3,4-Dihydroxybenzaldehyde, also known as protocatechuic aldehyde, is a phenolic aldehyde, a compound released from cork stoppers into wine.

This molecule can be used as a precursor in the vanillin synthesis by biotransformation by cell cultures of Capsicum frutescens, a type of Chili pepper.

[2] It is also found in the mushroom Phellinus linteus.

[3] Protocatechuic aldehyde regulates G protein-coupled estrogen receptor-1 (GPER-1) and exhibits protective effects in endothelial dysfunction and atherosclerosis.

[4] This article about an aromatic compound is a stub.