Prenylated chalcone from hops

They are flavonoids without the C-ring and are not frequently isolated from plants, possibly due to their instability. So, most of the chalcones presented in this review are synthetics [80, 79]. This kind of flavonoids, generally, are rather cytotoxic against human cancer cells. Thus, xantohumol, a prenylated chalcone from hops, inhibited the A-2780 cell line at a IC50 of 0.5 pM [56] and two synthetic chalcones inhibited the HeLa cell line at IC50 of 0.0038 pg/mL [80]. 

Chalcones, dihydrochalcones and aurones are not particularly important components of plant food materials, but they occur as notable pigments of flowers of many ornamental plants, such as the common snapdragon Antirrhinum spp., Scrophulariaceae) (Asteraceae), cosmos Cosmos spp.) and dahlia Dahlia spp.) from the Asteraceae family. Chalcones are also pigments of legume seeds (9-99) and woods. Prenylated chalcones are found in hop cones (10-98). 

Prenylated isoflavones are related to prenylated flavonoids (chal-cones and flavanones or dihydroflavones) located in mature female cones of hops Humulus lupulus, Cannabinaceae), which exhibit oestrogenic and anticarcinogenic effects. Their amount depends on the weather conditions and the hops variety. The most common compound is a chalcone xanthohumol (10-98), which does not exhibit oestrogenic activity. Its content in hop cones is around 1%. Xanthohumol is accompanied by the flavanone isoxanthohumol, which arises from xanthohumol by conversion in an acidic media during heating. Isoxanthohumol is therefore the main prenylated flavonoid in beer. At concentrations of about 10 to 100 times lower. 

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