Hypericum spp.—An Overview of the Extraction Methods and Analysis of Compounds

The Hypericum genus contains one of the few genera of flowering plants that contains a species with authorization for marketing as a traditional medicine, H. perforatum. Due to the fact that this is a large genus, comprising numerous species, a large amount of interest has been shown over the years in the study of its various pharmacological activities. The chemical composition of these species is quite similar, containing compounds belonging to the class of phloroglucinol derivatives, naphthodianthrones, phenols, flavonoids and essential oils. Taking all of this into consideration, the present study aims to offer an overview of the species of the genus from the point of view of their extraction techniques and analysis methods. An extensive study on the scientific literature was performed, and it revealed a wide range of solvents and extraction methods, among which ethanol and methanol, together with maceration and ultrasonication, are the most frequent. Regarding analysis methods, separation and spectral techniques are the most employed. Therefore, the present study provides necessary data for future studies on the species of the genus, offering a complete overview and a possible basis for their development.

Synthesis, Molecular Docking and DFT Studies of Biologically Active N-((3-(4-Nitrophenyl)-1-phenyl-1H-pyrazol-4-yl)methylene)aniline Derivatives

Some biologically active pyrazole clubbed imino molecules have been designed and synthesized from 1-phenyl-3-nitro phenyl-1H- pyrazol-4-carboxaldehyde and substituted aromatic amines via acid catalyzed condensation reaction. All the synthesized molecules were characterized by IR, 1H NMR, 13C NMR and mass spectral techniques. The in vitro antibactericidal property of the synthesized compounds was screened and compared with the results of theoretical molecular docking. Optimization of molecular geometry, DNA binding interaction and FMO analysis were also investigated by computational studies using Gaussian 16 package at B3LYP/6-31G(d,p) level. All the synthesized compounds exhibited moderate to good biological activities both experimentally and theoretically.

Synthesis, Characterization and Biological Activity of ONO Donor Schiff Base and its Metal Complexes

A new Schiff base ligand (E)-2-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)-N-(5- methyl-3-phenyl-1H-indol-2-yl)hydrazine carboxamide (L) (3) was synthesized by the reaction of N-(5-methyl-3-phenyl-1H-indol-2-yl)hydrazinecarboxamide (1) and 7-hydroxy-4-methyl-2-oxo-2Hchromene- 8-carbaldehyde (2). The Cu(II), Co(II), Ni(II) and Zn(II) metal complexes (4a-d) were synthesized and its structural elucidation was done by different spectral techniques. The Schiff base (3) behaves as ONO donor ligand and forms the complexes of the sort [M(L)(Cl)(H2O)2] for Cu(II) (4a) and Zn(II) (4d) and [M(L)2] for Co(II) (4b) and Ni(II) (4c). Compounds (3) and (4a-d) were tested in vitro for antimicrobial action, cytotoxicity property against Artemia salina and anti-tuberculosis assay against Mycobacterium tuberculosis (ATCC 25177). The metal complexes showed very good biological activity.

Synthesis, Characterization and Evaluation of Biological Activities of Sn(II) Complexes of Schiff Base Incorporating Sulpha Drugs

In this study, we report synthesis, characterization and biological activities of four sulpha drug based Schiff base ligands and their Sn(II) complexes. The Schiff bases and their Sn(II) complexes have been synthesized by traditional methods and characterized by the spectral techniques IR, NMR (1H and 13C), mass and TGA-DTA. Newly synthesized Schiff bases (L1-L4) and their Sn(II) complexes (C-1 to C-4) have been screened for antibacterial activity against bacterial strains S. aureus, S. pyogenus, E. coli, P. aeruginosa and antifungal activity against fungal strains C. albicans, A. niger, A. clavatus using broth micro dilution method. Best antimicrobial activity was shown by C-3 complex against E. coli (MIC, 50.0 µg/mL) and A. niger microbial strains (MIC, 100 µg/mL). Moreover, antimalarial activity against plasmodium falciparum was also studied. Complex C-3 was found to be more active against parasite P. falciparum (IC50, 0.04 µg/mL). Results showed that dichloride tin complexes are more active with respect to their corresponding Schiff base ligands.

Nickel(II)-Complex of Ceftibuten Dihydrate: Synthesis, Characterization and Thermal Study

Ceftibuten dihydrate is a semisynthetic, orally administered, third generation cephalosporin antibiotic which is effective against most of the pathogens causing infections in the respiratory tract. Complexation of ceftibuten dehydrate (Ligand, L) was performed with hydrated Ni(II) salt (Metal, M) in the ratio of 2:1 (L:M) in aqueous medium at 90 oC. The metal complex was then characterized by spectral techniques and thermal analyses. The FT-IR spectral data of metal complex suggested the monodentate bonding of metal ion to carboxylate group. Spectral evidence also supported the formation of five-membered ring via coordination of metal ion to β-lactam nitrogen and carboxylate group of parent drug. Thermal behavior of ligand and complex were studied. Thus, thermoanalytical (DSC and TGA) results also supported the formation of new metal complex, indicating the successful interaction of metal ion to ligand. Dhaka Univ. J. Pharm. Sci. 20(2): 219-225, 2021 (December)

Symmetry and Combinatorial Concepts for Cyclopolyarenes, Nanotubes and 2D-Sheets: Enumerations, Isomers, Structures Spectra & Properties

This review article highlights recent developments in symmetry, combinatorics, topology, entropy, chirality, spectroscopy and thermochemistry pertinent to 2D and 1D nanomaterials such as circumscribed-cyclopolyarenes and their heterocyclic analogs, carbon and heteronanotubes and heteronano wires, as well as tessellations of cyclopolyarenes, for example, kekulenes, septulenes and octulenes. We establish that the generalization of Sheehan’s modification of Pólya’s theorem to all irreducible representations of point groups yields robust generating functions for the enumeration of chiral, achiral, position isomers, NMR, multiple quantum NMR and ESR hyperfine patterns. We also show distance, degree and graph entropy based topological measures combined with techniques for distance degree vector sequences, edge and vertex partitions of nanomaterials yield robust and powerful techniques for thermochemistry, bond energies and spectroscopic computations of these species. We have demonstrated the existence of isentropic tessellations of kekulenes which were further studied using combinatorial, topological and spectral techniques. The combinatorial generating functions obtained not only enumerate the chiral and achiral isomers but also aid in the machine construction of various spectroscopic and ESR hyperfine patterns of the nanomaterials that were considered in this review. Combinatorial and topological tools can become an integral part of robust machine learning techniques for rapid computation of the combinatorial library of isomers and their properties of nanomaterials. Future applications to metal organic frameworks and fullerene polymers are pointed out.

Synthesis and Spectral Studies of Some Homo Dinuclear Lanthanide(III) Complexes of a Mesogenic Schiff Base

A mesogenic Schiff base, N,N’-di(4-decyloxysalicylidene)-1’,8’-diamino-3’,6’-dioxaoctane (H2L) and a series of homo dinuclear lanthanide(III) complexes of the type [Ln2(LH2)3(NO3)4](NO3)2, (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho) were synthesized and characterized by elemental analysis, mass spectrometry, FTIR, and NMR spectral techniques. The IR and NMR spectral evidences imply bonding of a neutral bidentate H2L species through two phenolate oxygen atoms in its zwitterionic form to LnIII, rendering the overall geometry of the complexes as a seven-coordinate polyhedron – possibly distorted mono-capped octahedron. Differential scanning calorimetry (DSC) and polarizing optical icroscopic (POM) studies reveal mesogenic properties (smectic-X, smectic-A and nematic mesophases) in the ligand over a wide range of temperature but none mesomorphism in the LnIII complexes synthesized under this study. Luminescence studies exhibit emissions of H2L and TbIII complex.

Analysis and Prediction of Electric Power System’s Stability Based on Virtual State Estimators

The stability of bilinear systems is investigated using spectral techniques such as selective modal analysis. Predictive models of bilinear systems based on inductive knowledge extracted by big data mining techniques are applied with associative search of statistical patterns. A method and an algorithm for the elementwise solution of the generalized matrix Lyapunov equation are developed for discrete bilinear systems. The method is based on calculating the sequence of values of a fixed element of the solution matrix, which depends on the product of the eigenvalues of the dynamics matrix of the linear part and the elements of the nonlinearity matrixes. A sufficient condition for the convergence of all sequences is obtained, which is also a BIBO (bounded input bounded output) systems stability condition for the bilinear system.

EVALUATION OF ANTI-MICROBIAL POTENTIAL OF STRUCTURALLY MODIFIED DERIVATIVES OF LEAD COMPOUND BERBERINE ISOLATED FROM ROOTS OF BERBERIS ARISTATA

The alkaloid berberine, the chief constituent of Berberis aristata, has been reported to have antimicrobial activity associated with it. Structural changes can be made to this lead compound to try to improve its effi cacy in terms of antimicrobial activity. In the present study, attempts have been made to evaluate anti-microbial potential of structurally modifi ed derivatives of berberine. The derivatives so synthesized were characterized on the basis of spectral techniques like 1H,13C NMR, UV, IR and MASS and by comparison with standard berberine. Structure-activity relationship studies revealed that methoxyl group is pharmacophore of berberine and is thus needed to be retained in the skeleton. Further incorporation of the electron-withdrawing group has pronounced effect on the antimicrobial activity. Further attempts could be made to extend the series with the incorporation of such electron-withdrawing groups to get potent antimicrobial agents.