Synthesis and anti-Trypanosoma cruzi activity of derivatives from nor-lapachones and lapachones

New naphthoquinone derivatives were synthesized and assayed against bloodstream trypomastigote forms of Trypanosoma cruzi, the etiological agent of Chagas’ disease. The compounds were rationalized based on hybrid drugs and appear as important compounds against this parasite. From nor-lapachol were prepared five substituted ortho-naphthofuranquinones, a non-substituted para-naphthofuranquinone, a new oxyrane and an azide and from -lapachone a new non-substituted para-naphthofuranquinone. Other five substituted ortho-naphthofuranquinones recently designed as cytotoxic, were also evaluated. The most active compounds were the ortho naphthofuranquinones 3-(4-methoxyphenylamino)-2,3-dihydro-2,2-dimethylnaphtho[1,2-b]furan-4,5-dione and 3-(3-nitrophenylamino)-2,3-dihydro-2,2-dimethylnaphtho[1,2-b]furan-4,5-dione with trypanocidal activity higher than that of benznidazole, the standard drug. The compounds were rationalized based on hybrid drugs and appear as important compounds against T. cruzi. The trypanocidal activity of these substances endowed with redox properties representing a good starting point for a medicinal chemistry program aiming the chemotherapy of Chagas’ disease.     

Antibacterial effect of some 2,6-disubstituted 4-anilinoquinazolines

Two synthetic 2,6-disubstituted 4-anilinoquinazolines exerted a significant effect on the G⁺ bacteriaBacillus subtilis andStaphylococcus aureus. None of 12 tested derivatives influencedEscherichia coli, Proteus mirabilis andPseudomonas aeruginosa. Derivatives having the aromatic ring non-substituted or substituted by bromine, the pyrimidine ring by phenyl, morpholine or piperidine and the aniline skeleton non-substituted or substituted by methyl or amino group exterted a considerable antibacterial activity.     

Direct semi-synthesis of the anticancer lead-drug protoapigenone from apigenin, and synthesis of further new cytotoxic protoflavone derivatives

Protoapigenone, a natural flavonoid possessing an unusual p-quinol moiety on its B-ring, is a novel prospective anticancer agent with low toxicity that is currently in development. The first economical, one-step synthesis of protoapigenone from apigenin is described on up to gram scale. 13 new 1'-O-alkylflavone analogs were also synthesized, either from apigenin or β-naphthoflavone. The in vitro cytotoxic activity of each compound was tested on six human cancer cell lines (HepG2, Hep3B, Ca9-22, A549, MCF-7 and MDA-MB-231). In the case of 1'-O-alkyl-protoapigenone derivatives, structure-activity relationships were found depending on the side-chain, and protoapigenone 1'-O-butyl ether was found to exert significantly stronger activity against three of the cell lines (Hep3B, MCF-7 and MDA-MB-231) than its non-substituted analog, protoapigenone itself. In contrast to this, all β-naphthoflavone derivatives bearing the same pharmacophore on their B-ring showed decreased cytotoxic activities when substituted with an O-alkyl side-chain at position 1', comparing to that of the non-substituted compound.     

Chondroitin sulphate modification in the alpha4 chain of human recombinant laminin-8 (alpha4beta1gamma1).

We have produced human laminin-8 (alpha4beta1gamma1) using recombinant technology. Approximately half of the recombinant laminin-8 (rLN-8) molecules were found to have a chondroitin sulphate modification in the alpha4 chain. The substituted and non-substituted forms were separated and tested for cell adhesion activity. Lower cell adhesion promoting activity was seen for the substituted form, but the integrin receptor utilization was similar. We also found the human rLN-8 to behave identically in cell adhesion assays compared to a human/mouse hybrid variant of rLN-8.     

Syntheses of N3-substituted thymine acyclic nucleoside phosphonates and a comparison of their inhibitory effect towards thymidine phosphorylase

A series of N(3)-substituted thymine acyclic nucleoside phosphonates bearing a number of (phosphonomethoxy)alkyl groups were synthesized and investigated for their ability to inhibit the human thymidine phosphorylase expressed in V79 Chinese hamster cells, as well as thymidine phosphorylase from SD-lymphoma, Escherichia coli and human placenta. In comparison to N(1)- substituted analogues which possess a considerable inhibitory activity towards thymidine phosphorylase from SD-lymphoma, the results showed a marginal inhibitory effect of these compounds. None of the presented N(3)-substituted derivatives possess a significant cytostatic activity.     

Carnosine as a stimulator of cytotoxic and phagocytic function of peritoneal macrophages]

Biochemical changes in peritoneal macrophages and their relatedness to the cytostatic and phagocytotic function in C3HA mice injected with a single intraperitoneal dose of 0.45 mM carnosine and 4-methyluracil or stimulated with peptone have been studied. During the first 24 hours after injection both carnosine and 4-methyluracil increase the activity of adenosine deaminase and purine nucleoside phosphorylase, the key enzymes of purine catabolism which is the main source of O2-. radicals in macrophages. In carnosine-stimulated macrophages the activity of membrane 5'-AMP nucleotidase decreases on days 1-3 after injection which points to alleviation of adenosine-induced inhibition as well as to macrophage activation. Carnosine increases the cytostatic and phagocytotic activities of macrophage coupled to O2-. production. The mechanism of the stimulating effect of carnosine on macrophages seems to consist in the dipeptide interaction with specific receptors localized on the plasma membrane of macrophagal cells.     

Studies on the interfacial behavior of DPPC/DPPG mixed monolayers in the presence of fluoxetine

A series of non-substituted 1,3,5-triaryl-2-pyrazolines and pyrazolines substituted with Fluoro (-F), Chloro (-Cl) and Bromo (-Br) groups at the 3-aryl pos     

Synthesis of novel antimitotic agents based on 2-amino-3-aroyl-5-(hetero)arylethynyl thiophene derivatives

Microtubules are dynamic structures that play a crucial role in cellular division and are recognized as an important target for cancer therapy. In search of new compounds with strong antiproliferative activity and simple molecular structure, a new series of 2-amino-3-(3′,4′,5′-trimethoxybenzoyl)-5-(hetero)aryl ethynyl thiophene derivatives was prepared by the Sonogashira coupling reaction of the corresponding 5-bromothiophenes with several (hetero)aryl acetylenes. When these compounds were analyzed in vitro for their inhibition of cell proliferation, the 2- and 3-thiophenyl acetylene derivatives were the most powerful compounds, both of which exerted cytostatic effects at submicromolar concentrations. In contrast, the presence of a more flexible ethyl chain between the (hetero)aryl and the 5-position of the thiophene ring resulted in significant reduction in activity relative to the 5-(hetero)aryl acetylene substituted derivatives. The effects of a selected series of compounds on cell cycle progression correlated well with their strong antiproliferative activity and inhibition of tubulin polymerization. We found that the antiproliferative effects of the most active compounds were associated with increase of the proportion of cells in the G₂/M and sub-G₁ phases of the cell cycle.     

A linear correlation between energy of LMCT band and oxygenation reaction rate of a series of catecholatoiron(III) complexes: initial oxygen binding during intradiol catechol oxygenation

The oxygen reactivity of catecholatoiron(III) complexes has been examined using a series of catecholate ligands as the substrate. All the complexes examined here, [Fe(III)(TPA)(R-Cat)]BPh(4) (1-9) (TPA: tris(pyridin-2-ylmethyl)amine; R-Cat: substituted catecholate ligand, R=3,5-(t)Bu(2) (1), 3,6-(t)Bu2 (2), 3,5-Me2 (3), 3,6-Me2 (4), 4-(t)Bu (5), 4-Me (6), H (7), 4-Cl (8) and 3-Cl (9)), exclusively afforded the intradiol cleaving products of the catecholate ligands upon exposure to O2. It was revealed that 1-7 can be categorized into two classes based on their electrochemical properties; i.e., the complexes having the dialkyl-substituted (group A) and the mono- or non-substituted (group B) catecholate ligands. In spite of their classification, these two groups show a linear correlation between the logarithm of the reaction rate constant with O2 and the energy of the catecholate-to-iron(III) LMCT band, although 2 shows a large negative deviation from the correlation line. Based on this LMCT-energy dependent reactivity of 1 and 3-9 as well as the very low reactivity of 2, we have discussed on the mechanisms of the reaction of [Fe(III)(TPA)(R-Cat)]BPh4 with O2.     

New bis(thiosemicarbazonate) gold(III) complexes inhibit HIV replication at cytostatic concentrations: potential for incorporation into virostatic cocktails

Four bis(thiosemicarbazonate)gold(III) complexes (1-4) with a general formula [Au(L)]Cl {L = L1, glyoxal-bis(N⁴-methylthiosemicarbazone); L2, glyoxal-bis(N⁴-ethylthiosemicarbazone); L3, diacetyl-bis(N⁴-methylthiosemicarbazone); L4, diacetyl-bis(N⁴-ethylthiosemicarbazone)} were synthesised and screened for activity against the human immunodeficiency virus (HIV). Complexes 1-4 were characterised using ¹H-NMR and IR spectroscopy; and their purity established by micronanalysis. Complex 3 inhibited viral infection of TZM-bl cells by 98% (IC₅₀ = 6.8 ± 0.6 μM) at a non toxic concentration of 12.5 μM while complex 4 inhibited infection of these cells by 72 and 98% (IC₅₀ = 5.3 ± 0.4 μM) at concentrations of 6.25 and 12.5 μM respectively. The mechanism of inhibition of infection in TZM-bl cells is presumably as a result of the cytostatic or anti-proliferative activity that was observed for complex 4 in real time cell electronic sensing (RT-CES) and carboxyflourescein succinimidyl ester (CFSE) analysis. Treatment of T lymphocytes from HIV infected individuals with 4 decreased CD4+ T cell expression (p = 0.0049) as demonstrated by multi-parametric flow cytometry without suppressing cytokine production. None of the ligands (L1-L4) demonstrated anti-viral activity, supporting the importance of metal (gold) complexation in these potential drugs. Complexes 3 and 4 were shown to have ideal lipophilicity values that were similar when shake flask (0.97 ± 0.5 and 2.42 ± 0.6) and in silico prediction (0.8 and 1.5) methods were compared. The activity and drug-like properties of complexes 3 and 4 suggests that these novel metal-based compounds could be combined with virus inhibitory drugs to work as cytostatic agents in the emerging class of anti-HIV drugs known as virostatics.     

Leukotriene C4 is an essential 5-lipoxygenase intermediate in A23187-induced macrophage cytostatic activity against P815 tumor cells

Resident peritoneal macrophages incubated with 3.5 x 10(-7) M Calcium ionophore A23187 in tumor cell growth medium (TGM) release large amounts of leukotriene (LT)E4 and an unidentified 5-lipoxygenase product, whereas A23187-stimulated macrophages produce in serum free medium LTD4, predominately. LTC4 and 3H-LTC4 incubated for 20 min at 37 degree C in serum containing TGM, convert into LTE4 and 3H-LTE4, respectively. Thus, LTC4 released from A23187-stimulated macrophages is an intermediate in TGM which rapidly converts into LTE4, probably because of the presence of gamma-glutamyl transpeptidase and cystenylglycinase in TGM. Macrophages express antitumor cytostatic activity towards P815 cells (49-53%) in a cocultured ratio (macrophage: tumor cell) 2:1 when stimulated with 3.5 x 10(-7) M A23187 in TGM. The 5-lipoxygenase inhibitor AA861 reverses the cytostatic activity by 42-58% and it inhibits also the formation of A23187-induced 5-lipoxygenase products from macrophages. Restoration of 38% macrophage- antitumor cytostatic activity by exogenous LTC4 (10(-8) M) indicates that LTC4 is an essential 5-lipoxygenase intermediate in the pathway of required signals underlying A23187-induced macrophage antitumor cytostatic activity. Macrophages not stimulated by A23187 do not express cytostatic activity in the presence of LTC4. This implies that besides LTC4, increased cytosolic [Ca2+] is required for A23187 induction of macrophage cytostatic activity.     

Cytostatic action of the peritoneal cells of Syrian hamsters on transformed cells

The cytostatic effect (CSE) of intact Syrian hamster peritoneal cells (PC) was determined by their capability to inhibit 3H-thymidine incorporation in target cells of HETR, which were placed in 1 X 10(4) or 4 X 10(4) cells per well together with 4 tenfold differing concentrations of PC (10(2)-10(5]. The optimum of CSE was seen with the use of maximal doses of PC and HETR in reaction. Maximal level of CSE with all effector-target cell rations was observed between 23-28 hours of contact. These data permit to suggest the role of HETR cells in activation of PC, as well as the transfer of cytostatic state in dense cell shift mediated by cell-cell contacts. The role of humoral cytostatic factor is also not excluded.     

Synthesis and in vitro antitumor evaluation of some indeno[1,2-c]pyrazol(in)es substituted with sulfonamide, sulfonylurea(-thiourea) pharmacophores, and some derived thiazole ring systems

The synthesis of a series of 3-(4-chlorophenyl)-[1,2-c]pyrazol(in)es substituted with benzenesulfonamide, N1,N3-disubstituted sulfonylurea, sulfonylthiourea pharmacophores, and some derived thiazolidinone and thiazoline ring systems is described. All the newly synthesized target compounds were subjected to the NCI-in vitro disease-oriented antitumor screening to be evaluated for their antitumor activity. Eight compounds namely; 2-4, 7, 8, 10, 13, and 16; showed promising broad spectrum antitumor activity against most of the tested subpanel tumor cell lines (GI50 < 100 microM). Compound 3, 4-(3-(4-chlorophenyl)-4H-indeno[1,2-c]pyrazol- 2-yl)-benzenesulfonamide; although it did not show the highest growth inhibitory value (GI50 (MG-MID) 13.2 microM), it proved to be the most active analog in this study with the highest cytostatic and cytotoxic potentials (TGI and LC50 (MG-MID) concentrations of 33.1 and 66.1 microM, respectively). In general, the oxidized pyrazoles displayed better antitumor activity than their parent pyrazoline analogs, whereas the benzenesulfonamides and the N1, N3-disubstituted sulfonylureas showed significant better antitumor spectrum than the sulfonylthioureido and the derived thiazole analogs.     

Cytostatic activity of novel 4'-aminochalcone-based imides

A series of nine 1-(4-((E)-3-arylacryloyl)phenyl)-1H-pyrrole-2,5-diones 3a-i (4'-aminochalcone-based maleimides) was synthesized as candidate cytotoxic agents. The efficacy of these potential cytotoxics were evaluated against three representative cell lines and more than half of the drug candidates proved to exhibit significant cytostatic activity in vitro. QSAR studies using statistical analyses on several physicochemical parameters and IC50 values resulted in a few very important correlations which will aid in later the amplification of the project. Representative test compounds were well tolerated by mice in in vivo survival and toxicity studies.     

Chemical reactivity and antimicrobial activity of N-substituted maleimides

Several N-substituted maleimides containing substituents of varying bulkiness and polarity were synthesised and tested for antimicrobial and cytostatic activity. Neutral maleimides displayed relatively strong antifungal effect minimum inhibitory concentrations (MICs in the 0.5-4 μg ml(-1) range); their antibacterial activity was structure dependent and all were highly cytostatic, with IC(50) values below 0.1 μg ml(-1). Low antimicrobial but high cytostatic activity was noted for basic maleimides containing tertiary aminoalkyl substituents. Chemical reactivity and lipophilicity influenced antibacterial activity of neutral maleimides but had little if any effect on their antifungal and cytostatic action. N-substituted maleimides affected biosynthesis of chitin and β(1,3)glucan, components of the fungal cell wall. The membrane enzyme, β(1,3)glucan synthase has been proposed as a putative primary target of N-ethylmaleimide and some of its analogues in Candida albicans cells.     

Utilization of 1,3-Dioxolanes in the Synthesis of α-branched Alkyl and Aryl 9-[2-(Phosphonomethoxy)Ethyl]Purines and Study of the Influence of α-branched Substitution for Potential Biological Activity

Syntheses of α-branched alkyl and aryl substituted 9-[2-(phosphonomethoxy)ethyl]purines from substituted 1,3-dioxolanes have been developed. Key synthetic precursors, α-substituted dialkyl [(2-hydroxyethoxy)methyl]phosphonates were prepared via Lewis acid mediated cleavage of 1,3-dioxolanes followed by reaction with dialkyl or trialkyl phosphites. The best preparative yields were achieved under conditions utilizing tin tetrachloride as Lewis acid and triisopropyl phosphite. Attachment of purine bases to dialkyl [(2-hydroxyethoxy)methyl]phosphonates was performed by Mitsunobu reaction. Final α-branched 9-[2-(phosphonomethoxy)ethyl]purines were tested for antiviral, cytostatic and antiparasitic activity, the latter one determined as inhibitory activity towards Plasmodium falciparum enzyme hypoxanthine-guanine-xanthine phosphoribosyltransfesase. In most cases biological activity was only marginal.     

Design,synthesis and biological evaluation of N2,N4-disubstituted-1,1,3-trioxo-2H,4H-pyrrolo[1,2-b][1,2,4,6]thiatriazine derivatives as HIV-1 NNRTIs

A series of N₂,N₄-disubstituted-1,1,3-trioxo-2H,4H-pyrrolo[1,2-b][1,2,4,6]thiatriazine derivatives (PTTDs) was designed and synthesized by a facile route. The biological assay results showed that five most potent compounds displayed inhibitory activity against HIV-1 at low micromolar concentrations (EC₅₀ = 5.1–8.9 μM). Structure–activity relationship analysis indicated that N₂-(3-halogenated-benzyl) analogues were more potent than N₂-(unsubstituted-benzyl) analogues. The N₄-substitutions contributed to the antiviral activity in the following order: 2-/3-cyano substituted benzyl > 2-/3-halogenated benzyl > non-substituted benzyl > 4-halogenated benzyl. Docking studies of the representative compound revealed the binding conformation of these compounds and provided critical insights for the further development of PTTD analogues.     

Synthesis, spectral properties, and antitumor activity of a new axially substituted phthalocyanine complex of zirconium(IV) with citric acid

The new axially substituted phthalocyanine (pc) complex of zirconium(IV) with citric acid is reported. It has been shown that the replacement of two Cl-atoms with two citric acid fragments takes place as the result of the reaction between [ZrCl2(pc)] and citric acid. The complex [Zr(citrate)2(pc)] was formed. The spectroscopic properties of the synthesized compound in DMSO, RPMI 1640 medium with and without fetal calf serum (FCS), H2O, and buffer (Tris) solutions have been described. Antitumor activity of this compound has been studied. The cytostatic activity was observed in the concentration range of 6.1-9.0x10(9) molecules [Zr(citrate)2(pc)]/cell and occurred in 4-6 h after treatment with [Zr(citrate)2(pc)] solution.     

Macrophage-mediated cytostatic activity blocks lymphoblast cell cycle progression independently in both G1 phase and S phase

Recent work has shown that macrophage-mediated cytostatic activity inhibits cell cycle traverse in G1 and/or S phase of the cell cycle without affecting late S, G2, or M phases. The present report is directed at distinguishing between such cytostatic effects on G1 phase or S phase using the accumulation of DNA polymerase alpha as a marker of G1 to S phase transition. Quiescent lymphocytes stimulated with concanavalin A undergo a semisynchronous progression from G0 to G1 to S phase with a dramatic increase in DNA polymerase alpha activity between 20 and 30 hr after stimulation. This increase in enzyme activity was inhibited, as was the accumulation of DNA, when such cells were cocultured with activated murine peritoneal macrophages during this time interval. However, if mitogen-stimulated lymphocytes were enriched for S-phase cells by centrifugal elutriation and cocultured with activated macrophages for 4-6 hr, DNA synthesis was inhibited but the already elevated DNA-polymerase activity was unaffected. Similar results were obtained when a virally transformed lymphoma cell line was substituted as the target cell in this assay. These results show that both G1 and S phase of the cycle are inhibited and suggest that inhibition of progression through the different phases may be accomplished by at least two distinct mechanisms.     

Synthesis and properties of new rubomycin derivatives

Condensation of rubomycin (daunorubicin) with respective hydrazides yielded novel substituted hydrazones: 13-cyanoacetyl hydrazone rubomycin, 13-L-phenylalanyl hydrazone rubomycin, 13-BOC-3-(uracilyl-1)-DL-alanyl hydrazone rubomycin and 13-BOC-3-(adenylyl-9)-DL-alanyl hydrazone rubomycin. With successive treatment of rubomycin with hydrazine hydrate and respective ketones novel asymmetric azines were prepared: 13-cyclopentylidene hydrazone rubomycin, 13-alpha,alpha'-dimethyl-cyclopentylidene hydrazone rubomycin and 13-(1-phenylethylidene-1) hydrazone rubomycin. 14-Adenylyl-N9-rubomycin was synthesized by interaction of 14-bromorubomycin with adenine and hydrogenation of its analog, 14-N-imidazolyl rubomycin by sodium borhydrite yielded 13-dihydro-14-N-imidazolyl rubomycin. There was observed correlation between the antimicrobial activity of the derivatives against B. mycoides and their cytostatic effect on the cells of murine leukemia NK/LI. The high in vitro activity of 13-cyclopentylidene hydrazone rubomycin showed satisfactory correlation with the results of the study on the antitumor effect in animals.