Advances in the synthesis and pharmacological activity of lupane-type triterpenoid saponins
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Abstract
Lupeol, betulin and betulinic acid are members of the so-called lupane-type triterpenoids. These natural products found worldwide in quite of lot of vegetables, fruits and plant species exhibit promising pharmacological activities including anti-inflammatory, anti-HIV and antitumor activities. Nevertheless, the poor pharmacokinetic properties of these cholesterol-like triterpenoids hampered further pharmaceutical developments. The synthesis of lupane-type saponins, i.e., sugar-derived lupanes, seems to be a good avenue to improve both their water solubility and pharmacological activity. The aims of this review are twofold: first, to describe the biological activity of naturally occurring lupane-type saponins, and second, report the different methodologies employed for the elaboration of glycosidic linkages at the C-3 and/or C-28 positions on the lupane core. The synthesis of both natural and unnatural lupane-type saponins is discussed with an emphasis on molecules exhibiting relevant biological activities.
Keywords
Chemical glycosylation Triterpenoid saponins Lupeol Betulin Betulinic acidAbbreviations
- A549
Human lung carcinoma
- Ara
α-l-Arabinopyranose
- BF3·OEt2
Boron trifluoride diethyletherate
- CGTase
Cyclodextrin glycosyltransferase
- d-Ara
α-d-Arabinopyranose
- DLD-1
Human colorectal adenocarcinoma
- Gal
β-d-Galactopyranose
- Glc
β-d-Glucopyranose
- HIV
Human immunodeficiency virus
- IC50
Half maximal inhibitory concentration
- Man
α-d-Mannopyranose
- PMT
Prodrug monotherapy
- Rha
α-l-Rhamnopyranose
- SAR
Structure-activity relationships
- TCA
Trichloroacetimidate
- TMSOTf
Trimethylsilyl trifluoromethanesulfonate
- Xyl
β-d-Xylopyranose
Notes
Acknowledgments
The authors wish to thank Dr. Yves Janin for proof-reading this manuscript and the anonymous reviewers for helpful comments and suggestions. The financial support of the Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT, fonds forestier 02) is gratefully acknowledged. C. G. wishes to acknowledge the Programme d’Aide Institutionnel à la Recherche de l’Université du Québec à Chicoutimi (PAIR-UQAC), the Fondation de l’UQAC as well as FQRNT for graduate scholarships.
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