Enantiomeric neolignans from Picrasma quassioides exhibit distinctive cytotoxicity on hepatic carcinoma cells through ROS generation and apoptosis induction

Three pairs of enantiomeric neolignans 1a/1b–3a/3b were isolated from the stems of Picrasma quassioides, and separated successfully by chiral-phase HPLC. Their structures were established by comprehensive spectroscopic analyses as well as ECD spectroscopy. The in vitro cytotoxicity of the isolates was evaluated against human hepatocellular carcinoma HepG2 and Hep3B cells. Among them, 1 and its enantiomers 1a/1b, 3 and 3a/3b displayed similar cytotoxicity in pair-wise comparison against HepG2 and Hep3B cells, and the similar effects of 2 and 2a/2b were found in Hep3B cells. Interestingly, 2a and 2b had different cytotoxic activities on HepG2 cells with IC₅₀ values of 35.6?μM and 104.4?μM, respectively. In addition, 2 exerted middle cytotoxicity against HepG2 cells with an IC₅₀ value of 78.6?μM. The different cytotoxicity between enantiomers 2a and 2b attracted our interest. To investigate the underlying mechanisms responsible for the distinct cytotoxicity, we further assessed the effects of 2a and 2b on cell cycle distribution, cell apoptosis and reactive oxygen species (ROS) generation. The results indicated that 2a had more significant effect than 2b on apoptosis induction and ROS generation, but both had no obvious effect on cell cycle of HepG2 cells. It is concluded that the different configurations of 2a/2b determined the enantioselective cytotoxicity on HepG2 cells through apoptosis induction and ROS generation.     

Dihydronaphthalenones from the endophytic fungus Botryosphaeria sp. BCC 8200

Five new dihydronaphthalenones (1, 2a/2b, 3a/3b), four of which were isolated as two inseparable mixtures of isomers, together with two known compounds, 7-hydroxy-2-(2-hydroxypropyl)-5-methylchromone (4) and siderin (5), were identified as secondary metabolites of the endophytic fungus Botryosphaeria sp. BCC 8200. The structures were elucidated by interpretation of NMR spectroscopic and mass spectrometry data. Compounds 2a/2b, 3a/3b, and 5 exhibited weak cytotoxic activities against cancer cell lines.     

Synthesis and biological evaluation of pyrano[4,3-b][1]benzopyranone derivatives as monoamine oxidase and cholinesterase inhibitors

A series of eighteen pyrano[4,3-b][1]benzopyranone derivatives (1a-9b) were synthesized, and structure-activity relationships of their monoamine oxidase (MAO) A and B, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory activities were evaluated. Most of the synthesized compounds exhibited weak inhibitory activity toward MAO-A, whereas compounds 2a, 2b, 4a, 4b, 5a, 5b, 6a, 6b, 8a and 8b showed potent inhibitory activities toward MAO-B. Intriguingly, compounds 5a, 5b, and 8a showed inhibitory activities comparable to pargylin, used as a positive control for MAO-B. Substitution of butoxy at the C3 position or of chlorine at the C8 position of pyrano[4,3-b][1]benzopyranone increased the inhibitory activity of the compound toward MAO-B. The results of a molecular docking study supported this structural effect. Most of the compounds exhibited no or slight inhibitory activity toward AChE and BChE, with exo type compounds bearing a butoxy group, such as compounds 2b, 5b and 8b, showing weak but distinct inhibitory activities toward BChE. This report is the first to identify pyrano[4,3-b][1]benzopyranone derivatives as potent and selective MAO-B inhibitors. 3-Butoxy-8-chloro-pyrano[4,3-b][1]benzopyranone (5b) may be useful as a lead compound for the development of MAO-B inhibitors.     

Synthesis and biological evaluation of nitrogen-containing chalcones as possible anti-inflammatory and antioxidant agents

A novel series of nitrogen-containing chalcones were synthesized by Mannich reaction and were screened for anti-inflammatory related activities such as inhibition of cyclooxygenase-2 (COX-2), trypsin and β-glucuronidase. The antioxidant potential was demonstrated using 1,1-diphenyl-2-picryl hydrazine (DPPH) radical scavenging activity. The results of the above studies shows that the compounds synthesized were found to be effective inhibitors of above pro-inflammatory enzymes, and were found to be possess moderate radical scavenging potential. Overall, the results of the studies reveal that the chalcones with N-methyl piperazine methyl and piperidine methyl substitution (4c, 3b, 4d, 6b) seems to be important for inhibition of β-glucuronidase. Whereas the chalcones with piperidine methyl substitution (8b, 7b, 7c, 6c, 4b, 3c, 3b) were observed as effective inhibitors of COX-2, while the same compounds were found to be less reactive against COX-1 as compared to COX-2.     

Stereoisomeric guaiacylglycerol-β-coniferyl aldehyde ether induces distinctive apoptosis by downregulation of MEK/ERK pathway in hepatocellular carcinoma cells

Two 8-O-4′-type neolignan epimers erythro-guaiacylglycerol-β-coniferyl aldehyde ether (1) and threo-guaiacylglycerol-β-coniferyl aldehyde ether (2) were isolated from the stems of Picrasma quassioides. Further chiral separation gave two pairs of enantiomers 1a/1b and 2a/2b. The cytotoxicity assay against hepatocellular carcinoma Hep3B and HepG2 cells was evaluated by MTT assay. The results showed that 1b (IC₅₀ = 45.56 μM) and 2b (IC₅₀ = 39.02 μM) had more cytotoxic effect than its enantiomers 1a (IC₅₀ = 82.66 μM) and 2a (IC₅₀ = 67.97 μM) in Hep3B cells, respectively. Moreover, 1b and 2b could induce more apoptotic cells as well as higher reactive oxygen species (ROS) generation than 1a and 2a at 50 μM. In addition, a further study on the phosphoinositide 3-kinase (PI3K)/AKT and mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathways was investigated. The results revealed that all compounds had no significant effect on PI3K/AKT pathway, however, 1b and 2b attenuated the relative levels of p-MEK and p-ERK when compared with 1a and 2a. Taken together, the absolute configurations of guaiacylglycerol-β-coniferyl aldehyde ether had an impact on the inhibitory effect on Hep3B cells. The inactivation of MEK/ERK signaling pathway might contribute to apoptosis induction and ROS generation in 1b- and 2b-treated cells.     

Design,synthesis, and biological evaluation of some novel 4-aminoquinazolines as Pan-PI3K inhibitors

A series of 4-aminoquinazolines derivatives containing hydrophilic group were designed and identified as potent Pan-PI3K inhibitors in this study. The results of antiproliferative assays in vitro showed that this series of compounds had strong inhibition of tumor growth, especially compound 7b for MCF-7 cells but weak inhibition to normal cells. PI3K kinase assay showed that 7b had high activity for three PI3K isoforms with the IC₅₀ values of picomole. The western blot assay indicated that 7b could decrease the phospho-Akt (S473) in a dose-dependent manner. Further experiments showed that 7b could induce apoptosis in MCF-7 cells. Four key hydrogen bonding interactions were found in the docking of 7b with PI3K kinase. All these results suggested that 7b is a potent PI3K inhibitor and could be considered as a potential candidate for the development of anticancer agents.     

Design,synthesis and biological evaluation of novel 1,3,4-trisubstituted pyrazole derivatives as potential chemotherapeutic agents for hepatocellular carcinoma

A series of novel 1,3,4-trisubstituted pyrazole derivatives were synthesized and evaluated for their cytotoxic activity against three different cancer cell lines namely HCT116, UO-31 and HepG2. Compounds 3b, 3d, 7b and 9 showed excellent anticancer activity against all the tested cancer cell lines and had better cytotoxic activities than the reference drug, Sorafenib. Therefore, these compounds were chosen to be further evaluated in a panel of HCC cell lines. Among them, 3b and 7b were the most active compounds against HCC cells used here. Further studies on the mechanism demonstrated that 3b and 7b induced apoptosis in addition to induction of cell cycle arrest at G2/M phase in HepG2 and Huh7 cells. Consistent with these results, caspase-3 assay was done and the results revealed that the pro-apoptotic activity of the target compounds could be due to the stimulation of caspases-3. In addition, CDK1 inhibition assay was done and it was found that compounds 3b and 7b inhibited CDK1 activities with IC₅₀ values of 2.38 and 1.52 µM, respectively. Finally, pyrazole derivatives 3b and 7b showed potent bioactivities, indicating that these compounds could be potent anticancer drugs in the future.     

Design,synthesis and in vitro apoptotic mechanism of novel pyrrolopyrimidine derivatives

In this work we described the synthesis and evaluation of cytotoxic and apoptotic activity of novel pyrrolopyrimidine derivatives against A549, PC3 and MCF-7 cells. Among the synthesized compounds, 6b, 8a, 9a and 7a, 8b displayed the significant cytotoxic activities against A549 and PC3 cells with IC₅₀ value of 0.35, 1.48, 1.56 and 1.04, 1.89 µM, respectively. It was found that A549 cells were more sensitive to synthesized compounds than PC3 and MCF-7 cells. In order to evaluate the mechanism of cytotoxic activity in A549, compounds 6b, 8a and 9a were selected for further studies. Annexin V binding assay and western blot analysis results revealed that 6b, 8a and 9a induced apoptosis in A549 cells by intrinsic apoptotic pathway through the activation pro-apoptotic proteins such as Bim, Bax, Bak, Puma and deactivation of anti-apoptotic proteins including Bcl-2, Mcl-1 and Bcl-XL accompanied by the activation of caspase-3, caspase-9 and cleavage of PARP. Also, compounds 6b, 8a and 9a triggered apoptosis in HCT116 wt cells via activation of caspase-3 and caspase-9, but not in HCT116 Bax/Bak KO cells, indicating resistance to 6b, 8a and 9a treatment.     

Synthesis and cytokinin activity of (R)-(+)- and (S)-(−)-dihydrozeatins and their ribosides

(R)-(+)- and (S)-(?)-dihydrozeatins [(R)-(+)- and (S)-(?)-6-(4-hydroxy-3-methylbutylamino)purines, 1a and 1b] and their ribosides {(?)-6-[(R)-4-hydroxy-3-methylbutylamino]- and (?)-6-[(S)-4-hydroxy-3-methyl-butylamino]-9-β-D-ribofuranosylpurines, 3a and 3b} were synthesized and tested for their cytokinin activity by four bioassay systems, the growth of tobacco callus, the seed germination of lettuce, the fr. wt increase of excised radish cotyledons and the retardation of chlorophyll degradation in radish cotyledons. In tobacco callus bioassay, 1a was more active than 1b. The ribosides 3a and 3b were not less active than their corresponding aglycones 1a and 1b. In other bioassays used the activity followed the order: 1a >3a >1b >3b. In tobacco callus bioassay and lettuce seed germination, trans-zeatin [6-(4-hydroxy-3-methylbut-trans-2-enylamino)purine] showed stronger cytokinin activity than 1a.     

Synthesis,biological evaluation and docking studies of novel benzopyranone congeners for their expected activity as anti-inflammatory,analgesic and antipyretic agents

8-Acetyl-7-hydroxy-4-phenyl-2H-benzopyran-2-one as starting material a number of 8-substituted derivatives (i.e., hydrazones 2a,b, imine 2c, chalcones 3, pyrazoles 4, 3-cyano-2-oxo-dihydropyridines 5, and/or 3-cyano-2-imino-dihydropyridines 6) were synthesized and assayed for their anti-inflammatory, analgesic and antipyretic activities. Compounds 3c, 4b and 4i showed significant anti-inflammatory, analgesic and antipyretic activities. In addition, 1, 3b, 4d, 4e, 5b, 6a, 6c, 6d, 6e showed anti-inflammatory activity, 2b, 4h, 5e exhibit analgesic activity, and 2b, 4h, 5e showed antipyretic effect. In addition, molecular modeling and docking of the tested compounds into cyclooxygenase II complexed with its bound inhibitor indomethacin (4COX) using molsoft icm 3.4-8C program was performed in order to predict the affinity and orientation of the synthesized compounds at the active site. Also, it was found that the active compounds 1, 4i, 6a–e interact with both Serine 530, and Tyrosine 385 amino acids which are the main amino acids involved in the mechanism of cyclooxygenase II inhibition.The synthesis of the pyrazole-containing new compounds 4 proved a successful hit; also, the 2-imino derivatives of 3-cyano-dihydropyridines were more successful than the 2-oxo derivatives.According to these results, we can conclude that compounds 1, 3c, 4b, 4i, and 6c appear to be the most interesting and seem potentially attractive as anti-inflammatory, analgesic, and antipyretic agents.     

Design,synthesis and evaluation of 2-(indolylmethylidene)-2,3-dihydro-1-benzofuran-3-one and 2-(indolyl)-4H-chromen-4-one derivatives as novel monoamine oxidases inhibitors

A series of 2-(indolylmethylidene)-2,3-dihydro-1-benzofuran-3-ones (aurone-indole hybrids) and 2-(indolyl)-4H-chromen-4-ones (flavone-indole hybrids) were designed, synthesized, and their monoamine oxidase (MAO) A and B inhibitory activities were evaluated. Compounds 5b and 11b showed potent inhibitory activities against MAO-A, comparable to that of pargyline used as a positive control, and most of the compounds, except for 2a and 10b, showed potent inhibitory activities against MAO-B. Compound 9a was the most potent and highly selective inhibitor of MAO-B (IC₅₀ value for MAO-B: 0.0026 μM, and MAO-A: >100 μM). Comparison of the inhibitory activities of 1a vs. 9a vs. 13a and 1b vs. 7b vs. 11b suggested that methoxy substitution at R¹ on the A-rings of flavonoids increases MAO-A inhibition whereas methoxy substitution at R² increased MAO-B inhibition. Comparison of 4a vs. 10a, 6a vs. 11a, 3b vs. 8b and 4b vs. 9b showed incremental increases in MAO-B inhibitory activity by R² substitution on the A ring. Comparison of the MAO-B inhibitory effects of the flavone-indole hybrids and aurone-indole hybrids showed that most of the aurone-indole hybrids were stronger inhibitors than the corresponding flavone-indole hybrids. Molecular docking analysis of compounds 1a and 9a with MAO-B further supported the above structural effects of these compounds on MAO-B inhibitory activity.This is the first report identifying aurone-indole hybrids as potent MAO-B inhibitors. The results reported here suggest that 2-(1H-indol-1-ylmethylene)-6-methoxy-3(2H)-benzofuranone (9a) might be a useful lead for the design and development of novel MAO-B inhibitors     

Design,synthesis, antiviral activity,and SARs of 13a-substituted phenanthroindolizidine alkaloid derivatives

On the basis of our previous structure–activity relationship (SAR) and antiviral mechanism studies, a series of 13a-substituted phenanthroindolizidine alkaloid analogues (3a–16a, 3b, 4b, 6b, 7b, 10b, and 14b) were designed targeting tobacco mosaic virus (TMV) RNA, synthesized, and evaluated for their antiviral activity against TMV for the first time. The bioassay results showed that most of the synthesized compounds (such as 4a, 6a, 7a, 11a, 14a, 6b, and 14b) exhibited good to excellent antiviral activity against TMV both in vitro and in vivo. Especially, for inactivation effect and curative effect, compounds 4a, 6a, 7a, 11a, 14a, and 14b showed higher activity at both concentrations (500 μg mL⁻¹ and 100 μg mL⁻¹) than commercial Ningnanmycin. Preliminary SARs showed that the substituted groups with hydrogen donor at 13a position were found to be favorable for keeping high antiviral activity. The present work demonstrates that 13a-substituted phenanthroindolizidines can be used as possible lead compounds for developing anti-TMV agents.     

Identification of new aryl hydrocarbon receptor (AhR) antagonists using a zebrafish model

A new series of 1,3-diketone, heterocyclic and α,β-unsaturated derivatives were synthesized and evaluated for their AhR antagonist activity using zebrafish and mammalian cells. Compounds 1b, 2c, 3b and 5b showed significant AhR antagonist activity in a transgenic zebrafish model. Among them, compound 3b, and 5b were found to have excellent AhR antagonist activity with IC₅₀ of 3.36 nM and 8.3 nM in a luciferase reporter gene assay. In stem cell proliferation assay, compound 5b elicited marked HSC expansion.     

1-Aryl-3-(4-methoxybenzyl)ureas as potentially irreversible glycogen synthase kinase 3 inhibitors: Synthesis and biological evaluation

Glycogen synthase kinase 3 (GSK-3) has become known for its multifactorial involvement in the pathogenesis of Alzheimer’s disease. In this study, a benzothiazole- and benzimidazole set of 1-aryl-3-(4-methoxybenzyl)ureas were synthesised as proposed Cys199-targeted covalent inhibitors of GSK-3β, through the incorporation of an electrophilic warhead onto their ring scaffolds. The nitrile-substituted benzimidazolylurea 2b (IC₅₀ = 0.086 ± 0.023 µM) and halomethylketone-substituted benzimidazolylurea 9b (IC₅₀ = 0.13 ± 0.060 µM) displayed high GSK-3β inhibitory activity, in comparison to reference inhibitor AR-A014418 (1, IC₅₀ = 0.072 ± 0.043) in our assay. The results suggest further investigation of 2b and 9b as potential covalent inhibitors of GSK-3β, since a targeted interaction might provide improved kinase-selectivity.     

Synthesis and anti-proliferative activity of some new quinoline based 4,5-dihydropyrazoles and their thiazole hybrids as EGFR inhibitors

Quinoline derivatives 2, 3, quinolinyl based pyrazolines 4a,b, 5 and quinolinyl pyrazolinyl thiazole hybrids 6a-d, 7a-c and 8a-d were synthesized and screened for their anti-proliferative activity against MCF-7, HeLa and DLD1 cancer cell lines as well as normal fibroblast WI-38. Most of the tested compounds showed promising anticancer activity in addition to their safety towards the normal cell line. Eight compounds eliciting superior cytotoxicity against DLD1 and safe to the normal cell line 2, 3, 5, 6a, 6b, 7b, 7c and 8a were evaluated for their efficacy as EGFR inhibitors. They revealed inhibitory activity at nanomolar level especially compounds 6b, 2 and 7c with IC₅₀ (31.80, 37.07 and 42.52 nM) in comparison to Gefitinib (IC₅₀ = 29.16 nM).     

Enantiomeric 4′-Truncated 3-deaza-1′,6′-isoneplanocins: Synthesis and antiviral properties including Ebola

Enantiomeric 3-deaza-1′,6′-isoneplanocins (C-3 unsubstituted 7a/7b and C-3 with a bromine 8a/8b) lacking the 4′-hydroxymethyl as mechanistically designed anti-viral targets have been prepared by utilizing the Ullmann reaction. Anti-Ebola properties were found for the D-like 7a and 8a and L-like 8b. All four products showed effects against human cytomegalovirus while D-like 7a/8a affected measles; 7a was effective versus norovirus and 8a inhibited Pichinde. Both 7a and 8a produced SAHase inhibitory effects. However, the anti-EBOV activity of 7a and 8a cannot be readily correlated with this observation due with their contrasting IC₅₀ values (8a > 7a). It is to be noted that 7b showed no effects on this enzyme and 8b was minimally inhibitory. These results offer preliminary insight into the differing mechanisms of action of D- and L- like structures and enlighten structural features to guide additional antiviral agent pursuit in the isoneplanocin series.     

Pyranocoumarins: A new class of anti-hyperglycemic and anti-dyslipidemic agents

A series of pyranocoumarin derivatives were synthesized and evaluated in vivo for their anti-hyperglycemic as well as anti-dyslipidemic activities. Compounds 7a, 7c, 8a, 8b, 8c, 8e and 8f have shown promising anti-hyperglycemic activities in sucrose loaded model (SLM) as well as sucrose challenged streptozotocin induced diabetic rat model (STZ). Compounds 8a and 8b were showing 38.0% and 42.0% blood glucose lowering activity in db/db mice model. In vitro anti-hyperglycemic activity evaluation exhibited that compounds 8a (IC₅₀ = 24.5 μM) and 8b (IC₅₀ = 36.2 μM) are potential PTP-1B inhibitors thereby revealing their possible mechanism of anti-diabetic action. Compounds 7a, 7b, 8a, 8b, 8d, 8e and 8f have shown significant anti-dyslipidemic activity in triton induced dyslipidemia in rats.     

Design,synthesis and biological activity of 3-oxoamino-benzenesulfonamides as selective and reversible LSD1 inhibitors

Lysine specific demethylase 1 (LSD1) is a flavin-dependent amine oxidase that selectively removes one or two methyl groups from H3 at Lys4 and is recognized as a promising therapeutic target for cancer and other diseases. Here, a series of 3-oxoamino-benzenesulfonamides were synthesized and evaluated for their inhibitory activity against LSD1. Compounds 7b and 7h showed the most potent inhibition with the IC₅₀ values of 9.5 and 6.9 μM, respectively. Furthermore, the LSD1 inhibition of 7b and 7h were reversible and selective. Docking study presented the possible binding mode between 7b, 7h and the LSD1 active site. Taken together, 3-oxoamino-benzenesulfonamides may represent a new class of reversible LSD1 inhibitors and 7b and 7h were two hit compounds deserved further structural optimization.     

Derivatives of (3S)-N-(biphenyl-2-ylmethyl)pyrrolidin-3-amine as selective noradrenaline reuptake inhibitors: Reducing P-gp mediated efflux by modulation of H-bond acceptor capacity

Derivatives of (3S)-N-(biphenyl-2-ylmethyl)pyrrolidin-3-amine are disclosed as a new series of noradrenaline reuptake inhibitors (NRI). Carboxamide 9e, carbamate 11b and sulfonamide 13a were identified as potent NRIs with excellent selectivity over SRI and DRI, good in vitro metabolic stability and weak CYP inhibition. Carbamate 11b demonstrated superior transit performance in MDCK-mdr1 cell lines with minimal P-gp efflux which was attributed to reduced HBA capacity of the carbamate group. Evaluation in vivo, in rat microdialysis experiments, showed 11b increased noradrenaline levels by 400% confirming good CNS penetration.     

Design,synthesis, in vivo,and in silico evaluation of new coumarin-1,2,4-oxadiazole hybrids as anticonvulsant agents

A novel series of coumarin-1,2,4-oxadiazole hybrids were designed, synthesized, and evaluated as anticonvulsant agents. The title compounds were easily synthesized from reaction of appropriate coumarins and 3-aryl-5-(chloromethyl)-1,2,4-oxadiazole derivatives. In vivo anticonvulsant activity of the synthesized compounds were determined using pentylenetetrazole (PTZ)- and maximal electroshock (MES)-induced seizures confirming that they were more effective against MES test than PTZ test. It should be noted that compounds 3b, 3c, and 3e showed the best activity in MES model which possessed drug-like properties with no neurotoxicity. Anticonvulsant activity of the most potent compound 3b was remarkably reduced after treatment with flumazenil which confirmed the participation of a benzodiazepine mechanism in the anticonvulsant activity. Also, docking study of compound 3b in the BZD-binding site of GABA_A receptor confirmed possible binding of 3b to the BZD receptors.