Natural tricyclic and hyper-polycyclic aromatic hydrocarbons: structure, biosynthesis, bioactivity, and synthesis

Covering: 1950 to up to the end of 2024Natural products containing polycyclic aromatic hydrocarbons (PAHs) feature at least two fused aromatic ring systems, conforming to Hückel's rule and representing an important class of secondary metabolites with a wide range of biological activities. Among them, the subtype of natural products containing tricyclic and greater than tricyclic systems has been neglected for a long time. This review summarizes the isolation, structural features, bioactivities, biosynthetic pathways, and chemical synthesis of this special subtype reported over the past decades. This review provides a current understanding of the tricyclic and hyper-PAHs represented by anthracene, phenanthrene, acenaphthalene, pyrene, fluoranthene, and tetraphene from organic, biosynthetic, and pharmacological perspectives.