Flavonoids from blue flowers of Nymphaea caerulea

Seven flavonols including the novel 3-(2"-acetylrhamnosides) of myricetin a nd quercetin (2 and 6), the rare kaempferol 3-(2"-acetylrhamnoside) and que rcetin 3-(3"-acetylrhamnoside), in addition to the 3-rhamnosides of kaempfe rol, quercetin and were isolated from blue flowers of the African water lil y Nymphaea caerulea (=Nymphaea capensis). Their structures were elucidated by a combination of chromatography and homo- and heteronuclear two-dimensio nal NMR techniques and electrospray MS for compound 2. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.