Synthesis and biological evaluation of novel 2-arylamino-3-(arylsulfonyl)quinoxalines as PI3Kα inhibitors

A series of novel 2-arylamino-3-(arylsulfonyl)quinoxalines was synthesized through a newly developed approach. All synthesized target compounds were screened for their cytotoxicities against cancer cell lines including PC3, A549, HCT116, HL60 and KB. Representative compounds with favorable cytotoxicities were tested for their PI3Kα inhibitory activities. Among the synthesized target compounds, 17 (PI3Kα IC₅₀: 0.07 μM) displayed the most potent cellular activities (IC₅₀ values of 0.14 μM, 0.07 μM, 0.95 μM and 0.05 μM against PC3, A549, HCT116 and HL 60, respectively).     

HIF-1α inhibitors: synthesis and biological evaluation of novel moracin O and P analogues

The natural products moracins O and P exhibited potent in vitro inhibitory activity against hypoxia-inducible factor (HIF-1), which is a key mediator during adaptation of cancer cells to tumour hypoxia. Systematic variations of the structures of benzofuran type moracins were made and structure-activity relationship analysis showed the importance of the 2-arylbenzofuran ring and the (R)-configuration of the core scaffold. Further evaluation of the representative compound 5 showed its inhibitory effect on HIF-1α protein accumulation and target gene expression under hypoxia.     

Synthesis and evaluation of aroylthiourea derivatives of 4-β-amino-4'-O-demethyl-4-desoxypodophyllotoxin as novel topoisomerase II inhibitors

A novel series of aroylthiourea derivatives of 4-β-amino-4′-O-demethyl-4-desoxy- podophyllotoxin were synthesized. Their cytotoxicities against three cancer cell lines were investigated by MTT assay. The kDNA decatenation assay indicated that compounds 5a, 5f, 5h and 5l inhibited topoisomerase II-mediated kDNA decatenation. DNA flow cytometric analysis revealed that compound 5a induced cell cycle arrest at G2/M phase in HCT-116 cell line.     

Design, synthesis, and biological evaluation of novel γ-carboline ketones as anticancer agents

A series of novel γ-carboline ketones were designed, synthesized and evaluated for their cytotoxic activity in vitro against six human cancer cell lines (A549, SGC, HCT116, MCF-7, K562 and K562R). Biological evaluation revealed that almost all of the new compounds displayed moderate to potent cytotoxic activities against the tested cells. Among them, seven of the fourteen new compounds show more potent cytotoxic activities against K562R cell line than that of the positive control, taxol. Primary mechanism research on the most potent compound 6f indicated that it was a potent tubulin polymerization inhibitor, with IC₅₀ value of 4.3 μM, equivalent to that of CA-4, and arresting cell cycle in G₂/M phase.     

Synthesis and biological evaluation of 1,9-disubstituted β-carbolines as potent DNA intercalating and cytotoxic agents

A series of novel 1,9-disubstituted β-carbolines was designed, synthesized and evaluated as cytotoxic and DNA intercalating agents. Compounds 7b, 7c, 8b and 8c exhibited the most potent cytotoxic activities with IC₅₀ values of lower than 20 μM against ten human tumor cell lines. The results indicated that (1) the 3-chlorobenzyl and 3-phenylpropyl substituents in position-9 of β-carboline nucleus were the suitable pharmacophoric group giving rise to significant antitumor agents; (2) the length of the alkylamino side chain moiety affected their cytotoxic potencies, and three CH₂ units were more favorable. In addition, these compounds were found to exhibit remarkable DNA intercalating effects.     

Synthesis, biological evaluation of 9-N-substituted berberine derivatives as multi-functional agents of antioxidant, inhibitors of acetylcholinesterase, butyrylcholinesterase and amyloid-β aggregation

A series of 9-N-substituted berberine derivatives were synthesized and biologically evaluated as antioxidant and inhibitors of acetylcholinesterase (AChE), butyrylcholinesterase and amyloid-β aggregation. Most of these compounds exhibited very good antioxidant activities, inhibitive activities of AChE and amyloid-β aggregation. Among them, compound 8d, (o-methylphenethyl)amino linked at the 9-position of berberine, was found to be a good antioxidant (with 4.05 μM of Trolox equivalents), potent inhibitor of AChE (an IC₅₀ value of 0.027 μM), and high active inhibitor of amyloid-β aggregation (an IC₅₀ value of 2.73 μM).     

Synthesis and biophysical evaluation of arylhydrazono-1H-2-indolinones as β-amyloid aggregation inhibitors

A series of isatin-3-arylhydrazones were synthesized and evaluated in vitro as inhibitors of Aβ_1-40 aggregation using a thioflavin T fluorescence method. An exploration of the effects on Aβ_1-40 aggregation of a number of diverse substituents at phenylhydrazone group and 5,6- positions of the indolinone nucleus led us to single out some new anti-aggregating compounds with IC₅₀ values in the low micromolar range. The most active compounds carry methoxy- or hydroxy- substituents in the indolinone 5,6-positions and lipophilic groups such as iPr and Cl at 4′- and 3′-position, respectively, of the phenylhydrazone moiety. Two derivatives are noteworthy, namely 18 (IC₅₀ = 0.4 μM) and 42 (IC₅₀ = 1.1 μM). The in vitro effects of the highly active, water soluble, compound 42 on the temporal evolution of Aβ_1-40 fibrils formation were further investigated by circular dichroism spectroscopy, transmission electron microscopy and dynamic light scattering studies, which clearly showed that this compound delayed and lowered the amyloid fibril formation.     

Synthesis of 4β-triazole-podophyllotoxin derivatives by azide-alkyne cycloaddition and biological evaluation as potential antitumor agents

A representative synthetic process of derivatizing the natural product podophyllotoxin utilizing the copper-catalyzed azide-alkyne cycloaddition (CuAAC) is described including molecular design, reaction optimization and X-ray structure confirmation. Evaluation of cytotoxicity against human cancer cell lines (Hela, K562 and K562/A02) using MTT assay proves that these triazole derivatives have good antitumor activities. High activities toward the drug resistant K562/A02 cell line reveal promising future for these derivatives. The rarely prepared 1,5-disubstituted triazole isomers, which would be omitted by the "click chemistry", were found to have superior cytotoxicities to that of the 1,4-disubstituted isomers.     

Synthesis and biological evaluation of new 4β-anilino-4'-O-demethyl-4-desoxypodophyllotoxin derivatives as potential antitumor agents

A series of new 4β-anilino-4′-O-demethyl-4-desoxypodophyllotoxin derivatives were prepared and evaluated for their cytotoxicities against four human cancer cell lines including KB, KB/VCR, A549 and 95D. Most compounds showed better growth-inhibition activities against tested cell lines than that of etoposide (VP-16). Preliminary structure-activity relationships (SARs) were concluded and it indicated that the side chains substituted at 4β position of podophyllotoxin significantly influenced the cytotoxic activity, especially for the drug resistance profile. In vivo studies of compound 26c on highly metastatic human lung cancer xenograft in nude mice showed that it can significantly inhibit tumor growth with administrating by oral route.     

Synthesis and biological evaluation of (±)-3-(2-(2-fluorobenzyloxy) naphthalen-6-yl)-2-aminopropanoic acid derivatives as novel PTP1B inhibitors

A series of novel nonphosphonate-based pTyr mimetics comprised (±)-3-(2-(2-fluorobenzyloxy)naphthalen-6-yl)-2-aminopropanoic acid derivatives were identified as reversible and competitive PTP1B inhibitors via a structure-based design approach. Among the compounds studied, 12h was found to have the best in vitro inhibition activity against PTP1B (IC₅₀ = 1.25 ± 0.24 μM) and the best selectivity (3-fold) between PTP1B and TCPTP. These results should provide suitable druglike lead compounds for the design of inhibitors of PTP1B as well as other PTPs.     

Chemical synthesis and evaluation of 17α-alkylated derivatives of estradiol as inhibitors of steroid sulfatase

Steroid sulfatase (STS) controls the levels of 3-hydroxysteroids available from circulating steroid sulfates in several normal and malignant tissues. This and the known involvement of active estrogens and androgens in diseases such as breast and prostate cancers thus make STS an interesting therapeutic target. Here we describe the chemical synthesis and characterization of an extended series of 17α-derivatives of estradiol (E2) using different strategies. A variant of the samarium-Barbier reaction with stoichiometric samarium metal and catalytic Kagan reagent formation was used for introducing low reactive benzyl substrates in position 17 of estrone (E1) whereas heterocyclic substrates were metalated and reacted with either the carbonyl or the 17-oxirane of E1. In vitro evaluation of the inhibitory potency of the new compounds against STS identified new inhibitors and allowed a more complete structure-activity relationship study of this family of 17α-derivatives of E2.     

Unprecedented synthesis, in vitro and in vivo anti-cancer evaluation of novel triazolonaphthalimide derivatives

An efficient synthesis method for fusing triazole ring onto the naphthalimide core was described. The anti-cancer activities of the generated triazolonaphthalimide derivatives were evaluated with five cancer cell lines. The compounds generally displayed higher potency than amonafide. 4d,4e carrying two amino side chains showed the strongest cytotoxicities. N-oxide 5, a prodrug of 4a, was designed and synthesized. The agent was expected to be activated under the hypoxic condition in tumor tissue. Compared with 4a, 5 manifested much lower cytotoxicity both in cancer cell lines and human normal cells in the in?vitro assays. However, N-oxide 5 performed potent anti-cancer activity in?vivo using S-180 sarcoma bearing mice. All the results suggested that 5 was a promising anti-cancer agent.     

Synthesis, characterization and biological evaluation of some 16β-azolyl-3β-amino-5α-androstane derivatives as potential anticancer agents

A series of new 16β-azolyl-3β-amino-5α-androstane derivatives were synthesized and characterized. The new compounds were screened for their anticancer activity against the human cancer cell lines SW480, A549, HepG2, HeLa and SiHa in vitro using the MTT assay. The results of the in vitro study showed that a number of compounds have shown IC₅₀ values lower than 20 μM against the five cancer cell lines.     

Synthesis of novel α-santonin derivatives as potential cytotoxic agents

Ten novel α-santonin derivatives have been synthesized as cytotoxic agents. The in vitro antitumor activity of these compounds has been evaluated against cancer cells lines. Structure-activity relationships indicate that α-methylene-γ-lactone and endoperoxide functionalities play important roles in conferring cytotoxicity. The compounds 2-4, possessing the α-methylene-γ-lactone group showed IC50 values between 5.70 and 16.40 μM. Mixture of isomers 5 and 6, with the α-methylene-γ-lactone and endoperoxide functionalities, displayed the greatest activity, with IC50 values between 1.45 and 4.35 μM. The biological assays conducted with normal cells revealed that the compounds 2, 5 and 6 are selective against cancer cells lines tested. Bioactive lactones described herein and in our previous report did not cause disruption of the cell membrane in mouse erythrocytes.     

Synthesis, biological evaluation, and molecular docking study of 3-(3'-heteroatom substituted-2'-hydroxy-1'-propyloxy) xanthone analogues as novel topoisomerase IIα catalytic inhibitor

Epoxide ring-opened xanthone derivatives were synthesized and tested for their topoisomerase inhibitory activity and cytotoxicity. Most of the compounds showed topo IIα specific inhibitory activity. To clarify the mechanism of action of these compounds, the most potent compound (compound 14) of the synthesized analogues was further studied by testing its ATPase inhibitory activity and through molecular docking experiments. The results showed that the topo IIα inhibitory activity of compound 14 was inversely proportional to ATP concentration. In the ATPase inhibitory test, ATP hydrolysis was reduced less efficiently by compound 14 (28.5±4.6%) than novobiocin (60.4±8.1%). Molecular docking study revealed compound 14 to have a stable binding pattern to the ATP-binding domain of human topo II.     

Synthesis and structure-activity relationship of 3-O-acylated (-)-epigallocatechins as 5α-reductase inhibitors

A series of 3-O-acylated (-)-epigallocatechins were synthesized and their inhibition of steroid 5α-reductase was studied. They were prepared from the reaction of EGCG with tert-butyldimethylsilyl chloride followed by reductive cleavage of the ester bond. The resultant (-)-epigallocatechins penta-O-tert-butyldimethylsilyl ether was esterified with different fatty acids then desilylated to provide the corresponding products. The activity of 3-O-acylated (-)-epigallocatechins increased with the increasing carbon numbers of the fatty acid moiety, reaching maximum for 16 carbon atoms (compound 4h) with an IC50 of 0.53 μM, which was ～12-fold more potent than EGCG (IC50=6.29 μM). Introduction of monounsaturated fatty acid provided the most potent compound 6 (IC50=0.48 μM), which showed moderate anti-tumor activity in vivo.     

Synthesis and antiviral evaluation of α-L-2'-deoxythreofuranosyl nucleosides

The synthesis of a series of α-l-2′-deoxythreofuranosyl nucleosides featuring the nucleobases A, T, C and U is described in seven steps from 1,2-O-isopropyledene-α-l-threose, involving a Vorbrüggen coupling and a Barton-McCombie deoxygenation protocol as the key steps. All analogues, including a phosphoramidate nucleoside phosphate prodrug of the T analogue, were evaluated against a broad panel of different viruses but found inactive, while also lacking notable cellular toxicity. The thymidine analogue showed inhibition to mitochondrial thymidine kinase-2 (TK-2), herpes simplex virus type 1 (HSV-1) TK, varicella-zoster virus (VZV) TK and Mycobacterium tuberculosis thymidylate kinase.     

Synthesis and in vitro evaluation of xylene linked carbamoyl bis-pyridinium monooximes as reactivators of organophosphorus (OP) inhibited electric eel acetylcholinesterase (AChE)

A series of carbamoyl bis-pyridinium monooximes linked with xylene linker were synthesized and their in-vitro reactivation potential was evaluated against acetylcholinesterase (AChE) inhibited by organophosphorus inhibitors (OP) such as sarin, DFP and VX and the data were compared with reactivation obtained with 2-PAM and obidoxime. Amongst the synthesized compounds, 3-carbamoyl-2′hydroxyiminomethyl-1-1′-(1,4-phenylenedimethyl)-bispyridinium dibromide (5e) 3-carbamoyl-2′hydroxyiminomethy l-1-1′-(1,3-phenylenedimethyl)-bispyridinium dibromide (5k) and 4-carbamoyl-2′hydroxyiminomethyl-1-1′-(1,3-phenylenedimethyl)-bispyridinium dibromide (5l) were found to be the most potent reactivators for electric eel AChE inhibited by sarin and DFP. However, in case of VX inhibited AChE, none of the synthesized oximes could surpass the reactivation potential of 2-PAM and obidoxime. The pKa values of all the oximes were determined and correlated with their observed reactivation potential.     

Synthesis and antibacterial evaluation of novel clarithromycin derivatives with C-4″ elongated arylalkyl groups against macrolide-resistant strains

Novel clarithromycin derivatives with C-4″ elongated arylalkyl groups were designed, synthesized and evaluated to probe the effect of different lengths of their C-4″ side chains on the activity against resistant bacterial strains. These derivatives had excellent activity against erythromycin-susceptible Streptococcus pneumoniae, Streptococcus aureus or Streptococcus pyogenes and some of them exhibited greatly improved activity against erythromycin-resistant strains. Compounds 18 and 16, which had the C-4″ elongated arylalkyl groups with eight atoms from the 4″-oxygen atom to the terminal benzene ring, were the most effective against S. pneumoniae expressing the erm gene and the erm and mef genes. In contrast, the most potent compounds 3, 5, 9, 17 and 18 against S. pneumoniae expressing the mef gene had C-4″ elongated arylalkyl groups with three to eight atoms between the 4″-oxygen atom and the terminal aromatic ring.     

Optically active 1,3,4,4-tetrasubstituted β-lactams: synthesis and evaluation as tumor cell growth inhibitors

The in vitro cytotoxicity assays of several enantiopure (3S,4S)- and (3R,4R)-1,3,4,4-tetrasubstituted β-lactams derived from amino acids have shown that the (3S,4S)-4-benzyl-1-p-methoxybenzyl-3-methyl-4-methoxycarbonyl derivative 2a, obtained from Phe, displays significant activity, which is comparable to that of the anticancer drug Doxorubicin against HT29 cell lines. Modifications at positions 1 and 4 of the β-lactam ring led to identify the Tyr(2,6-ClBz) analogu 26d with similar activity data to those of 2a. The synthesis and SAR of all these tetrasubstituted β-lactams are reported here.