Design, synthesis and biological evaluation of novel 2-methylpyrimidine-4-ylamine derivatives as inhibitors of Escherichia coli pyruvate dehydrogenase complex E1

As potential inhibitors of Escherichia coli pyruvate dehydrogenase complex E1 (PDHc E1), a series of novel 2-methylpyrimidine-4-ylamine derivatives were designed based on the structure of the active site of PDHc E1 and synthesized using 'click chemistry'. Their inhibitory activity in vitro against PDHc E1 and fungicidal activity were examined. Some of these compounds such as 3g, 3l, 3n, 3o, and 5b demonstrated to be effective inhibitors of PDHc E1 from E. coli and exhibited antifungal activity. SAR analysis indicated that both, the inhibitory potency against E. coli PDHc E1 and the antifungal activity of title compounds, could be increased greatly by optimizing substituent groups in the compounds. The structures of substituent group in 5-position on the 1,2,3-triazole and 4-position on the benzene ring in title compounds were found to play a pivotal role in both above-mentioned biological activities. Amongst all the compounds, compound 5b with iodine in the 5-position of 1,2,3-triazole and with nitryl group in the 4-position of benzene ring acted as the best inhibitor against PDHc E1 from E. coli. It was also found to be the most effective compound with higher antifungal activity against Rhizoctonia solani and Botrytis cinerea at the dosage of 100 μg mL(-1). Therefore, in this study, compound 5b was used as a lead compound for further optimization.     

Structure and activity relationship of 2-(substituted benzoyl)-hydroxyindoles as novel CaMKII inhibitors

A series of novel 2-substituted-5-hydroxyindoles were synthesized and evaluated for their inhibitory activity against CaMKII. Structure and activity relationship results indicated that potent inhibitory activity could be achieved by modification at the para-position of the phenyl ring of the high throughput screening hit compound 2. Among the prepared compounds, we identified 14 as a novel CaMKII inhibitor with an activity stronger than that of KN-93, a known CaMKII inhibitor.     

Benzoxazole derivatives as new VEGFR-2 inhibitors and apoptosis inducers: design,synthesis, in silico studies,and antiproliferative evaluation

In this study, a set of novel benzoxazole derivatives were designed, synthesised, and biologically evaluated as potential VEGFR-2 inhibitors. Five compounds (12d, 12f, 12i, 12l, and 13a) displayed high growth inhibitory activities against HepG2 and MCF-7 cell lines and were further investigated for their VEGFR-2 inhibitory activities. The most potent anti-proliferative member 12 l (IC₅₀ = 10.50 μM and 15.21 μM against HepG2 and MCF-7, respectively) had the most promising VEGFR-2 inhibitory activity (IC₅₀ = 97.38 nM). A further biological evaluation revealed that compound 12l could arrest the HepG2 cell growth mainly at the Pre-G1 and G1 phases. Furthermore, compound 12l could induce apoptosis in HepG2 cells by 35.13%. likely, compound 12l exhibited a significant elevation in caspase-3 level (2.98-fold) and BAX (3.40-fold), and a significant reduction in Bcl-2 level (2.12-fold). Finally, docking studies indicated that 12l exhibited interactions with the key amino acids in a similar way to sorafenib.     

Synthesis and biological evaluation of novel T-type Ca2+ channel blockers

A small molecule library of piperazinylalkylisoxazole derivatives containing about 600 compounds was designed, synthesized and evaluated for blocking effects on T-type Ca(2+) channel. Several ligands were identified to possess high inhibitory activity against the T-type Ca(2+) channel. The compound 21 with trifluoromethyl substituents at C(3)-position of phenyl group (R(1)) and C(2)-position of phenyl group (R(2)) showed the highest inhibitory activity with IC(50) value of 1.02 microM, which is comparable to that of mibefradil.     

Synthesis and bioactivity of 3,5-dimethylpyrazole derivatives as potential PDE4 inhibitors

A series of 3,5-dimethylpyrazole derivatives containing 5-phenyl-2-furan moiety were designed and synthesized as phosphodiesterase type 4 (PDE4) inhibitors. Bioassay results showed that the title compounds exhibited considerable inhibitory activity against PDE4B and blockade of LPS-induced TNFα release. Among the designed compounds, compound If showed the best inhibitory activity against PDE4B with the IC₅₀ value of 1.7?μM, which also showed good in vivo activity in animal models of asthma/COPD and sepsis induced by LPS. The primary structure–activity relationship (SAR) study and docking results suggested that introduction of the substituent groups to the phenyl ring at the para-position, especially methoxy group, was helpful to enhance inhibitory activity against PDE4B.     

Synthesis and Antiproliferative Activity of New Thiosemicarboxamide Derivatives

To discover new anticancer agents, two series of thiosemicarboxamide derivatives were synthesized and evaluated for their antiproliferative activity against human cancer cells in vitro. Most target compounds (especially 3f , 3g , and 3h ) exhibit potent antiproliferative activity against HeLa cells. Importantly, compound 3h , bearing a 4-methylphenyl substituent at N position of thiourea moiety, has significant and broad-spectrum inhibitory activities against cancer cells (HepG2, HeLa, MDA-MB231, A875, and H460 cells) with low IC₅₀ values (<5.0 μM) and shows low toxicity to normal LO2 and MRC-5 cells. Further studies show that compound 3h exerts high inhibitory activity in cancer cells by inducing the G2/M-phase arrest of cancer cells. Collectively, this study presents compound 3h as a new entity for the development of cell cycle arrest inducers for the treatment of cancer.     

Synthesis,Anti-Oomycete and Anti-fungal Activities of Novel Cinchona Alkaloid Derivatives Containing Sulfonate Moiety

Using cinchona alkaloid as the lead compound, twenty-four cinchona alkaloid sulfonate derivatives ( 1 a – l , 2 a – c , 3 a – c , 4 a – c , and 5 a – c ) were designed and prepared by modifying their C9 position, and structurally confirmed by ¹H-NMR, ¹³C-NMR, HR-MS and melting points. Moreover, the stereochemical configurations of compounds 1 f and 1 l were unambiguously confirmed by single-crystal X-ray diffraction. Furthermore, we determined the anti-oomycete and anti-fungal activities of these target compounds against Phytophthora capsici and Fusarium graminearum in vitro. The results showed that two compounds 4 b and 4 c exhibited prominent anti-oomycete activity, and the median effective concentration (EC₅₀) values of 4 b and 4 c against P. capsici were 22.55 and 16.32 mg/L, respectively. This study suggested that when the C9 position of cinchona alkaloid sulfonate derivatives is in the S configuration and the 6′-position methoxy group is not present, the anti-oomycete activity is superior. In addition, five compounds 1 e , 1 f , 1 k , 3 c and 4 c displayed significant anti-fungal activity, with EC₅₀ values of 43.64, 45.07, 80.18, 48.58 and 41.88 mg/L against F. graminearum, respectively. This result indicates that only when a specific substituent is introduced into the structural framework of the target compound, the corresponding compound exhibits significant inhibitory activity against fungi.     

Synthesis, topoisomerase I inhibition and structure-activity relationship study of 2,4,6-trisubstituted pyridine derivatives

For the development of new anticancer agents, phenyl, 2-pyridyl, 2-furyl, 2-thienyl, 2-furylvinyl and 2-thienylvinyl substituted derivatives on 2,4,6-position in pyridine moiety were prepared and evaluated for their topoisomerase I inhibitory activity. Among the thirteen prepared compounds, four compounds exhibited strong topoisomerase I inhibitory activity. A structure-activity relationship study indicated that the 2-thienyl-4-furylpyridine skeleton was important for topoisomerase I inhibitory activity.     

Combination of 4-anilinoquinazoline,arylurea and tertiary amine moiety to discover novel anticancer agents

In present study, 4-anilinoquinazolines scaffold, arylurea and tertiary amine moiety were combined to design, synthesize gefitinib analogs and discover novel anticancer agents. A series of 4-anilinoquinazoline derivatives (1, 2, 3 and 4) bearing arylurea and tertiary amine moiety at its 6-position were synthesized. Their antiproliferative activities in vitro were evaluated via MTT assay against A431 cell and A549 cell. The SAR of the title compounds was discussed. The compounds 2d, 2i and 2j with potent antiproliferative activities were evaluated their inhibitory activity against EGFR-TK. Compound 2j displayed potent inhibitory activity against EGFR-TK. In addition, compound 2j, at 50 mg/kg, can completely inhibit cancer growth in established nude mouse A549 xenograft model in vivo. These results suggest that the 4-anilinoquinazoline derivatives bearing diarylurea and tertiary amino moiety at its 6-position can serve as anticancer agents and EGFR inhibitors.     

Correlation of indoleamine-2,3-dioxigenase 1 inhibitory activity of 4,6-disubstituted indazole derivatives and their heme binding affinity

Indoleamine 2,3-dioxygenase 1 (IDO1) is a heme-containing enzyme that acts on the first and rate-limiting step of the tryptophan/kynurenine pathway. Since the pathway is one of the means of cancer immune evasion, IDO1 inhibitors have drawn interest as potential therapeutics for cancers. We found a 4,6-disubstituted indazole 1 as a hit compound that showed both IDO1 inhibitory activity and binding affinity for IDO1 heme. Structural modification of 1 yielded compound 6, whose relatively large substituent at the 4-position and proper size substituent at the 6-position were found to be important for the enhancement of IDO1 inhibitory activity and heme affinity. A series of compounds synthesized in this work were evaluated by in silico docking simulations and by in vitro experiments using a C129Y mutant of the pocket-A of IDO1. Our results revealed that proper substituents at the 6- and 4-positions of the compounds interact with pockets A and B, respectively, and that, in particular, a good fit in pocket-A is important for the compounds’ biological activities. Absorption spectral analysis of these compounds showed that they strongly bound to the ferrous heme rather than its ferric heme. Furthermore, we observed that the heme affinities of these compounds strongly correlate with their IDO1 inhibitory activities.     

Discovery of a novel class of 2-aminopyrimidines as CDK1 and CDK2 inhibitors

A series of new 2-(2-aminopyrimidin-4-yl)phenol derivatives were synthesized as potential antitumor compounds. Substitution with pyrrolidine-3,4-diol at the 4-position of phenol provided potent inhibitory activity against CDK1 and CDK2. X-ray crystal structural studies were performed to account for the effect of the substituent on both the enzymatic and cell growth inhibitory activities.     

Evaluation of dihydropyrimidin-(2H)-one analogues and rhodanine derivatives as tyrosinase inhibitors

A series of dihydropyrimidin-(2H)-one analogues and rhodanine derivatives were synthesized and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were evaluated. The results showed that some of the synthesized compounds exhibited significant inhibitory activities. Especially, compound 15 bearing a hydroxyethoxyl group at position-4 of phenyl ring exhibited most potent tyrosinase inhibitory activity with IC₅₀ value of 0.56 mM. The inhibition mechanism analysis of compound 15 demonstrated that the inhibitory effect of the compound on the tyrosinase was irreversible. These results suggested that such compounds might be served as lead compounds for further designing new potential tyrosinase inhibitors.     

Benzo[c][1,2,5]thiadiazole derivatives: A new class of potent Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) inhibitors

The Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) is an oncogenic phosphatase linked to various kinds of cancers. Consequently, SHP2 has emerged as a promising target for novel anti-cancer agents. Using scaffold-hopping strategy, a series of benzo[c][1,2,5]thiadiazole derivatives was designed from PTP1B inhibitors with 1H-2,3-Dihydroperimidine motif, synthesized and evaluated their biological activities against PTP1B and SHP2. Among them, the representative compound 11g displayed SHP2 inhibitory activity with IC₅₀ of 2.11?±?0.99?μM, exhibited 2.02-fold and 25-fold selectivity for SHP2 over SHP1 and PTP1B respectively and had no visible activity against TCPTP. These preliminary results could provide a possible opportunity for the development of novel SHP2 inhibitors with optimal potency and improved pharmacological properties.     

Selective activity against Mycobacterium tuberculosis of new quinoxaline 1,4-di-N-oxides

New series of 3-phenylquinoxaline 1,4-di-N-oxide with selective activity against Mycobacterium tuberculosis have been prepared and evaluated. Thirty-four of the seventy tested compounds showed an MIC value less than 0.2 μg/mL, a value on the order of the MIC of rifampicin. Furthermore, 45% of the evaluated derivatives showed a good in vitro activity/toxicity ratio. The most active and selective compounds carry a fluorine atom in the quinoxaline 7-position or in the phenyl substituent para-position. In conclusion, the potency, low cytotoxicity and selectivity of these compounds make them valid lead compounds for synthesizing new analogues, particularly compound 7-methyl-3-(4’-fluoro)phenylquinoxaline-2-carbonitrile 1,4-di-N-oxide (MIC <0.2 μg/mL and SI >500).     

Novel N-benzylpyridinium moiety linked to arylisoxazole derivatives as selective butyrylcholinesterase inhibitors: Synthesis,biological evaluation,and docking study

A novel series of N-benzylpyridinium moiety linked to arylisoxazole ring were designed, synthesized, and evaluated for their in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Synthesized compounds were classified into two series of 5a-i and 5j-q considering the position of positively charged nitrogen of pyridinium moiety (3- or 4- position, respectively) connected to isoxazole carboxamide group. Among the synthesized compounds, compound 5n from the second series of compounds possessing 2,4-dichloroaryl group connected to isoxazole ring was found to be the most potent AChE inhibitor (IC₅₀ = 5.96 µM) and compound 5j also from the same series of compounds containing phenyl group connected to isoxazole ring demonstrated the most promising inhibitory activity against BChE (IC₅₀ = 0.32 µM). Also, kinetic study demonstrated competitive inhibition mode for both AChE and BChE inhibitory activity. Docking study was also performed for those compounds and desired interactions with those active site amino acid residues were confirmed through hydrogen bonding as well as π-π and π-anion interactions. In addition, the most potent compounds were tested against BACE1 and their neuroprotectivity on Aβ-treated neurotoxicity in PC12 cells which depicted negligible activity. It should be noted that most of the synthesized compounds from both categories 5a-i and 5j-q showed a significant selectivity toward BChE. However, series 5j-q were more active toward AChE than series 5a-i.     

A new series of N2-substituted-5-(p-toluenesulfonylamino)phthalimide analogues as α-glucosidase inhibitors

Several members of a new family of non-sugar-type α-glycosidase inhibitors, bearing a 5-(p-toluenesulfonylamino)phthalimide moiety and various substituent at the N2 position, were synthesized and their activities were investigated. The newly synthesized compounds displayed different inhibition profile towards yeast α-glycosidase and rat intestinal α-glycosidase. Almost all the compounds had strong inhibitory activities against yeast α-glycosidase. Regarding rat intestinal α-glycosidase, only analogs with N2-aromatic substituents displayed varying degrees of inhibitory activities on rat intestinal maltase and lactase and nearly all compounds showed no inhibition against rat intestinal α-amylase. Structure–activity relationship studies indicated that 5-(p-toluenesulfonylamino)phthalimide moiety is a favorable scaffold to exert the α-glucosidase inhibitory activity and substituents at the N2 position have considerable influence on the efficacy of the inhibition activities.     

Synthesis and biological evaluation of heterocyclic bis-aryl amides as novel Src homology 2 domain containing protein tyrosine phosphatase-2 (SHP2) inhibitors

The Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) is a convergent node for oncogenic cell-signaling cascades including the PD-L1/PD-1 pathway. Consequently, SHP2 has emerged as a compelling target for novel anti-cancer agents. Replacing one of phenyl ring in PTP1B inhibitor 1 with heterocyclic ring led to a series of heterocyclic bis-aryl amide derivatives. The representative compound 7b displayed SHP2 inhibitory activity with IC₅₀ of 2.63 ± 0.08 μM, exhibited about 4-fold selectivity for SHP2 over TCPTP and had no detectable activity against SHP1 and PTP1B. These preliminary results could provide a possible opportunity for the development of novel SHP2 inhibitors with optimal potency and improved pharmacological properties.     

Synthesis and biological evaluation of N-aryl salicylamides with a hydroxamic acid moiety at 5-position as novel HDAC-EGFR dual inhibitors

A novel series of N-aryl salicylamides with a hydroxamic acid moiety at 5-position were synthesized efficiently. Their activities against EGFR kinase and HDACs were evaluated. All compounds displayed inhibitory activity against EGFR and HDACs. The antiproliferative activities of synthesized compounds were evaluated by MTT method against human cancer cell lines A431, A549 and HL-60. Compound 1o showed the most potent inhibitory activity against A431 and A549. Compounds 1k and 1n exhibited higher potency against HL-60 than gefitinib and SAHA. N-Aryl salicylamides with a hydroxamic acid moiety at 5-position is another new HDAC-EGFR dual inhibitors.     

Naphthofuroquinone derivatives: inhibition of receptor tyrosine kinases

A series of dinaphtho[1,2-b;2',3'-d]furan-7,12-dione derivatives were synthesized and evaluated for inhibitory activities against receptor tyrosine kinases. The naphthofuroquinone compounds with dialkylaminoethoxy group at C(5)-position (7, 8, 10, and 11) manifested strong inhibitory activities against epidermal growth factor receptor and vascular endothelial growth factor receptor. Docking study of 11 with EGFR was also performed.     

Four-membered heterocycles-containing 4-anilino-quinazoline derivatives as epidermal growth factor receptor (EGFR) kinase inhibitors

We report herein the design and synthesis of novel azaspirocycle or azetidine substituted 4-anilinoquinazoline derivatives. The EGFR inhibitory activities and in vitro antitumor potency of these newly synthesized compounds against two lung cancer cell lines HCC827 and A549 were evaluated. Most of the target compounds possess good inhibitory potency. In particular, compounds 21g with 2-oxa-6-azaspiro[3.4]octane substituent was found to possess higher EGFR inhibitory activities and similar antitumor potency comparing to the lead compound gefitinib with improved water solubility.