Background: The Cruciferous family of vegetables which includes Brassica Turnips showed antioxidant
and hepatoprotective effects. The phytochemical investigations of the aerial parts of the traditional
Japanese turnip vegetable (B. rapa L. 'hidabeni') revealed the presence of three chalcone glycosides, along with
other glycoside components. As many natural products inhibited Ag-stimulated degranulation in cellular system,
those chalcone glycosides have biological significance of suppressing antigen-stimulated degranulation in
rat basophilic leukemia RBL-2H3 cells.
Aim and Objective: Further investigation on the biological importance of those chalcone glycosides demands
ample quantities of well-defined compounds. Therefore, we report herein a convenient and concise synthetic
approach for the preparation of those chalcone glycosides.
Materials and Methods: 4'-O-β-D-Glucopyransoyl-4-hydroxy-3'-methoxychalcone and 4'-O-(β-D-Glucopyransoyl)-
3',4-dimethoxychalcone were synthesized using a three-step strategy includes: i) O-glucosylation of
4-OH of 4'-hydroxy-3'-methoxy acetophenone (Acetovanillone); ii) introduction of the cinnamoyl residue by
aldol condensation with p-benzyloxy benzaldehyde and p-methoxy benzaldehyde respectively; iii) full debenzylation
of all the sugar hydroxyl groups. Meanwhile, 4,4'-Di-O-β-D-glucopyransoyl-3-methoxychalcone was
synthesized by an alternative way where a double armed aglycon acceptor was utilized in a one pot double glycosylation
Results: Constructing the target chalcone glycosides: 4'-O-β-D-Glucopyransoyl-4-hydroxy-3'-methoxychalcone,
4'-O-(β-D-Glucopyransoyl)-3',4-dimethoxychalcone and 4,4'-Di-O-β-D-glucopyransoyl-3-methoxychalcone
were achieved in 13%, 14%, and 90% yields.
Conclusion: A simple and practical synthetic procedure by which the target chalcone glycosides were synthesized
could be a promising and viable method. Furthermore, this strategy could be utilized in the synthesis of
various O-diglycosyl chalcones having more complicated structures.