Organic and Medicinal Chemistry Letters最新文献

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Background: The discovery of clinically relevant inhibitors of HIV-RT for antiviral therapy has proven to be a challenging task. To identify novel and potent HIV-RT inhibitors, the quantitative structure-activity relationship (QSAR) approach became very useful and largely widespread technique forligand-based drug design.

Methods: We perform the two- and three-dimensional (2D and 3D) QSAR studies of a series of 1,2,3-thiadiazole thioacetanilides analogues to elucidate the structural properties required for HIV-RT inhibitory activity.

Results: The 2D-QSAR studies were performed using multiple linear regression method, giving r2 = 0.97 and q2 = 0.94. The 3D-QSAR studies were performed using the stepwise variable selection k-nearest neighbor molecular field analysis approach; a leave-one-out cross-validated correlation coefficient q2 = 0.89 and a non-cross-validated correlation coefficient r2 = 0.97 were obtained. Docking analysis suggests that the new series have comparable binding affinity with the standard compounds.

Conclusions: This approach showed that hydrophobic and electrostatic effects dominantly determine binding affinities which will further useful for development of new NNRTIs.

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Background: Extracts from the marine algae Cymopolia barbata have previously shown promising pharmacological activity including antifungal, antitumor, antimicrobial, and antimutagenic properties. Even though extracts have demonstrated such bioactivity, isolated ingredients responsible for such bioactivity remain unspecified. In this study, we describe chemical characterization and evaluations of biological activity of prenylated bromohydroquinones (PBQ) isolated from the marine algae C. barbata for their cytotoxic and chemopreventive potential.

Methods: The impact of PBQs on the viability of cell lines (MCF-7, HT29, HepG, and CCD18 Co) was evaluated using the MTS assay. In addition, their inhibitory impact on the activities of heterologously expressed cytochrome P450 (CYP) enzymes (CYP1A1, CYP1A2, CYP1B1, CYP2C19, CYP2D6, and CYP3A4) was evaluated using a fluorescent assay.

Results: 7-Hydroxycymopochromanone (PBQ1) and 7-hydroxycymopolone (PBQ2) were isolated using liquid and column chromatography, identified using 1 H and 13 C NMR spectra and compared with the spectra of previously isolated PBQs. PBQ2 selectively impacted the viability of HT29, colon cancer cells with similar potency to the known chemotherapeutic drug, fluorouracil (IC50, 19.82 ± 0.46 μM compared to 23.50 ± 1.12 μM, respectively) with impact toward normal colon cells also being comparable (55.65 ± 3.28 compared to 55.51 ± 3.71 μM, respectively), while PBQ1 had no impact on these cells. Both PBQs had potent inhibition against the activities of CYP1A1 and CYP1B1, the latter which is known to be a universal marker for cancer and a target for drug discovery. Inhibitors of CYP1 enzymes by virtue of the prevention of activation of carcinogens such as benzo-a-pyrene have drawn attention as potential chemopreventors. PBQ2 potently inhibited the activity of CYP1B1 (IC50 0.14 ± 0.04 μM), while both PBQ1 and PBQ2 potently inhibited the activity of CYP1A1 (IC50s of 0.39 ± 0.05 μM and 0.93 ± 0.26 μM, respectively). Further characterizations showed partial noncompetitive enzyme kinetics for PBQ2 with CYP1B1 with a Ki of 4.7 × 10-3 ± 5.1 × 10-4 μM and uncompetitive kinetics with CYP1A1 (Ki = 0.84 ± 0.07 μM); while PBQ1 displayed partial non competitive enzyme kinetics with CYP1A1 (Ki of 3.07 ± 0.69 μM), noncompetitive kinetics with CYP1A2 (Ki = 9.16 ± 4.68 μM) and uncompetitive kinetics with CYP1B1 (Ki = 0.26 ± 0.03 μM) .

Conclusions: We report for the first time, two isolated ingredients from C. barbata, PBQ1 and PBQ2, that show potential as valuable chemotherapeutic compounds. A hydroxyl moiety resident in PBQ2 appears to be critical for selectivity and potency against the cancer colon cells, HT29, in comparison to the three other malignant cell lines studied. PBQs also show potency against the activities of CYP1 enzyme which may be a lead in chemoprevention. This stud

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Background: Green catalyst fly ash: H2SO4 was prepared by mixing fly ash and sulphuric acid. Microwave irradiations are applied for solid phase cyclization of 5-bromo-2-thienyl chalcones and phenyl hydrazine hydrate in the presence of fly ash: H2SO4 yields, 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines. These pyrazolines were characterized by their physical constants and spectral data. The antimicrobial activities of all synthesized pyrazolines have been studied.

Results: Scanning electron microscopy (SEM) analysis shows the morphology changes between fly ash and the catalyst fly ash: H2SO4. The SEM photographs with the scale of 1 and 50 μm show the fly-ash particle is corroded by H2SO4 (indicated by arrow mark), and this may be due to dissolution of fly ash by H2SO4. The yields of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines is more than 75% using this catalyst under microwave heating. All pyrazolines showed moderate activities against antimicrobial strains.

Conclusion: We have developed an efficient catalytic method for synthesis of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines by solid phase cyclization using a solvent-free environmentally greener catalyst fly ash: H2SO4 under microwave irradiation between aryl chalcones and hydrazine hydrate. This reaction protocol offers a simple, economical, environment friendly, non-hazardous, easier work-up procedure, and good yields. All synthesized pyrazoline derivatives showed moderate antimicrobial activities against bacterial and fungal strains.

Background: We previously described the visceral antinociceptive property of α-bisabolol (BISA) in mouse models of visceral nociception induced by cyclophosphamide and mustard oil (MO). This study examined the effect of BISA in mouse models of visceral nociception induced by acetic acid, capsaicin, formalin, and the contribution of the nitric oxide system, α2, KATP, 5-HT3 and TRPV1 receptors to the effect of BISA on MO-evoked nociceptive behaviors. Mice were pretreated orally with BISA (50, 100 and 200 mg/kg) or vehicle, and the pain-related behavioral responses to intraperitoneal administration of acetic acid or intracolonic injection of MO were analyzed.

Results: BISA significantly suppressed the nociceptive behaviors in a dose-unrelated manner. The antinociceptive effect of BISA (50 mg/kg) was show to be glibenclamide resistant, but it was not blocked by pretreatment with the other antagonists tested. In the open-field test that detects sedative or motor abnormality, mice received 50 mg/kg BISA did not show any per se influence in ambulation frequency.

Conclusions: However, their precise antinociceptive mechanisms of action have not been determined.

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Background: Natural products isolated from plant sources have been demonstrated as potential candidates against several ailments. The scientific investigations on the underlying principles of phytotherapy can pave way for the convergence of traditional medicines and modern science and technologies.

Results: Quercetin 3-O-(2''-acetyl)-glucoside obtained from ethyl acetate fraction of Cleome viscosa is studied against inflammatory of carrageenan-induced rat paw edema ( in vivo) and microbial activity on ( in vitro). The structure of the glycoside is confirmed by means of hydrogen-1 nuclear magnetic resonance spectroscopy, carbon nuclear magnetic resonance spectroscopy, attached proton test, and mass spectrum. The flavonoid glycoside showed significant anti-inflammatory activity of on carrageenan-induced rat paw edema ( in vivo) and anti-microbial activity ( in vitro) on Staphylococcus aureus (gram positive) and Escherichia coli (gram negative). The anti-inflammatory effect of the flavonoid glycoside may be due to the inhibition of prostaglandin synthesis. Selective toxicity with flavonoid glycoside towards the gram-positive bacteria was found on S. aureus.

Conclusions: The present study reveals the anti-inflammatory and antimicrobial activities of an isolated quercetin 3-O-(2''-acetyl)-glucoside from a natural source ( C. viscosa).

Background: Gum ghatti is a proteinaceous edible, exudate tree gum of India and is also used in traditional medicine. A facile and ecofriendly green method has been developed for the synthesis of silver nanoparticles from silver nitrate using gum ghatti (Anogeissus latifolia) as a reducing and stabilizing agent. The influence of concentration of gum and reaction time on the synthesis of nanoparticles was studied. UV-visible spectroscopy, transmission electron microscopy and X-ray diffraction analytical techniques were used to characterize the synthesized nanoparticles.

Results: By optimizing the reaction conditions, we could achieve nearly monodispersed and size controlled spherical nanoparticles of around 5.7 ± 0.2 nm. A possible mechanism involved in the reduction and stabilization of nanoparticles has been investigated using Fourier transform infrared spectroscopy and Raman spectroscopy.

Conclusions: The synthesized silver nanoparticles had significant antibacterial action on both the Gram classes of bacteria. As the silver nanoparticles are encapsulated with functional group rich gum, they can be easily integrated for various biological applications.

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Background: Aminoquinoline/steroid conjugates were synthesized based on the fact that steroid transporters have been shown to accept and carry a variety of drugs. So, in continuing our research of antileishmanial and antitubercular drugs, aminoquinoline/steroid conjugates (12, 13, and 14) were regioselectively synthesized via 1, 3-dipolar cycloaddition of alkynes 3, 5, and 7 with azide 12. The aminoquinoline/steroids conjugates were evaluated in vitro against Leishmania major and Mycobacterium tuberculosis.

Results: Regioselective synthesis of the novel aminoquinoline/steroid conjugates was achieved in very high yield. All aminoquinoline/steroid conjugates (12, 13, and 14) exhibited best results against Leishmania and M. tuberculosis than the respective alkyne intermediate structures (3, 5, and 7, respectively). Among them, the compound 12 exhibited the best activity for M. tuberculosis (MIC = 8.8 μM). This result is comparable to drugs commonly used in tuberculosis treatment. Also, for antileishmanial assay, the aminoquinoline/steroid conjugates demonstrated a significant activity against promastigote and amastigote forms of L. major.

Conclusions: Addition of a steroid group to aminoquinoline molecules enhanced the leishmanicidal and antitubercular activities. These results highlight the importance of steroids as carrier.

Background: Curcumin and vanillin are the two useful compounds in food and medicine. Bismuth nitrate pentahydrate is an economical and ecofriendly reagent.

Method: Bismuth nitrate pentahydrate impregnated montmorillonite KSF clay and curcumin were subjected to microwave irradiation.

Results: Microwave-induced bismuth nitrate-promoted synthesis of vanillin from curcumin has been accomplished in good yield under solvent-free condition. Twenty-five different reaction conditions have been studied to optimize the process.

Conclusion: The present procedure for the synthesis of vanillin may find useful application in the area of industrial process development.

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Background: The nuclear-chemical method brought unique opportunity for synthesis of unknown and hardly available organic compounds. Presence of tritium labeling allows one-step preparation of radioactive markers for the investigation of chemical and biological processes.

Methods: The ion-molecular reactions of nucleogenic phenyl cations with 4-picoline have been carried out. The phenyl cations were generated by spontaneous tritium β-decay within the tritium-labeled benzene. Both additions to the nitrogen and substitutions about the aromatic ring were able to be studied simultaneously.

Results: Unusual substitutions on both the α- and β-positions of the ring system have been revealed.

Conclusion: By unknown direct phenylation of nitrogen atom tritium-labeled N-phenylpicolinium derivatives, perspective biological markers have been synthesized.

Background: The plasma membrane redox system (PMRS) has extensively been studied in erythrocytes. The PMRS plays an important role in maintaining plasma redox balance and provides a protective mechanism against oxidative stress. Earlier it was proposed that only NADH or NADPH provided reducing equivalents to PMRS; however, now it is acknowledged that some polyphenols also have the ability to donate reducing equivalents to PMRS.

Methods: Two different docking simulation softwares, Molegro Virtual Docker and Glide were used to study the interaction of certain plant polyphenols viz. quercetin, epigallocatechin gallate, catechin epicatechin and resveratrol with human erythroyte NADH-cytochrome b5 reductase, which is a component of PMRS and together with the identification of minimum pharmacophoric feature using Pharmagist.

Results: The derived common minimum pharmacophoric features show the presence of minimum bioactive component in all the selected polyphenols. Our results confirm wet lab findings which show that these polyphenols have the ability to interact and donate protons to the Human NADH-cytochrome b5 reductase.

Conclusion: With the help of these comparative results of docking simulation and pharmacophoric features, novel potent molecules can be designed with higher efficacy for activation of the PMRS system.