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N -(Alkoxyphenyl)-2-hydroxynaphthalene-1-carboxamides (series A) and N -(alkoxyphenyl)-1-hydroxynaphthalene-2-carboxamides (series B) affecting photosystem (PS) II inhibited photosynthetic electron transport (PET) in spinach chloroplasts. Their inhibitory activity depended on the compound lipophilicity as well as on the position of the alkoxy substituent. The most potent PET inhibitors were 2-hydroxy- N -phenylnaphthalene-1-carboxamide and N -[3-(but-2-yloxy)phenyl]-2-hydroxynaphthalene-1-carboxamide within series A (IC 50 = 28.9 and 42.5 µM, respectively) and 1-hydroxy- N -(3-propoxyphenyl)naphthalene-2-carboxamide and 1-hydroxy- N -(3-ethoxyphenyl)-naphthalene-2-carboxamide (IC 50 = 2.0 and 3.1 µM, respectively) within series B. The inhibitory activity of C′ (3) or C′ (4) alkoxy substituted compounds of series B was considerably higher than that of C′ (2) ones within series A. The PET-inhibiting activities of both series were compared with the PET inhibition of isomeric N -alkoxyphenyl-3-hydroxynaphthalene-2-carboxamides (series C) reported recently. Interactions of the studied compounds with chlorophyll a and aromatic amino acids present in pigment–protein complexes mainly in PS II were documented by fluorescence spectroscopy. The section between P 680 and plastoquinone Q B in the PET chain occurring on the acceptor side of PS II can be suggested as the site of action of the compounds.

Presented study evaluates effects of various Sb(III) concentrations on tomato plants (Solanum lycopersicum) cultivated hydroponically. Visual symptoms of antimony toxicity were observed only at two highest applied concentrations (50 and 100 mg/L). Dry weight of aboveground parts decreased significantly in variants treated with 25, 50 and 100 mg/L Sb(III), by ~12, 35 and 65 %, respectively, in comparison to the control. Statistically significant decrease of chlorophyll a and b was observed only after application of two highest studied concentrations 50 and 100 mg/L Sb(III). On the other hand concentration of total carotenoids in leaves rose with increasing external Sb(III) concentration. High concentrations (50 and 100 mg/L) of Sb(III) in nutrient solution caused that protein content in leaves dropped by ~20 and 39% relative to control. Accumulation of antimony in roots was about 5- (10 mg/L) to 27-times (25 mg/L) greater than that in shoots. The highest BAF factor value determined for shoots was ~55 at 10 mg/L Sb(III) and for roots it was ~821 at 50 mg/L Sb(III). Translocation factor values were in whole studied concentration range 5 – 100 mg/L Sb(III) < 1. The most effective translocation of antimony from roots to shoots was observes for variants treated with 10 mg/L of Sb(III).

Eight 1-[(2-chlorophenyl)carbamoyl]naphthalen-2-yl alkylcarbamates and eight 1-[(2-nitrophenyl)carbamoyl]naphthalen-2-yl alkylcarbamates were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The PET-inhibiting activity of the compounds was relatively low; the corresponding IC50 values ranged from 0.05 to 0.664 mmol/L; and the highest activity within the series of compounds was observed for 1-[(2-chlorophenyl)-carbamoyl]naphthalen-2-yl propylcarbamate. It has been proven that the compounds are PET-inhibitors in photosystem II. Despite rather low PET-inhibiting activities, primary structure-activity trends can be discussed.

Series of ten N-substituted 2-(aminoethyl)-6-fluorobenzothiazoles inhibited photosynthetic electron transport in spinach chloroplasts. The inhibitory activity linearly increased with hydrophobic contributions (expressed as hydrophobic constants π) and molar volumes of individual substituents in C(2) position of 6-fluorobenzothiazole scaffold to the optima π ca. 2 and MV ca. 233 cm3, while for more lipophilic and/or bulkier derivatives PET inhibiting activity linearly decreased. The site of inhibitory action of the tested compounds is situated on the donor side of photosystem II, and interaction of these compounds with aromatic amino acid residues in photosynthetic proteins was confirmed by fluorescence spectroscopy. Synthesis and characterization of five new Nα-(alkoxycarbonyl)-N-[(1R)-1-(6-fluoro-1,3-benzothiazol-2-yl)ethyl]-l-phenylalaninamides is presented as well.

Adverse effect of nickel on hydroponically cultivated plants of two Brasssica napus L. cultivars (Verona and Viking) was investigated. Dry mass of shoots and roots as well as some biochemical characteristics (concentration of photosynthetic pigments, TBARS and proteins) of plant leaves were determined. In addition, the content of nickel in plant organs was estimated. Visible symptoms of Ni toxicity were notable already at the lowest applied concentration (6 μmol · dm-3). Higher applied Ni concentrations (24, 60 and 120 μmol · dm-3) resulted in moderate to strong toxic effects on plants of both studied cultivars. After application of 6 and 12 μmol · dm-3 Ni shoot dry mass of cv. Viking was substantial lower than that of cv. Verona. Decrease of root dry mass after treatment with 6, 12 and 120 μmol · dm-3 Ni was similar for both cultivars. Strong decrease in content of photosynthetic pigments was observed after application of 120 μmol · dm-3. Comparing to the control, the content of these pigments in leaves of plants dropped under 50% (both cultivars). The highest applied Ni concentration 120 μmol · dm-3 caused that protein content in leaves dropped by 39% (cv. Verona) and 37% (cv. Viking) comparing to the control plants. After application of 120 μmol · dm-3 Ni the content of malondialdehyde in leaves was 2.64- (Viking) and 2.31- (Verona) times higher than that of control. Nickel amounts accumulated in roots of plants were higher than those in shoots. Accumulated Ni amounts in roots of cv. Verona plants were 1.3- (120 μmol · dm-3) to 1.9- (6 μmol · dm-3) times lower than those of cv. Viking plants, whereas metal amounts accumulated in shoots of cv. Verona plants were 1.2- (120 μmol · dm-3) to 1.8- (6 μmol · dm-3) times lower than those of cv. Viking plants.

In this work a series of 15 N-benzylamine substituted 5-amino-6-methyl-pyrazine-2,3-dicarbonitriles was prepared by the aminodehalogenation reactions using microwave assisted synthesis with experimentally set and proven conditions. This approach for the aminodehalogenation reaction was chosen due to its higher yields and shorter reaction times. The products of this reaction were characterized by IR, NMR and other analytical data. The compounds were evaluated for their antibacterial, antifungal and herbicidal activity. Compounds 3 (R = 3,4-Cl), 9 (R = 2-Cl) and 11 (R = 4-CF3) showed good antimycobacterial activity against Mycobacterium tuberculosis (MIC = 6.25 µg/mL). It was found that the lipophilicity is important for antimycobacterial activity and the best substitution on the benzyl moiety of the compounds is a halogen or trifluoromethyl group according to Craig’s plot. The activities against bacteria or fungi were insignificant. The presented compounds also inhibited photosynthetic electron transport in spinach chloroplasts and the IC50 values of the active compounds varied in the range from 16.4 to 487.0 µmol/L. The most active substances were 2 (R = 3-CF3), 3 (R = 3,4-Cl) and 11 (R = 4-CF3). A linear dependence between lipophilicity and herbicidal activity was observed.

Using model lead compounds Pb(NO3)2 and Pb(CH3CHOO)2, the mechanism and the site of action of Pb2+ ions in the photosynthetic apparatus of spinach chloroplasts were studied. Both compounds inhibited photosynthetic electron transport (PET) through photosystem 1 (PS1) and photosystem 2 (PS2), while Pb(NO3)2 was found to be more effective PET inhibitor. Using EPR spectroscopy the following sites of Pb2+ action in the photosynthetic apparatus were determined: the water-splitting complex and the Z•/D• intermediates on the donor side of PS2 and probably also the ferredoxin on the acceptor side of PS1, because cyclic electron flow in chloroplasts was impaired by treatment with Pb2+ ions. Study of chlorophyll fluorescence in suspension of spinach chloroplasts in the presence of Pb2+ ions confirmed their site of action in PS2. Using fluorescence spectroscopy also formation of complexes between Pb2+ and amino acid residues in photosynthetic proteins was confirmed and constants of complex formation among Pb2+ and aromatic amino acids were calculated for both studied lead compounds.

A series of twelve 2-[(E)-2-substituted-ethenyl]-1,3-benzoxazoles was designed. All the synthesized compounds were tested against three mycobacterial strains. The compounds were also evaluated for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleraceaL.) chloroplasts. 2-[(E)-2-(4-Methoxyphenyl)ethenyl]-1,3-benzoxazole, 2-[(E)-2-(2,3-dihydro-1-benzofuran-5-yl)ethenyl]-1,3-benzoxazole and 2-{(E)-2-[4-(methylsulfanyl)phenyl]ethenyl}-1,3-benzoxazole showed the highest activity againstM. tuberculosis,M. kansasii,andM. avium, and they demonstrated significantly higher activity againstM. aviumandM. kansasiithan isoniazid. The PET-inhibiting activity of the most activeortho-substituted compound 2-[(E)-2-(2-methoxyphenyl)ethenyl]-1,3-benzoxazole was IC50= 76.3 μmol/L, while the PET-inhibiting activity ofpara-substituted compounds was significantly lower. The site of inhibitory action of tested compounds is situated on the donor side of photosystem II. The structure-activity relationships are discussed.

In this study, a series of twenty-two ring-substituted 2-hydroxynaphthalene-1‑carboxanilides were prepared and characterized. Primary in vitro screening of the synthesized compounds was performed against Staphylococcus aureus, three methicillin-resistant S. aureus strains, Mycobacterium marinum, M. kasasii, M. smegmatis. and M. avium paratuberculosis. The compounds were also tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. 2-Hydroxy-N-phenylnaphthalene-1-carboxanilide and 2-hydroxy-N-(3-trifluoromethylphenyl)naphthalene-1-carboxamide (IC50 = 29 µmol/L) were the most active PET inhibitors. Some of tested compounds showed the antibacterial and antimycobacterial activity against the tested strains comparable or higher than the standards ampicillin or isoniazid. Thus, for example, 2-hydroxy-N-(3-nitrophenyl)naphthalene-1-carboxamide showed MIC = 26.0 µmol/L against methicillin-resistant S. aureus and MIC = 51.9 µmol/L against M. marinum, or 2-hydroxy-N-phenylnaphthalene-1-carboxamide demonstrated MIC = 15.2 µmol/L against M. kansasii. The structure-activity relationships for all compounds are discussed.

Ring-substituted 8-hydroxyquinoline-2-carboxanilides inhibited photosynthetic electron transport (PET) through photosystem (PS) II. Their inhibitory efficiency depended on the compound lipophilicity, the electronic properties of the substituent R and the position of the substituent R on the benzene ring. The most effective inhibitors showing IC 50 values in the range 2.3–3.6 μM were substituted in C′ (3) by F, CH 3 , Cl and Br. The dependence of the PET-inhibiting activity on the lipophilicity of the compounds was quasi-parabolic for 3-substituted derivatives, while for C′ (2) ones a slight increase and for C′ (4) derivatives a sharp decrease of the activity were observed with increasing lipophilicity. In addition, the dependence of PET-inhibiting activity on electronic Hammett’s σ parameter of the substituent R was observed with optimum σ value 0.06 for C′ (4) and 0.34 for C′ (3) substituted derivatives, while the value of σ parameter did not significantly influence the PET-inhibiting activity of C′ (2) substituted compounds. Interactions of the studied compounds with chlorophyll a and aromatic amino acids present in the pigment–protein complexes mainly in PS II were documented by fluorescence spectroscopy. The section between P680 and plastoquinone Q B occurring on the acceptor side of PS II can be suggested as the site of action of the compounds.

In this study, a series of N-substituted 2-aminobenzothiazoles was prepared according to a recently developed method. Twelve compounds were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the discussed compounds was also performed against fungal, bacterial and mycobacterial species. The biological activities of some compounds were comparable or higher than the standards phenoxymethylpenicillin or pyrazinamide. The most effective compounds demonstrated insignificant toxicity against the human monocytic leukemia THP-1 cell line. For all compounds, the structure-activity relationships are discussed.

Two series of thiosemicarbazone-based iron chelators (twenty-seven compounds) were designed and synthesized using a microwave-assisted approach. Quinoline and halogenated phenyl were selected as parent scaffolds on the basis of a similarity search. The lipophilicity of the synthesized compounds was measured using HPLC and then calculated. Primary in vitro screening of the synthesized compounds was performed against eight pathogenic fungal strains. Only a few compounds showed moderate activity against fungi, and (E)-2-(quinolin-2-ylvinyl)-N,N-dimethylhydrazine-carbothioamide appeared to be more effective than fluconazole against most of the fungal strains tested. Antiproliferative activity was measured using a human colon cancer cell line (HCT-116). Several of the tested compounds showed submicromolar antiproliferative activity. Compounds were also tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The structure-activity relationships are discussed for all of the compounds.

A series of twelve amides was synthesized via aminolysis of substituted pyrazinecarboxylic acid chlorides with substituted benzylamines. Compounds were characterized with analytical data and assayed in vitro for their antimycobacterial, antifungal, antibacterial and photosynthesis-inhibiting activity. 5-tert-Butyl-6-chloro-N-(4-methoxybenzyl)pyrazine-2-carboxamide (12) has shown the highest antimycobacterial activity against Mycobacterium tuberculosis (MIC = 6.25 µg/mL), as well as against other mycobacterial strains. The highest antifungal activity against Trichophyton mentagrophytes, the most susceptible fungal strain tested, was found for 5-chloro-N-(3-trifluoromethylbenzyl)-pyrazine-2-carboxamide (2, MIC = 15.62 µmol/L). None of the studied compounds exhibited any activity against the tested bacterial strains. Except for 5-tert-butyl-6-chloro-N-benzylpyrazine-2-carboxamide (9, IC50 = 7.4 µmol/L) and 5-tert-butyl-6-chloro-N-(4-chlorobenzyl)pyrazine-2-carboxamide (11, IC50 = 13.4 µmol/L), only moderate or weak photosynthesis-inhibiting activity in spinach chloroplasts (Spinacia oleracea L.) was detected.

A series of rhodanine derivatives was prepared. The synthetic approach, analytical and spectroscopic data of all synthesized compounds are presented. Lipophilicity of all the discussed rhodanine derivatives was analyzed using the RP-HPLC method. The compounds were tested for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts and reduce chlorophyll content in freshwater alga Chlorella vulgaris. Structure-activity relationships between the chemical structure, physical properties and biological activities of the evaluated compounds are discussed. For majority of the tested compounds the lipophilicity of the compound and not electronic properties of the R1 substituent were decisive for PET-inhibiting activity. The most potent PET inhibitor was (5Z)-5-(4-bromobenzylidene)-2-thioxo-1,3-thiazolidin-4-one (IC(50) = 3.0 μmol/L) and the highest antialgal activity was exhibited by (5Z)-5-(4-chlorobenzylidene)-2-thioxo-1,3-thiazolidin-4-one (IC(50) = 1.3 μmol/L).

In this study, a series of twenty-two 5-chloro-2-hydroxy-N-[2-(arylamino)-1-alkyl-2-oxoethyl]benzamides and ten 4-chloro-2-hydroxy-N-[2-(arylamino)-1-alkyl-2-oxoethyl]benzamides is described. The compounds were analyzed using RP-HPLC to determine lipophilicity. Primary in vitro screening of the synthesized compounds was performed against mycobacterial, bacterial and fungal strains. They were also evaluated for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The compounds showed biological activity comparable with or higher than the standards isoniazid, fluconazole, penicillin G or ciprofloxacin. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds as well as their structure-activity relationships are discussed.

In this study a series of eight 1-[(2-chlorophenyl)carbamoyl]naphthalen-2-yl N‑alkylcarbamates was prepared and characterized. The discussed compounds were prepared by microwave-assisted and conventional synthesis. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The PET-inhibiting activity of the compounds was moderate; the highest activity within the series of compounds was observed for 1-[(2-chlorophenyl)carbamoyl]naphthalen-2-yl N-propylcarbamate, and the compounds were found to inhibit PET in photosystem II.

A series of N-alkyl-3-(alkylamino)pyrazine-2-carboxamides and their N-alkyl-3-chloropyrazine-2-carboxamide precursors were prepared. All compounds were characterized by analytical methods and tested for antimicrobial and antiviral activity. The antimycobacterial MIC values against Mycobacterium tuberculosis H37Rv of the most effective compounds, 3-(hexylamino)-, 3-(heptylamino)- and 3-(octylamino)-N-methyl-pyrazine-2-carboxamides 14‒16, was 25 μg/mL. The compounds inhibited photosystem 2 photosynthetic electron transport (PET) in spinach chloroplasts. This activity was strongly connected with the lipophilicity of the compounds. For effective PET inhibition longer alkyl chains in the 3-(alkylamino) substituent in the N-alkyl-3-(alkylamino)pyrazine-2-carboxamide molecule were more favourable than two shorter alkyl chains. ispartof: Molecules vol:20 issue:5 pages:8687-711 ispartof: location:Switzerland status: published

A series of fifteen new N-alkoxyphenylanilides of 3-hydroxynaphthalene-2-carboxylic acid was prepared and characterized. Primary in vitro screening of the synthesized compounds was performed against Staphylococcus aureus, three methicillin-resistant S. aureus strains, Mycobacterium tuberculosis H37Ra and M. avium subsp. paratuberculosis. Some of the tested compounds showed antibacterial and antimycobacterial activity against the tested strains comparable with or higher than that of the standards ampicillin or rifampicin. 3-Hydroxy-N-(2-propoxyphenyl)naphthalene-2-carboxamide and N-[2-(but-2-yloxy)-phenyl]-3-hydroxynaphthalene-2-carboxamide had MIC = 12 µM against all methicillin-resistant S. aureus strains, thus their activity is 4-fold higher than that of ampicillin. The second mentioned compound as well as 3-hydroxy-N-[3-(prop-2-yloxy)phenyl]-naphthalene-2-carboxamide had MICs = 23 µM and 24 µM against M. tuberculosis respectively. N-[2-(But-2-yloxy)phenyl]-3-hydroxynaphthalene-2-carboxamide demonstrated higher activity against M. avium subsp. paratuberculosis than rifampicin. Screening of the cytotoxicity of the most effective antimycobacterial compounds was performed using THP-1 cells, and no significant lethal effect was observed for the most potent compounds. The compounds were additionally tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. N-(3-Ethoxyphenyl)-3-hydroxynaphthalene-2-carboxamide (IC50 = 4.5 µM) was the most active PET inhibitor. The structure-activity relationships are discussed.

Series of seventeen new multihalogenated 1-hydroxynaphthalene-2-carboxanilides was prepared and characterized. All the compounds were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. 1-Hydroxy-N-phenylnaphthalene-2-carboxamides substituted in the anilide part by 3,5-dichloro-, 4-bromo-3-chloro-, 2,5-dibromo- and 3,4,5-trichloro atoms were the most potent PET inhibitors (IC50 = 5.2, 6.7, 7.6 and 8.0 µM, respectively). The inhibitory activity of these compounds depends on the position and the type of halogen substituents, i.e., on lipophilicity and electronic properties of individual substituents of the anilide part of the molecule. Interactions of the studied compounds with chlorophyll a and aromatic amino acids present in pigment-protein complexes mainly in PS II were documented by fluorescence spectroscopy. The section between P680 and plastoquinone QB in the PET chain occurring on the acceptor side of PS II can be suggested as the site of action of the compounds. The structure-activity relationships are discussed.

In this study a series of twelve n-alkoxy-substituted 2-hydroxynaphthalene-1-carboxanilides was prepared and characterized. The discussed compounds were prepared by microwave-assisted synthesis. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The highest PET inhibition was observed for meta-substituted compounds, whereas 2-hydroxy-N-(3-propoxyphenyl)naphthalene-1-carboxamide showed the highest PET inhibition within the whole series. In spite of medium or moderate PET-inhibiting activity it was found that the compounds inhibit PET in photosystem II. The activity of all positional isomers is strongly influenced by lipophilicity and the length/bulkiness of the alkoxy chain.

Pyrazinamide (PZA) is one of the most important molecules in the world. It is counted among the first-line antituberculotic drugs together with rifampicin, isoniazide, ethambutol or streptomycine. Using it as anti-tubercular agent it can shorten the time needed for treatment by two thirds and acts as sterilising drug. On the other hand, due to its small molecule and unique chemical properties, that makes this compound very suitable for structural modifications, new ways of use have appeared, such as antiviral, herbicidal, antibacterial, antineoplastic activities.There was prepared a series of 3-chloropyrazine-2-carboxamide, which is a derivative of PZA, and was treated with a group of aliphatic, alicyclic amines and saturated heterocycles containing nitrogen. All the final compounds were prepared using microwave reactor with focused field according to the experimentally set conditions. This approach was chosen according to higher yields, shorter reaction times and better conversion.Every product of this type of aminodehalogenation reaction was characterized chemically by melting point, 1H, 13C NMR and IR spectra, elemental analysis and lipophilicity (calculated and experimentally set). In vitro biological screenings followed.Antimycobacterial evaluation has been made against 4 mycobacterial strains (M. tuberculosis, M. kansasii and 2 strains of M. avium) and isoniazide has been used as a standard. Next screening has been focused on antibacterial and antifungal tests against 8 bacterial and 8 fungal stems. There have been used 5 antibiotics (neomycin, bacitracin, penicillin G, ciprofloxacin, phenoxymethylpenicillin) and 4 antimycotics (amphotericin B, voriconazole, nystatin, fluconazole) as standards. Minimal inhibition concentration has been set as 90% inhibition resp. 50% inhibition of control. The last evaluation has been focused on testing of herbicidal activity of these new compounds. The main principle of this measurement has been the inhibition of photosynthetic electron transport in chloroplasts that have been taken from spinach (Spinacea oleracea). The Hill reaction has been used together with DCMU (Diurone®) as standard. Inhibition concentration IC50 has been recorded and the determination of site of action in photosynthetic apparatus (PA) of studied compounds has been performed using an artificial electron donor 1,5-diphenylcarbazide. Fluorescence measurements have been also used for monitoring the interaction of PZA analogues with amino acids residues present in PA.The results showed some antifungal activities but it was not enough to predict any structure-activity relationships. On the contrary, there was found a conspicuous relationship between lipophilicity and herbicidal activity in the aliphatic amines group.

In this study a series of twelve ring-substituted 8-hydroxyquinoline2-carboxanilides was prepared and characterized. The discussed compounds were prepared by using microwave-assisted synthesis. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The compounds were found to inhibit PET in photosystem II. Significant PET-inhibiting activity was observed for meta-substituted compounds showing IC50 values close to that of photosystem II herbicide DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea, IC50 = 1.9 μmol/L). N-(3-Fluorophenyl)-8-hydroxyquinoline-2-carboxamide showed the highest PET inhibition. The activity of metaand para-substituted compounds strongly decreased with lipophilicity increase and electron-withdrawing effect. No influence of any of these parameters on PET-inhibiting activity of ortho-substituted compounds was observed.

In this study, a series of twenty-two ring-substituted 3-hydroxy-N-phenylnaphthalene-2-carboxanilides were prepared and characterized. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four Staphylococcus strains and against two mycobacterial species. 3-Hydroxy-N-(2-methoxyphenyl)naphthalene-2-carboxamide showed high biological activity (MIC = 55.0 µmol/L) against S. aureus as well as methicillin-resistant strains. N-(2-Fluorophenyl)-3-hydroxynaphthalene-2-carboxamide showed higher activity (MIC = 28.4 µmol/L) against M. marinum than the standard isoniazid and 3-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide expressed higher activity (MIC = 13.0 µmol/L) against M. kansasii than the standard isoniazid. Cytotoxicity assay of effective antimicrobial compounds was performed using the human monocytic leukemia THP-1 cell line. The PET-inhibiting activity expressed by IC50 value of the most active compound 3-hydroxy-N-(3-nitrophenyl)naphthalene-2-carboxamide was 16.9 μmol/L. The structure-activity relationships of all compounds are discussed.

In this study, a series of 22 ring-substituted 1-hydroxynaphthalene-2-carboxanilides were prepared and characterized. Primary in vitro screening of the synthesized compounds was performed against Mycobacterium marinum, Mycobacterium kansasii and Mycobacterium smegmatis. The compounds were also tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Most of tested compounds showed the antimycobacterial activity against the three strains comparable or higher than the standard isoniazid. N-(3-Fluorophenyl)-1-hydroxynaphthalene-2-carboxamide showed the highest biological activity (MIC=28.4μmol/L) against M. marinum, N-(4-fluorophenyl)-1-hydroxynaphthalene-2-carboxamide showed the highest biological activity (MIC=14.2μmol/L) against M. kansasii, and N-(4-bromophenyl)-1-hydroxynaphthalene-2-carboxamide expressed the highest biological activity (MIC=46.7μmol/L) against M. smegmatis. This compound and 1-hydroxy-N-(3-methylphenyl)naphthalene-2-carboxamide were the most active compounds against all three tested strains. The PET inhibition expressed by IC50 value of the most active compound 1-hydroxy-N-(3-trifluoromethylphenyl)naphthalene-2-carboxamide was 5.3μmol/L. The most effective compounds demonstrated insignificant toxicity against the human monocytic leukemia THP-1 cell line. For all compounds, structure-activity relationships are discussed.

A series of twenty substituted 2-hydroxy-3-[(2-aryloxyethyl)amino]propyl 4-[(alkoxycarbonyl)amino]benzoates were prepared and characterized. As similar compounds have been described as potential antimycobacterials, primaryin vitroscreening of the synthesized carbamates was also performed against two mycobacterial species. 2-Hydroxy-3-[2-(2,6-dimethoxyphenoxy)ethylamino]-propyl 4-(butoxycarbonylamino)benzoate hydrochloride, 2-hydroxy-3-[2-(4-methoxyphenoxy)ethylamino]-propyl 4-(butoxycarbonylamino)benzoate hydrochloride, and 2-hydroxy-3-[2-(2-methoxyphenoxy)ethylamino]-propyl 4-(butoxycarbonylamino)benzoate hydrochloride showed higher activity againstM. aviumsubsp.paratuberculosisandM. intracellularethan the standards ciprofloxacin, isoniazid, or pyrazinamide. Cytotoxicity assay of effective compounds was performed using the human monocytic leukaemia THP-1 cell line. Compounds with predicted amphiphilic properties were also tested for their effects on the rate of photosynthetic electron transport (PET) in spinach (Spinacia oleraceaL.) chloroplasts. All butyl derivatives significantly stimulated the rate of PET, indicating that the compounds can induce conformational changes in thylakoid membranes resulting in an increase of their permeability and so causing uncoupling of phosphorylation from electron transport.

In this study a series of twenty-five ring-substituted 3-hydroxy-N-phenylnaphthalene-2-carboxanilides were prepared. The procedures for synthesis of the compounds are presented. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four Staphylococcus strains. Several compounds showed noteworthy biological activity especially against methicillin-resistant Staphylococcus aureus strains. For all the compounds structure-activity relationships (SAR) are discussed.

Inhibition of photosynthetic electron transport (PET) in spinach chloroplasts by nineteen 2-benzylsulphanylbenzimidazoles (BZA) was studied. BZA were found to inhibit photosynthetic electron transport (PET) and for their inhibitory efficiency, electronic properties of the R substituent on the benzyl moiety are decisive. The PET inhibiting activity of the studied BZA expressed as IC50 varied in the range from 28.5 μM (R = 3,5-(CF3)2) to 394.5 μM (R = 2,4-(NO2)2). For compounds with R = H, 4-CH3, 3-CH3, 3-OCH3, 4-F, 3-F, 4-Cl, 3-Cl, 2-Cl, 4-Br, 3-Br, 3,4-F2, 3,4-Cl2, 3-CF3, 3,5-(CF3)2 linear increase of the inhibitory activity with the increasing value of the substituent’s σ constant up to 0.86 was observed. Further increase of the σ constant resulted in a sharp activity decrease of the corresponding compounds (R = 2-F-6-Cl, 2-NO2, 3,5-(NO2)2, 2,4-(NO2)2). Using EPR spectroscopy and an artificial electron donor diphenyl carbazide it was found that the site of BZA action in the photosynthetic apparatus is situated on the donor side of PS 2, prior to the Z·/D· intermediate.

In this study, a series of new seven ring-substituted 4-chloro-2-styrylquinazoline derivatives were prepared. The procedures for synthesis of the compounds are presented. The compounds were analyzed using RP-HPLC to determine lipophilicity. They were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds are discussed, as well as their structure-activity relationships (SAR).

In this study a series of twenty-five substituted quinoline-2-carboxanilides were prepared. The procedures for synthesis of the compounds are presented. The compounds were tested for their activity related to inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. For all the compounds the structure-activity relationships (SAR) are discussed.