Fluoroquinolones: novel class of gastrointestinal dietary lipid digestion and absorption inhibitors

Synthesis and Characterization of Short α and β-Mixed Peptides with Excellent Anti-Lipase Activities

Obesity is a source of significant pathologies and deadly diseases, including heart disease, diabetes, and cancer. One of the most intriguing strategies in the hunt for new anti-obesity medications is the inhibition of pancreatic lipase (PL). This study presents a novel application of short α and β-mixed peptides as pancreatic lipase inhibitors. These peptides were synthesized in the solution phase and characterized using FTIR and 1H-NMR. L-proline is present in a high percentage of natural anti-lipase peptides and was used as a β-amino acid in this study to enhance anti-lipase activity and proteolytic stability. Moreover, L-α-proline was converted to β-amino acid derivatives using the Arndt-Eistert method with the advantage of stereo control at the α-carbon. The synthesized peptides with anti-lipase activity are N-Boc-β-Pro-Gly-OBz (93%), N-Boc-O-Bz-Tyr-β-Pro-β-Pro-Gly-OBz (92%), N-Boc-O-Bz-Tyr-β-Pro-COOH (91%), N-Boc-Phe-β-Pro-OCH3 (90%), and N-Boc-O-Bz-Tyr-β-Pro-OCH3 (89%). These peptides may function as lead molecules for further modification to more significant molecules, which can help control obesity.

Pancreatic lipase inhibitors: The road voyaged and successes

Human pancreatic lipase (triacylglycerol acyl hydrolase EC3.1.1.3) is the most widely studied member of the human lipase superfamily related to carboxyl esterase. It is secreted from the acinar cell of pancreas and has strong preference for triacylglycerides over cholesterol esters, phospholipids, and galactolipids. Apart from the hydrolysis of triacylglycerides, pancreatic lipase may cause the hydrolysis of retinyl esters in vivo. So, it is very much evidenced that pancreatic lipase with its cofactor colipase has prominent role in efficient digestion of dietary fat. Hence, the modulation of human pancreatic lipase may represent a new insight in the discovery of a number of therapeutics that can inhibit the absorption of fat in body and can be used in obesity and other related metabolic disorders. Even, the only Food and drug administration (FDA) approved antiobesity drug, orlistat, is also an inhibitor of pancreatic lipase. This review summarizes studies about structure, mechanistic approach of pancreatic lipase enzyme while emphasizing on the various synthetic pancreatic lipase inhibitors with their structure activity relationship (SAR).

Fluoroquinolones as a potentially novel class of antidiabesity and antiproliferative compounds: synthesis and docking studies

Intense efforts by the pharmaceutical industry have been made to identify new targets for obesity diabetes (diabesity). Pancreatic triacylglycerol lipase (PL) inhibition is an interesting putative target for obesity management. Fluoroquinolones (FQs) have been identified as potent inhibitors of PL. The aim of this research was to synthesize novel FQs and evaluate their in vitro antilipolytic and antiproliferative properties. Characterization of the synthesized FQs was carried out with NMR, MS, IR, and EA. Like orlistat, potential FQs’ modulation of PL was quantified colorimetrically (n = 3) and was further supported by docking studies. Compared with cisplatin, FQs’ antiproliferative propensities against a panel of obesity related colorectal cancer cell lines were investigated with Sulforhodamine B assay. Twelve novel FQs (2A–5A, 2B–5B, and 2C–5C) were synthesized and characterized. The PL-IC50 values of tested FQs were in the range of 6.8–165.7 μmol/L. FQ 4A was the most active antiproliferative compound against HCT116 with an IC50 value of 3.5 μmol/L. Their selectivity of growth inhibition for safety examination using normal periodontal ligament fibroblasts (PDL) in comparison with cisplatin’s lack of differential cytotoxicity was reported. Lipophilicity and hydrogen bonding were found essential for both activities. Conclusively, FQs are robustly proven for their emerging in vitro anti-obesity and antiproliferative activities.

Computational approaches for the discovery of natural pancreatic lipase inhibitors as antiobesity agents

Obesity is becoming one of the greatest threats to global health in the 21st century and therefore the development of novel antiobesity drugs is one of the top priorities of global drug research. An important treatment strategy includes the reduction of intestinal fat absorption through the inhibition of pancreatic lipase (PL). Natural products provide a vast pool of PL inhibitors with novel scaffolds that can possibly be developed into clinical products. Computational drug design methods have become increasingly invaluable in the drug discovery process. In recent years, the discovery of new antiobesity PL inhibitors has been facilitated by the application of computational methods. This review highlights some computer-aided drug design techniques utilized in the discovery of natural PL inhibitors.

Facile synthesis of model 2,4-diaryl-1,3,4-thiadiazino[5,6-h]fluoroquinolones

A Selected set of 2,4-diaryl-7-oxo-1,2,4-thiadiazino[5,6-h]quinoline-8-carboxylic acids 6a–e has been prepared via reaction of the parent 7-chloro-8-nitro-10-cyclopropyl-6-fluoroquinolone 4 with the appropriate N′-(aryl)benzothiohydrazide 5a–e in presence of triethylamine. Structures of the new heterocyclics 6a–e are supported by spectral data and confirmed by single-crystal X-ray crystallography for 6a.

Pancreatic lipase inhibitory activity of selected pharmaceutical agents

Twenty-five structurally diverse compounds have been tested in vitro for their pancreatic lipase (PL) inhibitory activity. Despite the diversity of tested compounds, the relationship comprising structural attributes of the compounds could be established to correlate with the observed inhibitory activity. Compounds that exerted inhibitory action through surface activity were of different profile from the rest of compounds. When co-incubated with orlistat (OsT), important synergistic effects for some compounds (orphenadrine, gliclazide, cefuroxime and sulfacetamide) were revealed, while antagonistic effects were demonstrated for others (camphor sulfonic acid and dinitro salicylic acid). Docking studies for the most active molecules were performed and molecular interaction forces with the PL active site were identified. The results suggested co-binding of OsT along with the other inhibitor in the binding site in cases of synergistic effect but not in the case of antagonistic effect. These results were additionally supported by affinity capillary electrophoresis. In conclusion, synergistic lipase inhibitory activity between OsT and some other pharmaceutical compounds was demonstrated for the first time, which might help improve the pharmacological effect of OsT.

Heterocycles [h]-fused onto 4-oxoquinoline-3-carboxylic acid. Part XII: synthesis of 5-fluoro-7-oxodihydo[1,3,4]thiadiazino [5,6-h]quinoline-8-carboxylic acid and ester

Direct interaction of dithizone with 7-chloro-6- fluoro-8-nitro-4-oxoquinoline-3-carboxylic acid or with its ester delivered the corresponding novel 1,3,4-thiadiazino [5,6-h]quinoline 3-carboxylic acid, or its ester which was then hydrolyzed to the respective acid. Structures of the latter tricyclic hybrids were deduced from analytical and spectral data and confirmed by single crystal X-ray structure determination of the ester derivative. The free acid showed moderate activity against Staphylococcus aureus with a MIC value of 25 μg mL−1.

Antilipase and antiproliferative activities of novel fluoroquinolones and triazolofluoroquinolones

Fluoroquinolones (FQs) have been identified recently as potent inhibitors of pancreatic lipase (PL). The aim of this study was to synthesize novel FQs and triazolofluoroquinolones (TFQs) and to evaluate them in vitro with respect to their antilipolytic efficacy and potency properties. The PL-IC₅₀ values of 12 FQs and TFQs (3 (a-c)-6 (a-c)) were in the range of 12.5-189.1 μm. These values are further supported by docking studies. The suggested association between obesity and colorectal cancer initiated the evaluation of antiproliferative activity of the new FQs and TFQs against a panel of obesity-related colorectal cells (HT29, HCT116, SW620 CACO2, and SW480). Sulforodamine B colorimetric assay revealed that some derivatives exhibited unselective cytotoxicity against HT29, HCT116, SW620 CACO2, and SW480. Remarkably, FQ 4a's selective cytotoxicity against HCT116 was found valuable with IC₅₀ value of 4.2 μm which exceeds that of cisplatin with a substantial selective cytotoxicity in periodontal ligament fibroblasts. In conclusion, FQ and TFQ derivatives may unveil new antiobesity and anticancer agents in the future.