Beta resorcylic acid lactones (RALs) from fungi: chemistry, biology, and biosynthesis.

β-Resorcylic acid lactones (RALs) are one of the major polyketides produced by fungi, and some of them have a diverse array of biological activities. Most RALs feature a 14-membered macrocyclic ring fused to β-resorcylic acid (2,4-dihydroxybenzoic acid). In this review, more than 100 RAL-type of compounds are structurally classified into three groups; 14-membered RALs with 17R configuration, 14-membered RALs with 17S configuration, and benzopyranones/benzofuranones, and they are reviewed comprehensively in terms of chemistry, biological activities, and biosynthetic pathways.