A mycotoxin produced by Penicillium species — a hydroxylated derivative within the viridicatin family of quinoline alkaloids. Viridicatol occurs in mould-damaged cereals alongside related Penicillium metabolites, contributing to the complex chemical mixture of spoiled grain. Like viridicatin, it is far less studied than the regulated mycotoxins (aflatoxins, ochratoxin A, deoxynivalenol), yet its detection signals poor storage and probable co-contamination. Grain management — rapid drying, moisture monitoring, and segregation of suspect lots — addresses the whole spectrum of storage mycotoxins at once. Viridicatol underscores how much of grain toxicology lies beyond current regulatory lists.