APP and Alzheimer disease: Neuronal SH‐SY5Y cells transfected with either the wild‐type or the 717 valine‐to‐glycine amyloid precursor protein mutated gene are used as an AD model and treated with 5‐(4ʹ‐hydroxyphenyl)‐γ‐valerolactone, 5‐(3ʹ,4ʹ‐dihydroxyphenyl)‐γ‐valerolactone and 5‐(3ʹ‐hydroxyphenyl)‐γ‐valerolactone‐4ʹ‐sulfate.