities

Five new withanolide derivatives (1,9-12) were isolated from the roots of Withania somnifera together with fourteen known compounds (2-8, 13-19). On the basis of spectroscopic and physiochemical evidence, compounds 1 and 9-12 were determined to be (20S,22R)-3α,6α-epoxy-4β,5β,27- trihydroxy-1-oxowitha-24-enolide (1), 27-O-β-D-glucopyranosylpubesenolide 3-O-β-D-glucopyranosyl (1→6)-β-D-glucopyranoside (withanoside VIII, 9), 27-O-β-D-glucopyranosyl (1→6)-β-D- glucopyranosylpubesenolide 3-O-β-D-glucopyranosyl (1→6)-β-D- glucopyranoside (withanoside IX, 10), 27-O-β-D-glucopyranosylpubesenolide 3-O-β-D-glucopyranoside (withanoside X, 11), and (20R,22R)-1α, 3β,20,27-tetrahydroxywitha-5,24-dienolide 3-O-β-D-glucopyranoside (withanoside XI, 12). Of the isolated compounds, 1, withanolide A (2), (20S,22R)-4β,5β,6α,27-tetrahydroxy-1-oxowitha-2,24-dienolide (6), withanoside IV (14), withanoside VI (15) and coagulin Q (16) showed significant neurite outgrowth activity at a concentration of 1 μM on a human neuroblastoma SH-SY5Y cell line.