Isoastilbin is a dihydroflavonol glycoside compound in Rhizoma Smilacis glabrae and Astragalus membranaceus. Isoastilbin inhibits glucosyltransferase (GTase) with an IC50 value of 54.3 μg/mL, and also inhibits tyrosinase activity. Isoastilbin shows neuroprotective, antioxidation, antimicrobial and anti-apoptotic properties and has the potential for Alzheimer’s disease research.