1. Determination of bezaﬁbrate, methotrexate, cyclophosphamide, orlistat and enalapril in waste and surface waters using on-line solid-phase extraction liquid chromatography coupled to polarity-switching electrospray tandem mass spectrometry
Araceli Garcia-Ac, Pedro A. Segura, Christian Gagnonb and Sebastien Sauve*. J. Environ. Monit., 2009, 11, 830–838
In this work ﬁve pharmaceuticals drugs were selected for monitoring in the environment: bezaﬁbrate, a lipid regulator and enalapril, a cardiovascular drug, because they might pose an environmental risk from a quantitative point of view, due to their large sale ﬁgures. For toxicological effects, the cytostatic agents cyclophosphamide and methotrexate, have been chosen because they are pharmacologically designed to kill cells, they are highly toxic, carcinogenic and mutagenic. Orlistat is a lipase inhibitor, an important drug both in terms of sales volumes and potential toxic effects. It is now generally agreed that orlistat is an irreversible and potent inhibitor of pancreatic lipase in several species, including man.
2. Synthesis and biological investigation of the β-thiolactone and β-lactam analogs of tetrahydrolipstatin
Sylvain Aubry, Geneviève Aubert, Thierry Cresteil and David Crich*. Org. Biomol. Chem., 2012, 10, 2629–2632
With compounds 14, 22 and 23 in hand, their capacity to inhibit porcine pancreatic lipase was ﬁrst assessed with the aid of the 6’-methylresoruﬁn ester of 1,2-di-O-lauryl-rac-glycero-3-glutaric acid as substrate, and Orlistat as control. Orlistat proved to be the best inhibitor of porcine pancreatic lipase with an IC50 of 7.5 nM, but its cis-isomer 14, which retained the β-lactone functionality, showed only a two-fold loss of activity (IC50 = 15 nM) (Table 1, entries 1 and 2). This observation potentially opens the way to more extensive studies of Orlistat analogs bearing a cis- rather than a trans-disubstituted β-lactone as potential inhibitors of fatty acid synthase. In contrast to Orlistat and 14, neither the β-thiolactone 22 nor the β-lactam 23 inhibited the lipase to any signiﬁcant extent (Table 1, entries 3 and 4), thereby revealing the importance of the reactivity of the β-lactone for lipase inhibition. In addition, none of the synthetic intermediates (11–13, 15–16, 18–21) prepared, revealed any inhibition of the pancreatic lipase.
3. Target validation using in-cell small molecule clickable imaging probes
Brahma Ghosh* and Lyn H. Jones*. Med. Chem. Commun.,2014, 5,247–254
In addition to demonstrating their ability as tools for proteomic profiling of hitherto unknown targets of Orlistat in human hepatocytes, the investigators also explored THL-derived molecules for their potential as probes for cellular imaging of Orlistat targets. In a representative experiment, live HepG2 cells pre-incubated with the alkyne-tagged THL-R (or DMSO) were reacted with rhodamine azide under CuAAC click chemistry conditions and, following immunofluorescence staining to visualize the known target fatty acid synthase (FAS), were imaged using epifluorescence microscopy. Rhodamine fluorescence was observed in the THL-R treated cells (but was minimal in the DMSO control) and importantly, it colocated with the FAS signal. Additionally, imaging showed the rhodamine reporter-tagged THL-R/FAS complex to be distributed primarily in one organelle, the endoplasmic reticulum (ER), consistent with previous findings that Orlistat induced-ER stress leads to downstream inhibition of protein synthesis in tumour cells.
4. Natural products in anti-obesity therapy
Ilze Vermaak, Alvaro M. Viljoen* and Josias H. Hamman. Nat. Prod. Rep., 2011, 28, 1493–1533
The rhizomes of Panax japonicus C.A. Mey. (Araliaceae) are sometimes used as a substitute for ginseng roots in China and Japan. It has been used in the treatment of hyperlipidemia, hypertension, and Type II diabetes in China, Europe, Korea and Japan. Chikusetsusaponins III (67), IV and V, and 28-deglycosylchikusetsusaponins IV and V (68) were isolated from the rhizomes. Mice were fed a high-fat diet containing 1 and 3% total chikusetsusaponins or 0.012 and 0.024% orlistat (positive control) for 9 weeks. Ten out of ﬁfteen mice in the high-fat diet plus 0.024% orlistat group died within 5 weeks due to severe diarrhea. Orlistat administered at 0.012% did not cause diarrhea but it also did not signiﬁcantly reduce increases in body weight caused by a high-fat diet. Supplementation with 1 and 3% total chikusetsusaponins resulted in signiﬁcant reductions in body weight and adipose tissue weight compared to the high-fat diet control group. In rats, administration of an oral lipid emulsion supplemented with chikusetsusaponin (1000 mg kg-1) resulted in a signiﬁcantly reduced plasma triacylglycerol level after two hours.