Although there are numerous claims of remote group participation leading to the synthesis of the expected glycosides with improved anomeric geometry outcome in glycosylation, there is still a lack of enough strong evidence and this has led to a long-term debate, particularly for equatorial 4-O group participation. In this work, we were able to synthesize and isolate a stable seven-membered trichlorooxazepine ring bridging intermediate with a high yield by employing a 2-azido-2-deoxy-glucopyranosyl donor, which provides strong evidence to support the putative participation of the equatorial 4-O group in glycosylation.

Berberine (BBR), a natural alkaloid compound, is used as a non-prescription drug in China for treating diarrhea and gastroenteritis. Many studies have revealed that BBR possesses anticancer effect. However, the molecular mechanisms underlying its anticancer action is far from being fully elucidated. This study is aimed to determine the effect of BBR on the hedgehog (Hh) activity and the growth of cancers addiction to Hh activity. The Hh activity was determined by dual luciferase assays and quantitative RT-PCR analyses. The growth inhibition of BBR on medulloblastoma which was obtained from ptch+/−;p53−/− mice was analyzed by 5-bromo-2-deoxyuridine (Brdu) assays and by allografting the medulloblastoma into nude mice. The data were statistically analyzed by one-way analysis of variance (ANOVA), and multiple comparison between the groups was performed using Dunnett’s method. In this study, we found that BBR significantly inhibited the Hh pathway activity. Meanwhile, we observed that BBR failed to affect the transcriptional factors activities provoked by tumor necrosis factor-α (TNF-α) and Prostaglandin E2 (PGE2), thus suggesting its unique property against Hh pathway activity. Further studies revealed that BBR inhibited the Hh pathway activity by potentially targeting the critical component Smoothened (Smo) and most likely shared the same binding site on Smo with cyclopamine, a classical Smo inhibitor. Finally, we demonstrated that BBR obviously suppressed the Hh-dependent medulloblastoma growth in vitro and in vivo. Collectively, our study uncovered a novel molecular mechanism responsible for the anticancer action of BBR, thus opening the way for the usage of BBR for therapeutics of cancers addiction to aberrant Hh pathway activity.