APP and early-onset autosomal dominant Alzheimer disease: ent-Kaur-15-en-17-al-18-oic acid, extracted from the Chinese well known folk herb Leontopodium longifolium, performed a significantly neuroprotective effect on amyloid beta peptide 25-35 (Aβ25-35)-induced SH-SY5Y cells neurotoxicity in Alzheimer’s disease.