Determination of the structure of sinalexin, a phytoalexin produced by white mustard (Sinapis alba) under biotic or abiotic elicitation, is described. Additionally, the isolation and synthesis of 4-hydroxybenzylisothiocyanate, the major antifungal component isolated from extracts of white mustard, and optimized conditions for the isolation of the phytotoxin destruxin B are described.