Discovery and optimization of 3,4,5-trimethoxyphenyl substituted triazolylthioacetamides as potent tubulin polymerization inhibitors

Based on our previous research, three series of new triazolylthioacetamides possessing 3,4,5-trimethoxyphenyl moiety were synthesized, and evaluated for antiproliferative activities and inhibition of tubulin polymerization. The most promising compounds 8b and 8j demonstrated more significant antiproliferative activities against MCF-7, HeLa, and HT-29 cell lines than our lead compound 6. Moreover, analogues 8f, 8j, and 8o manifested more potent antiproliferative activities against HeLa cell line with IC₅₀ values of 0.04, 0.05 and 0.16?μM, respectively, representing 100-, 82-, and 25-fold improvements of the activity compared to compound 6. Furthermore, the representative compound, 8j, was found to induce significant cell cycle arrest at the G₂/M phase in HeLa cell lines via a concentration-dependent manner. Meanwhile, compound 8b exhibited the most potent tubulin polymerization inhibitory activity with an IC₅₀ value of 5.9?μM, which was almost as active as that of CA-4 (IC₅₀?=?4.2?μM). Additionally, molecular docking analysis suggested that 8b formed stable interactions in the colchicine-binding site of tubulin.     

Novel aromatic sulfonyl naphthalene-based boronates as 20S proteasome inhibitors

A novel series of non-peptide proteasome inhibitors (PIs) that act on chymotrypsin-like (ChT-L) of the proteasome were developed. These PIs bearing 4-aromatic sulfonyl naphthalene-based scaffold and Leu-boronic moiety as covalent bonding group displayed far better activity than PI-8182 for inhibiting ChT-L in preliminary biological activity test. The results showed that 2a (IC₅₀?=?6.942?μM, MCF-7) and 2c (IC₅₀?=?6.905?μM, MCF-7) displayed higher anti-proliferative activities than Bortezomib (IC₅₀?=?18.37?μM, MCF-7) under our experimental conditions. Furthermore, in the microsomal stability assay, 2a demonstrated excellent metabolic stability profiles with 56% remaining after 40?min, as compared to Bortezomib of which approximately 30% was remaining. The compounds 2a, 2c emerged as promising lead compounds for the development of novel non-peptide boronate PIs.     

Discovery of novel 2,3-dihydro-1H-inden-1-amine derivatives as selective monoamine oxidase B inhibitors

Inhibition of MAO-B has been an effective strategy for the treatment of Parkinson’s disease. To find more potent and selective MAO-B inhibitors with novel chemical scaffold, we designed and synthesized a series of new 2,3-dihydro-1H-inden-1-amine derivatives on basis of our previous study. Furthermore, the corresponding structure-activity relationship (SAR) of these compounds is detailedly discussed. Compounds L4 (IC₅₀?=?0.11?μM), L8 (IC₅₀?=?0.18?μM), L16 (IC₅₀?=?0.27?μM) and L17 (IC₅₀?=?0.48?μM) showed similar MAO-B inhibitory activity as Selegiline. Moreover, L4, L16 and L17 also exhibited comparable selectivity with Selegiline, indicating that L4, L16 and L17 could be promising selective MAO-B inhibitors for further study.     

Exploring membrane permeability of Tomatidine to enhance lipid mediated nucleic acid transfections

Intracellular delivery of nucleic acids is one of the critical steps in the transfections. Prior findings demonstrated various strategies including membrane fusion, endosomal escape for the efficient cytoplasmic delivery. In our continuing efforts to improve the nucleic acids transfections, we harnessed cell permeable properties of Tomatidine (T), a steroidal alkaloid abundantly found in green tomatoes for maximizing intracellular delivery of lipoplexes. We doped Tomatidine into liposomes of cationic lipid with amide linker (A) from our lipid library. Six liposomal formulations (AT) of Lipid A (1?mM) with varying concentrations of Tomatidine (0–1?mM) were prepared and evaluated for their transfection efficacies. Owing to its signature characteristic of cell membrane permeability, Tomatidine modulated endocytosis process, enhanced the intracellular delivery of the lipoplexes, and in turn increased the transfection efficacy of cationic liposomes. Our findings provide ‘proof of concept’ for enhancing transfections in gene delivery applications with Tomatidine in cationic liposomal formulations. These findings can be further applied in lipid mediated gene therapy and drug delivery applications.     

Isoxazole-tethered diarylheptanoid analogs: Discovery of a new drug-like PAR2 antagonist

A new class of isoxazole-tethered diarylheptanoids having characteristic 1,3-syn-diol and 1,3-anti-diol chemophoric moieties, e.g. 4a–d and 5a–c respectively, have been designed and synthesized starting from d-glucose following a stereo-conserved general synthetic strategy. The isoxazole heterocycle was installed using our recently elaborated methodology deploying Magtrieve? as a selective oxidizing agent. Two of these new analogs 4a and 5a exhibited significantly improved in vitro drug-like properties including solubility, metabolic stability, cell permeability and lack of nonspecific cytotoxicity when compared with curcumin-I. In a HEK293 cell-based intracellular calcium [Ca²⁺]_i release assay, 4a and 5a, when tested at 30?μM, inhibited the trypsin agonist induced protease-activated receptor-2 (PAR2) activity by 80% and 70% respectively. IC₅₀ of 4a (SB70) has been determined as 6?μM which is in the same range of current benchmarks for PAR2 antagonists.     

Synthesis,biological evaluation and 3D-QSAR studies of 1,2,4-triazole-5-substituted carboxylic acid bioisosteres as uric acid transporter 1 (URAT1) inhibitors for the treatment of hyperuricemia associated with gout

As a part of our ongoing research to develop novel URAT1 inhibitors, 19 compounds (1a-1s) based on carboxylic acid bioisosteres were synthesized and tested for in vitro URAT1 inhibitor activity (IC₅₀). The structure-activity relationship (SAR) exploration led to the discovery of a highly potent novel URAT1 inhibitor 1g, which was 225-fold more potent than the parent lesinurad in vitro (IC₅₀?=?0.032?μM for 1g against human URAT1 vs 7.20?μM for lesinurad). Besides, 3D-QSAR pharmacophore models were established based on the activity of the compounds (1a-1s) by Accelrys Discovery Studio 2.5/HypoGen. The best hypothesis, Hypo 1, was validated by three methods (cost analysis, Fisher’s randomization and leave-one-out). Although compound 1g is among the most potent URAT1 inhibitors currently under development in clinical trials, the Hypo1 appears to be favorable for future lead optimization.     

Synthesis, in vitro and in vivo biological evaluation,COX-1/2 inhibition and molecular docking study of indole-N-acylhydrazone derivatives

The objective of this work was to obtain and evaluate anti-inflammatory in vitro, in vivo and in silico potential of novel indole-N-acylhydrazone derivatives. In total, 10 new compounds (3a–j) were synthesized in satisfactory yields, through a condensation reaction in a single synthesis step. In the lymphoproliferation assay, using mice splenocytes, 3a and 3b showed inhibition of lymphocyte proliferation of 62.7% (±3.5) and 50.7% (±2), respectively, while dexamethasone presented an inhibition of 74.6% (±2.4). Moreover, compound 3b induced higher Th2 cytokines production in mice splenocytes cultures. The results for COX inhibition assays showed that compound 3b is a selective COX-2 inhibitor, but with less potency when compared to celecoxib, and compound 3a not presented selectivity towards COX-2. The molecular docking results suggest compounds 3a and 3b interact with the active site of COX-2 in similar conformations, but not with the active site of COX-1, and this may be the main reason to the COX-2 selectivity of compound 3b. In vivo carrageenan-induced paw edema assays were adopted for the confirmation of the anti-inflammatory activity. Compound 3b showed better results in suppressing edema at all tested concentrations and was able to induce an edema inhibition of 100% after 5?h of carrageenan injection at the 30?mg?kg^?1 dosage, corroborating with the COX inhibition and lymphoproliferation results. I addition to our experimental results, in silico analysis suggest that compounds 3a and 3b present a well-balanced profile between pharmacodynamics and pharmacokinetics. Thus, our preliminary results revealed the potentiality of a new COX-2 selective derivative in the modulation of the inflammatory process.     

Structure-activity relationships and docking studies of synthetic 2-arylindole derivatives determined with aromatase and quinone reductase 1

In our ongoing effort of discovering anticancer and chemopreventive agents, a series of 2-arylindole derivatives were synthesized and evaluated toward aromatase and quinone reductase 1 (QR1). Biological evaluation revealed that several compounds (e.g., 2d, IC₅₀?=?1.61?μM; 21, IC₅₀?=?3.05?μM; and 27, IC₅₀?=?3.34?μM) showed aromatase inhibitory activity with half maximal inhibitory concentration (IC₅₀) values in the low micromolar concentrations. With regard to the QR1 induction activity, 11 exhibited the highest QR1 induction ratio (IR) with a low concentration to double activity (CD) value (IR?=?8.34, CD?=?2.75?μM), while 7 showed the most potent CD value of 1.12?μM. A dual acting compound 24 showed aromatase inhibition (IC₅₀?=?9.00?μM) as well as QR1 induction (CD?=?5.76?μM) activities. Computational docking studies using CDOCKER (Discovery Studio 3.5) provided insight in regard to the potential binding modes of 2-arylindoles within the aromatase active site. Predominantly, the 2-arylindoles preferred binding with the 2-aryl group toward a small hydrophobic pocket within the active site. The C-5 electron withdrawing group on indole was predicted to have an important role and formed a hydrogen bond with Ser478 (OH). Alternatively, meta-pyridyl analogs may orient with the pyridyl 3′-nitrogen coordinating with the heme group.     

Target ROS to induce apoptosis and cell cycle arrest by 5,7-dimethoxy-1,4-naphthoquinone derivative

The 1,4-naphthoquinone derivatives bearing 5,7-dimethoxyl moiety were designed, synthesized, and tested as the antitumor agents against five human cancer cell lines (A549, Hela, HepG2, NCI-H460 and HL-60). All the compounds are described herein for the first time. The structure-activity relationships indicated that the presence of chlorine atom at the 2-position was crucial for the antiproliferative activity. Further, the electrochemical properties of the representative compounds (7e, 8e and 9e) were evaluated and a definite correlation between the redox potential and the antiproliferative activity. The most potent compound 9e displayed significant anti-leukemic activity with IC₅₀ value of 3.8?μM in HL-60 cells and weak cytotoxicity with IC₅₀ of 40.7?μM in normal cells WI-38. In mechanistic study for 9e, the increased numbers of apoptotic cells and increased cell population at G2/M phase correlated with ROS generation. Together, our results suggested that the derivatives of 2-chlorine-1,4-naphthoquinone might be the promising candidates for the treatment of promyelocytic leukemia.     

Distant Neighbor Base Sequence Context Effects in Human Nucleotide Excision Repair of a Benzo[a]pyrene-derived DNA Lesion

The effects of non-nearest base sequences, beyond the nucleotides flanking a DNA lesion on either side, on nucleotide excision repair (NER) in extracts from human cells were investigated. We constructed two duplexes containing the same minor groove-aligned 10S (+)-trans-anti-B[a]P-N²-dG (G?) DNA adduct, derived from the environmental carcinogen benzo[a]pyrene (B[a]P): 5′-C-C-A-T-C-G?-C-T-A-C-C-3′ (CG?C-I), and 5′-C-A-C3-A4-C5-G?-C-A-C-A-C-3′ (CG?C-II). We used polyacrylamide gel electrophoresis to compare the extent of DNA bending, and molecular dynamics simulations to analyze the structural characteristics of these two DNA duplexes. The NER efficiencies are 1.6(± 0.2)-fold greater in the case of the CG?C-II than the CG?C-I sequence context in 135-mer duplexes. Gel electrophoresis and self-ligation circularization experiments revealed that the CG?C-II duplex is more bent than the CG?C-I duplex, while molecular dynamics simulations showed that the unique -C3-A4-C5- segment in the CG?C-II duplex plays a key role. The presence of a minor groove-positioned guanine amino group, the Watson-Crick partner to C3, acts as a wedge; facilitated by a highly deformable local -C3-A4- base step, this amino group allows the B[a]P ring system to produce a more enlarged minor groove in CG?C-II than in CG?C-I, as well as a local untwisting and enlarged and flexible Roll only in the CG?C-II sequence. These structural properties fit well with our earlier findings that in the case of the family of minor groove 10S (+)-trans-anti-B[a]P-N²-dG lesions, flexible bends and enlarged minor groove widths constitute NER recognition signals, and extend our understanding of sequence context effects on NER to the neighbors that are distant to the lesion.     

Discovery of a potent tyrosine kinase AXL inhibitor bearing the 3-((2,3,4,5-tetrahydro-1H-benzo[d]azepin-7-yl)amino)pyrazine core

Starting from the recently launched FLT3/AXL multi-targeted inhibitor Gilteritinib (5), we conducted a side-chain ring closure medicinal chemistry approach leading to the identification of compound 15c as a highly potent AXL inhibitor in the biochemical and cellular anti-proliferative assays, with IC₅₀ values of 1.2 and 0.3?nM, respectively. Compared with the reference compound 5, our new discovered AXL inhibitor 15c is more potent in both assays.     

Discovery of 1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazoles as novel class of corticotropin releasing factor 1 receptor antagonists

A new class of corticotropin releasing factor 1 (CRF₁) receptor antagonists characterized by a tricyclic core ring was designed and synthesized. Novel tricyclic derivatives 2a–e were designed as CRF₁ receptor antagonists based on conformation analysis of our original 2-anilinobenzimidazole CRF₁ receptor antagonist. The synthesized tricyclic derivatives 2a–e showed CRF₁ receptor binding activity with IC₅₀ values of less than 400?nM, and the 1,2,3,4-tetrahydropyrimido-[1,2-a]benzimidazole derivative 2e was selected as a lead compound with potent in vitro CRF₁ receptor binding activity (IC₅₀?=?7.1?nM). To optimize the pharmacokinetic profiles of lead compound 2e, we explored suitable substituents on the 1-position and 6-position, leading to the identification of compound 42c-R, which exhibited potent CRF₁ receptor binding activity (IC₅₀?=?58?nM) with good oral bioavailability (F?=?68% in rats). Compound 42c-R exhibited dose-dependent inhibition of [¹²⁵I]-CRF binding in the frontal cortex (5 and 10?mg/kg, p.o.) as well as suppression of locomotor activation induced by intracerebroventricular administration of CRF in rats (10?mg/kg, p.o.). These results suggest that compound 42c-R successfully binds CRF₁ receptors in the brain and exhibits the potential to be further examined for clinical studies.     

A thiol-inducible and quick-response DNA cross-linking agent

Three new 2,4-dinitrobenzenesulfonyl derivatives 1–3 were successfully prepared for the first time using a simple process. They were efficiently triggered by thiols (glutathione and l-cysteine) to release the corresponding phenol derivatives (4–6) within 5?min. The quick response of 1–3 toward thiols was determined by ¹H NMR and HPLC. Moreover, our results indicated that 1 could induce DNA cross-linking in the presence of glutathione, probably due to the quinone methide formation of phenol intermediate 4 followed by departure of 2,4-dinitrobenzenesulfonyl group.     

Two new lathyrane-type diterpenoid glycosides with IL-6 production inhibitory activity from the roots of Euphorbia kansui

As part of our ongoing search for anti-inflammatory compounds from higher plants, we isolated and elucidated two new diterpenoid glycosides, kansuingol A (1) and kansuingol B (2), from the roots of Euphorbia kansui. These structures were elucidated by extensive spectroscopic methods such as NMR and MS. Compounds were assessed for their IL-6 production inhibitory activity in PMA?+?A23187-stimulated HMC-1 cells. As a result, compounds 1 and 2 exerted inhibitory activities in the production of IL-6 with IC₅₀ values of 2.96, and 1.94?μM, respectively. Further, kansuingol A (1) decreased mRNA expressions of TNF-α and IL-6.     

Design,synthesis and evaluation of vilazodone-tacrine hybrids as multitarget-directed ligands against depression with cognitive impairment

Depression, a severe mental disease, is greatly difficult to treat and easy to induce other neuropsychiatric symptoms, the most frequent one is cognitive impairment. In this study, a series of novel vilazodone-tacrine hybrids were designed, synthesized and evaluated as multitarget agents against depression with cognitive impairment. Most compounds exhibited good multitarget activities and appropriate blood-brain barrier permeability. Specifically, compounds 1d and 2a exhibited excellent 5-HT_1A agonist activities (1d, EC₅₀?=?0.36?±?0.08?nM; 2a, EC₅₀?=?0.58?±?0.14?nM) and 5-HT reuptake inhibitory activities (1d, IC₅₀?=?20.42?±?6.60?nM; 2a, IC₅₀?=?22.10?±?5.80?nM). In addition, they showed moderate ChE inhibitory activities (1d, AChE IC₅₀?=?1.72?±?0.217?μM, BuChE IC₅₀?=?0.34?±?0.03?μM; 2a, AChE IC₅₀?=?2.36?±?0.34?μM, BuChE IC₅₀?=?0.10?±?0.01?μM). Good multitarget activities with goodt blood-brain barrier permeability of 1d and 2a make them good lead compounds for the further study of depression with cognitive impairment.     

Rational design of bis-indolylmethane-oxadiazole hybrids as inhibitors of thymidine phosphorylase

Inhibition of Thymidine phosphorylase (TP) is continuously studied for the design and development of new drugs for the treatment of neoplastic diseases. As a part of our effort to identify TP inhibitors, we performed a structure-based virtual screening (SBVS) of our compound collection. Based on the insights gained from structures of virtual screening hits, a scaffold was designed using 1,3,4-oxadiazole as the basic structural feature and SAR studies were carried out for the optimization of this scaffold. Twenty-five novel bis-indole linked 1,3,4-oxadiazoles (7–31) were designed, synthesized and tested in vitro against E. coli TP (EcTP). Compound 7 emerged as potent TP inhibitor with an IC₅₀ value of 3.50?±?0.01?μM. Docking studies were carried out using GOLD software on thymidine phosphorylase from human (hTP) and E. coli (EcTP). Various hydrogen bonding, hydrophobic interactions, and π-π stacking were observed between designed molecules and the active site amino acid residues of the studied enzymes.     

Semisynthesis of ent-norstrobane diterpenoids as potential inhibitor for factor Xa

A semisynthesis of two ent-strobane diterpenoids strobols C (7) and D (14) was accomplished via a Wagnar-Meerwein rearrangement. Compounds 7, 14, and the intermediate products were evaluated for their inhibition on factor Xa (FXa). Among all the compounds screened for FXa inhibitory activity, three compounds 6, 7, and 9 showed significant inhibitory activities with IC₅₀ values of 1067?±?164, 81?±?11, 1023?±?89?nM, respectively. The inhibitory activity on FXa described in this study highlight the importance of structural modification based on natural products in the development of FXa inhibitors.     

Novel oxazolxanthone derivatives as a new type of α-glucosidase inhibitor: synthesis,activities, inhibitory modes and synergetic effect

Xanthone derivatives have shown good α-glucosidase inhibitory activity and have drawn increased attention as potential anti-diabetic compounds. In this study, a series of novel oxazolxanthones were designed, synthesized, and investigated as α-glucosidase inhibitors. Inhibition assays indicated that compounds 4–21 bearing oxazole rings exhibited up to 30-fold greater inhibitory activity compared to their corresponding parent compound 1b. Among them, compounds 5–21 (IC₅₀?=?6.3?±?0.4–38.5?±?4.6?μM) were more active than 1-deoxynojirimycin (IC₅₀?=?60.2?±?6.2?μM), a well-known α-glucosidase inhibitor. In addition, the kinetics of enzyme inhibition measured by using Lineweaver–Burk analysis shows that compound 4 is a competitive inhibitor, while compounds 15, 16 and 20 are non-competitive inhibitors. Molecular docking studies showed that compound 4 bound to the active site pocket of the enzyme while compounds 15, 16, and 20 did not. More interestingly, docking simulations reveal that some of the oxazolxanthone derivatives bind to different sites in the enzyme. This prediction was further confirmed by the synergetic inhibition experiment, and the combination of representative compounds 16 and 20 at the optimal ratio of 4:6 led to an IC₅₀ value of 1.9?±?0.7?μM, better than the IC₅₀ value of 7.1?±?0.9?μM for compound 16 and 8.6?±?0.9?μM for compound 20.     

Synthesis and biological evaluation of Ginsenoside Compound K analogues as a novel class of anti-asthmatic agents

Ginsenoside Compound K (CK) showed potent activity against IgE for the treatment of asthma. A series of CK analogues were then synthesized by straightforward procedures. The in vivo anti-IgE activity evaluations using the OVA-induced asthmatic mouse model revealed preliminary SARs of the CK analogues, which showed that the sugar type, modifications on A-ring and the C20 side chain of CK all affected much on the activities. Primary SARs optimization led to the discovery of compounds T1, T2, T3, T8 and T12, which displayed superior or comparable anti-asthmatic effects (IgE value?=?1237.11?±?106.28, 975.82?±?160.32, 1136.96?±?121.85, 1191.08?±?107.59 and 1258.27?±?148.70?ng/mL, respectively) in comparison with CK (1501.85?±?184.66?ng/mL). These potent compounds could serve as leads for further development.     

Lipid accumulation inhibitory activities of novel isoxazole-based chenodeoxycholic acids: Design,synthesis and preliminary mechanism study

In continuation of our drug discovery program on hyperlipidemia, a series of novel isoxazole-chenodeoxycholic acid hybrids were designed, synthesized and evaluated for their lipid-lowering effects. Preliminary screening of all the synthesized compounds was done by using a 3T3-L1 adipocyte model, in which the most active compound 16b could significantly reduce the lipid accumulation up to 30.5% at a nontoxic concentration 10?μM. Further mechanism studies revealed that 16b blocked lipid accumulation via activating FXR-SHP signaling pathway, efficiently down-regulated the expression of key lipogenesis regulator SREBP-1c.