Synthesis of N-substituted piperazinyl carbamoyl and acetyl derivatives of tetrahydropapaverine: potent antispasmodic agents

The synthesis and structure-activity-relationship (SAR) for a series of N-substituted piperazinyl carbamoyl 7-15 and piperazinyl acetyl 18-26 derivatives of tetrahydropapaverine have been carried out. The general synthetic methods of carbamoyl tetrahydropapaverine analogues involve N-substituted piperazines and carbamoyl imidazole tetrahydropapaverine as starting materials. Another route for synthesizing these compounds, involving the formation of carbamoyl imidazole piperazine has also been explored. Acylation of tetrahydropapaverine followed by substitution with various piperazinyl moities afforded the acetyl tetrahydropapaverine derivatives. Variously substituted piperazines have been used to monitor the effect of electron releasing and electron withdrawing substituents upon the antispasmodic activity of the molecules. Effect of varying electron densities on the antispasmodic activity, by altering the position of these groups on the benzene ring has also been monitored. Pharmacological methods involve the in vitro antispasmodic activity studies on a freshly removed guinea pig ileum using a force displacement transducer amplifier connected to a physiograph. Among the analogues synthesized in the present study, a promising compound 7, a potent muscle relaxant as compared to papaverine has been obtained.     

Phytochemical Analysis,Antispasmodic, Myorelaxant,and Antioxidant Effect of Dysphania ambrosioides (L.) Mosyakin and Clemants Flower Hydroethanolic Extracts and Its Chloroform and Ethyl Acetate Fractions

Dysphania ambrosioides (L.) Mosyakin and Clemants is an annual or ephemeral perennial herb used traditionally in the Mediterranean region in folk medicine to treat various illnesses, including those related to the digestive system. This study aims to assess the antispasmodic, myorelaxant, and antioxidant effects of D. ambrosioides flower hydroethanolic extract and its chloroform and ethyl acetate fractions in a comparative study to evaluate the result of the extraction type on the potential activity of the extract. Both rat and rabbit jejunum were used to evaluate the antispasmodic and myorelaxant effect, while the antioxidant effect was evaluated using DPPH, a ferric reducing power assay, and a beta-carotene bleaching test. LC/MS-MS analysis was carried out to reveal the composition of the different types of extract. Following the results, the hydroethanolic extract showed a significant myorelaxant effect (IC₅₀ = 0.39 ± 0.01 mg/mL). Moreover, it was shown that the hydroethanolic extract demonstrated the best antispasmodic activity (IC₅₀ = 0.51 ± 0.05 mg/mL), followed by the ethyl acetate (IC₅₀ = 4.05 ± 0.32 mg/mL) and chloroform (IC₅₀ = 4.34 ± 0.45 mg/mL) fractions. The antioxidant tests showed that the hydroethanolic extract demonstrated high antioxidant activity, followed by the ethyl acetate and chloroform fractions. The LC/MS-MS analysis indicates that the plant extract was rich in flavonoids, to which the extract activity has been attributed. This study supports the traditional use of this plant to treat digestive problems, especially those with spasms.     

Antispasmodic Effect of Asperidine B,a Pyrrolidine Derivative,through Inhibition of L-Type Ca2+ Channel in Rat Ileal Smooth Muscle

Antispasmodic agents are used for modulating gastrointestinal motility. Several compounds isolated from terrestrial plants have antispasmodic properties. This study aimed to explore the inhibitory effect of the pyrrolidine derivative, asperidine B, isolated from the soil-derived fungus Aspergillus sclerotiorum PSU-RSPG178, on spasmodic activity. Isolated rat ileum was set up in an organ bath. The contractile responses of asperidine B (0.3 to 30 µM) on potassium chloride and acetylcholine-induced contractions were recorded. To investigate its antispasmodic mechanism, CaCl₂, acetylcholine, Nω-nitro-l-arginine methyl ester (l-NAME), nifedipine, methylene blue and tetraethylammonium chloride (TEA) were tested in the absence or in the presence of asperidine B. Cumulative concentrations of asperidine B reduced the ileal contraction by ~37%. The calcium chloride and acetylcholine-induced ileal contraction was suppressed by asperidine B. The effects of asperidine B combined with nifedipine, atropine or TEA were similar to those treated with nifedipine, atropine or TEA, respectively. In contrast, in the presence of l-NAME and methylene blue, the antispasmodic effect of asperidine B was unaltered. These results suggest that the antispasmodic property of asperidine B is probably due to the blockage of the L-type Ca²⁺ channel and is associated with K⁺ channels and muscarinic receptor, possibly by affecting non-selective cation channels and/or releasing intracellular calcium.     

Synthesis and Antibacterial Activity of New Azole,Diazole and Triazole Derivatives Based on p-Aminobenzoic Acid

The p-aminobenzoic acid was applied for the synthesis of substituted 1-phenyl-5-oxopyrrolidine derivatives containing benzimidazole, azole, oxadiazole, triazole, dihydrazone, and dithiosemicarbazide moieties in the structure. All the obtained compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Salmonella enteritidis, Escherichia coli, and Pseudomonas aeruginosa by using MIC and MBC assays. This study showed a good bactericidal activity of γ-amino acid and benzimidazoles derivatives. The antimicrobial activity of the most promising compounds was higher than ampicillin. Furthermore, two benzimidazoles demonstrated good antimicrobial activity against L. monocytogenes (MIC 15.62 µg/mL) that was four times more potent than ampicillin (MIC 65 µg/mL). Further studies are needed to better understand the mechanism of the antimicrobial activity as well as to generate antimicrobial compounds based on the 1-phenyl-5-oxopyrrolidine scaffold.     

Antibacterial activity of methylated chitosan and chitooligomer derivatives: Synthesis and structure activity relationships

The purpose of this study was to synthesize series of methylated chitosaccharide derivatives, possessing various degree of methylation, and to determine their structure activity relationship (SAR) with regard to their antibacterial effect against Staphylococcus aureus. Chitosan polymer and chitooligomers were used as starting materials and were methylated by reaction with methyl iodide. Depending on the reaction conditions the degree of N-quaternization ranged from 0% to 74%, with varying degree of N,N-dimethylation, N-monomethylation and O-methylation. More selective N-quaternization could be obtained with protection group strategy. At pH 5.5 the chitosaccharide polymers and their methylated derivatives were active against S. aureus with minimal inhibitory concentration (MIC) ranging from 16 to 512 μg/mL. At pH 7.2 the non-quaternized derivatives were inactive but their highly N-quaternized derivatives showed MIC as low as 8 μg/mL. The chitooligomers, as well as their derivatives, were inactive at both pH’s. The SAR studies revealed that N-quaternization was mainly responsible for the antibacterial effects at pH 7.2, whereas it did not contribute to the antibacterial activity under acidic conditions.     

Synthesis and antimicrobial activity of sulphamethoxazole-based ureas and imidazolidine-2,4,5-triones

Progression of drug resistance among bacterial and fungal pathogens justifies the development of novel antimicrobial agents. Thus, a series of novel sulphamethoxazole-based ureas and imidazolidine-2,4,5-triones have been designed and synthesised. The urea derivatives were obtained by the reaction of sulphamethoxazole and isocyanates, and their cyclisation to imidazolidine-2,4,5-triones was performed via oxalyl chloride. All synthesised derivatives were evaluated in vitro to determine their activity against gram-positive and gram-negative bacteria, fungi, Mycobacterium tuberculosis, and atypical mycobacteria and their cytotoxicity. The growth of mycobacteria was inhibited within the range of 4–1000 µM and M. tuberculosis was the least-susceptible strain. 4-(3-Heptylureido)-N-(5-methylisoxazol-3-yl)benzenesulphonamide was identified as the most promising compound because it exhibited the highest activity against atypical mycobacteria at minimum inhibitory concentrations, from 4 µM, and with acceptable toxicity (selectivity indices for M. avium and M. kansasii higher than 16 and 62.5, respectively). Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, were inhibited at concentrations starting from 125 µM, whereas the investigated derivatives exhibited almost no antifungal potency and activity against gram-negative species.     

Synthesis of Halopyrazole Matrine Derivatives and Their Insecticidal and Fungicidal Activities

Matrine is a traditional botanical pesticide with a broad-spectrum biological activity that is widely applied in agriculture. Halopyrazole groups are successfully introduced to the C13 of matrine to synthesize eight new derivatives with a yield of 78–87%. The insecticidal activity results show that the introduction of halopyrazole groups can significantly improve the insecticidal activity of matrine on Plutella xylostella, Mythimna separata and Spodoptera frugiperda with a corrected mortality rate of 100%, which is 25–65% higher than matrine. The fungicidal activity results indicate that derivatives have a high inhibitory effect on Ceratobasidium cornigerum, Cibberella sanbinetti, Gibberrlla zeae and Collectot tichum gloeosporioides. Thereinto, 4-Cl-Pyr-Mat has the best result, with an inhibition rate of 23–33% higher than that of matrine. Therefore, the introduction of halogenated pyrazole groups can improve the agricultural activity of matrine.     

Anti-microbial activity of anhydride copolymers and their derivatives prepared by ionizing radiation

Methyl methacrylate/maleic anhydride (MMA/MAn) copolymers were synthesized using gamma rays. Preparation conditions such as irradiation dose, comonomer composition and type of diluent affecting the degree of comonomer conversion were investigated. The suitable diluent for obtaining reasonable MMA/MAn copolymer yield was acetone. The higher copolymer yield was achieved when the amount of methyl methacrylate in comonomer feed solutions as well as irradiation dose increased. The effect of ZnCl₂ on the MMA/MAn copolymer yield and structure was studied. Characterization of the prepared MMA/MAn copolymers was performed using FTIR, and thermogravimetric and viscometric analysis. The derivatives of MMA/MAn copolymers were obtained by treating them with different reagents such as sulpha-drugs, hydroxylamine hydrochloride and 4-amino sodium salyciliate. The antimicrobial activity of MMA/MAn copolymers and their derivatives was examined. The activity of such copolymers against Staphylococcus aureus and Escherichia coli increased by increasing MAn content in the copolymer. The MMA/MAn copolymers treated with sulpha-drugs exhibited particularly high biological activity against different microorganisms. These results revealed that the prepared MMA/MAn copolymer and its derivatives have a broad antimicrobial activity.     

Structures and biological activity of cinnamoyl derivatives of coumarins and dehydroacetic acid and their boron difluoride complexes

Computer-assisted screening for Kohonen self-organizing maps in terms of the quantitative structure??activity relationship (QSAR) model revealed the high potential activity of cinnamoyl derivatives of coumarin and dehydroacetic acid and their boron difluoride complexes against a number of biological targets, including HIV-1 integrase. The pronounced inhibitory properties of dehydroacetic acid derivatives and their boron difluoride complexes against HIV-1 integrase were experimentally confirmed by in vitro testing of their antiviral activity with respect to HIV-infected cells. The data obtained suggests a correlation between the structure of the compounds studied and their biological activity.     

Novel NO-releasing derivatives of betulinic acid with antitumor activity

Thirteen novel NO-releasing derivatives of betulinic acid (BA) bearing two types of NO-donors (nitrates and furoxans) were synthesized and evaluated for their antitumor activity. The results showed that furoxan-based derivatives exhibited higher antitumor activity than nitrate-based derivatives, with compounds 11a and 11b displaying promising potency against B16 cell lines and HepG2 cell lines (IC50 < 1 μmol/L). Wesupposed that NO-releasing amount of these derivatives which can be detected by Griess method may contribute more to their antitumor activity. As a result, furoxan-based derivatives released larger amount of NO than that of nitrate-based derivatives, which partially explained the higher anti-tumor activity of the former.     

Semisynthetic Derivatives of Selected Amaryllidaceae Alkaloids as a New Class of Antimycobacterial Agents

The search for novel antimycobacterial drugs is a matter of urgency, since tuberculosis is still one of the top ten causes of death from a single infectious agent, killing more than 1.4 million people worldwide each year. Nine Amaryllidaceae alkaloids (AAs) of various structural types have been screened for their antimycobacterial activity. Unfortunately, all were considered inactive, and thus a pilot series of aromatic esters of galanthamine, 3-O-methylpancracine, vittatine and maritidine were synthesized to increase biological activity. The semisynthetic derivatives of AAs were screened for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Ra and two other mycobacterial strains (M. aurum, M. smegmatis) using a modified Microplate Alamar Blue Assay. The most active compounds were also studied for their in vitro hepatotoxicity on the hepatocellular carcinoma cell line HepG2. In general, the derivatization of the original AAs was associated with a significant increase in antimycobacterial activity. Several pilot derivatives were identified as compounds with micromolar MICs against M. tuberculosis H37Ra. Two derivatives of galanthamine, 1i and 1r, were selected for further structure optimalization to increase the selectivity index.     

Exploring the potential of xanthene derivatives as trypanothione reductase inhibitors and chloroquine potentiating agents

Xanthene derivatives were synthesized and evaluated for their potential as trypanothione reductase (TryR) inhibitors and chloroquine (CQ) potentiating agents. Some derivatives displayed inhibitory activity against TryR comparable to known tricyclic anti-depressants. On the other hand a number of derivatives increased CQ accumulation and potentiating effects in a resistant strain of Plasmodium falciparum with one compound also displaying strong intrinsic antimalarial activity.     

Diels-Alder adducts of 3-N-substituted derivatives of (−)-Cytisine as influenza A/H1N1 virus inhibitors; stereodifferentiation of antiviral properties and preliminary assessment of action mechanism

The synthesis and anti-influenza activity study of Diels-Alder adducts of 3-N-substituted derivatives of (−)-cytisine with N-substituted maleimides are described. Synthesized compounds were studied for antiviral activity against influenza virus A/California/07/09 (H1N1)pdm09 in MDCK. The values of CC₅₀, IC₅₀ and selectivity indexes (SI) of obtained derivatives were determined. It was shown that anti-influenza activity of ‘α-endo’ adducts is higher (SI of three samples is 79 and higher) than activity of ‘β-endo’ adducts. By means of ‘time-of-addition’ experiment it was established that the leading compound (3aS,4R,8S,12R,12aR,12bS)-10-benzyl-2-phenyloctahydro-1H-4,12a-etheno-8,12-methanopyrrolo[3′,4':3,4]pyrido[1,2-a][1,5]diazocine-1,3,5(4H)-trione (16a) demonstrates anti-influenza activity at the middle and late stages of the virus life cycle. The possibility of interaction of synthesized derivatives with the active sites of the PA_N and PB2 was estimated via in silico approach. The difference in the locations of ‘α-endo’ and ‘β-endo’ adducts in PB2 active site (5JUN) is offered as an explanation of the dependence of their virus-inhibiting properties on stereochemistry.     

Microwave-Assisted Synthesis,Biological Activity Evaluation,Molecular Docking,and ADMET Studies of Some Novel Pyrrolo [2,3-b] Pyrrole Derivatives

Novel pyrrolo [2,3-b] pyrrole derivatives were synthesized and their hypolipidemic activity was assessed in hyperlipidemic rats. The chemical structures of the new derivatives were confirmed through spectral analysis. Compounds 5 and 6 were revealed to be the most effective hypolipidemic agents, with considerable hypocholesterolemic and hypotriglyceridemic effects. They appear to be promising candidates for creating new powerful derivatives with anti-atherosclerotic and hypolipidemic properties. As for antimicrobial activity, some of the tested compounds showed moderate activity against Pseudomonas aeruginosa: compound 2 revealed an MIC value of 50 μg/mL, compared to 25 μg/mL for ciprofloxacin. Compound 3 showed good antimicrobial activity against Staphylococcus aureus, comparable to ciprofloxacin, and roughly half the activity of ampicillin, according to MIC values. Compound 2 has an MIC approximately 25% of that of clotrimazole against Candida albicans. Compound 2 also showed the highest antioxidant activity with 59% inhibition of radical scavenging activity. Additionally, the cytotoxic activity of these new derivatives 1–7 was investigated and most of them showed good anticancer activity against the three tested cell lines.     

Antimicrobial and antispasmodic tetrahydroanthracenes from Cassia singueana

Four tetrahydroanthracene derivatives with antimicrobial and antispasmodic activities have been isolated from Cassia singueana. The evidence described in the following indicates them to be torosachrysone (1), germichrysone (4), and two new dimeric tetrahydroanthracenes, singueanol-I (7) or 6,6′-dimethoxy-3, 3′,8,8′,9,9′-hexahydroxy-3,3′,7,7′-tetramethyl-3,3′,4,4′-tetrahydro(10,10′-bianthracen)-1,1′(2H,2′H)-dione, and singueanol-II (8) or 6,6′-dimethoxy-3,3′,8,8′,9,9′-hexahydroxy-3,3′,7,7′-tetramethyl-3,3′,4,4′-tetrahydro(5,10′-bianthracen)- 1′(2H,2′H)-dione.     

Synthesis and antispasmodic activity evaluation of bis-(papaverine) analogues

A new series of N-substituted bis-(tetrahydropapaverine) ring systems have been synthesised in expectation of better antispasmodic activity in comparison with papaverine. The synthesis of the targeted heterocycles is described along with a discussion of their structure activity relationship. The general synthetic methods of bis-(tetrahydropapaverine) analogues involve tetrahydropapaverine, various piperazines, diisocyanates and diisothiocyanates as starting materials. Pharmacological evaluation involves the in vitro antispasmodic activity on a freshly removed guinea pig ileum using a force displacement transducer amplifier connected to a physiograph. Among the analogues synthesized in the present study, N,N'-bis-[2-carbamoyl-1-(3,4-dimethoxybenzyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolinyl]piperazine (22), was found to be the most potent muscle relaxant (IC(50): 0.31 microM).     

Synthesis and Evaluation of 11-Butyl Matrine Derivatives as Potential Anti-Virus Agents

Matrine derivatives were reported to have various biological activities, especially the ester, amide or sulfonamide derivatives of matrine deriving from the hydroxyl or carboxyl group at the end of the branch chain after the D ring of matrine is opened. In this work, to investigate whether moving away all functional groups from the C-11 branch chain could have an impact on the bioactivities, such as anti-tobacco mosaic virus (TMV), insecticidal and fungicidal activities, a variety of N-substituted-11-butyl matrine derivatives were synthesized. The obtained bioassay result showed that most N-substituted-11-butyl matrine derivatives had obviously enhanced anti-TMV activity compared with matrine, especially many compounds had good inhibitory activity close to that of commercialized virucide Ningnanmycin (inhibition rate 55.4, 57.8 ± 1.4, 55.3 ± 0.5 and 60.3 ± 1.2% at 500 μg/mL; 26.1, 29.7 ± 0.2, 24.2 ± 1.0 and 27.0 ± 0.3% at 100 μg/mL, for the in vitro activity, in vivo inactivation, curative and protection activities, respectively). Notably, N-benzoyl (7), N-benzyl (16), and N-cyclohexylmethyl-11-butyl (19) matrine derivatives had higher anti-TMV activity than Ningnanmycin at both 500 and 100 μg/mL for the four test modes, showing high potential as anti-TMV agent. Furthermore, some compounds also showed good fungicidal activity or insecticidal activity.     

Evaluation of bactericidal and fungicidal activity of ferrocenyl or phenyl derivatives in the diphenyl butene series

Some ferrocene compounds, such as tamoxifen derivatives hydroxyferrocifen 1 and ferrociphenol 2, show strong antiproliferative activity on hormone-dependent and hormone-independent breast cancer cells. In order to evaluate their antimicrobial activity, they were tested, together with their purely organic analogs, on the bacteria Pseudomonas aeruginosa and Staphylococcus aureus and the fungus Candida albicans. It has been found that the compounds bearing alkylamino chains are active, and in these cases the antimicrobial activity increases for compounds bearing two amino chains. These dialkyamino compounds are equally as active as doxycycline on P. aeruginosa and S. aureus but superior to it on C. albicans. The results show that there are no general correlation between the antitumoral activity and the bactericidal and fungicidal activities of these compounds. The ferrocene derivatives and their organic analogs have similar activity on bacteria and fungus. This bactericidal and fungicidal behaviour is a novel area of activity for these entities.     

Indole- and Pyrazole-Glycyrrhetinic Acid Derivatives as PTP1B Inhibitors: Synthesis,In Vitro and In Silico Studies

Regulating insulin and leptin levels using a protein tyrosine phosphatase 1B (PTP1B) inhibitor is an attractive strategy to treat diabetes and obesity. Glycyrrhetinic acid (GA), a triterpenoid, may weakly inhibit this enzyme. Nonetheless, semisynthetic derivatives of GA have not been developed as PTP1B inhibitors to date. Herein we describe the synthesis and evaluation of two series of indole- and N-phenylpyrazole-GA derivatives (4a–f and 5a–f). We measured their inhibitory activity and enzyme kinetics against PTP1B using p-nitrophenylphosphate (pNPP) assay. GA derivatives bearing substituted indoles or N-phenylpyrazoles fused to their A-ring showed a 50% inhibitory concentration for PTP1B in a range from 2.5 to 10.1 µM. The trifluoromethyl derivative of indole-GA (4f) exhibited non-competitive inhibition of PTP1B as well as higher potency (IC₅₀ = 2.5 µM) than that of positive controls ursolic acid (IC₅₀ = 5.6 µM), claramine (IC₅₀ = 13.7 µM) and suramin (IC₅₀ = 4.1 µM). Finally, docking and molecular dynamics simulations provided the theoretical basis for the favorable activity of the designed compounds.     

A study on synthesis and antimicrobial activity of 4-acyl-pyrazoles

4-Acyl-pyrazole-3-carboxylic acids (1) were synthesized via the reaction of 4-acyl-2,3-furandiones (F) with hydrazone (1-benzylidene-2-(2,5-dimethyl-phenyl)-hydrazine) by heating under solid phase and their acid chlorides (2) were obtained. Then these derivatives were easily converted into the corresponding derivatives such as ester, amide, ureide, pyrazolo-pyridazine, etc. Totally 62 new compounds were synthesized. The structures of these new synthesized compounds were determined by spectroscopic methods and the in vitro antibacterial activity of newly synthesized compounds were carried out against some gram-positive and gram-negative bacteria by well diffusion method (zone inhibition). Our results have showed that these new synthesized compounds have much potent of antibacterial activity owing to containing of pyrazole and/or pyridazine, chromone, oxazine, furane, and pyrrole rings. Some of the new pyrazole derivatives exhibited higher activities than reference drugs against the representative bacteria.