6-Hydroxyflavones and Other Flavonoids of Crocus

Abstract

Abstract 6-Hydroxyflavones have been identified for the first time in the Iridaceae, in leaves of three Crocus species. Three new glycosides have been characterised: 6 -hydroxyluteolin 7- rhamnosylglucoside, scutellarein 7-glucoside and scutellarein 7-methyl ether 6 -glucoside, as well as two known glycosides: 6 -hydroxyluteolin 7-glucoside and 6 -hydroxyluteolin 7-methyl ether 6 - glucoside. 6 -Hydroxyluteolin and scutellarein glycosides have been found before in Bromeliaceae. Commelinaceae, Cyperaceae and Orchidaceae, but this is the first record of the respective 7-methylethers in the Monocotyledoneae. Acacetin and tricin have been identified as aglycones in C. laevigatus an d C. heuffelianus leaves, respectively and the occurrence of mangiferin confirmed in C. aureus leaves. Two of the major flavonol glycosides present in flowers of cultivated species were identified as kaempferol 3-sophoroside and kaempferol 3- rutinoside-7-glucoside. However none of the flavonoids identified appears to contribute to yellow petal colour in Crocus, which is probably entirely carotenoid-based.