Isolation, Synthesis and Bioassay of Natural 6,8-Di-C-glycosylflavonoids
Date Issued
2009
Date
2009
Author(s)
Ku), Angela Fay Ku (Chien-Hui
Abstract
Dendrobium huoshanense is a traditional medicinal plant that has been proven to enhance body immunity, scavenge active oxygen metabolites, prevent ophthalmic disorders, inhibit inflammation and suppress the growth of cancer cells in recent pharmacological studies. Since apigenin 6,8-di-C-glycosides were isolated from this herb with limited amount and species in previous work, our study focused on the synthesis of the analogues of apigenin 6,8-di-C-glycosides. Posterior to selective benzylation, acetylation and reductive transformation of the starting material, (±)-naringenin, 6-C-glycosylation was promoted by trimethylsilyl trifluoromethanesulfonate (TMSOTf) via O-to-C glycoside rearrangement. Followed by hydrogenolysis, 8-C-glycosylation, benzylation and sequential oxidations with ceric ammonium nitrate (CAN) and pyridinium dichromate (PDC), dehydrogenation with iodine and the subsequent deprotection of benzyl and acetyl groups gave a series of apigenin 6,8-di-C-glycosides. In addition, luteolin 6,8-di-C-glycosides were obtained by employing a one-pot two-step hydroxylation with 2-iodoxybenzoic acid (IBX) and sodium dithionite (Na2S2O4) in a sequence. Therefore, this strategy created an access to the synthesis of 6,8-C-glycosylflavonoids bearing different glycosides at the designated positions with stereoselectivity. These analogues were further screened for their bioactivities, such as the anti-inflammatory activity, to establish the structure–activity relationship.
Subjects
flavonoid
apigenin
narigenin
luteolin
eriodictyol
glycosylation
SDGs
Type
thesis
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