The chemical structures, biological activities, and biosynthesis of tropolone natural products

<p indent="0mm">Tropolone natural products (tropolonoids) containing a unique seven-membered non-benzenoid aromatic ring are found in bacteria, fungi, plants, and animals. The tropolone skeleton is a rare feature of secondary metabolites. Considering the remarkable biological activities inherent in the tropolonoids, a multitude of studies have been meticulously conducted by researchers. These studies encompass the isolation, structural identification, and elucidation of biosynthetic pathways. This review summarizes the diverse structures and biological activities of tropolonoids and highlights four biosynthetic pathways for the tropolone skeleton in different organisms. It aims to provide theoretical references for scholars to further explore the new chemistry and industrial applications of tropolone natural products from mother nature.