Phytochemicals Analysis, In Vitro Antibacterial Activities of Extracts, and Molecular Docking Studies of the Isolated Compounds from Melhania zavattarii Cufod Leaves.

Melhania zavattarii Cufod is an endemic plant species to Ethiopia and is used to treat ailments related to kidney infection. The phytochemical composition and biological activity of M. zavattarii have been not reported yet. Therefore, the present work aimed to investigate phytochemical constituents and evaluate the antibacterial activity of different solvents' leaf extracts and analyze the molecular binding capacity of isolated compounds from the chloroform leaf extract of M. zavattarii. Accordingly, preliminary phytochemical screening was tested by using standard procedures and the result indicated that phytosterols and terpenoids as major and others like alkaloids, saponins, flavonoids, tannins, phlobatannin, and coumarins were detected as minor in extracts. Antibacterial activity of the extracts was evaluated using the disk diffusion agar method, and the activities revealed that chloroform extract showed the highest inhibition zones, 12.08 ± 0.38, 14.00 ± 0.50, and 15.58 ± 0.63 mm against Escherichia coli at 50, 75, and 125 mg/mL concentrations, respectively, compared to that of n-hexane and methanol extracts at respective concentrations. Methanol extract showed the highest zone of inhibition 16.42 + 0.52 against Staphylococcus aureus at 125 mg/mL concentration compared to that of n-hexane and chloroform extracts. Two compounds, namely, ß-amyrin palmitate (1) and lutein (2) were isolated and identified for the first time from the chloroform leaf extract of M. zavattarii, and structural elucidations of these compounds were accomplished by using spectroscopic methods (IR, UV, and NMR). For the molecular docking study, 1G2A, which is a protein of E. coli and chloramphenicol standard target, was selected. Binding energies of -9.09, -7.05, and -6.87 kcal/mol were calculated for ß-amyrin palmitate, lutein, and chloramphenicol, respectively. The drug-likeness property result indicated that both ß-amyrin palmitate and lutein violated two rules of Lipinski's rule of five with molecular weight (g/mol) > 500 and LogP > 4.15. In the near future, further phytochemical investigation and biological activity evaluation should be conducted on this plant.

Design, synthesis, biological screening and molecular docking studies of novel multifunctional 1,4-di (aryl/heteroaryl) substituted piperazine derivatives as potential antitubercular and antimicrobial agents.

In this paper, two series of novel multifunctional 1, 4-di (aryl/heteroaryl) substituted piperazine derivatives (6a-d & 7a-d) were synthesized, characterized, and evaluated for their antitubercular, antibacterial, and antifungal activities. A step-wise reduction, bromination and substitution reactions on various aldehydes resulted in alcohols (2a-d), bromides (3a-d), and titled novel compounds (6a-d & 7a-d) in moderate to good yields (48-85%). The novel compounds were evaluated for their antitubercular and antimicrobial activities. Compound 7a exhibited promising antitubercular activity (MIC: 0.65 µg/mL) almost equal to the Rifampicin, while the rest of the compounds were moderately active against MTB H37Rv except 6b. Compounds 7a and 6b showed good activity against tested fungal pathogens. Compounds 7a and 7b were proven as the best bacterial agents. Molecular docking studies were in agreement with the in-vitro results. Docking analyses show that all the synthesized molecules bind to the target protein Mtb RNAP (PDB ID: 5UHC) fairly strongly. All the compounds were evaluated for their in vitro cytotoxicity effect using the MTT assay method against human cancer cell line MCF-7. The compounds demonstrated growth inhibitory effect on the cell line with significant IC50 values ranging between 8.20 and 34.45 µM. Most importantly, compound 7a displayed good binding affinity towards the tested protein with binding energy -7.30 kcal/mol and a stronger hydrogen bond distance of 2.2 Å with ASN-493 residue. Thus, the present research highlighted the potential role of novel piperazine derivatives as potential antitubercular, and antimicrobial candidates and further good research into optimization might result in the development of new antitubercular drug candidates.

Branching Ratios, Radiative Lifetimes, and Transition Dipole Moments for YbOH.

Medium resolution (Δν̃ ∼ 3 GHz) laser-induced fluorescence (LIF) excitation spectra of a rotationally cold sample of YbOH in the 17300-17950 cm-1 range have been recorded using two-dimensional (excitation and dispersed fluorescence) spectroscopy. High resolution (Δλ ∼ 0.65 nm) dispersed laser-induced fluorescence (DLIF) spectra and radiative decay curves of numerous bands detected in the medium resolution LIF excitation spectra were recorded. The vibronic energy levels of the X̃2Σ+ state were predicted using a discrete variable representation approach and compared with observations. The radiative decay curves were analyzed to produce fluorescence lifetimes. DLIF spectra resulting from high resolution (Δν̃ < 10 MHz) LIF excitation of individual low-rotational lines in the Ã2Π1/2(0,0,0)-X̃2Σ+(0,0,0), Ã2Π1/2(1,0,0)-X̃2Σ+(0,0,0), and [17.73]Ω = 0.5(0,0,0)-X̃2Σ+(0,0,0) bands were also recorded. The DLIF spectra were analyzed to determine branching ratios which were combined with radiative lifetimes to obtain transition dipole moments. The implications for laser cooling and trapping of YbOH are discussed.

Large amplitude motion within acetylene-rare gas complexes hosted in helium droplets.

Near-infrared spectroscopy of the C2H2-Ar, Kr complexes was performed in the spectral region overlapping the ν3/ν2 + ν4 + ν5 Fermi-type resonance of C2H2. The experiment was conducted along the HElium NanoDroplet Isolation (HENDI) technique in order to study the coupling dynamics between a floppy molecular system (C2H2-Ar and C2H2-Kr) and a mesoscopic quantum liquid (the droplet). Calculations were performed using a spectral element based close-coupling program and state-of-the-art 2-dimensional potential energy surfaces to determine the bound states of the C2H2-Ar and C2H2-Kr complexes and simulate the observed spectra. This furnished a quantitative basis to unravel how the superfluid and non-superfluid components of the droplet affect the rotation and the deformation dynamics of the hosted complex.

Dual fluorescence of (E)-N-(4-(dimethylamino)benzylidene)-2H-1,2,4-triazol-3-amine (DMABA-Amtr): A ground state perspective.

We present the absorption and fluorescence spectra of (E)-N-(4-(dimethylamino)benzylidene)-2H-1,2,4-triazol-3-amine (DMABA-Amtr), an electron donor-π-acceptor system. The molecule shows a single fluorescence emission band in non-polar solvents while dual emissions were observed in polar aprotic solvents. Although several researchers over the years provide different explanations for the mechanism of the phenomena, based on solvent assisted excited state geometry changes of such systems, it is still a matter of controversy since such systems are unique as they contradict Kasha's rule. The emission spectrum of the molecule shows strong dependence on solvent polarity and excitation wavelength. This observation together with a single iso-emissive point found in the area normalize emission spectra indicates the presence of two ground state equilibrium structures of the compound which are both fluorescent. Density functional theory (DFT) and time-dependent (TD-DFT) calculations also support the experimental findings.

Supersonic Jet Spectroscopy and Density Functional Theory Study of Isomeric Diazines: 1,4- and 1,8-Diazatriphenylene. Why Do They Differ So Deeply?

We report on laser-induced fluorescence excitation and dispersed fluorescence spectra of two isomeric compounds: 1,4- and 1,8-diazatriphenylene (1,4- and 1,8-DAT) isolated in supersonic molecular jets, and their 1:1 complexes with protic solvents. We found that the ground and excited state vibronic patterns of bare 1,4-DAT differ significantly from those of 1,8-DAT, and those of the complexes of both isomers. A marked activity of several out-of-plane vibrations in 1,4-DAT and the symptoms of the distortion of the S1 excited molecule were diagnosed from the vibronic spectra, whereas planar structures were predicted for 1,8-DAT in S0 and S1 states. An anharmonic double-minimum potential along an out-of-plane coordinate has been derived and used to predict higher overtones of the S1 state vibration at 113 cm-1. Large enhancement of fluorescence was observed upon formation of 1:1 complexes of 1,4-DAT with water or methanol, which is explained in terms of an increased separation of interacting (n,π*) and (π,π*) electronic states in the H-bonded complexes, and/or a suppression of the intersystem crossing process.

Spectroscopic study of jet-cooled deuterated porphycenes: unusual isotopic effects on proton tunneling.

Porphycene (Pc) is a well-known model for studying double hydrogen transfer, which shows vibrational-mode-specific tunneling splitting when isolated in supersonic jets or helium nanodroplets. The effect of deuteration on tunneling splitting is reported for jet-cooled heterogeneous, deuterated Pc samples (Pc-d(mix)) with the prevailing contribution of Pc-d12 isotopologue. The sample introduced into the gas phase using laser desorption is studied by means of laser-induced fluorescence (LIF) and single vibronic level fluorescence (SVLF) measurements, in combination with quantum chemical calculations. The influence of molecular symmetry is studied by comparing Pc, Pc-d12, and Pc-d11. The spectra of Pc-d12 show strong similarity to those of the parent undeuterated porphycene (Pc). Comparable tunneling splitting is observed in the two isotopologues, both for the 0-0 transition and the most efficient promoting 2Ag mode. In contrast, an unusual isotopic effect is observed for the totally symmetrical 4Ag mode. While this vibration behaves as a neutral mode in Pc, neither enhancing nor decreasing the tunneling efficiency, it strongly promotes hydrogen transfer in Pc-d12. This observation is explained in terms of modification of the displacement vectors of the 4Ag mode upon deuteration. It demonstrates that isotope substitution affects hydrogen transfer even when the weak structural modifications are far from the reaction center, emphasizing the strongly multidimensional nature of the tunneling process.

Vibrations of porphycene in the S0 and S1 electronic states: single vibronic level dispersed fluorescence study in a supersonic jet.

Supersonic jet-isolated porphycene has been studied using the techniques of laser-induced fluorescence excitation, single vibronic level fluorescence, and spectral hole burning, combined with quantum mechanical calculations of geometry and vibrational structure of the ground and lowest electronically excited singlet states. Porphycene is a model for coherent double hydrogen tunneling in a symmetrical double well potential, as evidenced by tunneling splittings observed in electronic absorption and emission. The results led to reliable assignment of low frequency modes in S0 and S1 electronic states. The values of tunneling splitting were determined for ground state vibrational levels. In the case of tautomerization-promoting 2A(g) mode, tunneling splitting values significantly increase with the vibrational quantum number. Mode coupling was demonstrated by different values of tunneling splitting obtained for coexcitation of two or more vibrations. Finally, alternation of relative intensity patterns for the components of 2A(g) tunneling doublet observed for excitation and emission into different vibrational levels suggests that the energy order of levels corresponding to (+) and (-) combinations of nuclear wave functions is different for even and odd vibrational quantum numbers.