Natural Phenyldihydroisocoumarins: Sources, Chemistry and Bioactivity

The present review gives an overview about naturally occurring phenyldihydroisocoumarins, their sources, and bioactivities. In total, 54 compounds are covered, including eight substances which are in fact alkaloids or protoalkaloids. These nitrogen containing compounds were exclusively found in the Papaveraceae family. The remaining 46 compounds have been reported from twelve different source families, ranging from mosses to angiosperms. Six of the nitrogen free compounds feature additional rings, while 40 are simple phenyldihydroisocoumarins with substituents in all possible positions, except 3, 2’, and 6’. Common substituents of these simple phenyldihydroisocoumarins are hydroxy groups, methoxy groups, and glucosyloxy groups; on the other hand, acuminosyloxy and rutinosyloxy groups have so far been found only in one and two naturally occurring phenyldihydroisocoumarins, respectively. Though a number of bioactivities have been proven for phenyldihydroisocoumarins, ranging from anticancer and antidiabetic to antimicrobial and anti-inflammatory activities, so far only one taxon, Hydrangea macrophylla var. thunbergii, is widely used. Moreover, the usage of this taxon is mainly due to the sweet taste properties of the contained phenyldihydroisocoumarin phyllodulcin and less based on the alleged health-promoting effects of its constituents.