p-Hydroxybenzaldehyde (4-Hydroxybenzaldehyde, 4-Formylphenol, p-Formylphenol), which can be found in the orchids Gastrodia elata, Galeola faberi and vanilla, is a hydroxybenzaldehyde that reacts with NAD+ and H2O to produce 4-hydroxybenzoate, NADH, and 2 protons. p-Hydroxybenzaldehyde at 101.7 μM can significantly reduce the GABA-induced chloride current of GABAA receptors(α1β2γ2S subtype) expressed.