New water soluble glycosides of 11-keto-β-boswellic acid: A paradigm

Abstract

Though several glycosides of various triterpenes are known, but surprisingly no boswellic acid glycosides are reported so far. With a view to make water soluble boswellic acids, prepared glycosides of 11-keto boswellic acid for the first time. Naturally occurring boswellic acids which are anti-inflammatory agents are lipophylic in nature and thus, become a limiting factor in terms of their bioavailability. Among boswellic acids, 11-keto-β-boswellic acid is found to exhibit superior biological activity and hence successfully prepared its glucosyl and maltosyl derivatives viz., 11-keto-β-boswellic acid-24-O-β-D-glucopyranoside (9) and 11-keto-β-boswellic acid-24-O-α-D-glucopyranosyl-(1 → 4)-β-D-glucopyranoside (15) which are water soluble. Both these compounds are soluble in water to the extent of 10% (w/w) which is very significant.

Synthesis and anti-cancer activities of glycosides and glycoconjugates of diterpenoid isosteviol

“…The deprotection of hydroxyl groups of glycoconjugates 20-23, 26, and 27 carried out according to the standard procedure (sodium methoxide in methanol at room temperature or even at −40°C) resulted in the hydrolysis of the glycosidic bond. Deacetylation reactions carried out in methanol in the presence of Na 2 CO 3 at room temperature, 33 as well as in a solution of 10% Et 3 N in a mixture of methanol-water-hexane, 34 also resulted in the hydrolysis of the glycosidic bond. The anomeric protons of glycosides 7, 8, 10, 12, 13, 15, and 16 and glycoconjugates 20, 21, 26, and 27 in the 1 H NMR spectra resonated as a doublet at 5.3-5.8 ppm with coupling constants of 7.9-9.7 Hz indicating the formation of a β-anomer.…”