ABSTRACT

The objective of the current study was to develop novel compounds – memantine derivatives with antimicrobial activity designed for application in treatment of bacterial and fungal infections in patients suffering Alzheimer disease. To realize this objective a series of six memantine hybrid molecules were synthesized, characterized by data - ¹H NMR, ¹³C NMR, MS, X-ray and tested for their therapeutic properties as anti-Alzheimer agents and their antimicrobial potential.

The structure of the most active hybrid molecule 4-Phe-memantine (3b) was analyzed by single crystal X-ray diffraction and differential thermal analysis (DTA). The DTA measurement shows two endothermic effects the first in the 145 – 165 °C region and the second around 210 – 250 °C the first related to the release of a water molecule the second is the melting of the compound. No polymorphic changes associated to the temperature variations were detected. The single crystal X-ray study showed that compound 3b crystallize in a non-centrosymmetric manner (space group P2₁2₁2₁), with highly preserved geometry of the memantine and amino acid moieties.

The compounds were evaluated for their antimicrobial potential against clinically significant conditionally pathogenic Gram-negative bacteria and Gram-positive bacteria. Compounds 3b, 3c and 3e at 10 mM were the most active against Gram (+), Gram (-) bacteria and the yeast strains. The highest activity was demonstrated by 3b with MIC of 0.156 mM and MBC of 0.3 mM against Salmonella enterica (NBIMCC 8691). This compound as well strongly inhibited (up to 62.9%) the radial growth rate of Fusarium graminearum (NBIMCC 2294).

The interaction between extended aromatic species increases with system size at greater rate than interactions between aliphatic analogues or mixed aliphatic-aromatic ones. A series of complexes formed by benzene and cyclohexane with several acenes and their saturated derivatives has been computationally studied by using the TPSS-D3BJ/def2-TZVPP level of calculation. Considering prototypical structures, the equilibrium distances and interaction energies of the complexes have been obtained. The results are used to check on the characteristics of similar π-extended π, s-extended π, π-extended s and s-extended s complexes.

The detection and quantification of ions or neutral molecules by fluorescent sensors are of utmost importance in chemistry, medicine and environmental sciences. In this context, BODIPYs (boron dipyrromethenes) are outstanding chromophores for the development of fluorescent sensors owing to their excellent photophysical properties and the possibility of modulating such properties by chemical changes in their structure. We have recently reported a new class of BODIPY dyes, the N-BODIPYs, that is, BODIPYs with N-moieties attached to the boron atom. These new dyes have the advantage, over the widely extended F-BODIPYs, that up to four different groups can be attached to the boron through the nitrogen atoms. This structural feature expands the possibility of BODIPY functionalization, thus increasing the versatility of the dyes for different photonic applications. Particularly, we found, in certain N-BODIPYs, a photoinduced electron transfer (PET) from the N-moiety attached to the boron towards the BODIPY core that quenches the fluorescence of the dye. In this communication, we explore the possibility of modulating this PET for the development of fluorescent off/on sensors based on N-BODIPYs.

Series of new synthesized biologically active phthalazinone derivatives were obtained. Starting from the amino acid methyl esters of 4-benzyl-1(2H)-phthalazinone 2a,b which were synthesized from the aceto hydrazide of 4-benzyl-1(2H)-phthalazinone 1 via azide coupling method. The hydrazides 3a,b were prepared from hydrazinolysis of corresponding esters 2a,b. N-alkyles-2-(4-Benzyl-1-oxo-1H-phthalazin-2-yl)-methyl-acetamide 4a-f and the dipeptides methyl {2-[2-(4-Benzyl-1-oxo-1H-phthalazin-2-yl)-acetylamino]-acetylamino}-alkanoates 6a-c were obtained by the reaction of corresponding hydrazide 3a with amines and amino acid esters respectively via azide coupling method.

Similarly; N-alkyles-3-[2-(4-Benzyl-1-oxo-1H-phthalazin-2-yl)-acetylamino] 5a-f and the dipeptides methyl{3-[2-(4-Benzyl-1-oxo-1H-phthalazin-2-yl)-acetylamino]-propionylamino} alkanoates 7a-c were obtained by the reaction of corresponding hydrazide 3b with amines and amino acid esters respectively via azide coupling method

Radical cyclizations are considered efficient synthetic strategies to assembly heterocycles. Most radical cyclizations are based on the addition to C-C double or triple bonds. On the contrary, the addition to C-O double bonds is rarely reported, since it proceed reversibly due to the formation of thermodynamically unfavorable alkoxy radicals. Herein we report our attempts to construct substituted pyrrolidin-3-ols by tin-mediated radical cyclization of 5-phenylseleno-3-aza-pentanals. These rings are widely represented in natural products and drug candidates with various biological activities.

Background: A novel series of fused imidazole was prepared from the reaction of 2- bromoacetyl-3-phenyl-1,3,4-thiadiazole with various heterocyclic amines under microwave irradiation. The structures of all the novel products were elucidated based on the elemental analysis and spectral data.

Results: In addition, the biological activity of the newly synthesized compounds was evaluated and the results obtained indicate their potency as anti-inflammatory, analgesic and anti- ulcer agents.

Conclusion: The binding mechanism of the most active compounds was studied using MOE to analyze the molecular interactions.

The present study focuses on the microwave assisted extraction of Annona reticulata leaves in ethanol. The extract obtained was subjected to column chromatography and the fractionation was done to get different fractions. Preliminary phytochemical screening was done and the fractions were subjected to total phenolic and flavanoid content estimation. The crude extract contained 502 mg GAE/100g of phenolic content and among the fractions AM8 contained the maximum amount of phenolic content that is 360 mg GAE/100g. The flavanoid content present in the crude extract of the Annona reticulata was found to be 127mg QE/100g. Among all the tested fractions, the fraction AM8 showed more flavanoids i.e. 112 mg QE/100g and 118 AN/100g. The antioxidant activity has been studied in-vitro by using DPPH, hydrogen peroxide assay. DPPH, H₂O₂ and Nitric-oxide scavenging effect of Annona reticulata L. leaf extracts were found to be dose dependant with maximum inhibition at highest concentration. Methanolic extract of the leaves of Annona reticulata Linn. is found to have most potent anti-oxidant activity in DPPH, H₂O₂ Radical scavenging methods. IC50 value DPPH and H₂O₂ inhibition of methanolic extract at highest concentration (400μg/ml) are 62.58 ± 1.15, 68.27 ± 1.05 and 64.01 ± 1.02. The results suggest that all the tested extracts are having antioxidant property, but the methanol is having significantly higher flavonoid and phenol content. Due to presence of higher flavonoid and phenol content in methanol, it may be considered as the fraction with better pharmacological property in comparison to other tested extracts.

Starting from methyl-1,4-Dioxo-3-phenyl-3,4-dihydro-1H-phthalazin-2-yl-acetate (2) eighteen newly Phthalazine dione derivatives were synthesized. The starting material 2 was prepared by N-alkylation of 2-phenyl-2,3-dihydrophthalazine-1,4-dione (1) with ethyl chloro acetate under reflux over night. 2-(1,4-dioxo-3-phenyl-3,4-dihydrophthalazin-2(1H)-yl)acetohydrazide (3) was prepared by hydrazinolysis of ester 2 with hydrazine hydrate under reflux. Monopeptide 4a-c were prepared via azide coupling method by coupling of hydrazide 3 with different methyl ester of glycine, β-alanine and L-leucine respectively. The hydrazides 5a-c were prepared by hydrazinolysis of esters 4a-c with hydrazine hydrate respectively. Similarly; dipeptides 6a-i were prepared form coupling of methyl esters of glycine, β-alanine and L-leucine with hydrazides 5a-c via azide coupling method. Schiff’s base hydrazones 7a-i were prepared by condensation of hydrazides 5a-c with different aldehydes such as 4-chlorobenzaldehyde, 4-methoxybenzaldehyde and 4-nitrobenzaldehyde.

The anti-bacterial activities of the synthesized compound were screened in vitro against E.coli, Salmonella and Staphylococcus aureus with comparison to 2-phenyl-2,3-dihydrophthalazine-1,4-dione (1). The results showed that most compounds have activities against E.coli and a little compounds were sensitive to Salmonella but there no significance response to Staphylococcus aureus. Also the anti-cancer activities were assayed and some synthesized phthalazinedione has high activity in inhibition of HEPG2 and MCF-7 cancer cell lines.

The development of new chiral chromophoric systems able to emit circularly polarized light (aka circularly polarized luminescence or CPL) has attracted a great deal of attention due to their application in the improvement and potential development of multiple photonic technologies such as 3D optical displays, biological probes, CPL lasers or light-emission systems for asymmetric photosynthesis. Among all the chromophoric systems enabling CPL, simple organic molecules (SOMs) have the advantage of showing high and easily tunable absorption and fluorescence, together with easy manipulation for manufacturing processes. Particularly, BODIPYs (boron dipyrromethenes) are outstanding chromophores owing to their excellent and tunable photophysical properties. Unfortunately, SOMs usually possess weak CPL activities, compared to other systems such as lanthanides or supramolecular aggregates.

The achievement of chirality in SOMs towards CPL emission is not an easy task. In many cases, the chiral perturbation of the chromophore comes together with a distortion of the structure, leading to a decrease in the fluorescence (for example, it has been observed for helicenes). In this sense, the boron atom in BODIPYs offers a privileged position for the chiral perturbation of the chromophore without altering its photophysical signature, as reported by us for O-BODIPYs having atropoisomeric BINOL attached to the boron.

We report in this communication an unexplored strategy to transfer chirality to the BODIPY chromophore, based on attaching chiral carbons directly to the boron atom, that is, C*-BODIPYs. The starting hypothesis is that the closer proximity of the chiral center to the BODIPY core will achieve a more efficient chiral perturbation over the chromophore.

Nowadays, constructing solid acid catalysts with well-defined structures, environmentally benign, high catalytic activity, easy separation, and high chemical stability is the most important area of industrial and environmental concerns. Over the past few decades, porous conjugated polymers have been employed as stable catalysts support for various organic transformations. Among these materials, graphitic carbon nitride (g-C₃N₄) has been widely studied in the field of photocatalysis and heterogeneous catalysis, due to its high surface area and great physical and chemical stability. Herein, we report the synthesis of sulfonated graphitic carbon nitride (Sg-C₃N₄) as an efficient solid acid catalyst for the preparation of various biologically nitrogen-containing heterocyclic compounds under mild reaction conditions.