Synthesis of glycosides of resveratrol, pterostilbene, and piceatannol, and their anti-oxidant, anti-allergic, and neuroprotective activities.

Resveratrol was glucosylated to its 3- and 4'-β-glucosides by cultured cells of Phytolacca americana. On the other hand, cultured P. americana cells glucosylated pterostilbene to its 4'-β-glucoside. P. americana cells converted piceatannol into its 4'-β-glucoside. The 3- and 4'-β-glucosides of resveratrol were further glucosylated to 3- and 4'-β-maltosides of resveratrol, 4'-β-maltoside of which is a new compound, by cyclodextrin glucanotransferase. Resveratrol 3-β-glucoside and 3-β-maltoside showed low 2,2-diphenyl-1-picrylhydrazyl free-radical-scavenging activity, whereas other glucosides had no radical-scavenging activity. Piceatannol 4'-β-glucoside showed the strongest inhibitory activity among the stilbene glycosides towards histamine release from rat peritoneal mast cells. Pterostilbene 4'-β-glucoside showed high phosphodiesterase inhibitory activity.