An enzymatic synthesis of glucuronides of azetidinone-based cholesterol absorption inhibitors

Ezetimibe and Cancer: Is There a Connection?

The high level of serum cholesterol caused by the excessive absorption of cholesterol can lead to hypercholesteremia, thus promoting the occurrence and development of cancer. Ezetimibe is a drug that reduces cholesterol absorption and has been widely used for the treatment of patients with high circulating cholesterol levels for many years. Mechanistically, ezetimibe works by binding to NPC1L1, which is a key mediator of cholesterol absorption. Accumulating data from preclinical models have shown that ezetimibe alone could inhibit the development and progression of cancer through a variety of mechanisms, including anti-angiogenesis, stem cell suppression, anti-inflammation, immune enhancement and anti-proliferation. In the past decade, there has been heated discussion on whether ezetimibe combined with statins will increase the risk of cancer. At present, more and more evidence shows that ezetimibe does not increase the risk of cancers, which supports the role of ezetimibe in anti-cancer. In this review, we discussed the latest progress in the anti-cancer properties of ezetimibe and elucidated its underlying molecular mechanisms. Finally, we highlighted the potential of ezetimibe as a therapeutic agent in future cancer treatment and prevention.

Aromatic O-glycosylation

Carbohydrates carrying an aromatic aglycon are important natural products and thus key synthetic targets. However, due to the electron-withdrawing properties of aromatic rings, phenols are difficult to glycosylate. This review covers the most common carbohydrate donors used for aromatic O-glycosylation (anomeric acetates, halides, trichloroacetimidates and thioglycosides) as well as some less common donors. The scope of the review is to give practical examples of aromatic O-glycosylations and to offer guidelines for glycosylation of typical aromatic residues. Anomeric acetates or trichloroacetimidates, activated under acidic conditions, are preferred for electron rich aromatic aglycons, while glycosyl halides, activated using basic conditions, are preferred for electron deficient aromatic residues.

Catabolism of 4-fluoro-3-iodobenzylguanidine and meta-iodobenzylguanidine by SK-N-SH neuroblastoma cells

BACKGROUND

A fluorine substituted derivative of meta-iodobenzylguanidine (MIBG), 4-fluoro-3-iodobenzylguanidine (FIBG), is retained in SK-N-SH human neuroblastoma cells in vitro to a higher degree than the MIBG.

METHOD

To investigate whether the higher retention of FIBG is due to differences in the catabolic degradation of the two tracers, in vitro paired-label studies were performed using SK-N-SH cells.

RESULTS

No detectable amount of benzyl amines, benzoic acids or hippuran derivatives, potential catabolites of these tracers, were seen in either case. Even after 48 h, the cell culture supernatants contained exclusively intact I-MIBG and I-FIBG. In contrast, in some cases, HPLC analysis of cell lysates indicated the presence of a very polar compound(s) as the predominant species with smaller quantities of intact tracers. The per cent total radioactivity in the lysate at each time point that was associated with intact I-FIBG was (average [range]) 25.4% [20.3-30.5], 22.5% [19.3-25.6], and 18.8% [14.3-23.3], at 0 h, 24 h and 48 h, respectively. The corresponding values for I-MIBG were 24.3% [21.0-27.5], 19.1% [11.7-26.5] and 17.4% [14.6-20.1]. No significant amount of activity was associated with high molecular weight species for either halobenzylguanidine, indicating that protein binding was not a major factor.

Synthesis of fluorescent biochemical tools related to the 2-azetidinone class of cholesterol absorption inhibitors

Fluorescent analogues of the cholesterol absorption inhibitor (CAI), Sch 58235, have been designed and synthesized as single enantiomers. Biological testing reveals that they are potent CAIs and are suitable tools for the investigation of the azetidinone CAI mechanism of action (MOA).