Diarylheptanoids with inhibitory effects on melanogenesis from the rhizomes of Curcuma comosa in B16 melanoma cells

The methanolic extract from the dried rhizomes of Curcuma comosa cultivated in Thailand was found to inhibit melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extract, three new diarylheptanoids, diarylcomosols I–III, were isolated together with 12 known diarylheptanoids. Their chemical structures were elucidated on the basis of chemical and physicochemical evidence. The diarylheptanoids inhibited melanogenesis, and several structural requirements of the active constituents for the inhibition were clarified. In particular, (3R)-1,7-bis(4-hydroxyphenyl)-(6E)-6-hepten-3-ol exhibited stronger inhibitory effect [IC₅₀ = 0.36 μM] without inducing cytotoxicity. The biological effect was much stronger than that of a reference compound, arbutin [IC₅₀ = 174 μM]. We conclude that diarylheptanoid analogs are promising therapeutic agents for the treatment of skin disorders.     

Design and synthesis of novel chromenone derivatives as interleukin-5 inhibitors

A novel series of chromenone analogs were synthesized and evaluated for their inhibitory activity against interleukin-5. Among them 5-(cyclohexylmethoxy)-3-[3-hydroxy-3-(4-hydroxyphenyl)propyl]-4H-chromen-4-one (9b, 94% inhibition at 30 μM, IC₅₀ = 4.0 μM) and 5-(cyclohexylmethoxy)-3-[3-hydroxy-3-(4-methoxyphenyl)propyl]-4H-chromen-4-one (9c, 94% inhibition at 30 μM, IC₅₀ = 6.5 μM) showed the most potent activity. According to the SAR studies introduction of propanone unit in between chromenone and ring B as in 5-(cyclohexylmethoxy)-3-[3-(4-phenyl)-3-oxopropyl]-4H-chromen-4-ones (8) moderately increased the activity. However, the reduction of these propanones 8 to propanols 9 remarkably enhanced the activity. A small substituent at position 4 of ring B in 9, especially with hydrogen bonding capability, provides favorable contribution. Disappearance of IL-5 inhibitory activity upon saturation of chroman-4-one of 9 to chroman-4-ones 10 proves the critical importance of planar chromen-4-one unit of this scaffold in the IL-5 inhibition.     

Identification of novel quinazolin-4(3H)-ones as inhibitors of thermolysin,the prototype of the M4 family of proteinases

A combinatorial series of novel quinazolin-4(3H)-ones were synthesised and their structures were established based on spectroscopic data (IR, NMR, EI-MS, and FAB-MS). The compounds were tested for inhibition of the zinc metalloproteinase thermolysin (TLN) utilizing a chemical array-based approach. Some of the compounds were found to inhibit TLN, with IC₅₀ values ranging from 0.0115 μM (compound 3) to 122,637 μM (compound 29). Compound 3 [3-phenyl-2-(trifluoromethyl) quinazolin-4(3H)-one] (IC₅₀ = 0.0115 μM) and compound 35 [3-(isopropylideneamino)-2,2-dimethyl-2,3-dihydroquinazolin-4 (1H)-one] (IC₅₀ = 0.2477 μM) were found to be the most potent inhibitors.     

Synthesis and cytotoxic potential of heterocyclic cyclohexanone analogues of curcumin

A series of 18 heterocyclic cyclohexanone analogues of curcumin have been synthesised and screened for their activity in both adherent and non-adherent cancer cell models. Cytotoxicity towards MBA-MB-231 breast cancer cells, as well as ability to inhibit NF-κB transactivation in non-adherent K562 leukemia cells were investigated. Three of these analogues 3,5-bis(pyridine-4-yl)-1-methylpiperidin-4-one B1, 3,5-bis(3,4,5-trimethoxybenzylidene)-1-methylpiperidin-4-one B10, and 8-methyl-2,4-bis((pyridine-4-yl)methylene)-8-aza-bicyclo[3.2.1]octan-3-one C1 showed potent cytotoxicity towards MBA-MB-231, MDA-MB-468, and SkBr3 cell lines with EC₅₀ values below 1 μM and inhibition of NF-κB activation below 7.5 μM. The lead drug candidate, B10, was also able to cause 43% of MDA-MB-231 cells to undergo apoptosis after 18 h. This level of activity warrants further investigation for the treatment of ER-negative breast cancer and/or chronic myelogenous leukemia as prototypical cellular models for solid and liquid tumors.     

Bis(4-hydroxy-2H-chromen-2-one): Synthesis and effects on leukemic cell lines proliferation and NF-κB regulation

Synthesis of the bis-4-hydroxycoumarin-type compound, 3,3′-[3-(2-hydroxyphenyl)-3-oxopropane-1,1-diyl]bis(4-hydroxy-2H-chromen-2-one), was performed by two alternative pathways, either involving a basic organocatalyzed 1,4-conjugate addition tandem reaction of 4-hydroxycoumarin on chromone-3-carboxylic acid, or a double condensation of 4-hydroxycoumarin on ω-formyl-2′-hydroxyacetophenone. The anti-proliferative effects of the bis-4-hydroxycoumarin-type compound on human K-562 (chronic myeloid leukaemia) and JURKAT (acute T-cell leukaemia) cell lines using trypan blue staining, as well as its involvement in nuclear factor-kappa B (NF-κB) regulation analyzed by luciferase reporter gene assay, gene expression analysis and western blots were analysed. This compound inhibited TNFα-induced NF-κB activation in K-562 (IC₅₀ 17.5 μM) and JURKAT (IC₅₀ 19.0 μM) cell lines, after 8 h of incubation. Interestingly, it exerted mainly cytostatic effects at low doses on both cell lines tested, whereas it decreased JURKAT cell viability starting at 50 μM from 24 h of treatment. Importantly, it did not affect the viability of peripheral blood mononuclear cells (PBMCs) from healthy donors, even at concentrations above 100 μM.     

Synthesis and biological evaluation of novel 2-(substituted phenylaminocarbonylmethylthio)-6-(2,6-dichlorobenzyl)-pyrimidin-4(3H)-ones as potent HIV-1 NNRTIs

A series of novel 2-(phenylaminocarbonylmethylthio)-6-(2,6-dichlorobenzyl)-pyrimidin-4(3H)-ones have been designed and synthesized. All of the new compounds were evaluated for their anti-HIV activities in MT-4 cells. Most of these new compounds showed moderate to potent activities against wild-type HIV-1 with an EC₅₀ ranging from 4.48 μM to 0.18 μM. Among them, 2-[(4-bromophenylamino)carbonylmethylthio]-6-(2,6-dichlorobenzyl)-5-methylpyrimidin-4(3H)-one 4b3 was identified as the most promising compound (EC₅₀ = 0.18 ± 0.06 μM, CC₅₀ >243.56 μM, SI >1326). The structure–activity relationship (SAR) of these new congeners is discussed.     

Coumarin-thiazole and -oxadiazole derivatives: Synthesis,bioactivity and docking studies for aldose/aldehyde reductase inhibitors

In continuation of our previous efforts directed towards the development of potent and selective inhibitors of aldose reductase (ALR2), and to control the diabetes mellitus (DM), a chronic metabolic disease, we synthesized novel coumarin-thiazole 6(a–o) and coumarin-oxadiazole 11(a–h) hybrids and screened for their inhibitory activity against aldose reductase (ALR2), for the selectivity against aldehyde reductase (ALR1). Compounds were also screened against ALR1. Among the newly designed compounds, 6c, 11d, and 11g were selective inhibitors of ALR2. Whereas, (E)-3-(2-(2-(2-bromobenzylidene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one 6c yielded the lowest IC₅₀ value of 0.16 ± 0.06 μM for ALR2. Moreover, compounds (E)-3-(2-(2-benzylidenehydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6a; IC₅₀ = 2.94 ± 1.23 μM for ARL1 and 0.12 ± 0.05 μM for ARL2) and (E)-3-(2-(2-(1-(4-bromophenyl)ethylidene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6e; IC₅₀ = 1.71 ± 0.01 μM for ARL1 and 0.11 ± 0.001 μM for ARL2) were confirmed as dual inhibitors. Furthermore, compounds 6i, 6k, 6m, and 11b were found to be selective inhibitors for ALR1, among which (E)-3-(2-(2-((2-amino-4-chlorophenyl)(phenyl)methylene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6m) was most potent (IC₅₀ = 0.459 ± 0.001 μM). Docking studies performed using X-ray structures of ALR1 and ALR2 with the given synthesized inhibitors showed that coumarinyl thiazole series lacks the carboxylate function that could interact with the anionic binding site being a common ALR1/ALR2 inhibitors trait. Molecular docking study with dual inhibitor 6e also suggested plausible binding modes for the ALR1 and ALR2 enzymes. Hence, the results of this study revealed that coumarinyl thiazole and oxadiazole derivatives could act as potential ALR1/ALR2 inhibitors.     

Four isoflavanones from the stem bark of Platycelphium voënse

From the stem bark of Platycelphium voënse (Leguminosae) four new isoflavanones were isolated and characterized as (S)-5,7-dihydroxy-2′,4′-dimethoxy-3′-(3″-methylbut-2″-enyl)-isoflavanone (trivial name platyisoflavanone A), (±)-5,7,2′-trihydroxy-4′-methoxy-3′-(3″-methylbut-2″-enyl)-isoflavanone (platyisoflavanone B), 5,7-dihydroxy-4′-methoxy-2″-(2?-hydroxyisopropyl)-dihydrofurano-[4″,5″:3′,2′]-isoflavanone (platyisoflavanone C) and 5,7,2′,3″-tetrahydroxy-2″,2″-dimethyldihydropyrano-[5″,6″:3′,4′]-isoflavanone (platyisoflavanone D). In addition, the known isoflavanones, sophoraisoflavanone A and glyasperin F; the isoflavone, formononetin; two flavones, kumatakenin and isokaempferide; as well as two triterpenes, betulin and β-amyrin were identified. The structures were elucidated on the basis of spectroscopic evidence. Platyisoflavanone A showed antibacterial activity against Mycobacterium tuberculosis in the microplate alamar blue assay (MABA) with MIC = 23.7 μM, but also showed cytotoxicity (IC₅₀ = 21.1 μM) in the vero cell test.     

The regulation of inflammatory cytokine secretion in macrophage cell line by the chemical constituents of Rhus sylvestris

In our preliminary screening study on the anti-inflammatory activity, eight triterpenes, one sterol, and one chalcone were isolated from the CH₂Cl₂-soluble extract of the stems and leaves of Rhus sylvestris Siebold and Zucc (Anacardiaceae). On the basis of their spectroscopic data, these compounds were identified as 10α-cucurbitadienol (1), glut-5-en-3-ol (2), β-amyrin acetate (3), β-amyrin (4) and lupeol (5), cycloart-24-en-3-one (6), cycloart-25-en-3,24-dione (7), 24-hydroxycycloart-25-en-3-one (8), β-sitosterol (9), and 2′-hydroxy-4,4′-dimethoxychalcone (10). All of them were isolated from this plant for the first. Furthermore, the compounds in non-cytotoxic concentrations (0–1.0 μM) were tested for their ability to block inflammatory cytokine secretion in the presence of LPS in the murine RAW264.7 macrophage cell line. Among the compounds that were tested, compounds 8 and 9 reduced the LPS-induced secretion of IL-6, as well as TNF-α, in a mouse RAW264.7 macrophage cell line. Moreover, compounds 2, 3, 7, and 10 specifically diminished only the secretion of TNF-α even in 0.01 μM concentrations. It is thus suggested that they are potential therapeutics of TNF-α-related diseases and conditions, such as transplant rejection, type II diabetes, and atherosclerosis.     

Design,synthesis and biological evaluation of 5-amino-4-(1H-benzoimidazol-2-yl)-phenyl-1,2-dihydro-pyrrol-3-ones as inhibitors of protein kinase FGFR1

Fibroblast growth factor receptor 1 (FGFR1) plays an important role in tumorigenesis and is therefore an attractive target for anticancer therapy. Using molecular docking approach we have identified inhibitor of FGFR1 belonging to 5-amino-4-(1H-benzoimidazol-2-yl)-phenyl-1,2-dihydro-pyrrol-3-ones with IC₅₀ value of 3.5 μM. A series of derivatives of this chemical scaffold has been synthesized and evaluated for inhibition of FGFR1 kinase activity. It was revealed that the most promising compounds 5-amino-1-(3-hydroxy-phenyl)-4-(6-methyl-1H-benzoimidazol-2-yl)-1,2-dihydro-pyrrol-3-one and 5-amino-4-(1H-benzoimidazol-2-yl)-1-(3-hydroxy-phenyl)-1,2-dihydro-pyrrol-3-one inhibit FGFR1 with IC₅₀ values of 0.63 and 0.32 μM, respectively, and posses antiproliferative activity against KG1 myeloma cell line with IC₅₀ values of 5.6 and 9.3 μM. Structure–activity relationships have been studied and binding mode of this chemical class has been proposed.     

Development of novel tetrahydrothieno[2,3-c]pyridine-3-carboxamide based Mycobacterium tuberculosis pantothenate synthetase inhibitors: Molecular hybridization from known antimycobacterial leads

Twenty six 2,6-disubstituted 4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxamide derivatives were designed by molecular hybridization approach using and synthesized from piperidin-4-one by five step synthesis. Compounds were evaluated for Mycobacterium tuberculosis (MTB) pantothenate synthetase (PS) inhibition study, in vitro activities against MTB, cytotoxicity against RAW 264.7 cell line. Among the compounds, 6-(4-nitrophenylsulfonyl)-2-(5-nitrothiophene-2-carboxamido)-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxamide (11) was found to be the most active compound with IC₅₀ of 5.87 ± 0.12 μM against MTB PS, inhibited MTB with MIC of 9.28 μM and it was non-cytotoxic at 50 μM. The binding affinity of the most potent inhibitor 11 was further confirmed biophysically through differential scanning fluorimetry.     

Design,synthesis and biological evaluation of N-arylphenyl-2,2-dichloroacetamide analogues as anti-cancer agents

Our earlier research has shown that N-phenyl-2,2-dichloroacetamide analogues had much higher anti-cancer activity than the lead compound sodium dichloroacetate (DCA). In this current study, a variety of N-arylphenyl-2,2-dichloroacetamide analogues were synthesized via Suzuki coupling reaction and their anti-cancer activity was evaluated. The results showed that N-terphenyl-2,2-dichloroacetamide analogues had satisfactory anti-cancer activity. Among them, N-(3,5-bis(benzo[d][1,3]dioxol-5-yl)phenyl)-2,2-dichloroacetamide (6 k) had an IC₅₀ of 2.40 μM against KB-3-1 cells, 1.04 μM against H460 cells and 1.73 μM against A549 cells.     

Exploration of 2-benzylbenzimidazole scaffold as novel inhibitor of NF-κB

For finding the novel inhibitor of nuclear factor κB activity, a series of benzimidazole derivatives were rationally designed, synthesized and systematically studied for their in vitro activities against LPS induced NF-κB inhibition in RAW 264.7 cells using the SEAP assay based on the flexible chalcone JSH ((E)-1-(2-hydroxy-6-(isopentyloxy)phenyl)-3-(4-hydroxy phenyl)prop-2-en-1-one) which was previously reported. Although most of the benzimidazole derivatives showed strong inhibitory activity in low micromolar potency, 2-(4-methoxybenzyl)-1H-benzo[d]imidazole (3m; IC₅₀ = 1.7 μM) and 2-(2-methoxybenzyl)-1H-benzo[d]imidazole (3n; IC₅₀ = 2.4 μM) showed the best inhibition. The structure activity relationship revealed that 2-benzylbenzimidazole scaffold with hydrogen bonding acceptor on phenyl ring appears as a pharmacophore.     

Isolation and characterization of sesquiterpenes from Arecophila saccharicola YMJ96022401 with NO production inhibitory activity

Sesquiterpenes, arecoic acids A–F and arecolactone, were isolated from the ethyl acetate extracts of the fermented broth of Arecophila saccharicola YMJ96022401 along with two known analogues 1,7α,10α-trihydroxyeremophil-11(13)-en-12,8-olide and 1,10α,13-trihydroxyeremophil-7(11)-en-12,8-olide. Their structures were elucidated on the basis of spectroscopic data analyses. The inhibitory effects of all of these compounds on nitric oxide (NO) production in lipopolysaccharide (LPS, 200 μg/mL)-activated murine macrophage RAW264.7 cells were also evaluated. Among these compounds, 1,7α,10α-trihydroxyeremophil-11(13)-en-12,8-olide significantly inhibited NO production without any cytotoxicity, and its average maximum inhibition (E_max) at 100 μM and median inhibitory concentration (IC₅₀) were 85.7% ± 0.8% and 16.5 ± 1.0 μM, respectively. Arecolactone was the most potent, with the E_max at 12.5 μM and IC₅₀ being 94.7% ± 0.8% and 1.32 ± 0.1 μM, respectively, but displayed cytotoxicity at considerable higher concentrations than 25 μM. Analyses of Western blotting indicated that arecolactone (0.8–12.5 μM) inhibited induction of inducible NO synthase (iNOS) by LPS, which involved suppression of NF-κB activation and the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs) in activated RAW 264.7 cells. In addition, arecolactone concentration-dependently prevented the vascular hyporeactivity to phenylephrine induced by LPS (300 ng/mL) through iNOS pathway in isolated rat thoracic aortic rings. These results indicated that both of these naturally occurring iNOS inhibitors may provide a rationale for the potential anti-inflammatory effect of A. saccharicola YMJ96022401.     

Synthesis,biological evaluation of novel 4,5-dihydro-2H-pyrazole 2-hydroxyphenyl derivatives as BRAF inhibitors

A series of novel 4,5-dihydropyrazole derivatives (3a–3t) containing hydroxyphenyl moiety as potential V600E mutant BRAF kinase (BRAF^V600E) inhibitors were designed and synthesized. Docking simulation was performed to insert compounds 3d (1-(5-(5-chloro-2-hydroxyphenyl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone) and 3m (1-(3-(4-chlorophenyl)-5-(3,5-dibromo-2-hydroxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone) into the crystal structure of BRAF^V600E to determine the probable binding model, respectively. Based on the preliminary results, compound 3d and 3m with potent inhibitory activity in tumor growth may be a potential anticancer agent. Results of the bioassays against BRAF^V600E, MCF-7 human breast cancer cell line and WM266.4 human melanoma cell line all showed several compounds had potent activities IC₅₀ value in low micromolar range, among them, compound 3d and compound 3m showed strong potent anticancer activity, which were proved by that 3d: IC₅₀ = 1.31 μM for MCF-7 and IC₅₀ = 0.45 μM for WM266.5, IC₅₀ = 0.22 μM for BRAF^V600E, 3m: IC₅₀ = 0.97 μM for MCF-7 and IC₅₀ = 0.72 μM for WM266.5, IC₅₀ = 0.46 μM for BRAF^V600E, which were comparable with the positive control Erlotinib.     

Xanthine oxidase inhibitory terpenoids of Amentotaxus formosana protect cisplatin-induced cell death by reducing reactive oxygen species (ROS) in normal human urothelial and bladder cancer cells

The diterpenoids (+)-ferruginol (1), ent-kaur-16-en-15-one (2), ent-8(14),15-sandaracopimaradiene-2α,18-diol (3), 8(14),15-sandaracopimaradiene-2α,18,19-triol (4), and (+)-sugiol (5) and the triterpenoids 3β-methoxycycloartan-24(24¹)-ene (6), 3β,23β-dimethoxycycloartan-24(24¹)-ene (7), 3β,23β-dimethoxy-5α-lanosta-24(24¹)-ene (8), and 23(S)-23-methoxy-24-methylenelanosta-8-en-3-one (9), isolated from Amentotaxus formosana, showed inhibitory effects on xanthine oxidase (XO). Of the compounds tested, compound 5 was a potent inhibitor of XO activity, with an IC₅₀ value of 6.8 ± 0.4 μM, while displaying weak ABTS radical cation scavenging activity. Treatment of the bladder cancer cell line, NTUB1, with 3–10 μM of compound 5 and 10 μM cisplatin, and immortalized normal human urothelial cell line, SV-HUC1, with 0.3–1 μM and 10–50 μM of compound 5 and 10 μM cisplatin, respectively, resulted in increased viability of cells compared with cytotoxicity induced by cisplatin. Treatment of NTUB1 with 20 μM cisplatin and 10 or 30 μM of compound 5 resulted in decreased ROS production compared with ROS production induced by cisplatin. These results indicate that 10 or 30 μM of compound 5 in NTUB1 cells may mediate through the suppression of XO activity and reduction of reactive oxygen species (ROS) induced by compound 5 cotreated with 20 μM cisplatin and protection of subsequent cell death.     

Potent and selective HIV-1 ribonuclease H inhibitors based on a 1-hydroxy-1,8-naphthyridin-2(1H)-one scaffold

Optimization studies using an HIV RNase H active site inhibitor containing a 1-hydroxy-1,8-naphthyridin-2(1H)-one core identified 4-position substituents that provided several potent and selective inhibitors. The best compound was potent and selective in biochemical assays (IC₅₀ = 0.045 μM, HIV RT RNase H; 13 μM, HIV RT-polymerase; 24 μM, HIV integrase) and showed antiviral efficacy in a single-cycle viral replication assay in P4-2 cells (IC₅₀ = 0.19 μM) with a modest window with respect to cytotoxicity (CC₅₀ = 3.3 μM).     

Synthesis of 1-(methanesulfonyl- and aminosulfonylphenyl)acetylenes that possess a 2-(N-difluoromethyl-1,2-dihydropyridin-2-one) pharmacophore: Evaluation as dual inhibitors of cyclooxygenases and 5-lipoxygenase with anti-inflammatory activity

A hitherto unknown class of linear acetylene regioisomers were designed such that a SO₂Me or SO₂NH₂ group was located at the ortho-, meta- or para-position of the acetylene C-1 phenyl ring, and a N-difluoromethyl-1,2-dihydropyridin-2-one moiety was attached via its C-5 position to the C-2 position on an acetylene template (scaffold). All three SO₂Me regioisomers, and the 4-SO₂NH₂ analog, were potent inhibitors of 5-lipoxygenase (5-LOX IC₅₀ = 3.2–3.5 μM range) relative to the reference drug caffeic acid (IC₅₀ = 4.0 μM). The SO₂Me regioisomers exhibited weak cyclooxygenease-1 (COX-1) and -2 (COX-2) inhibitory activity with a modest COX-2 selectivity index. The most potent 3-SO₂Me, 4-SO₂Me and 4-SO₂NH₂ compounds, with respective ED₅₀ values of 66.1, 68.5 and 86.5 mg/kg po, exhibited comparable oral anti-inflammatory (AI) activity to that of the reference drug ibuprofen (ED₅₀ = 67.4 mg/kg po). The N-difluoromethyl-1,2-dihydropyridin-2-one moiety provides a novel pharmacophore for the design of cyclic hydroxamic mimetics capable of inhibiting 5-LOX for exploitation in the development of 5-LOX inhibitory AI drugs.     

1,5-Benzodiazepine inhibitors of HCV NS5B polymerase

Optimization through parallel synthesis of a novel series of hepatitis C virus (HCV) NS5B polymerase inhibitors led to the identification of (R)-11-(4-benzyloxy-2-fluorophenyl)-6-hydroxy-3,3-dimethyl-10-(6-methylpyridine-2-carbonyl)-2,3,4,5,10,11-hexahydro-dibenzo[b,e][1,4]diazepin-1-one 11zc and (R)-11-(4-benzyloxy-2-fluorophenyl)-6-hydroxy-3,3-dimethyl-10-(2,5-dimethyloxazol-4-carbonyl)-2,3,4,5,10,11-hexahydro-dibenzo[b,e][1,4]diazepin-1-one 11zk as potent (replicon EC₅₀ = 400 nM and 270 nM, respectively) and selective (CC₅₀ > 20 μM) inhibitors of HCV replication. These data warrant further lead-optimization efforts.