A series of novel N-(4-methyl-3-((4-(pyridin-3-yl)pyrimidin-2-yl)amino)phenyl)piperidine-4-carboxamide derivatives 10(a–f), 12(a–c) and 14(a–c) were synthesized and characterized by FTIR, 1H-NMR, mass spectral and elemental analysis. The efficacy of these derivatives to inhibit in vivo angiogenesis was evaluated using chick chorioallantoic membrane (CAM) model and their DNA cleavage abilities were evaluated after incubating with calf thymus DNA followed by gel electrophoresis. These novel piperidine analogues efficiently blocked the formation of blood vessels in vivo in CAM model and exhibited differential migration and band intensities in DNA binding/cleavage assays. Among the tested compounds 10a, 10b, 10c, 12b, 14b and 14c showed significant anti-angiogenic and DNA cleavage activities compared to their respective controls and the other derivatives used in this study. These observations suggest that the presence of electron donating and withdrawing groups at positions 2, 3 and 4 of the phenyl ring of the side chain may determine their potency and as anticancer agents by exerting both anti-angiogenic and cytotoxic effects
An increased incidence of fungal infections, both invasive and superficial, has been witnessed over the last two decades. Candida species seem to be the main etiology of nosocomial fungal infections worldwide with Candida albicans, which is commensal in healthy individuals, accounting for the majority of invasive Candida infections with about 30-40% of mortality.
Results
New aromatic and heterocyclic esters 5a-k of 1-aryl-3-(1H-imidazol-1-yl)propan-1-ols 4a-d were successfully synthesized and evaluated for their anti-Candida potential. Compound 5a emerged as the most active congener among the newly synthesized compounds 5a-k with MIC value of 0.0833 μmol/mL as compared with fluconazole (MIC value >1.6325 μmol/mL). Additionally, molecular modeling studies were conducted on a set of anti-Candida albicans compounds.
Conclusion
The newly synthesized esters 5a-k showed more potent anti-Candida activities than fluconazole. Compounds 7 and 8 revealed significant anti-Candida albicans activity and were able to effectively satisfy the proposed pharmacophore geometry, using the energy accessible conformers (Econf?<?20 kcal/mol).
In view of wide range of biological activities of oxazole, a new series of oxazole analogues was synthesized and its chemical structures were confirmed by spectral data (Proton/Carbon-NMR, IR, MS etc.). The synthesized oxazole derivatives were screened for their antimicrobial and antiproliferative activities.
Results and discussion
The antimicrobial activity was performed against selected fungal and bacterial strains using tube dilution method. The antiproliferative potential was evaluated against human colorectal carcinoma (HCT116) and oestrogen- positive human breast carcinoma (MCF7) cancer cell lines using Sulforhodamine B assay and, results were compared to standard drugs, 5-fluorouracil and tamoxifen, respectively.
Conclusion
The performed antimicrobial activity indicated that compounds 3, 5, 6, 8 and 14 showed promising activity against selected microbial species. Antiproliferative screening found compound 14 to be the most potent compound against HCT116 (IC50?=?71.8 µM), whereas Compound 6 was the most potent against MCF7 (IC50?=?74.1 µM). Further, the molecular docking study has been carried to find out the interaction between active oxazole compounds with CDK8 (HCT116) and ER-α (MCF7) proteins indicated that compound 14 and 6 showed good dock score with better potency within the ATP binding pocket and may be used as a lead for rational drug designing of the anticancer molecule.
The plant Alisma plantago-aquatica Linnaeus, which is widely distributed in southwest of China, is the main material of traditional Chinese medicine “Zexie”. It was used as folk medicine for immune-modulation, anti-tumor, anti-inflammatory and antibacterial. Previous chemical studies on A. plantago-aquatica reported the identification of triterpenes, diterpenes, sesquiterpenes, steroids, alkaloids and phenolic acid. Terpenes and phenolic acid were regard as major secondary metabolites from this medicine plant.
Results
A new phenolic acid, plantain A (1), along with four known compounds (2–5) were isolated and identified from A. plantago-aquatica by extensive chromatographic and spectrometric methods. In the present study, the levels of TNF-α, IL-1β, COX-2, PEG2 and TGF-β1 were increased in model group rats, whereas on treatment with the isolated compound (1 and 4) at 50 mg/kg, there was a significant decrease in the cytokine levels. Therefore, the anti-CNP effect of 1 and 4 may be related to their anti-inflammatory properties.
Conclusions
A new phenolic acid and four known phenolic compounds were isolated from A. plantago-aquatica. Moreover, compounds 1 and 4 shows significant anti-chronic prostatitis activity in rats.
The emergence of bacterial resistance is a major public health problem. It is essential to develop and synthesize new therapeutic agents with better activity. The mode of actions of certain newly developed antimicrobial agents, however, exhibited very limited effect in treating life threatening systemic infections. Therefore, the advancement of multi-potent and efficient antimicrobial agents is crucial to overcome the increased multi-drug resistance of bacteria and fungi. Cancer, which remains as one of the primary causes of deaths and is commonly treated by chemotherapeutic agents, is also in need of novel and efficacious agents to treat resistant cases. As such, a sequence of novel substituted benzamides was designed, synthesized and evaluated for their antimicrobial and anticancer activities.
Methodology
All synthesized compounds were characterized by IR, NMR, Mass and elemental analysis followed by in vitro antimicrobial studies against Gram-positive (Staphylococcus aureus), Gram-negative (Salmonella typhi and Klebsiella pneumoniae) bacterial and fungal (Candida albicans and Aspergillus niger) strains by the tube dilution method. The in vitro anticancer evaluation was carried out against the human colorectal carcinoma cell line (HCT116), using the Sulforhodamine B assay.
Results, discussion and conclusion
Compound W6 (MICsa, st, kp?=?5.19 µM) emerged as a significant antibacterial agent against all tested bacterial strains i.e. Gram-positive (S. aureus), Gram-negative (S. typhi, K. pneumoniae) while compound W1 (MICca, an?=?5.08 µM) was most potent against fungal strains (A. niger and C. albicans) and comparable to fluconazole (MIC?=?8.16 µM). The anticancer screening demonstrated that compound W17 (IC50?=?4.12 µM) was most potent amongst the synthesized compounds and also more potent than the standard drug 5-FU (IC50?=?7.69 µM).
Sydnone is a heterocycle that exhibits remarkable pharmacological activities, including antimicrobial, anti-inflammatory, analgesic, antipyretic and antioxidant activities. Thiosemicarbazones are of compounds that contain the –NHCSNHN=C< linkage group and are considerable interest because they exhibit important chemical properties and potentially beneficial biological activities. Similarly, thiosemicarbazones having carbohydrate moieties also exhibit various significant biological activities.
Results
The compounds of 3-formyl-4-phenylsydnones were obtained by Vilsmeyer-Haack’s formylation reaction and were transformed into thiosemicarbazones by condensation reaction with N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)thiosemicarbazide. Reaction were performed in the presence glacial acetic acid as catalyst using microwave-assisted heating method. Reaction yields were 43?85 %. The antimicrobial activities of these thiosemicarbazones were screened in vitro by using agar well diffusion and MIC methods. Among these thiosemicarbazones, compounds 4k, 4l, 4m and 4n were more active against all tested bacterial strains, especially against S. epidermidis, B. subtilis and E. coli. The MIC values in these cases are 0.156, 0.156 and 0.313 μg/mL, respectively. All compounds showed weak to moderate antifungal activity against C. albicans and A. niger than nystatin (MIC = 0.156?0.625 μg/mL vs. MIC = 0.078 μg/mL of nystatin), and thiosemicarbazones 4l, 4m and 4n exhibited significant activity with MIC = 0.156 μg/mL. These compounds also had good antifungal activity against F. oxysporum similarly to nystatin (MIC = 0.156 μg/mL). Among the tested compounds having halogen group 4k, 4l, 4m and 4n showed highest activity against three strains of fungal organisms.
Conclusions
In summary, we have developed a clean and efficient methodology for the synthesis of novel thiosemicarbazone derivatives bearing sydnone ring and d-glucose moiety; the heterocyclic and monosaccharide system being connected via ?NH?C(=S)NH?N=C< linker using molecular modification approach. The methodology could be further extended and used for the synthesis of other thiosemicarbazones of biological importance. 4-Formyl-3-arylsydnone N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)thiosemicarbazones have been synthesized under microwave-assisted heating conditions. Almost all obtained compounds showed remarkable activities against the tested microorganisms. Among the tested compounds having halogen group 4k, 4l, 4m and 4n showed highest activity against all tested strains of bacterial and fungal organisms.
Graphical abstract:Synthesis and antibacterial and antifungal activities of N-(tetra-O-acetyl-β-D-glucopyranosyl)thiosemicarbazones of substituted 4-formylsydnones
This research work was executed to determine chemical composition, anti-oxidant and anti-microbial potential of the essential oils extracted from the leaves and stem of Daphne mucronata Royle. From leaves and stem oils fifty-one different constituents were identified through GC/MS examination. The antioxidant potential evaluated through DPPH free radical scavenging activity and %-inhibition of peroxidation in linoleic acid system. The stem’s essential oil showed the good antioxidant activity as compared to leaves essential oil. Results of Antimicrobial activity revealed that both stem and leaves oils showed strong activity against Candida albicans with large inhibition zone (22.2?±?0.01, 18.9?±?0.20 mm) and lowest MIC values (0.98?±?0.005, 2.44?±?0.002 mg/mL) respectively. Leaves essential was also active against Escherichia coli with inhibition zone of 8.88?±?0.01 mm and MIC values of 11.2?±?0.40 mg/mL. These results suggested that the plant’s essential oils would be a potential cradle for the natural product based antimicrobial as well as antioxidant agents.
Re(I) tricarbonyl complexes exhibit immense potential as fluorescence imaging agents. However, only a handful of rhenium complexes have been utilized in biological imaging. The present study describes the synthesis of four novel rhenium complexes, their characterization and preliminary biological studies to assess their potential as biological imaging agents.
Results
Four facial rhenium tricarbonyl complexes containing a pyridyl triazine core, (L1 = 5,5′(3-(2-pyridyl)-1,2,4-triazine-5,6-diyl)-bis-2-furansulfonic acid disodium salt and L2 = (3-(2- pyridyl)-5,6-diphenyl-1,2,4-triazine-4′,4′′-disulfonic acid sodium salt) have been synthesized by utililzing two different Re metal precursors, Re(CO)5Br and [Re(CO)3(H2O)3]OTf in an organic solvent mixture and water, respectively. The rhenium complexes [Re(CO)3(H2O)L1]+ (1), Re(CO)3L1Br (2), [Re(CO)3(H2O)L2]+ (3), and Re(CO)3L2Br (4), were obtained in 70–85% yield and characterized by 1H NMR, IR, UV, and luminescence spectroscopy. In both H2O and acetonitrile, complexes display a weak absorption band in the visible region which can be assigned to a metal to ligand charge transfer excitation and fluorescent emission lying in the 650–710 nm range. Cytotoxicity assays of complexes 1, 3, and 4 were carried out for rat peritoneal cells. Both plant cells (Allium cepa bulb cells) and rat peritoneal cells were stained using the maximum non-toxic concentration levels of the compounds, 20.00 mg ml?1 for 1 and 3 and 5.00 mg ml?1 for 4 to observe under the epifluorescence microscope. In both cell lines, compound concentrated specifically in the nuclei region. Hence, nuclei showed red fluorescence upon excitation at 550 nm.
Conclusions
Four novel rhenium complexes have been synthesized and characterized. Remarkable enhancement of fluorescence upon binding with cells and visible range excitability demonstrates the possibility of using the new complexes in biological applications.
Discovery of potent inhibitors of urease (jack bean) enzyme is the first step in the development of drugs against diseases caused by ureolytic enzyme.
Results
Thirty-two derivatives of barbituric acid as zwitterionic adducts of diethyl ammonium salts were synthesized. All synthesized compounds (4a–z and 5a–s) were screened for their in vitro inhibition potential against urease enzyme (jack bean urease). The compounds 4i (IC50 = 17.6 ± 0.23 µM) and 5l (IC50 = 17.2 ± 0.44 µM) were found to be the most active members of the series, and showed several fold more urease inhibition activity than the standard compound thiourea (IC50 = 21.2 ± 1.3 µM). Whereas, compounds 4a–b, 4d–e, 4g–h, 4j–4r, 4x, 4z, 5b, 5e, 5k, 5n–5q having IC50 values in the range of 22.7 ± 0.20 µM–43.8 ± 0.33 µM, were also found as potent urease inhibitors. Furthermore, Molecular Dynamics simulation and molecular docking studies were carried out to analyze the binding mode of barbituric acid derivatives using MOE. During MD simulation enol form is found to be more stable over its keto form due to their coordination with catalytic Nickel ion of Urease. Additionally, structural–activity relationship using automated docking method was applied where the compounds with high biological activity are deeply buried within the binding pocket of urease. As multiple hydrophilic crucial interactions with Ala169, KCX219, Asp362 and Ala366 stabilize the compound within the binding site, thus contributing greater activity.
Conclusions
This research study is useful for the discovery of economically, efficient viable new drug against infectious diseases.
Zanthoxylum buesgenii is a shrub used in Sierra Leone as remedy to cure venereal diseases, arthritis, and rheumatism whereas leaves and barks are employed to treat leprosy and to relieve pain. In South West Region of Cameroon, the plant locally called "Mbem" by Lewoh-Lebang community, is orally given to patients as aphrodisiac decoction and to increase sperm count. Previous chemical studies on Zanthoxylum species reported the identification of lignans, coumarins, diterpenes, sesquiterpenes, steroids, alkaloids and benzopropanoids. Besides, structurally diverse compounds belonging to these classes of secondary metabolites have been reported as trypanocidal, antileishmanial, antimycobacterial and cytotoxic metabolites.
Results
We therefore investigated the alkaloidal constituents of Z. buesgenii. In the course of the study, two benzophenanthridines [1-methoxy-12-methyl-12,13-dihydro-[1,3]dioxolo[4',5':4,5]benzo[1,2-c]phenanthridine-2,13-diol (1) and isofagaridine (2)] were identified among them one new. Alongside, three known furoquinolines [maculine (3), kokusaginine (4) and teclearverdoornine (5)] were also obtained and their structures were established on the basis of their NMR data and by comparison with those previously reported. Furthermore, the cytotoxicities of metabolites (1-4) isolated in substantial amount were evaluated against a series of multidrugs-resistant cancer cell lines. While compounds 2-4 showed selective cytotoxicities, compound 1 displayed activities against all cancer cells.
Conclusions
The observed activities corroborate those previously reported on similar benzophenanthridine alkaloids indicating that compounds 1 and 2 can chemically be explored to develop other chemotherapeutic agents.
An alarming requirement for finding newer antidiabetic glitazones as agonists to PPARγ are on its utmost need from past few years as the side effects associated with the available drug therapy is dreadful. In this context, herein, we have made an attempt to develop some novel glitazones as PPARγ agonists, by rational and computer aided drug design approach by implementing the principles of bioisosterism. The designed glitazones are scored for similarity with the developed 3D pharmacophore model and subjected for docking studies against PPARγ proteins. Synthesized by adopting appropriate synthetic methodology and evaluated for in vitro cytotoxicity and glucose uptake assay. Illustrations about the molecular design of glitazones, synthesis, analysis, glucose uptake activity and SAR via 3D QSAR studies are reported.
Results
The computationally designed and synthesized ligands such as 2-(4-((substituted phenylimino)methyl)phenoxy)acetic acid derivatives were analysed by IR, 1H-NMR, 13C-NMR and MS-spectral techniques. The synthesized compounds were evaluated for their in vitro cytotoxicity and glucose uptake assay on 3T3-L1 and L6 cells. Further the activity data was used to develop 3D QSAR model to establish structure activity relationships for glucose uptake activity via CoMSIA studies.
Conclusion
The results of pharmacophore, molecular docking study and in vitro evaluation of synthesized compounds were found to be in good correlation. Specifically, CPD03, 07, 08, 18, 19, 21 and 24 are the candidate glitazones exhibited significant glucose uptake activity. 3D-QSAR model revealed the scope for possible further modifications as part of optimisation to find potent anti-diabetic agents.
The extracts from the aerial parts of Portulaca quadrifida have been reported to show the total flavonoid content, antioxidant and antibacterial activities.
Results
Our results revealed that the total flavonoid content of methanol and chloroform extracts is 2.335?±?0.0097 and 1.7312?±?0.0082 mgQE/100 g respectively. The two extracts also showed good antioxidant activity and total phenolic content as well as weak to moderate antibacterial activity against some bacteria.
Conclusions
The extracts the aerial parts of the P. quadrifida showed good total flavonoid content, DPPH radical scavenging activity and antibacterial activity. In addition to this, the extracts also showed the presence of some important compounds by phytochemical analysis.
One of the most popular techniques for cancer detection is the nuclear medicine technique. The present research focuses on Platelet-12-lipoxygenase (P-12-LOX) as a promising target for treating and radio-imaging tumor tissues. Curcumin was reported to inhibit this enzyme via binding to its active site.
Results
A novel curcumin derivative was successfully synthesized and characterized with yield of 74%. It was radiolabeled with the diagnostic radioisotope technetium-99m with 84% radiochemical yield and in vitro stability up to 6 h. The biodistribution studies in tumor bearing mice confirmed the high affinity predicted by the docking results with a free binding energy value of (ΔG ?50.10 kcal/mol) and affinity (13.64 pki) showing high accumulation in solid tumor with target/non-target ratio >6.
Conclusion
The newly synthesized curcumin derivative, as a result of a computational study on platelet-12 lipoxygenase, showed its excellent free binding energy (?G ?50.10 kcal/mol) and high affinity (13.64 pKi). It could be an excellent radio-imaging agent that targeting tumor cells via targeting of P-12-LOX.
Graphical abstract This novel curcumin derivative was successfully synthesized and radiolabeled with technetium-99m and biologically evaluated in tumor bearing mice that showed high accumulation in solid tumor with target/non-target ratio >6 confirming the affinity predicted by the docking results. Predicted binding mode of a new curcumin derivative in complex with 12-LOX active site. b Curcumin itself in the 12-LOX active site biological distribution of 99mTc-curcumin derivative complex in solid tumor bearing Albino mice
Coumarins are the phytochemicals, which belong to the family of benzopyrone, that display interesting pharmacological properties. Several natural, synthetic and semisynthetic coumarin derivatives have been discovered in decades for their applicability as lead structures as drugs. Coumarin based conjugates have been described as potential AChE, BuChE, MAO and β-amyloid inhibitors. Therefore, the objective of this review is to focus on the construction of these pharmacologically important coumarin analogues with anti-Alzheimer’s activities, highlight their docking studies and structure–activity relationships based on their substitution pattern with respect to the selected positions on the chromen ring by emphasising on the research reports conducted in between year 1968 to 2017.
Most of the benzyladenine and furfuryladenine derivatives inhibit tumor/cancer cell growth; their toxicity is lesser than the compounds used for the treatment of cancer now-a-days. Many cytokinin derivatives are tested for anticancer activity.
Results
A series of transition metal complexes containing N6-benzyl/furfuryl aminopurines of formula [Mn(FAH)2(H2O)(Cl3)]2.Cl2(1), [Co(FAH)2(H2O)(Cl3)]2.Cl2(2), [Co(FAH)2(Cl4)]2 .[Co(FAH)2(H3O)(Cl3)].Cl2(3), [Ni(FAH)2(H2O)(Cl3)]2.Cl2. (H2O) (4), [Zn(BAH)Br3] (5) and [Cd2(BAH)2(μ-Br)4Br2]n(6) (where BAH and FAH benzyladeninium and furfuryladeninium cations respectively) have been synthesized and characterized. Crystal structures of (1-4) have similar distorted octahedral coordination geometry, while (5) and (6) have distorted tetrahedral geometry and octahedral geometries respectively. In (1-4) two halide ions and two cytokinin cations (BAH+/FAH+) are laterally coordinated to the metal ion. A water molecule and a halide ion are axially coordinated. But the coordination sphere of (5) consists of N7 coordinated benzyladeninium ion and three halide ions. The complex (6) is a coordination polymer bridged by bromide anions. A common notable feature in (1-4) is the presence of one or more lattice chloride anions. They help in a chain formation by N-H…Cl halide involving hydrogen bonding interactions in between the Hoogsteen site hydrogen.
Conclusions
The observed crystal structures emphasize the role of the halide ions in developing the supramolecular architectures by halide involving hydrogen bonding interactions. Also most of the reported cobalt cytokinin complexes possess tetrahedral coordination geometry, but some cobalt complexes have distorted octahedral coordination geometry, which are discussed and compared.
A simple solvent-free protocol for the preparation of flunixin, a potent non-narcotic, non-steroidal anti-inflammatory drugs is reported using boric acid as catalyst. Its salt, flunixin meglumine are then prepared under reflux in EtOH. This sustainable method are then extended for the synthesis of a series of 2-(arylamino) nicotinic acid derivatives. The present protocol combines non-hazardous neat conditions with associated benefits like excellent yield, straightforward workup, and use of readily available and safe catalyst in the absence of any solvent, which are important factors in the pharmaceutical industry. The pathway for catalytic activation of 2-chloronicotic acid with boric acid was also investigated using Gaussian 03 program package.
A sensitive, specific, reproducible and optimized high performance liquid chromatography with fluorescence detection (HPLC-FLD) method for the determination of bergapten in rat plasma was established and applied to the pharmacokinetic and bioavailability study in rat after oral and intravenous administration of bergapten. The method was also successfully applied to the excretion study of bergapten after an oral administration of bergapten at a dose of 15 mg kg?1 to rats. The sample preparation was achieved using liquid–liquid extraction. Isoimperatorin was used as the internal standard (IS). The analytes were detected by using fluorescence detection at an excitation and emission wavelength of 288 and 478 nm, respectively. Using aqueous formic acid (0.1 %, v/v) and acetonitrile as the mobile phase, the chromatographic separation was achieved on a Hedera? ODS column at a flow rate of 1 mL min?1. The lower limit of quantitation (LLOQ) of bergapten was 2 ng mL?1. The HPLC-FLD method was successfully applied to the pharmacokinetic, bioavailability and excretion study of bergapten in rats.
Graphical abstract An high performance liquid chromatography with fluorescence detection (HPLC-FLD) method for the pharmacokinetic and bioavailability study in rat after administration of bergapten.
Derivatives of fulgides have been shown to have interesting photochromic properties. We have synthesised a number of such derivatives and have found, in some cases, that crystals can be made to change colour on crushing, a phenomenon we have termed “tribochromism”. We have studied a number of derivatives by X-ray crystallography, to see if the colour is linked to molecular structure or crystal packing, or both, and our structural results have been supported by calculation of molecular and lattice energies.
Results
A number of 5-dicyanomethylene-4-diphenylmethylene-3-disubstitutedmethylene-tetrahydrofuran-2-one compounds have been prepared and structurally characterised. The compounds are obtained as yellow or dark red crystals, or, in one case, both. In two cases where yellow crystals were obtained, we found that crushing the crystals gave a deep red powder. Structure determinations, including those of the one compound which gave both coloured forms, depending on crystallisation conditions, showed that the yellow crystals contained molecules in which the structure comprised a folded conformation at the diphenylmethylene site, whilst the red crystals contained molecules in a twisted conformation at this site. Lattice energy and molecular conformation energies were calculated for all molecules, and showed that the conformational energy of the molecule in structure IIIa (yellow) is marginally higher, and the conformation thus less stable, than that of the molecule in structure IIIb (red). However, the van der Waals energy for crystal structure IIIa, is slightly stronger than that of structure IIIb – which may be viewed as a hint of a metastable packing preference for IIIa, overcome by the contribution of a more stabilising Coulomb energy to the overall more favourable lattice energy of structure IIIb.
Conclusions
Our studies have shown that the crystal colour is correlated with one of two molecular conformations which are different in energy, but that the less stable conformation can be stabilised by its host crystal lattice.
An efficient and rapid regiospecific approach for the synthesis of cyclic and acyclic nucleosides of 2-oxonicotinonitriles was performed. Whereas, glycosylation of 2-oxonicotinonitriles 1a, b with peracetylated sugars (namely, peracetylated glucose, galactose and ribose) under MWI tolerated exclusively the desired N-nucleosides 2a, b, 4a, b and 6a, b in significant yields (75–86%) and in short reaction time (5–7 min.). The same products were obtained under the conventional conditions, using halo-sugar with low yields in hard conditions. Similarly, the acyclic nucleosides 8a, b and 9a, b were obtained under MWI and conventional conditions via reaction of 1a, b with 4-bromo butyl acetate and 2-acetoxyethoxymethyl bromide. Finally, deprotection of the latter blocked N-nucleosides was performed via treatment with aqueous methanolic solution containing a catalytic amount of triethyl amine to give the desired free nucleosides 3a, b, 5a, b, 7a, b, 10a, b and 11a, b, respectively. The free nucleosides (3a, b, 5a, b, 7a, b and 11a, b) were evaluated against Gram (+?ve) bacteria, Gram (–ve) bacteria and one pathogenic Fungi namely, Aspergillus flavus. Good results were obtained for compounds 7a, b and 11a, b compared with the used standard drugs (Cefotaxime and Dermatin).
We report a combined experimental and computational study aimed at elucidating the structure of N-terminal fragment ions of the c type produced by electron transfer dissociation of photo-leucine (L*) peptide ions GL*GGKX. The c4 ion from GL*GGK is found to retain an intact diazirine ring that undergoes selective photodissociation at 355 nm, followed by backbone cleavage. Infrared multiphoton dissociation action spectra point to the absence in the c4 ion of a diazoalkane group that could be produced by thermal isomerization of vibrationally hot ions. The c4 ion from ETD of GL*GGK is assigned an amide structure by a close match of the IRMPD action spectrum and calculated IR absorption. The energetics and kinetics of c4 ion dissociations are discussed.
