Near-infrared fluorescent probe with large Stokes shift for specific detection of lysine.

A new near-infrared (NIR) fluorescent probe CL based on coumarin- dicyanoisophorone was synthesized. Addition of Lys to probe CL solution in DMF/H2O (9:1, v/v) medium resulted in noticeable enhancement in the intensity of the fluorescence emission at 702 nm, accompanying distinct color change from yellow to pink. While addition of other amino acids and biothiols (Gly, Hcy, GSH, Glu, Val, Tyr, Arg, Trp, Lys, His, Leu, Phe, Asp and Met) did not bring about substantial changes in both fluorescence emission and color. The detection limit was calculated to be 0.51 µM. Job's plot test revealed that probe CL and Lys formed a complex of 1:1 stoichiometry. Probe CL showed high stability and could be used to recognize Lys in a wide pH range of 4.0-10.0. The sensing mechanism was proposed and verified by 1H NMR spectral measurement. The dual-modal fluorescence turn-on and colorimetric NIR probe with an extremely large Stokes shift of 280 nm may be utilized for highly specific and practical sensing of Lys.

Cellulose nanocrystal as an enhancing core for antitumor polymeric micelles to overcome biological barriers.

Polymeric micelles are extensively studied nanocarriers to improve the solubility, blood circulation, biodistribution, and adverse effects of chemotherapeutic drugs. However, the antitumor efficacy of polymeric micelles is often restricted due to multiple biological barriers, including blood fluid shear stress (FSS) and limited tumor penetration in vivo. Herein, cellulose nanocrystal (CNC) as a green material with rigidity and rod-shaped structure is developed to be an enhancing core for polymeric micelles to overcome these biological barriers. Doxorubicin (DOX) loaded methoxy poly (ethylene glycol)-block-poly (D, L-lactic acid) (mPEG-PLA, PP) ligated CNC nanoparticles (PPC/DOX NPs) are fabricated via one-pot synthesis. In comparison to the self-assembled DOX loaded mPEG-PLA micelles (PP/DOX NPs), PPC/DOX NPs exhibit remarkable improvements in FSS resistance, cellular internalization, blood circulation, tumor penetration, and antitumor efficacy owing to the unique rigidity and rod-shaped structure of CNC core. Moreover, PPC/DOX NPs present various advantages beyond DOX·HCl and CNC/DOX NPs. The superiority of PPC/DOX NPs in antitumor efficacy reveals the effectiveness of adopting CNC as the enhancing core for polymeric micelles, suggesting that CNC is a promising biomaterial in advancing nanomedicine.

Design, synthesis and biological evaluation of alkynyl-containing maleimide derivatives for the treatment of drug-resistant tuberculosis.

A series of alkynyl-containing maleimides with potent anti-tuberculosis (TB) activity was developed through a rigid group substitution strategy based on our previous study. Systematic optimization of the two side chains flanking the maleimide core led to new compounds with potent activity against Mycobacterium tuberculosis (MIC < 1 µg/mL) and low cytotoxicity (IC50 > 64 µg/mL). Among them, compound 29 not only possessed good activity against extensively drug-resistant TB and favorable hepatocyte stability, but also displayed good intracellular antimycobacterial activity in macrophages. This study lays a good foundation for identifying new alkynyl-containing maleimides as promising leads for treating drug-resistant TB.

Design, Synthesis, and Biological Evaluation of Pyrrole-2-carboxamide Derivatives as Mycobacterial Membrane Protein Large 3 Inhibitors for Treating Drug-Resistant Tuberculosis.

In this work, pyrrole-2-carboxamides were designed with a structure-guided strategy based on the crystal structure of MmpL3 and a pharmacophore model. The structure-activity relationship studies revealed that attaching phenyl and pyridyl groups with electron-withdrawing substituents to the pyrrole ring and attaching bulky substituents to the carboxamide greatly improved anti-TB activity. Most compounds showed potent anti-TB activity (MIC < 0.016 µg/mL) and low cytotoxicity (IC50 > 64 µg/mL). Compound 32 displayed excellent activity against drug-resistant tuberculosis, good microsomal stability, almost no inhibition of the hERG K+ channel, and good in vivo efficacy. Furthermore, the target of the pyrrole-2-carboxamides was identified by measuring their potency against M. smegmatis expressing wild-type and mutated variants of the mmpL3 gene from M. tuberculosis (mmpL3tb) and determining their effect on mycolic acid biosynthesis using a [14C] acetate metabolic labeling assay. The present study provides new MmpL3 inhibitors that are promising anti-TB agents.

Identification of novel benzothiopyranones with ester and amide motifs derived from active metabolite as promising leads against Mycobacterium tuberculosis.

We reported three distinct series of novel benzothiopyranones, derived from an active metabolite (M-1) of anti-TB agent 6b. These small molecules were evaluated for their biological activities against a range of Mycobacterium tuberculosis (M. tuberculosis) strains. Preliminary druggability evaluation demonstrated that M-1 showed good aqueous solubility and hepatocyte stability. Benzothiopyranones with acyl, sulfonyl and phosphoryl groups exhibited potent in vitro inhibitory activity against M. tuberculosis H37Rv and low cytotoxicity. In particular, compound 3d, containing a benzoate fragment, displayed marked metabolic stability and potent in vitro activity against drug-resistant tuberculosis clinical strains. Further druggability evaluation based on the identified compounds 3d, 4e and 5b is ongoing for the discovery of promising anti-TB agents.

Magnesium Lithospermate B Attenuates High-Fat Diet-Induced Muscle Atrophy in C57BL/6J Mice.

Magnesium lithospermate B (MLB) is a primary hydrophilic component of Danshen, the dried root of Salvia miltiorrhiza used in traditional medicine, and its beneficial effects on obesity-associated metabolic abnormalities were reported in our previous study. The present study investigated the anti-muscle atrophy potential of MLB in mice with high-fat diet (HFD)-induced obesity. In addition to metabolic abnormalities, the HFD mice had a net loss of skeletal muscle weight and muscle fibers and high levels of muscle-specific ubiquitin E3 ligases, namely the muscle atrophy F-box (MAFbx) and muscle RING finger protein 1 (MuRF-1). MLB supplementation alleviated those health concerns. Parallel changes were revealed in high circulating tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), skeletal TNF receptor I (TNFRI), nuclear factor-kappa light chain enhancer of activated B cells (NF-κB), p65 phosphorylation, and Forkhead box protein O1 (FoxO1) as well as low skeletal phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt) phosphorylation. The study revealed that MLB prevented obesity-associated skeletal muscle atrophy, likely through the inhibition of MAFbx/MuRF-1-mediated muscular degradation. The activation of the PI3K-Akt-FoxO1 pathway and inhibition of the TNF-α/TNFRI/NF-κB pathway were assumed to be beneficial effects of MLB.

Design, synthesis and biological evaluation of diamino substituted cyclobut-3-ene-1,2-dione derivatives for the treatment of drug-resistant tuberculosis.

Mycobacterium tuberculosis (Mtb) ATP synthase is an important target for treating drug-resistant infections and sterilizing the bacteria, spurring intensive efforts to develop new TB therapeutics based on this target. In this work, four novel series including furan-2(5H)-ketone (3, 4), maleimide (5) and squaramide (6) derivatives were designed, respectively, through the strategy of scaffold morphing and hydrogen-bond introduction, using the selective Mtb ATP synthase inhibitor compound 2 as the lead compound. The result demonstrated that diamino substituted cyclobut-3-ene-1,2-dione compounds 6ab and 6ah displayed good to excellent in vitro anti-TB activities (MIC 0.452-0.963 µg/mL) with low cytotoxicity (IC50 > 64 µg/mL). In addition, not only did compound 6ab show effective activity against clinically isolated resistant strains, it also revealed good druggability profiles including improved metabolic stability, no hERG channel inhibition potential, and acceptable oral bioavailability. The preliminary result of docking study and in vitro anti-bedaquiline-resistant strain test compared to compound 2 suggested that Mtb ATP synthase is most likely the target of compound 6ab. The structure-activity relationship laid a good foundation for the identification of novel squaramides as a potential treatment of drug-resistant tuberculosis.

An efficient and concise access to 2-amino-4H-benzothiopyran-4-one derivatives.

A highly efficient and convenient protocol was developed to access 2-amino-4H-benzothiopyran-4-ones through a process of conjugated addition-elimination. The sulfinyl group was proved to be the optimum leaving group by thorough investigations on the elimination of sulfide, sulfinyl, and sulfonyl groups at the 2-position of benzothiopyranone. Most 2-aminobenzothiopyranones were obtained in good to excellent yields under refluxing in isopropanol within 36 h. This method is base-free and the substrate scope in terms of electronic properties of the substituents of the benzothiopyranone is broad. The ten grams scale-up synthesis of the representative compounds 4a and 4d was implemented to show the practical application of this reaction, which afforded the corresponding compounds in good yields and excellent chemical purity without requiring column chromatographical purification.

Identification of novel benzothiopyranone compounds against Mycobacterium tuberculosis through scaffold morphing from benzothiazinones.

In this study, three novel series of benzoxazinone, benzothiopyranone and benzopyranone derivatives were designed through scaffold morphing from benzothiazinones to target DprE1. All compounds were evaluated for their in vitro activities against Mycobacterium tuberculosis and cytotoxicity against Vero cell line. Among these three series, the benzothiopyranone series displayed excellent antimycobacterial activity and low cytotoxicity. In particular, compound 6b exhibited potent in vitro activity against both drug-susceptible and drug-resistant tuberculosis clinical strains with MICs <0.016 µg/mL. In addition, compound 6b demonstrated excellent ADME/T and PK properties and potent in vivo efficacy with bactericidal activity in an acute mouse model of tuberculosis. The antituberculosis effect of compound 6b is most likely attributed to its excellent anti-DprE1 activity. As such, compound 6b is under evaluation as a potential clinical candidate for treatment of tuberculosis. The current study provided new insight into the structural and pharmacological requirements for DprE1 inhibitors as potent antitubercular agents.

An efficient and facile access to highly functionalized pyrrole derivatives.

A straightforward and one-pot synthesis of pyrrolo[3,4-c]pyrrole-1,3-diones via Ag(I)-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with N-alkyl maleimide, followed by readily complete oxidation with DDQ, has been successfully developed. Further transformation with alkylamine/sodium alkoxide alcohol solution conveniently afforded novel polysubstituted pyrroles in good to excellent yields. This methodology for highly functionalized pyrroles performed well over a broad scope of substrates. It is conceivable that this efficient construction method for privileged pyrrole scaffolds could deliver more active compounds for medicinal chemistry research.

Discovery of novel xanthine compounds targeting DPP-IV and GPR119 as anti-diabetic agents.

A series of xanthine derivatives as potent dual ligands targeting DPP-IV and GPR119 was discovered through an approach of the merged pharmacophores of GPR119 agonists and DPP-IV inhibitor linagliptin. Systematic optimization of general structure 5 led to the identification of compound 20i with selective DPP-IV inhibition, good GPR119 agonism activity and favorable metabolic stability. Docking study was performed to elucidate the potent DPP-IV inhibition of 20i. Compound 20i may serve as a tool compound for further design of anti-diabetic drugs targeting both DPP-IV and GPR119.

An improved efficient synthesis of the antibacterial agent torezolid.

An improved and efficient method for the preparation of torezolid based on Suzuki cross-coupling reaction as the key step was developed on a gram scale in five steps. The total yield was 44% and the optical purity of torezolid by the improved method was above 99%.

Design and synthesis of novel benzimidazole derivatives as anti-tuberculosis agents.

In recent studies some urea derivatives have been identified as potent anti-tuberculosis agents by targeting mycobacterial membrane protein large 3 (MmpL3). However, this compound series as exemplified by AU1235 exhibited poor in vitro pharmacokinetic profile. With AU1235 as the lead, we have identified a novel benzimidazole series as potential anti-tuberculosis agents by using scaffold hopping approach. Among these synthesized compounds, 2-aminobenzimidazole derivative 8b showed the potent anti-tuberculosis activity with the MIC value of 0.03 microg x mL(-1). This compound also showed improved metabolic stability compared to AU1235. Our investigation indicated that benzimidazole derivatives are the promising lead for further optimization as anti-tuberculosis agents.

Design, synthesis and evaluation of novel diaryl urea derivatives as potential antitumor agents.

A novel series of diaryl ureas containing different linker groups were designed and synthesized. Their in vitro antitumor activity against MX-1, A375, HepG2, Ketr3 and HT-29 was evaluated using the standard MTT assay. Compounds having a rigid linker group such as vinyl, ethynyl and phenyl showed significant inhibitory activity against a variety of cancer cell lines. Specifically, compound 23 with a phenyl linker group demonstrated broad-spectrum antitumor activity with IC50 values of 5.17-6.46 µM against five tested tumor cell lines. Compound 23 is more potent than reference drug sorafenib (8.27-15.2 µM), representing a promising lead for further optimization.

Design, synthesis and hepatoprotective activity of analogs of the natural product goodyeroside A.

Goodyeroside A, a natural product isolated from the Goodyera species, possesses significant hepatoprotective activity and has a novel skeleton not previously observed in other synthetic drugs used for the treatment of hepatitis. Herein, we report a highly stereoselective synthesis of goodyeroside A and related analogs with varying substituents at the α position of the carbonyl group to explore the structure-activity relationships of goodyeroside A. The absolute configuration of analog 5d was confirmed by single crystal X-ray analysis. The results from in vitro and in vivo studies indicate that 5a, the fully acetylated compound of goodyeroside A, is worthy of further investigation as a lead to identify novel hepatoprotective agents.

[Design, synthesis and in vitro activity of glycinamide-bearing compounds as DPP-IV inhibitors].

To research the structure-activity relationship (SAR) of glycinamide-bearing compounds that used as inhibitors of dipeptidyl peptidase IV (DPP-IV), P32/98 and compound A were chosen as the leading compounds, heterocycles containing nitrogen atom were introduced to form amide, and different residues on a-position of carbonyl were designed. The nineteen designed compounds were synthesized by a simple route and were evaluated as inhibitors of DPP-IV. All of the structures were characterized by 1H NMR and HRMS. The preliminary SAR result was obtained.

[Synthesis and antiinflammation activity of aromatic aminoketone compounds, a new type of PAF-receptor antagonist].

A series of aromatic aminoketones were synthesized by Mannich reaction. Structures of these compounds were confirmed by 1H NMR, MS and HRMS or element analysis. Pharmacological screening showed that most target compounds inhibited the release of beta-glucuronidase in polymorphonuclear leucocytes by PAF (platelet activating factor) and compounds MA12, MA13, MA18, MA21 and MA33 were more active. The study suggests that target compounds are potential PAF receptor antagonists and their anti-inflammatory activities are due to the inhibition of release of lysosomal enzyme.