Association between infection with Helicobacter pylori and atopy in young Ethiopian children: A longitudinal study.

BACKGROUND: Epidemiological evidence from developed countries indicates that Helicobacter pylori infection correlates with a reduced risk of atopy and allergic disorders; however, limited data are available from low-income countries. OBJECTIVE: We examined associations between H. pylori infection in early childhood and atopy and reported allergic disorders at the age of 6.5 years in an Ethiopian birth cohort. METHODS: A total of 856 children (85.1% of the 1006 original singletons in a population-based birth cohort) were followed up at age six and half years. An interviewer-led questionnaire administered to mothers provided information on demographic and lifestyle variables. Questions on allergic disease symptoms were based on the International Study of Asthma and Allergies in Children (ISAAC) core allergy and environmental questionnaire. Serum samples were analysed for total IgE levels and anti-H. pylori cytotoxin-associated gene A (CagA) IgG antibody using commercially available ELISA kits. Stool samples were analysed for H. pylori antigen using a rapid immunochromatographic test. The independent effects of H. pylori infection (measured at age of 3, 5 and 6.5 years) on prevalence and incidence of atopy and reported allergic disorders (measured at age of 6.5 years) were determined using multiple logistic regression. RESULTS: In cross-sectional analysis, current H. pylori infection at age 6.5 years was inversely, though not significantly, related to prevalence of atopy and "any allergic condition" at age 6.5 years. However, detection of H. pylori infection at any point up to age 6.5 years was associated with a significantly reduced odds of both atopy and "any allergic condition" (adjusted OR AOR, 95% CI, 0.54; 0.32-0.92, P = .02, and .31; 0.10-0.94, P = .04, respectively). In longitudinal analyses, H. pylori infection at age 3 was inversely associated with incidence of atopy (AOR, 95% CI, 0.49; 0.27-0.89, P = .02). Furthermore, among H. pylori-infected children, those with a CagA+ strain had a more pronounced reduction in odds of atopy (AOR = 0.35 vs 0.63 for CagA+ vs CagA-), and this reduction reached borderline significance. CONCLUSION: These data are consistent with the hypothesis that early exposure to H. pylori is inversely associated with atopy and allergic conditions. A possible modest protective association against atopy was observed in those infected with a more virulent CagA+ strain of H. pylori.

The behavior of a paramagnetic system in electric and magnetic fields as exemplified by revisiting Li@B10H14.

The electric and magnetic properties of the Li@B10H14 complex, considered as a novel inorganic electride-type system with potential for second-order non-linear optical (NLO) applications, have already been studied. However, the reported C2v structure is not the global energy minimum and therefore its electronic and magnetic properties need to be revisited. Moreover, by applying more accurate computational protocols (ROHF-CCSD/CCSD(T) and larger basis sets) we show that the model chemistry used earlier (UMP2/6-31+G(d)) is not sufficient for reliable description of the NLO responses of this open-shell doublet complex. The global minimum based on the Cs symmetry is significantly (by ca. 25 kcal mol-1) more stable than the C2v structure and it should be viewed as a system with moderate NLO responses. An excess of unpaired electron density is also responsible for the contact and pseudo-contact contributions to the magnetic properties, which was not considered in the earlier work.

Cryptophanes for Methane and Xenon Encapsulation: A Comparative Density Functional Theory Study of Binding Properties and NMR Chemical Shifts.

The host-guest chemistry of cryptophanes is an active research area because of its applications in sensor design, targeting small molecules and atoms in environmental and medical sciences. As such, the computational prediction of binding energies and nuclear magnetic resonance (NMR) properties of different cryptophane complexes are of interest to both theoreticians and experimentalists working in host-guest based sensor development. Herein we present a study of 10 known and some newly proposed cryptophanes using density functional theory (DFT) calculations. We benchmark the description of nonbonding interactions by different DFT functionals against spin-component-scaled, second-order Møller-Plesset theory (SCS-MP2) and predict novel host molecules with enhanced affinity toward methane and Xenon, two representative systems of high interest. We demonstrate the power and limitations of the different computational methods in describing the binding and NMR properties of these established and novel host systems. The results show the importance of including dispersion corrections in the DFT functionals. The overall analysis of the dispersion corrections indicated that results obtained from pure DFT functionals should be used cautiously when conclusions are drawn for molecular systems with considerable weak interactions. Proposed analogues of cryptophane-A, where the alkoxy bridges are replaced by alkyl chains, are predicted to display enhanced affinity toward both methane and Xenon.

Relativistic effects on the NMR parameters of Si, Ge, Sn, and Pb alkynyl compounds: Scalar versus spin-orbit effects.

The NMR chemical shifts and indirect spin-spin coupling constants of 12 molecules containing 29Si, 73Ge, 119Sn, and 207Pb [X(CCMe)4, Me2X(CCMe)2, and Me3XCCH] are presented. The results are obtained from non-relativistic as well as two- and four-component relativistic density functional theory (DFT) calculations. The scalar and spin-orbit relativistic contributions as well as the total relativistic corrections are determined. The main relativistic effect in these molecules is not due to spin-orbit coupling but rather to the scalar relativistic contraction of the s-shells. The correlation between the calculated and experimental indirect spin-spin coupling constants showed that the four-component relativistic density functional theory (DFT) approach using the Perdew's hybrid scheme exchange-correlation functional (PBE0; using the Perdew-Burke-Ernzerhof exchange and correlation functionals) gives results in good agreement with experimental values. The indirect spin-spin coupling constants calculated using the spin-orbit zeroth order regular approximation together with the hybrid PBE0 functional and the specially designed J-coupling (JCPL) basis sets are in good agreement with the results obtained from the four-component relativistic calculations. For the coupling constants involving the heavy atoms, the relativistic corrections are of the same order of magnitude compared to the non-relativistically calculated results. Based on the comparisons of the calculated results with available experimental values, the best results for all the chemical shifts and non-existing indirect spin-spin coupling constants for all the molecules are reported, hoping that these accurate results will be used to benchmark future DFT calculations. The present study also demonstrates that the four-component relativistic DFT method has reached a level of maturity that makes it a convenient and accurate tool to calculate indirect spin-spin coupling constants of "large" molecular systems involving heavy atoms.

Mechanism and Site Selectivity in Visible-Light Photocatalyzed C-H Functionalization: Insights from DFT Calculations.

Visible-light photocatalyzed (VLPC) late-stage C-H functionalization is a powerful addition to the chemical synthesis toolkit. VLPC has a demonstrated potential for discovery of elusive and valuable transformations, particularly in functionalization of bioactive heterocycles. In order to fully harvest the potential of VLPC in the context of complex molecule synthesis, a thorough understanding of the elementary processes involved is crucial. This would enable more rational design of suitable reagents and catalysts, as well as prediction of activated C-H sites for functionalization. Such knowledge is essential when VLPC is to be employed in retrosynthetic analysis of complex molecules. Herein, we present a density functional theory (DFT) study of mechanistic details in the C-H functionalization of bioactive heterocycles exemplified by the methylation of the antifungal agent voriconazole. Moreover, we show that readily computed atomic charges can predict major site-selectivity in good agreement with experimental studies and thus be informative tools for the identification of active C-H functionalization sites in synthetic planning.

Chiral recognition by fullerenes: CHFClBr enantiomers in the C82 cage.

Density-functional theory and symmetry-adapted perturbation theory calculations on complexes of the enantiomers of CHFClBr with the most stable isomer of C82-3 fullerene show that despite the guests being too large for the host cage, they are nevertheless stabilized by electrostatic interactions. The complexation leads to considerable strain on the cage and the guests accompanied by compression of the bonds of the guest molecule, resulting in considerable complexation-induced changes in the infrared (IR), vibrational circular dichroism (VCD), nuclear magnetic resonance (NMR), and UV-vis spectra. The effect of chiral recognition is pronounced only for the 19F signal in the NMR spectra and in a sign reversal of the rotational strength of the νCH stretching vibration of S-CHFClBr@C82-3 in the VCD spectrum as compared to that of the free guest, making the sign of this band for the C82 complexes with the S- and R-guest enantiomers the same. This is a surprising result since vibrational circular dichroism is considered a reliable method for determining the absolute chirality of small molecules and for establishing dominant conformations in biopolymers.

NMR absolute shielding scale and nuclear magnetic dipole moment of (207)Pb.

An absolute shielding scale is proposed for (207)Pb nuclear magnetic resonance (NMR) spectroscopy. It is based on ab initio calculations performed on an isolated tetramethyllead Pb(CH3)4 molecule and the assignment of the experimental resonance frequency from the gas-phase NMR spectra of Pb(CH3)4, extrapolated to zero density of the buffer gas to obtain the result for an isolated molecule. The computed (207)Pb shielding constant is 10 790 ppm for the isolated molecule, leading to a shielding of 10799.7 ppm for liquid Pb(CH3)4 which is the accepted reference standard for (207)Pb NMR spectra. The new experimental and theoretical data are used to determine µ((207)Pb), the nuclear magnetic dipole moment of (207)Pb, by applying the standard relationship between NMR frequencies, shielding constants and nuclear moments of two nuclei in the same external magnetic field. Using the gas-phase (207)Pb and (reference) proton results and the theoretical value of the Pb shielding in Pb(CH3)4, we find µ((207)Pb) = 0.59064 µN. The analysis of new experimental and theoretical data obtained for the Pb(2+) ion in water solutions provides similar values of µ((207)Pb), in the range of 0.59000-0.59131 µN.

Structure, NMR and Electronic Spectra of [m.n]Paracyclophanes with Varying Bridges Lengths (m, n = 2-4).

Extending our earlier studies on cyclophanes, we here report the structure, chemical shifts, spin-spin coupling constants, absorption and emission properties of [m.n]paracyclophanes, m, n = 2-4, obtained using a combination of experimental and computational techniques. Accurate values of proton chemical shifts as well as of JHH for the bridges are determined. The experimental chemical shifts, coupling constants, absorption and emission wavelengths are satisfactorily reproduced using density functional theory calculations, using both the B3LYP and ωB97X-D functionals. The geometries predicted using a functional that includes dispersion corrections (ωB97X-D) are in a better agreement with available experimental values than those obtained using the B3LYP method. Up to 8 UV-vis absorption/emission bands have been observed (or anticipated in the region below 200 nm) and assigned on the basis of quantum-chemical calculations. Optimized excited-state geometries showed that the distances between the aromatic bridgehead carbon atoms of all the [m.n]paracyclophanes in the excited state decrease compared to the ground-state geometries by ca. 0.2-0.9 Å, the largest being for [4.4]paracyclophane, though the rather large differences in the calculated emission wavelength compared to experiment cast some doubts on the accuracy of the excited-state geometries.

Indirect NMR spin-spin coupling constants in diatomic alkali halides.

We report the Nuclear Magnetic Resonance (NMR) spin-spin coupling constants for diatomic alkali halides MX, where M = Li, Na, K, Rb, or Cs and X = F, Cl, Br, or I. The coupling constants are determined by supplementing the non-relativistic coupled-cluster singles-and-doubles (CCSD) values with relativistic corrections evaluated at the four-component density-functional theory (DFT) level. These corrections are calculated as the differences between relativistic and non-relativistic values determined using the PBE0 functional with 50% exact-exchange admixture. The total coupling constants obtained in this approach are in much better agreement with experiment than the standard relativistic DFT values with 25% exact-exchange, and are also noticeably better than the relativistic PBE0 results obtained with 50% exact-exchange. Further improvement is achieved by adding rovibrational corrections, estimated using literature data.

Mercury Methylation by Cobalt Corrinoids: Relativistic Effects Dictate the Reaction Mechanism.

The methylation of Hg(II) (SCH3 )2 by corrinoid-based methyl donors proceeds in a concerted manner through a single transition state by transfer of a methyl radical, in contrast to previously proposed reaction mechanisms. This reaction mechanism is a consequence of relativistic effects that lower the energies of the mercury 6p1/2 and 6p3/2 orbitals, making them energetically accessible for chemical bonding. In the absence of spin-orbit coupling, the predicted reaction mechanism is qualitatively different. This is the first example of relativity being decisive for the nature of an observed enzymatic reaction mechanism.

Is Helicobacter Pylori infection inversely associated with atopy? A systematic review and meta-analysis.

BACKGROUND: The role Helicobacter Pylori (H. pylori) infection plays in the aetiology of atopy remains unclear, although a possible protective role has been hypothesized. OBJECTIVE: The aim of this study was to undertake a systematic review and meta-analysis of epidemiological studies to quantify the association between H. pylori infection and atopy. METHODS: A comprehensive literature search in MEDLINE/PUBMED and EMBASE (up to August 2013) was carried out to identify all observational epidemiological studies (cross-sectional, cohort and case-control) published in English that evaluated the association between H. pylori infection and objectively measured atopy (measured by allergen skin tests or specific IgE). The quality of included studies was assessed by the Newcastle-Ottawa scale. Random-effects meta-analyses were performed to obtain pooled estimates of effect. RESULTS: Twenty-two observational studies involving 21 348 participants were identified as eligible for inclusion in the review, of which 16 were included in the meta-analysis. H. pylori infection was associated with a significantly reduced odds of atopy (pooled odds ratio (OR) 0.82; 95% confidence interval (CI) 0.73 - 0.91; P < 0.01). Subgroup analysis according to atopy definition revealed a slightly greater protective effect for atopy defined as raised allergen-specific IgE (OR 0.75; 95% CI 0.62 - 0.92; P < 0.01; seven studies). Findings did not differ according to the population age (adult or children), methodological quality or study design. CONCLUSION AND CLINICAL RELEVANCE: Evidence from epidemiological studies suggests that H. pylori infection is associated with an estimated 18% reduction in odds of atopy. If the observed association is causal, more insights into the underlying mechanisms could provide clues to possible therapeutic opportunities in allergic disease.

Absolute NMR shielding scales and nuclear spin-rotation constants in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br and (127)I).

We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br, (127)I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

Spin-rotation and NMR shielding constants in XF molecules (X = B, Al, Ga, In, and Tl).

Accurate spin-rotation and absolute shielding constants in a series of XF molecules (X = (11)B, (27)Al, (69)Ga, (115)In, and (205)Tl) determined using high-level ab initio coupled-cluster and four-component relativistic density-functional theory (DFT) calculations are presented. The accuracy of the results is established by comparing the relativistically and vibrationally corrected calculated values with available experimental data; for spin-rotation and shielding constants for which no experimental data exist, we provide new and reliable values. For both properties, our results can be considered as reference values against which more approximate quantum-chemical methods can be benchmarked.

Ab initio and relativistic DFT study of spin-rotation and NMR shielding constants in XF6 molecules, X = S, Se, Te, Mo, and W.

We present an analysis of the spin-rotation and absolute shielding constants of XF6 molecules (X = S, Se, Te, Mo, W) based on ab initio coupled cluster and four-component relativistic density-functional theory (DFT) calculations. The results show that the relativistic contributions to the spin-rotation and shielding constants are large both for the heavy elements as well as for the fluorine nuclei. In most cases, incorporating the computed relativistic corrections significantly improves the agreement between our results and the well-established experimental values for the isotropic spin-rotation constants and their anisotropic components. This suggests that also for the other molecules, for which accurate and reliable experimental data are not available, reliable values of spin-rotation and absolute shielding constants were determined combining ab initio and relativistic DFT calculations. For the heavy nuclei, the breakdown of the relationship between the spin-rotation constant and the paramagnetic contribution to the shielding constant, due to relativistic effects, causes a significant error in the total absolute shielding constants.

Cytotoxic Cu(II) Complexes with a Novel Quinoline Derivative Ligand: Synthesis, Molecular Docking, and Biological Activity Analysis.

The utilization of metallodrugs as a viable alternative to organic molecules has gained significant attention in modern medicine. We hereby report synthesis of new imine quinoline ligand (IQL)-based Cu(II) complexes and evaluation of their potential biological applications. Syntheses of the ligand and complexes were achieved by condensation of 7-chloro-2-hydroxyquinoline-3-carbaldehyde and 2,2'-thiodianiline, followed by complexation with Cu(II) metal ions. The synthesized ligand and complexes were characterized using UV-vis spectroscopy, TGA/DTA, FTIR spectroscopy, 1H and 13C NMR spectroscopy, and pXRD. The pXRD diffractogram analysis revealed that the synthesized ligand and its complexes were polycrystalline systems, with nanolevel average crystallite sizes of 13.28, 31.47, and 11.57 nm for IQL, CuL, and CuL 2 , respectively. The molar conductivity confirmed the nonelectrolyte nature of the Cu(II) complexes. The biological activity of the synthesized ligand and its Cu(II) complexes was evaluated with in vitro assays, to examine anticancer activity against the MCF-7 human breast cancer cell line and antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. The CuL complex had the highest cytotoxic potency against MCF-7 breast cancer cells, with an IC50 of 43.82 ± 2.351 µg/mL. At 100 µg/mL, CuL induced the largest reduction of cancer cell proliferation by 97%, whereas IQL reduced cell proliferation by 53% and CuL 2 by 28%. The minimum inhibitory concentration for CuL was found to be 12.5 µg/mL against the three tested pathogens. Evaluation of antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl revealed that CuL exhibited the highest antioxidant activity with IC50 of 153.3 ± 1.02 µg/mL. Molecular docking results showed strong binding affinities of CuL to active sites of S. aureus, E. coli, and estrogen receptor alpha, indicating its high biological activity compared to IQL and CuL 2 .

Antibacterial and Cytotoxicity of Extracts and Isolated Compounds from Artemisia abyssinica: A Combined Experimental and Computational Study.

Artemisia abyssinica is a widely cultivated hedge plant in Ethiopia. Traditionally, they have been used to treat a variety of health conditions, including intestinal problems, infectious diseases, tonsillitis, and leishmaniasis. Silica gel chromatographic separation of the methanol and ethyl acetate extracts of the leaves, roots, and stem barks of A. abyssinica led to the isolation of 12 compounds, labeled as 1-12. Among these, compounds 1, 3, 4, 5, and 7-11 are reported as new to the genus Artemisia. The extracts and isolated compounds from A. abyssinica were evaluated for their in vitro antibacterial activity against four bacterial strains: Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, using the disc diffusion assay. All of the extracts displayed weak antibacterial activity, with inhibition zone diameters (IZDs) ranging from 6.10 ± 0.3 to 9.30 ± 0.20 mm. The isolated compounds, on the other hand, exhibited weak to moderate antibacterial activity, with IZDs ranging from 6.00 ± 0.300 to 13.50 ± 0.50 mm. The most potent antibacterial activity was observed for compound 6, which showed an IZD of 13.30 ± 0.50 mm against E. coli and 13.50 ± 0.50 mm against P. aeruginosa. This activity was comparable to that of the positive control ceftriaxone, which had IZDs of 14.1 ± 0.3 and 13.8 ± 0.5 mm against E. coli and P. aeruginosa, respectively. The in silico molecular docking analysis against DNA gyrase B revealed that compound 5 showed a higher binding affinity (-6.9 kcal/mol), followed by compound 10 (-6.7 kcal/mol) and compound 12 (-6.3 kcal/mol), whereas ciprofloxacin showed -7.3 kcal/mol. The binding affinities of compounds 5, 11, 10, and 9 were found to be -5.0, -4.3, -4.2, and -4.0 kcal/mol against S. aureus Pyruvate kinase, respectively, whereas ciprofloxacin showed a binding affinity of -4.9 kcal/mol, suggesting that compound 5 had a better binding affinity compared with ciprofloxacin. The effect of extracts of A. abyssinica was evaluated for cytotoxic activity against the breast cancer cell line (MCF-7) by the MTT assay. The extracts induced a decrease in cell viability and exerted a cytotoxic effect at a concentration of 20 µg/mL. The highest percent cell viability was observed for the methanol extract of the stem (92.9%), whereas the least was observed for the methanol extract of the root (34.5%). The result of the latter was significant compared with the positive control. The binding affinities of the isolated compounds were also assessed against human topoisomerase inhibitors IIß. Results showed that compound 5 showed a binding affinity of -6.0 kcal/mol, followed by 11 (-5.4 kcal/mol), 10 (-5.0 kcal/mol), and 11 (-4.9 kcal/mol). Similar to ciprofloxacin, compounds 4, 5, 6, 9, 10, and 12 comply with Lipinski's rule of five. Overall, the comprehensive investigation of the chemical constituents and their biological activities reinforces the traditional medicinal applications of A. abyssinica and warrants further exploration of this plant as a source of novel therapeutic agents.

In Silico Molecular Docking Analysis, Cytotoxicity, and Antibacterial Activities of Constituents of Fruits of Cucumis dipsaceus.

Cucumis dipsaceus (Cucurbitaceae) is a plant traditionally used against diarrhea, teeth-ach, wounds, stomach ache, meningitis, and cancer. The extracts of C. dipsaceus after silica gel column chromatography gave nine compounds identified using spectroscopic methods such as hexacosane (1), octadecane (2), 17-(-5-ethyl-2,6-dihydroxy-6-methylhept-3-en-2-yl)-9-(hydroxymethyl)-13-methylcyclopenta[α]phenanthren-3-ol (3), erythrodiol (4), (9,12)-propyl icosa-9,12-dienoate (5), α-spinasterol (6), 16-dehydroxycucurbitacin (7), cucurbitacin D (8), and 23,24-dihydroisocucurbitacin D (9). Compounds 3 and 4 are new to the genus Cucumis. α-Spinasterol showed better inhibition zone diameter = 13.67 ± 0.57, 15.00 ± 0.10, and 13.33 ± 0.57 mm against Escherichia coli, Pseudomonas aeruginosa, and Streptococcus pyogenes compared with the other tested samples. α-Spinasterol (-8.0 kcal/mol) and 3 (-7.6 kcal/mol) displayed high binding affinity against DNA Gyrase compared to ciprofloxacin (-7.3 kcal/mol). α-Spinasterol and 16-dehydroxycucurbitacin showed better binding affinity against protein kinase. The cytotoxicity results revealed that the EtOAc extract showed the highest potency with IC50 = 16.05 µg/mL. 16-Dehydroxycucurbitacin showed a higher binding affinity (-7.7 kcal/mol) against human topoisomerase IIß than etoposide. The cytotoxicity and antibacterial activities and in silico molecular docking analysis displayed by the constituents corroborate the traditional use of the plant against bacteria and cancer.

Spin-rotation and NMR shielding constants in HCl.

The spin-rotation and nuclear magnetic shielding constants are analysed for both nuclei in the HCl molecule. Nonrelativistic ab initio calculations at the CCSD(T) level of approximation show that it is essential to include relativistic effects to obtain spin-rotation constants consistent with accurate experimental data. Our best estimates for the spin-rotation constants of (1)H(35)Cl are CCl = -53.914 kHz and C(H) = 42.672 kHz (for the lowest rovibrational level). For the chlorine shielding constant, the ab initio value computed including the relativistic corrections, σ(Cl) = 976.202 ppm, provides a new absolute shielding scale; for hydrogen we find σ(H) = 31.403 ppm (both at 300 K). Combining the theoretical results with our new gas-phase NMR experimental data allows us to improve the accuracy of the magnetic dipole moments of both chlorine isotopes. For the hydrogen shielding constant, including relativistic effects yields better agreement between experimental and computed values.

Biosynthesis of Silver Nanoparticles Functionalized with Histidine and Phenylalanine Amino Acids for Potential Antioxidant and Antibacterial Activities.

Due to biochemically active secondary metabolites that assist in the reduction, stabilization, and capping of nanoparticles, plant-mediated nanoparticle synthesis is becoming more and more popular. This is because it allows for ecologically friendly, feasible, sustainable, and cost-effective green synthesis techniques. This study describes the biosynthesis of silver nanoparticles (AgNPs) functionalized with histidine and phenylalanine using the Lippia abyssinica (locally called koseret) plant leaf extract. The functionalization with amino acids was meant to enhance the biological activities of the AgNPs. The synthesized nanoparticles were characterized using UV-Visible absorption (UV-Vis), powder X-ray diffraction (pXRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The surface plasmonic resonance (SPR) peak at about 433 nm confirmed the biosynthesis of the AgNPs. FTIR spectra also revealed that the phytochemicals in the plant extract were responsible for the capping of the biogenically synthesized AgNPs. On the other hand, the TEM micrograph revealed that the morphology of AgNP-His had diameters ranging from 5 to 14 nm. The antibacterial activities of the synthesized nanoparticles against Gram-positive and Gram-negative bacteria showed a growth inhibition of 8.67 ± 1.25 and 11.00 ± 0.82 mm against Escherichia coli and Staphylococcus aureus, respectively, at a concentration of 62.5 µg/mL AgNP-His. Moreover, the nanoparticle has an antioxidant activity potential of 63.76 ± 1.25% at 250 µg/mL. The results showed that the green-synthesized AgNPs possess promising antioxidant and antibacterial activities with the potential for biological applications.

Organic-inorganic hybrid salt and mixed ligand Cr(III) complexes containing the natural flavonoid chrysin: Synthesis, characterization, computational, and biological studies.

Organic-inorganic hybrid salt and mixed ligand Cr(III) complexes (Cr1 and Cr2) containing the natural flavonoid chrysin were synthesized. The metal complexes were characterized using UV-Vis, Fourier-transform infrared, MS, SEM-EDX, XRD, and molar conductance measurements. Based on experimental and DFT/TD-DFT calculations, octahedral geometries for the synthesized complexes were suggested. The powder XRD analysis confirms that the synthesized complexes were polycrystalline, with orthorhombic and monoclinic crystal systems having average crystallite sizes of 21.453 and 19.600 nm, percent crystallinities of 51% and 31.37%, and dislocation densities of 2.324 × 10-3 and 2.603 × 10-3 nm-2 for Cr1 and Cr2, respectively. The complexes were subjected to cytotoxicity, antibacterial, and antioxidant studies. The in vitro biological studies were supported with quantum chemical and molecular docking computational studies. Cr1 showed significant cytotoxicity to the MCF-7 cell line, with an IC50 value of 8.08 µM compared to 30.85 µM for Cr2 and 18.62 µM for cisplatin. Cr2 showed better antibacterial activity than Cr1. The higher E HOMO (-5.959 eV) and dipole moment (10.838 Debye) values of Cr2 obtained from the quantum chemical calculations support the observed in vitro antibacterial activities. The overall results indicated that Cr1 is a promising cytotoxic drug candidate.