Dihydroresveratrol Type Dihydrostilbenoids: Chemical Diversity, Chemosystematics, and Bioactivity

Background: Dihydrostilbenoids, a diverse class of natural products differing from stilbenoids by the missing double bond in the ethylene chain linking the aromatic moieties, have been reported from fungi, mosses, ferns, and flowering plants. Objective: Occurrence, structure, and bioactivity of naturally occurring dihydroresveratrol type dihydrostilbenoids are discussed in this review. Method: A Reaxys database search for dihydroresveratrol derivatives with possible substitutions on all atoms, but excluding non-natural products and compounds featuring additional rings involving the ethyl connecting chain, was performed. Results: Structures include simple dihydroresveratrol derivatives, compounds substituted with complex side chains composed of acyl moieties and sugars, and compounds containing polycyclic cores attached to dihydrostilbenoid units. Dihydrostilbenoids have a wide spectrum of bioactivities ranging from expectable antioxidant and anti-inflammatory activities to interesting neuroprotective and anticancer activity. The anticancer activity in particular is very pronounced for some plant-derived dihydrostilbenoids and makes them interesting lead compounds for drug development. Apart from some reports on dihydroresveratrol derivatives as phytoalexins against plant-pathogenic fungi, only very limited information is available on the ecological role of these compounds for the organisms producing them. Conclusion: Dihydrostilbenoids are a class of natural products possessing significant biological activities; their scattered but not ubiquitous occurrence throughout the kingdoms of plants and fungi is not easily explained. We are convinced that future studies will identify new sources of dihydrostilbenoids, and we hope that the present review will inspire such studies and will help in directing such efforts to suitable source organisms and towards promising bioactivities.