Efficient and diversity-oriented total synthesis of Riccardin C and application to develop novel macrolactam derivatives

One-Pot Tandem Coupling Method for the Short-Step Formal Synthesis of Riccardin C

One-pot reactions reduce reagent amounts and circumvent process treatments, such as work-up and purifications in multi-step reactions. In this study, we achieved the formal total synthesis of riccardin C through a one-pot reaction by simultaneously linking four units through two Sonogashira coupling reactions and one Suzuki coupling reaction, followed by reduction and deprotection. Thus, this one-pot method comprised five steps and did not require the purification of intermediate reaction mixtures, which saves resources, such as reagents and solvents, and expedites the work process.

Design, synthesis and structure-activity relationship of 4-(1,1,1,3,3,3-hexafluoro-2-hydroxyisoprop-2-yl)phenylsilane derivatives as liver X receptor agonists

Liver X receptor (LXR) α and LXRβ are nuclear receptors playing key roles in lipid metabolism, and LXR ligands are attractive drug candidates for metabolic disorders. Here we report the structural development of 4-(1,1,1,3,3,3-hexafluoro-2-hydroxyprop-2-yl)phenylsilane derivatives as LXR agonists bearing silyl functionalities as the hydrophobic pharmacophore, based on the structure of the known sulfonamide LXR agonist T0901317. Most of the synthesized compounds exhibit agonistic activity toward LXRs, but the LXR subtype-selectivity differs depending upon the substituents on the silicon atom. Among them, tri(n-propyl) derivative 12 shows potent LXR-agonistic activity with moderate α subtype-selectivity, while dimethylphenylsilyl derivative 19 shows modest β-selectivity. These results indicate that silanes can serve as an alternative to the sulfonamide moiety of LXR agonists, and are promising structural options for the development of novel subtype-selective LXR agonists.

Total synthesis of antiallergic bicyclic peptide seongsanamide A

The first total synthesis of antiallergic depsipeptide seongsanamide A has been achieved and also the relative and absolute stereochemistry of the natural product has been confirmed.

First triclosan-based macrocyclic inhibitors of InhA enzyme

Two macrocyclic derivatives based on the triclosan frame were designed and synthesized as inhibitors of Mycobacterium tuberculosis InhA enzyme. One of the two molecules M02 displayed promising inhibitory activity against InhA enzyme with an IC₅₀ of 4.7 μM. Molecular docking studies of these two compounds were performed and confirmed that M02 was more efficient as inhibitor of InhA activity. These molecules are the first macrocyclic direct inhibitors of InhA enzyme able to bind into the substrate pocket. Furthermore, these biaryl ether compounds exhibited antitubercular activities comparable to that of triclosan against M. tuberculosis H37Rv strain.

Anti-MRSA activity of isoplagiochin-type macrocyclic bis(bibenzyl)s is mediated through cell membrane damage

We synthesized three geometrical isomers of a macrocyclic bis(bibenzyl) based on isoplagiochin, a natural product isolated from bryophytes, and evaluated their antibacterial activity towards methicillin-resistant Staphylococcus aureus (anti-MRSA activity). The isomer containing a 1,4-linked ring (5) showed only weak activity, whereas the isomers containing a 1,3-linked (6) or 1,2-linked (7) C ring showed potent anti-MRSA activity. Molecular dynamics calculations indicated that these differences are probably due to differences in the conformational flexibility of the macrocyclic ring; the active compounds 6 and 7 were more rigid than 5. In order to understand the action mechanism of anti-MRSA activity, we investigated the cellular flux of a fluorescent DNA-binder, ethidium bromide (EtBr), in the presence and absence of these macrocycles. The active compound 6 increased the levels of EtBr inflow and outflow in S. aureus cells, as did our potent anti-MRSA riccardin derivative (4), indicating that these compounds increased the permeability of the cytoplasmic membrane. Inactive 5 had no effect on EtBr inflow or outflow. Furthermore, compound 6 abrogated the normal intracellular concentration gradients of Na(+) and K(+) in S. aureus cells, increasing the intracellular Na(+) concentration and decreasing the K(+) concentration, while 5 had no such effect. These results indicate that anti-MRSA-active macrocyclic bis(bibenzyl) derivatives directly damage the gram-positive bacterial membrane, resulting in increased permeability.