Synthesis and potent antitumor activity of new arylamino derivatives of nor-beta-lapachone and nor-alpha-lapachone

Several arylamino derivatives of nor-beta-lapachone were synthesized in moderate to high yields and found to show very potent cytotoxicity against six neoplastic cancer cells: SF-295 (central nervous system), HCT-8 (colon), MDAMB-435 (breast), HL-60 (leukaemia), PC-3 (prostate), and B-16 (murine melanoma), with IC(50) below 1 microg/mL. Their cytotoxicities were compared to doxorubicin and with their synthetic precursors, beta-lapachone and nor-beta-lapachone. The activity against a normal murine fibroblast L-929 showed that some of the compounds were selective against cancer cells. The absence of hemolytic activity (EC(50)>200 microg/mL), performed with erythrocyte suspensions, suggests that the cytotoxicity of the compounds was not related to membrane damage of mouse erythrocytes. For comparison purposes, one isomeric compound based on nor-alpha-lapachone was also synthesized and showed lower activity than the related ortho-derivative. The modified arylamino quinones appear as interesting new lead compounds in anti-cancer drug development.     

Trypanosoma cruzi: activities of lapachol and alpha- and beta-lapachone derivatives against epimastigote and trypomastigote forms

Derivatives of natural quinones with biological activities, such as lapachol, alpha- and beta-lapachones, have been synthesized and their trypanocidal activity evaluated in vitro in Trypanosoma cruzi cells. All tested compounds inhibited epimastigote growth and trypomastigote viability. Several compounds showed similar or higher activity as compared with current trypanocidal drugs, nifurtimox and benznidazole. The results presented here show that the anti-T. cruzi activity of the alpha-lapachone derivatives can be increased by the replacement of the benzene ring by a pyridine moiety. Free radical production and consequently oxidative stress through redox cycling or production of electrophilic metabolites are the potential biological mechanism of action for these synthetic quinones.     

Synthesis of Disulfide‐Bridged N‐Phenyl‐N′‐(alkyl/aryl/heteroaryl)urea Derivatives and Evaluation of Their Antimicrobial Activities

The discovery of new antimicrobial agents is extremely needed to overcome multidrug‐resistant bacterial and tuberculosis infections. In the present study, eight novel substituted urea derivatives ( 10a – 10h ) containing disulfide bond were designed, synthesized and screened for their in vitro antimicrobial activities on standard strains of Gram‐positive and Gram‐negative bacteria as well as on Mycobacterium tuberculosis. According to the obtained results, antibacterial effects of the compounds were found to be considerably better than their antimycobacterial activities along with their weak cytotoxic effects. Molecular docking studies were performed to gain insights into the antibacterial activity mechanism of the synthesized compounds. The interactions and the orientation of compound 10a (1,1′‐((disulfanediylbis(methylene))bis(2,1‐phenylene))bis(3‐phenylurea)) were found to be highly similar to the original ligand within the binding pocket E. faecalis β‐ketoacyl acyl carrier protein synthase III (FabH). Finally, a theoretical study was established to predict the physicochemical properties of the compounds.     

Synthesis and biological evaluation of 21-arylidenepregnenolone derivatives as neuroprotective agents

A series of 21-arylidenepregnenolone derivatives and their corresponding epoxides were synthesized. The neuroprotective effects of these steroidal compounds against amyloid-β(25-35) (Aβ(25-35))- and hydrogen peroxide (H(2)O(2))-induced neurotoxicity in PC12 cells, and oxygen-glucose deprivation (OGD)-induced neurotoxicity in SH-SY5Y cells were evaluated. The bioassay results indicated that several 3β-pregn-21-benzylidene-20-one derivatives displayed potent in vitro neuroprotective effects in different screening models, for example, compounds 2b, 3a, 3b, and 3s showing significant activities against Aβ(25-35)-induced neurotoxicity in PC12 cells, 2b showing significant activities against H(2)O(2)-induced neurotoxicity in PC12 cells, and 2g, 3b, and 3e showing potent protection against OGD insult. The results suggested that introduction of an arylidene group into steroidal nucleus played an important role in neuroprotective activity, while the formation of epoxy group at C-5,6 could be also important for the neuroprotective activity in some degree. The pharmacological data reported here are helpful for the design of novel steroidal neuroprotective candidates.     

Investigating the activity of 2-substituted alkyl-6-(2,5-dioxopyrrolidin-1-yl)hexanoates as skin penetration enhancers

Skin penetration enhancers are used in the formulation of transdermal delivery systems for drugs that are otherwise not sufficiently skin-permeable. We generated two series of esters by multi-step synthesis with substituted 6-aminohexanoic acid as potential transdermal penetration enhancers by multi-step synthesis. The synthesis of all newly prepared compounds is presented here. Structure confirmation of all generated compounds was accomplished by (1)H NMR, (13)C NMR, IR and MS spectroscopy. All the prepared compounds were analyzed using RP-HPLC and their lipophilicity (logk) was determined. The hydrophobicity (logP/ClogP) of the studied compounds was also calculated using two commercially available programs and 3D structures of the selected compounds were investigated by means of ab initio calculations of geometry and molecular dynamic simulations. All the synthesized esters were tested for their in vitro transdermal penetration-enhancing activity and showed higher enhancement ratios than oleic acid. The highest enhancement ratios were exhibited by compound 5f (C((2)) substituted with piperidine-2-one, C(11) ester chain) and 5a (C((2)) substituted with piperidine-2-one, C(6) ester chain). The series with a ω-lactam ring (piperidin-2-one; 5a-g), showed slightly higher activities than those with morpholine (6a-6g). All of the agents showed minimal anti-proliferative activity (IC(50) >6.25μM), indicating they would have low cytotoxicity when administered as chemical penetration enhancers. The relationships between the lipophilicity and the chemical structure of the studied compounds, as well as the correlation between their chemical structure and transdermal penetration-enhancing activity, are discussed.     

Isolation and characterization of light-dependent hemolytic cytotoxin from harmful red tide phytoplankton Chattonella marina

Chattonella marina (C. marina), a raphidophycean flagellate, is a causative organism of red tide, and highly toxic to fish. In this study, we found that the cell-free methanol extract prepared from this flagellate exhibited potent hemolytic activity against rabbit erythrocytes. Interestingly, the hemolytic activity of the extract was absolutely light-dependent, and no hemolytic activity was detected in the dark even at very high concentration. Gel filtration chromatography of the methanol extract on a column of Sephadex LH-20 revealed that the extract contained hemagglutinin as well as hemolytic agents, and the substances responsible for these activities were separately eluted. These results suggest that the hemagglutinating and hemolytic activities were derived from distinct compounds. The hemolytic fraction obtained after gel filtration (F4) caused marked inhibition of the growth of C. marina itself and other species of phytoplanktons. Furthermore, F4 showed a potent cytotoxicity toward various mammalian cultured cell lines including human tumor cells (HeLa cells) in a dose-dependent manner. The cytotoxicity was also light-dependent, and no cytotoxic effect was exhibited in any cell lines tested in the dark. After further purification procedures via preparative thin-layer chromatography and subsequent HPLC, a major hemolytic agent was obtained as highly purified form. Since the methanol extracts prepared from other raphidophycean flagellates such as Heterosigma akashiwo, Olisthodiscus luteus, and Fibrocapsa japonica showed light-dependent hemolytic activity toward rabbit erythrocytes, it was suggested that the light-dependent hemolytic agents commonly exist at least in these raphidophycean flagellates.     

Synthesis of natural product-like polyprenylated phenols and quinones: Evaluation of their neuroprotective activities

Twenty-seven natural product-like polyprenylated phenols and quinones were synthesized and their neuroprotective activity was tested using human monoamine oxidase B (MAO-B) and SH-SY5Y cells. Eight compounds inhibited MAO-B (IC₅₀ values < 25 μM) and the inhibition mode and molecular docking of two (8c and 16c) were investigated. Compounds inhibiting MAO-B activity were additionally tested for their ability to protect SH-SY5Y cells from peroxide injury. Three derivatives (3c, 8c and 16c) exhibited both MAO-B inhibitory and neuroprotective activity. A structure activity-relationship study showed that a phenolic hydroxyl group and a longer side chain are important for both activities.     

Synthesis,Antiproliferative and Cytotoxic Activities,DNA Binding Features and Molecular Docking Study of Novel Enamine Derivatives

Novel enamine derivatives were synthesized from the reaction of lactone and chalcones and their antiproliferative and cytotoxic activities against six cancer cell lines (e. g., HeLa, HT29, A549, MCF7, PC3 and Hep3B) and one normal cell lines (e. g., FL) were investigated along with their mode of interactions with CT‐DNA. Most of the enamine derivatives with IC₅₀ values of 86–168 μM demonstrated much stronger antiproliferative activity than the starting molecules against the cancer cells. While, among the enamine derivatives, four compounds displayed higher cytotoxic potency than the control drugs (5‐fluorouracil and cisplatin) against the Hep3B cell lines, these compounds did not exhibit any significant toxicity against normal cells, FL. The UV/VIS spectral data suggest that eight compounds cause hypochromism with a slight bathochromic shift (～6 nm), indicating that they bind to the DNA by way of an intercalative or minor groove binding mode. The binding constants of the compounds are in the range of 0.1×103 M^?1–2.3×104 M^?1. The antiproliferative activity of studied enamine derivatives could possibly be due to their DNA binding as well as their cytotoxic properties. In addition to these assays, the chalcones and enamine derivatives were investigated by molecular docking to calculate the synergistic effect of antiproliferative activities against six human cancer cell lines.     

Block versus random amphiphilic copolymers as antibacterial agents

We examined the antibacterial and hemolytic activities in a series of amphiphilic block and random copolymers of poly(vinyl ether) derivatives prepared by base-assisting living cationic polymerization. Block and random amphiphilic copolymers with similar monomer compositions showed the same level of activity against Escherichia coli . However, the block copolymers are much less hemolytic compared to the highly hemolytic random copolymers. These results indicate that the amphiphilic copolymer structure is a key determinant of activity. Furthermore, the block copolymers induced dye leakage from lipid vesicles consisting of E. coli -type lipids, but not mammalian lipids, while the random copolymers disrupted both types of vesicles. In addition, both copolymers displayed bactericidal and hemolytic activities at concentrations 1 or 2 orders of magnitude lower than their critical (intermolecular) aggregation concentrations (CACs), as determined by light scattering measurements. This suggests that polymer aggregation or macromolecular assembly is not a requisite for the antibacterial activity and selectivity against bacteria over human red blood cells (RBCs). We speculate that different single-chain conformations between the block and random copolymers play an important role in the antibacterial action and underlying antibacterial mechanisms.     

Synthesis, cytotoxicity, and hemolytic activity of 6'-O-substituted dioscin derivatives

Dioscin derivatives (1-12) with a variety of substitutions at the 6'-OH of the chacotriosyl residue and the 3',6'-anhydrosaponin derivatives (26, 30, and 32) were synthesized. All these derivatives showed much lower cytotoxicity than that of the parent dioscin, while their hemolytic activities were partially retained depending on the various 6'-O-substitutions.     

Synthesis of dihydronaphthofurandiones and dihydrofuroquinolinediones with trypanocidal activity and analysis of their stereoelectronic properties

The synthesis of dihydronaphthofurandione and dihydrofuroquinolinedione derivatives 4-11 was performed through Diels-Alder reactions of dihydrobenzofurandione 1 with several carbodienes and acrolein N,N-dimethylhydrazone. Then, the use of 5-bromobenzofurandione 2 toward 1,3-pentadiene and the 1-azadiene afforded quinones 6 and 11 with a total regioselectivity. All the prepared quinones were tested for trypanocidal activity in vitro against Trypanosoma epimastigotes, Tulahuen strain. Among the tested compounds, the furoquinolinediones 10 and 11 have shown potent trypanocidal activities but, only the 1,5-regioisomer (11) was found active as a redox cycling agent. Calculation of their stereoelectronic properties by the density-functional theory method provided a new insight for the trypanocidal activity of these heterocyclic quinones.     

Synthesis and antiproliferative activity of alkylphosphocholines

Alkylphosphocholines (APC) with one or more methylene groups in the alkyl chain replaced by oxygen atoms or carbonyl groups, or both have been assembled modularly using omega-diols as central building blocks. Out of 25 new compounds of this kind, 11 were evaluated for their antiproliferative activity on four cell lines and compared with miltefosine to evaluate their hemolytic activity (HA) and cytotoxicity on non-tumoral cells (MT2), used as markers of adverse effects. Compound 13 was more active on cancer cell lines than on non-tumoral cells and the data were similar for MTT and thymidine incorporation assays. It had less HA than miltefosine. Compound 13 could therefore be a candidate for the preparation of compounds with higher cytotoxicity on cancer cells and lower general toxicity.     

Antiproliferative activity of various flavonoids and related compounds: additive effect of interferon-alpha2b

The antiproliferative activity of several natural and synthetic flavonoids and some related compounds was evaluated in vitro against a cell line derived from a human cervical carcinoma (WISH cells). According to their activities, the most potent derivatives were 2'-nitroflavone (14), 2',6-dinitroflavone (15) and the n-buthyl ester of caffeic acid (29). When these compounds were tested in the presence of recombinant human interferon-alpha2b (rhIFN-alpha2b), a cytokine exhibiting an antimitogenic action on WISH cells, an additive effect on cell growth inhibition was observed. Time course studies of the antiproliferative action exerted by the active derivatives or the rhIFN-alpha2b suggested that these compounds induced cell death.     

Newly synthesized dopamine ester derivatives and assessment of their antioxidant,antimicrobial and hemolytic activities

Preparation of dopamine derivatives was carried out as a response to the increasing demand for new lipophilized antioxidants in food, cosmetic and pharmaceutical industries. A large series of dopamine esters (DA-C₃ to DA-C_18:1) with increasing lipophilicity was synthesized using lipase from Candida antarctica (Novozyme 435) as a biocatalyst. The highest conversion yield (52.75%) was reached when caprylic acid (DA-C₈) was used as acyl donor. Synthesized compounds were purified and evaluated for their antioxidant activity using the DPPH and the ABTS tests. Results showed that esterification had little effect on radical-scavenging capacity. However, long chain fatty acid esters displayed higher protective effect of oil against oxidation at 70 °C as compared to the parent dopamine or to the BHT. The hemolytic activity of dopamine esters was studied. Middle chain length derivatives (DA-C₈ and DA-C₁₂) of dopamine and oleic acid derivative (DA-C_18:1) showed the highest hemolytic activity against human erythrocyte. The antimicrobial activities of dopamine esters were also evaluated using well diffusion and minimal inhibition concentration methods. Among all the tested compounds, DA-C₈ and DA-C₁₂ exhibited the highest antibacterial activities. These results open up potential applications by using dopamine derivatives as antioxidants and antimicrobial compounds in cosmetic, food and pharmaceutical industries.     

In vitro activation of the rhesus macaque myeloid alpha-defensin precursor proRMAD-4 by neutrophil serine proteinases

Alpha-defensins are mammalian antimicrobial peptides expressed mainly by cells of myeloid lineage or small intestinal Paneth cells. The peptides are converted from inactive 8.5-kDa precursors to membrane-disruptive forms by post-translational proteolytic events. Because rhesus myeloid pro-alpha-defensin-4 (proRMAD-4((20-94))) lacks bactericidal peptide activity in vitro, we tested whether neutrophil azurophil granule serine proteinases, human neutrophil elastase (NE), cathepsin G (CG), and proteinase-3 (P3) have in vitro convertase activity. Only NE cleaved proRMAD-4((20-94)) at the native RMAD-4 N terminus to produce fully processed, bactericidal RMAD-4((62-94)). The final CG cleavage product was RMAD-4((55-94)), and P3 produced both RMAD-4((55-94)) and RMAD-4(57-94). Nevertheless, NE, CG, and P3 digests of proRMAD4 and purified RMAD-4((62-94)), RMAD-4((55-94)), and RMAD-4(57-94) peptides had equivalent in vitro bactericidal activities. Bactericidal peptide activity assays of proRMAD-4((20-94)) variants containing complete charge-neutralizing D/E to N/Q or D/E to A substitutions showed that (DE/NQ)-proRMAD-4((20-94)) and (DE/A)-proRMAD-4((20-94)) were as active as mature RMAD-4((62-94)). Therefore, proregion Asp and Glu side chains inhibit the RMAD-4 component of full-length proRMAD-4((20-94)), perhaps by a combination of charge-neutralizing and hydrogen-bonding interactions. Although native RMAD-4((62-94)) resists NE, CG, and P3 proteolysis completely, RMAD-4((62-94)) variants with disulfide pairing disruptions or lacking disulfide bonds were degraded extensively, evidence that the disulfide array protects the alpha-defensin moiety from degradation by the myeloid converting enzymes. These in vitro analyses support the conclusion that rhesus macaque myeloid pro-alpha-defensins are converted to active forms by serine proteinases that co-localize in azurophil granules.     

CXCL8((3-73))K11R/G31P antagonizes ligand binding to the neutrophil CXCR1 and CXCR2 receptors and cellular responses to CXCL8/IL-8

We recently reported that CXCL8((3-73))K11R is a high affinity agonist of neutrophil activation and chemotactic responses. In this report we employed CXCL8((3-73))K11R as a template to generate CXCL8/IL-8 analogues with antagonist activities, using site-directed mutagenesis to introduce conservative amino acid substitutions into the first turn within the molecule's beta-pleated sheet region (G31P, P32G) and, in association with these, into the putative receptor-recognition site (T12S, H13F, F17S). We then examined their impact on the analogues' biological activities and found that a G31P substitution rendered CXCL8((3-73))K11R a high affinity antagonist of CXCL8/IL-8. The ranking (in the order of decreasing CXCL8/IL-8 antagonist activities) of the CXCL8((3-73))K11R analogues we generated was, G31P>T12S/G31P>H13F/G31P>T12S/H13F/G31P>P32G approximately T12S/P32G approximately H13F/P32G>T12S/H13F/P32G; CXCL8((3-73))K11R/F17S did not inhibit CXCL8/IL-8-dependent responses. CXCL8((3-73))K11R/G31P had no discernible agonist (beta-glucuronidase release, chemotactic) activity, but at 12.5 ng/ml it bound to purified neutrophils more avidly than did 1.25 microg/ml CXCL8/IL-8. Furthermore, CXCL8((3-73))K11R/G31P competitively antagonized the binding of CXCR1- and CXCR2-specific antibodies to these receptors. Taken together, these data thus provide further impetus to the study of the potential efficacy of CXCL8((3-73))K11R/G31P as a broad-spectrum antagonist of the ELR-CXC chemokines in experimental and clinical settings.     

N2-benzyl-N1-(1-(1-naphthyl)ethyl)-3-phenylpropane-1,2-diamines and conformationally restrained indole analogues: development of calindol as a new calcimimetic acting at the calcium sensing receptor

The synthesis and calcimimetic activities of two new families of compounds are described. The most active derivatives of the first family, N(2)-(2-chloro-(or 4-fluoro-)benzyl)-N(1)-(1-(1-naphthyl)ethyl)-3-phenylpropane-1,2-diamine (4b and 4d, respectively, tested at 10 microM) produced 98+/-6% and 95+/-4%, respectively, of the maximal stimulation of [(3)H]inositol phosphates production obtained by 10mM Ca(2+) in CHO cells expressing the rat calcium sensing receptor (CaSR). The second family of calcimimetics was obtained by conformationally restraining the compounds of type 4 to provide the 2-aminomethyl derivatives 5. One of these compounds, (R)-2-[N-(1-(1-naphthyl)ethyl)aminomethyl]indole ((R)-5a, calindol), displayed improved calcimimetic activity compared to 4b and 4d as well as stereoselectivity. In the presence of 2mM Ca(2+), calindol stimulated [(3)H]inositol phosphates accumulation with an EC(50) of 1.0+/-0.1 or 0.31+/-0.05 microM in cells expressing the rat or the human CaSR, respectively. The calcimimetic activities of these novel compounds were shown to be due to a specific interaction with the CaSR.     

Influence of growth temperature and lipopolysaccharide on hemolytic activity of Serratia marcescens.

Log-phase cells of Serratia marcescens cultured at 30 degrees C were approximately 10-fold more hemolytic than those grown at 37 degrees C. By using a cloned gene fusion of the promoter-proximal part of the hemolysin gene (shlA) to the Escherichia coli alkaline phosphatase gene (phoA), hemolysin gene expression as a function of alkaline phosphatase activity was measured at 30 and 37 degrees C. No difference in alkaline phosphatase activity was observed as a function of growth temperature, although more hemolysin was detectable immunologically in whole-cell extracts of cells grown at 30 degrees C. The influence of temperature was, however, growth phase dependent, because the hemolytic activities of cells cultured to early log phase at 30 and 37 degrees C were comparable. Given the outer membrane location of the hemolysin, lipopolysaccharide (LPS) was examined as a candidate for mediating the temperature effect on hemolytic activity. Silver staining of LPS in polyacrylamide gels revealed a shift towards shorter O-antigen molecules at 37 degrees C relative to 30 degrees C. Moreover, there was less binding of O-antigen-specific bacteriophage to S. marcescens with increasing growth temperature, a finding consistent with temperature-mediated changes in LPS structure. Smooth strains of S. marcescens were 20- to 30-fold more hemolytic than rough derivatives, a result confirming that changes in LPS structure can influence hemolytic activity. The alkaline phosphatase activity of rough strains harboring the shlA-phoA fusion was threefold lower than that of smooth strains harboring the fusion plasmids, a result consistent with a decrease in hemolysin gene expression in rough strains. The absence of a similar effect of temperature on gene expression may be related to less-marked changes in LPS structure as a function of temperature compared with a smooth-to-rough mutational change.