The modulatory role of sulfated and non-sulfated small molecule heparan sulfate-glycomimetics in endothelial dysfunction: absolute structural clarification, molecular docking and simulated dynamics, SAR analyses and ADMET studies

The conceptual technology of small molecule glycomimetics, exemplified by compounds C1-4, has shown promising protective effects against lipid-induced endothelial dysfunction, restorative effects on diabetic endothelial colony forming cells, and preventative effects on downstream vascular calcification amongst other important in vitro and ex vivo studies. We report the optimised synthesis of an array of 17 small molecule glycomimetics, including the regio-, enantio- and diastereo-meric sulfated scaffolds of a hit structure along with novel desulfated examples. For the first time, the absolute stereochemical configurations of C1-4 have been clarified based on an identified and consistent anomaly with the Sharpless asymmetric dihydroxylation reaction. We have investigated the role and importance of sulfation pattern, location, regioisomers, and spatial orientation of distal sulfate groups on the modulation of endothelial dysfunction through their interaction with hepatocyte growth factor (HGF). In silico studies demonstrated the key interactions the persulfated glycomimetics make with HGF and revealed the importance of both sulfate density and positioning (both point chirality and vector) to biological activity. In vitro biological data of the most efficient binding motifs, along with desulfated comparators, support the modulatory effects of sulfated small molecule glycomimetics in the downstream signaling cascade of endothelial dysfunction. In vitro absorption, distribution, metabolism, elimination and toxicity (ADMET) data demonstrate the glycomimetic approach to be a promising approach for hit-to-lead studies.

Synthesis and Spectroscopic Analysis of Piperine- and Piperlongumine-Inspired Natural Product Scaffolds and Their Molecular Docking with IL-1β and NF-κB Proteins

Inspired by the remarkable bioactivities exhibited by the natural products, piperine and piperlongumine, we synthesised eight natural product-inspired analogues to further investigate their structures. For the first time, we confirmed the structure of the key cyclised dihydropyrazolecarbothioamide piperine analogues including the use of two-dimensional (2D) 15N-based spectroscopy nuclear magnetic resonance (NMR) spectroscopy. Prior investigations demonstrated promising results from these scaffolds for the inhibition of inflammatory response via downregulation of the IL-1β and NF-κB pathway. However, the molecular interaction of these molecules with their protein targets remains unknown. Ab initio calculations revealed the electronic density function map of the molecules, showing the effects of structural modification in the electronic structure. Finally, molecular interactions between the synthesized molecules and the proteins IL-1β and NF-κB were achieved. Docking results showed that all the analogues interact in the DNA binding site of NF-κB with higher affinity compared to the natural products and, with the exception of 9a and 9b, have higher affinity than the natural products for the binding site of IL-1β. Specificity for the molecular recognition of 3a, 3c and 9b with IL-1β through cation-π interactions was determined. These results revealed 3a, 3c, 4a, 4c and 10 as the most promising molecules to be evaluated as IL-1β and NF-κB inhibitors.

Eletefine, a stephaoxocane alkaloid from cissampelos glaberrima

A novel isoquinoline alkaloid bearing an oxocane ring (stephaoxocane type (Kashiwaba, N.; Morooka, S.; Kimura, M.; Ono, M.; Toda, J.; Suzuki, H.; Sano, T. J. Nat. Prod. 1996, 59, 803)), has been isolated from the roots of Cissampelos glaberrima. This compound was given the trivial name eletefine (1) and its structure assigned on the basis of spectroscopic data and conversion to the corresponding ketone (2).