Synthesis and cytotoxic activities of pyrrole[2,3-d]pyridazin-4-one derivatives

1-Methyl-2-phenyl (1) and 1,3-dimethyl-2-phenyl (2)-substituted pyrrole[2,3-d]pyridazinones, as well as their tetracyclic analogues 3-6, were synthesized and evaluated in vitro by the National Cancer Institute against 60 human tumor cell lines derived from nine cancer cell types. Biological results showed that the antitumor activities of these compounds were related to the planarity of their ring systems with potency increasing in the order 2<4 congruent with 5<6<3. Among them, the most potent compound 3 showed significant cell line cytotoxicity, particularly against the renal cancer subpanel [GI(50) (microM) 5.07] and displayed significant potency [GI(50) (microM) 3.04-4.32] against MOLT-4, SR (leukemia), NCI-H460 (non-small cell lung), HCT-116 (colon), and SF-295 (CNS) cancer cells, respectively.     

Acetylcholinesterase and butyrylcholinesterase inhibitory compounds from Corydalis cava (Fumariaceae)

Tubers of Corydalis cava were extracted with ethanol and fractionated using n-hexane, chloroform and ethanol. Repeated column chromatography, preparative TLC and crystallization led to the isolation of fifteen isoquinoline alkaloids. The chemical structures of the isolated compounds were determined on the basis of spectroscopic techniques and by comparison with literature data. All isolated compounds were tested for human blood acetylcholinesterase (HuAChE) and human plasma butyrylcholinesterase (HuBuChE) inhibitory activity. (+)-Canadaline inhibited acetylcholinesterase as well as butyrylcholinesterase in a dose-dependent manner with IC50 values of 20.1 +/- 1.1 microM and 85.2 +/- 3.2 microM, respectively. (+)-Canadine, with an IC50 value of 12.4 +/- 0.9 microM, was the most potent inhibitor of acetylcholinesterase, whilst (+/-)-corycavidine and (+)-bulbocapnine were effective inhibitors of butyrylcholinesterase with IC50 values of 46.2 +/- 2.4 microM and 67.0 +/- 2.1 microM, respectively. The other isolated alkaloids were considered inactive (IC50 > 100 microM).     

Chemical constituents of the new endophytic fungus Mycosphaerella sp. nov. and their anti-parasitic activity

Chemical investigation of a new endophytic fungus, Mycosphaerella sp. nov. strain F2140, associated with the foliage of the plant Psychotria horizontalis (Rubiaceae) in Panama, resulted in the isolation of cercosporin (1) and a new cercosporin analog (3) as the major components. The structures of minor compounds in the extract were elucidated by detailed spectroscopic analysis as 2-(2-butyl)-6-ethyl-3-hydroxy-6-methylcyclohex-2-ene-1,5-dione (4), 3-(2-butyl)-6-ethyl-5-hydroxy-2-methoxy-6-methyl-cyclohex-2-enone (5), and an isomer of 5 (6). To study the influence of the hydroxy groups on the anti-parasitic activity of cercosporin, compound 1 was acetylated to obtain derivative 2. The isolated compounds 1- 6 were tested in vitro to determine their anti-parasitic activity against the causal agents of malaria (Plasmodium falciparum), leishmaniasis (Leishmania donovani), and Chagas disease (Trypanosoma cruzi). Cytotoxicity and potential anticancer activity of these compounds were evaluated using mammalian Vero cells and MCF7 cancer cell lines, respectively. Compounds 1 and 2 displayed high potency against L. donovani (IC50 0.46 and 0.64 microM), T. cruzi (IC50 1.08 and 0.78 microM), P. falciparum (IC50 1.03 and 2.99 microM), and MCF7 cancer cell lines (IC50 4.68 and 3.56 microM). Compounds 3-6 were not active in these assays at a concentration of 10 microg/mL.     

Effects of anonaine on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells

The effects of anonaine, an aporphine isoquinoline alkaloid, on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells were investigated. Anonaine at concentration ranges of 0.01-0.2 microM showed a significant inhibition of dopamine content at 24 h, with an IC(50) value of 0.05 microM. Anonaine at 0.05 microM inhibited tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) activities to 38.4-40.2% and 78.4-90.2% of control levels at 12-24 h and 3-6 h, respectively. TH activity was more influenced than AADC activity. Anonaine also decreased intracellular cyclic AMP levels, but not intracellular Ca(2+) concentrations. In addition, anonaine (0.05 microM) reduced L-DOPA (50 microM and 100 microM)-induced increases in dopamine content at 24 h. However, anonaine (0.05 microM) did not enhance L-DOPA (50 microM and 100 microM)-induced cell death after 24 h. These results suggest that anonaine inhibits dopamine biosynthesis by mainly reducing TH activity without aggravating L-DOPA-induced cytotoxicity in PC12 cells.     

Spongolactams, farnesyl transferase inhibitors from a marine sponge: isolation through an LC/MS-guided assay, structures, and semisyntheses

Novel nitrogenous diterpenoids, spongolactams A-C (1-3), were isolated as trace components of an Okinawan marine sponge, Spongia sp., by an LC/MS-guided assay for farnesyl transferase (FTase) inhibitors. Their structures were elucidated by spectroscopic analyses. To evaluate their structures and biological activity, the metabolites were semisynthesized from the known furanoditerpene 5, obtained from the same sponge. Three related compounds 4, 13, and 16 were also semisynthesized. The IC50 values against FTase for 1-3 were 23, 130, and >260 microM, respectively, while the IC50 values against a human tumor cell line were 2.0, 3.5, and 20 microM, respectively. The structure-activity relationships within the six compounds suggest some positive correlation between FTase inhibitory and cytotoxic activities.     

Electrochemiluminescence quenching as an indirect method for detection of dopamine and epinephrine with capillary electrophoresis

An electrochemiluminescence (ECL) inhibition method was developed as an indirect detection method for the determination of dopamine and epinephrine separated by capillary electrophoresis (CE). When the concentration of Ru(bpy)(3) (2+) was 50 muM diluted by 50 mM phosphate (pH 8.5) in the cell and 0.5 M tripropylamine (TPA) was added to the running buffer (10 mM phosphate, pH 9.0), an inhibition of ECL of the Ru(bpy)(3) (2+)/TPA system by the analytes was observed. Under the optimized conditions, the relative standard deviations of migration time and negative peak area were less than 1% and 3%, respectively, for 1 microM dopamine or 1 microM epinephrine (n = 10). Linear ranges of 0.1-10 microM for both analytes and the detection limits (signal-to-noise ratio S/N = 3) of 10 nM for dopamine and 30 nM for epinephrine were obtained.     

Development of selective inhibitors against plasma kallikrein.

Specific plasma kallikrein inhibitors were designed and synthesized and their structure-activity relationship was studied. trans-4-Aminomethylcyclohexanecarbonyl (Tra)-lysyl-4-ethoxycarbonylanilide inhibited plasma kallikrein and plasmin with IC50 values of 23 and 210 microM, respectively, indicating that this compound is fairly specific to plasma kallikrein. Tra-arginyl-4-ethoxycarbonylanilide inhibited plasma kallikrein and plasmin with IC50 values of 16 and 480 microM, respectively. Tra-homoarginyl-4-carboxyanilide inhibited plasma kallikrein and plasmin with IC50 values of 14 microM and 1 mM, respectively. Finally, Tra-Arg(Mts)-4-acetylanilide (ACA) exhibited potent and selective inhibitory activity against plasma kallikrein (IC50 value for plasma kallikrein: 2 microM and for plasmin: 42 microM).     

A new chromene isolated from Ageratum conyzoides

From the ethanol extract of the whole plant of Ageratum conyzoides L. (Compositae), one new chromene, 2,2-dimethylchromene 7-methoxy-6-O-beta-D-glucopyranoside, was isolated, together with thirteen known compounds, seven of which were being reported for the first time. The compounds were all characterized by MS, IR, 1D- and 2D-NMR spectroscopy. 7,3',5'-Tri-O-methyltricetin (7), precocene II (9), 3,5,7,4'-tetrahydroxyflavone (13) and 5,6,7,3',4',5'-hexamethoxyflavone (14) exhibited inhibitory activity on the P-388 cancer cell line with IC50 values of 12.8, 24.8, 3.5 and 7.8 microM respectively, while compound 9 exhibited inhibitory activity on the HT-29 cancer cell line with an IC50 value of 61 microM; the others showed no significant cytotoxic activity on the cell lines tested.     

Synthesis and cytotoxicity studies of novel [1,2,4]triazolo[1,5-a]pyrimidine-7-amines

A series of novel N-anilino-5-methyl-2-(3-(5-(alkylaminomethyl)furan-2-yl-methylthio)propyl)-[1,2,4]triazolo-[1,5-a]pyrimidine-7-amine derivatives were synthesized and evaluated for their in vitro cytotoxicity against two cancer cell lines, Bel-7402 and HT-1080. Compounds 9, 14, 19 and 23 possessed marked cytotoxicity, especially 23 (with IC(50) values of 15.0 microM and 7.8 microM against Bel-7402 and HT-1080 cell lines, respectively), which had emerged as lead compound. The activity was found to depend strongly on substitution pattern of the side chains at C-2 position, and 4-triflouromethylanilino substituent at C-7 position was an option for anticancer potency.     

Penicillenols from Penicillium sp. GQ-7, an endophytic fungus associated with Aegiceras corniculatum

Six new tetramic acids derivatives, penicillenols A(1), A(2), B(1), B(2), C(1), and C(2) (1-6), together with citrinin, phenol A acid, phenol A, and dihydrocitrinin, were identified from Penicillium sp. GQ-7, an endophytic fungus associated with Aegiceras corniculatum. Their structures were elucidated on the basis of comprehensive spectral analysis. All the new compounds were evaluated for their cytotoxic effects on four cell lines by the MTT method. Penicillenols A(1) and B(1) showed cytotoxicities against HL-60 cell line with IC(50) values of 0.76 microM and 3.20 microM, respectively.     

Leishmanicidal and cholinesterase inhibiting activities of phenolic compounds from Allanblackia monticola and Symphonia globulifera

In a preliminary antiprotozoal screening of several Clusiaceae species, the methanolic extracts of Allanblackia monticola and Symphonia globulifera showed high in vitro leishmanicidal activity. Further bioguided phytochemical investigation led to the isolation of four benzophenones: guttiferone A (1), garcinol (2), cambogin (3) and guttiferone F (4), along with three xanthones: allanxanthone A (5), xanthone V1 (6) and globulixanthone C (7) as active constituents. Compounds 1 and 6 were isolated from S. globulifera leaves, while compounds 2-5 were obtained from A. monticola fruits. Guttiferone A (1) and F (4) showed particulary strong leishmanicidal activity in vitro, with IC50 values (0.2 microM and 0.16 microM, respectively) comparable to that of the reference compound, miltefosine (0.46 microM). Although the leishmanicidal activity is promising, the cytotoxicity profile of these compounds prevent at this state further in vivo biological evaluation. In addition, all the isolated compounds were tested in vitro for their anticholinesterase properties. The four benzophenones showed potent anticholinesterase properties towards acetylcholinesterase (AChE) and butylcholinesterase (AChE). For AChE, the IC50 value (0.66 microM) of garcinol (2) was almost equal to that of the reference compound galanthamine (0.50 microM). Furthermore, guttiferone A (1) and guttiferone F (4) (IC50 = 2.77 and 3.50 microM, respectively) were more active than galanthamine (IC50 = 8.5) against BChE.     

Biophysical evaluation of two red-shifted hypocrellin B derivatives as novel PDT agents

Two novel cyclohexane-1,2-diamino and N,N dimethyl amino-propyl substituted hypocrellin B derivatives, abbreviated as CHA2HB and DMAHB, respectively were synthesized. These derivatives exhibited enhanced absorption in phototherapeutic window. Photodynamic action of these derivatives, investigated using optical and electron spin resonance methods, depended on both Type I and Type II mechanisms. Gel electrophoresis indicated 1O2/O2(.-) mediated DNA damage. CHA2HB displayed 20 fold increase in light dependent cytotoxicity on colon cancer cell line (HCT 116) than the well-known hypocrellin B (HB). The light induced, LD(50) values for CHA2HB and DMAHB were found to be 0.1 microM and 1.5 microM, respectively. The singlet oxygen generating efficiency followed the order HB>CHA(2)HB>DMAHB. But, the enhanced red absorption as well as the hydrophilicity renders the CHA2HB a better photodynamic therapeutic agent.     

Syntheses and biological activity of amamistatin B and analogs

Amamistatins A and B, natural products isolated from a strain of Nocardia, showed growth inhibition against three human tumor cell lines (IC(50) 0.24-0.56 microM). Structurally related mycobactins affect the growth of both mycobacterial and human cells through interference with iron chelation. To further probe the biological activity of this class of compounds, the total syntheses of amamistatin B and two analogs were completed, and the synthetic samples were screened for tumor cell growth inhibition, HDAC inhibition, and Mycobacterium tuberculosis growth inhibition. Amamistatin B (15) and diastereomer 18 were both active against MCF-7 cells (IC(50) 0.12-0.20 microM), and less so against PC-3 cells (IC(50) 8-13 microM). Amamistatin B only moderately inhibited the growth of M. tuberculosis (MIC 47 microM) but showed growth promotion of Mycobacterium smegmatis and other bacteria.     

Ianthesine E, a new bromotyrosine-derived metabolite from the Great Barrier Reef sponge Pseudoceratina sp

The new compound ianthesine E (1) was isolated from the Great Barrier Reef marine sponge Pseudoceratina sp. along with the known metabolites 11-hydroxyaerothionin (2), aerothionin (3) and 11,19-dideoxyfistularin 3 (4). Structures were determined on the basis of their spectroscopic data. The compounds were tested for inhibition of [(3)H] DPCPX binding to adenosine A(1) receptors in a whole cell binding assay. At 100 microM, aerothionin was the most potent, inhibiting 67% of binding, followed by ianthesine E and 11-hydroxyaerothionin which inhibited 61% of binding, and 11,19-dideoxyfistularin which initiated 51% of binding Ianthesine E (EC(50) 60 microM), aerothionin (EC(50) 42 microM) and 11,19-dideoxyfistularin-3 (EC(50) 2.6 microM) exhibited moderate cytotoxicity against the HeLa cell line.     

Cytotoxic germacranolide sesquiterpene from Inula cappa

A new germacranolide, inulacappolide (1), was isolated from the EtOH extract of the whole plant of Inula cappa along with 16 known compounds. The structure of inulacappolide was a rare 1(10)-saturated type of germacran-6,12-olide, identified as 2alpha-acetoxy-3beta-hydroxy-9beta-angeloyloxygermacra-4-en-6alpha,12-olide by spectral analysis (IR, HR-ESI/MS, (1)H-NMR, (13)C-NMR, HMQC, HMBC, NOESY). In vitro, it showed antiproliferative effects against human cervical cancer HeLa, human leukemia K562 and human nasopharyngeal carcinoma KB cell lines with IC(50) values of 1.2 microM, 3.8 microM and 5.3 microM, respectively.     

Cytotoxicity of constituents from Mexican propolis against a panel of six different cancer cell lines

The cytotoxicity of 39 compounds, including eighteen flavonoids (flavanones, 1-10; flavones, 11-17; flavanol, 18), sixteen phenolic acid derivatives (aromatic acids, 19-24; aldehyde, 25; esters, 26-34) and five glycerides (35-39), isolated from Mexican propolis, were evaluated against a panel of six different cancer cell lines; murine colon 26-L5 carcinoma, murine B16-BL6 melanoma, murine Lewis lung carcinoma, human lung A549 adenocarcinoma, human cervix HeLa adenocarcinoma and human HT-1080 fibrosarcoma. A phenylpropanoid-substituted flavanol, (2R,3S)-8-[4-phenylprop-2-en-1-one]-4',7-dihydroxy-3',5-dimethoxyflavan-3-ol (18), showed the most potent cytotoxicity against A549 cells (IC50, 6.2 microM) and HT-1080 cells (IC50, 3.9 microM), stronger than those of the clinically used anticancer drug, 5-fluorouracil (IC50, 7.5 microM and 5.4 microM, respectively). Based on the observed results, the structure-activity relationships are discussed.     

Synthesis of novel 1,3,4-trisubstituted pyrazole derivatives and their evaluation as antitumor and antiangiogenic agents

Several 1,3,4-trisubstituted pyrazole derivatives were synthesized and screened for their cytotoxic effect in a primary 3 tumor cell line test at 10(-4) M drug concentration. Compounds 19 and 20 reduced the growth of one or more of these cell lines to less than 32% and escalated up to evaluation in the full panel of 60 human tumor cell lines at a minimum of 5 concentrations at 10 fold dilutions. Compound N'-(1-[1-[4-nitrophenyl]-3-phenyl-1H-pyrazol-4-yl]methylene)-2-chlorobenzohydrazide 19 proved to be the most active of these derivatives with full panel median growth inhibition (GI50), total growth concentration (TGI) and median lethal concentration (LC50) mean graph mid-point (MG-MID) of 3.79, 12.5 and 51.5 microM, respectively. In addition, compounds 19, 39, 40, 41, 43, 45, 47 were tested for their antiangiogenic properties by testing their ability to inhibit human umbilical vein endothelial cells (HUVECs) proliferation, cord formation and migration in response to chemoattractant. 3-Acetyl-2-(1-(4-nitrophenyl)-3-phenylpyrazol-4-yl)-5-(4-pyridyl)-1,3,4-oxadiazoline 39 showed significant antiangiogenic profile at non-cytotoxic doses, with HUVEC proliferation inhibition IC50 of 7.60 microM, chemotaxis IC50 of 0.86 microM and was superior to the reference celecoxib 2 in both tests. Furthermore, in contrary to the references TNP-470 and celecoxib, all the tested compounds interfered with the migratory function of HUVECs in response to vascular endothelium growth factor (VEGF) rather than the endothelial cells proliferation.     

Studies on the monoamine oxidase (MAO) inhibitory potency of TL-1, isolated from a fungus, Talaromyces luteus

The compound tentatively named TL-1 was isolated from Talaromyces luteus as a metabolite having monoamine oxidase (MAO) inhibitory potency. TL-1 showed mixed-type inhibition of MAO in mouse liver when kynuramine was used as a substrate, and the IC50 was 6.6 microM. The inhibition constants (Ki) for MAO-A and -B in mouse liver were 39.9 and 7.85 microM, respectively. On the other hand, the Ki values for MAO-A and -B in mouse brain were 74.0 and 0.71 microM, respectively. Despite the marked structural resemblance between TL-1 and 7-episclerotiorin, the latter compound had little inhibitory effect on MAO.     

Electrochemical study of heavy metals and metallothionein in yeast Yarrowia lipolytica

The bioaccumulation of heavy metals (cadmium, nickel, cobalt and zinc) and the effect of these metals on the production of metallothionein and metallothionein-like proteins (MT) in Yarrowia lipolytica was studied by electrochemical methods. The concentrations of heavy metals were determined by differential pulse voltammetry (DPV). A combination of the constant current chronopotentiometric stripping analysis (CPSA) and adsorptive transfer stripping technique (AdTS) was used to determine the content of MT in cells. Both the bioaccumulation of heavy metals and the production of MT in different cell compartments of Y. lipolytica exposed to heavy metals were monitored. The LD(50) of each metal was determined from the number of viable cells in yeast cultures: LD(50)Cd (37.5 microM), LD(50)Ni (570 microM), LD(50)Co (700 microM), and LD(50)Zn (1800 microM). The highest concentrations of heavy metals were found in the cell wall and membrane debris while the lowest concentrations were detected in the cytoplasm. Cadmium and nickel showed the most significant effect on the production of MT. This study provides new insights into the ecophysiology of microorganisms and demonstrates the potential use of these electrochemical methods in biotechnology.     

Development of plasmin-selective inhibitors and studies of their structure-activity relationship

Various compounds were synthesized by combining three components at positions P1, P1' and P2'. Of these, N-(trans-4-aminomethylcyclohexanecarbonyl)-Tyr(O-2-bromobenzylo xycarbonyl)- octylamide inhibited plasmin selectively with IC50 values of 0.80 and 0.23 microM towards S-2251 and fibrin, respectively. This compound also inhibited plasma kallikrein, urokinase, thrombin and trypsin with IC50 values of 10, > 50, > 50 and 1.6 microM, respectively.