The present review describes 108 new examples of naturally occurring flavans and
flavanones having cytotoxic potential, which have been reported during the period of 2005 to
mid-2020. These compounds are found either as aglycones or as glycosides, comprising
flavans, flavanones, isoflavanones and miscellaneous flavanones (homo- and bi-flavanones).
The main topics addressed in this review are source, structure, and cytotoxic activity in detail
and the structure-activity relationship.