Composition and antimicrobial activity of the essential oil of Heracleum thomsonii (Clarke) from the cold desert of the western Himalayas

Volatile oil composition of hydro-distilled (HD) and supercritical carbon dioxide (SC-CO(2)) essential oil of freshly collected aerial parts of Heracleum thomsonii (Umbeliferae) from the western Himalayas was studied by GC-FID and GC-MS. Results revealed qualitative and quantitative dissimilarity in the composition of hydro-distilled and SC-CO(2) extracted oils. Nineteen constituents, which accounted for 89.32% of total constituents in HD oil, represented by limonene (4.31%), (Z)-β-ocimene (3.69%), terpinolene (22.24%), neryl acetate (36.19%), nerol (9.51%) and p-cymene-8-ol (2.61%) were identified. In SC-CO(2) extracted oil, 24 constituents representing 89.95% of total constituents were identified. Terpinolene (5.08%), germacrene D (2.17%), neryl acetate (51.62%), nerol (9.78%), geranyl acetate (2.06%), α-bisabolol (2.48%) and 1-nonadecanol (4.96%) were the dominating constituents. In?vitro antimicrobial activity of hydro-distilled oil was conducted against microrobial strains including two Gram-positive (Staphylococcus aureus and Bacillus subtilis) and five Gram-negative (Burkholderia cepacia, Escherichia coli, Enterobacter cloacae, Klebseilla pneumoniae and Pseudomonas aeruginosa) bacteria as well as seven fungi (Candida albicans, Issatchenkia orientalis, Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus, Aspergillus sydowii and Trichophyton rubrum) using broth microdilution method. The results of bioassay showed that the oil exhibited moderate to high antimicrobial activity against fungi C. albicans (MIC 625 μg?ml(-1)), A. parasiticus (MIC 312.5 μg?ml(-1)), A. sydowii (MIC 312.5 μg?ml(-1)), T. rubrum (MIC 625 μg?ml(-1)), Gram-positive bacteria B. subtilis (MIC 625?μg?ml(-1)) and Gram-negative bacteria P. aeruginosa (MIC 312.5 μg?ml(-1)).     

Mimicking the role of the antenna in photosynthetic photoprotection

One mechanism used by plants to protect against damage from excess sunlight is called nonphotochemical quenching (NPQ). Triggered by low pH in the thylakoid lumen, NPQ leads to conversion of excess excitation energy in the antenna system to heat before it can initiate production of harmful chemical species by photosynthetic reaction centers. Here we report a synthetic hexad molecule that functionally mimics the role of the antenna in NPQ. When the hexad is dissolved in an organic solvent, five zinc porphyrin antenna moieties absorb light, exchange excitation energy, and ultimately decay by normal photophysical processes. Their excited-state lifetimes are long enough to permit harvesting of the excitation energy for photoinduced charge separation or other work. However, when acid is added, a pH-sensitive dye moiety is converted to a form that rapidly quenches the first excited singlet states of all five porphyrins, converting the excitation energy to heat and rendering the porphyrins kinetically incompetent to readily perform useful photochemistry.     

Photoconductivity and photoluminescence in chemically deposited films of (Cd–Zn)S:CdCl2, Ho

Results of SEM, XRD, optical absorption/reflectance, photoconductivity (PC), and photoluminescence (PL) are presented for (Cd–Zn)S:CdCl₂, Ho films prepared by chemical deposition technique by direct dipping either at room temperature (RT) or at 60 °C in a water bath. SEM studies show the presence of non-uniform distribution of particles. XRD studies show lines of CdS, ZnS along with lines of CdCl₂ and Ho. PL is found to be pronounced in films of RT preparation and for those prepared at 60 °C, PC is higher. Optical absorption/reflectance studies show the presence of Ho corresponding to the transition ⁵I₈→⁵F₁/⁵G₆. Emissions corresponding to the transitions ⁵S₂/⁵ F₄→⁵ I₈, ⁵G₅→⁵I₇, and ³H₅→⁵I₈ are observed in PL emission spectra.     

Photoconductive properties of some chemically deposited (Cd–Pb)s films

Films of (Cd–Pb)S have been prepared using chemical deposition in aqueous alkaline bath and their subsequent condensation on substrates. Important achievements in terms of electrical response, optical absorption and photoconductivity (PC) excitation spectra, SEM, XRD and photoluminescence (PL) studies are presented and discussed. From the photocurrent curves, the ratio I_PC (saturated photocurrent)/I_DC (dark current) was observed to be of the order of 10⁶ for the systems prepared with CdCl₂, and to be 10⁷ when doped with samarium nitrate. Values of trap depth E, lifetime and mobility are evaluated from the PC decay. Band-gaps are determined from the two spectra. Diffraction lines in XRD studies are associated to CdS and PbS, and according to SEM studies layered growth of the films takes place. PL of samarium doped (Cd–Pb)S films shows an emission peak in the green-yellow region under 365?nm excitation. The PL brightness decreases with temperature.     

Sensitive enantioseparation and determination of isoprenaline in human plasma and pharmaceutical formulations

A simple, sensitive and fast RPHPLC method was developed and validated for the enantioselective determination of (RS)‐isoprenaline (Ipn) in human plasma. The enantiomers were converted to diastereomeric derivatives using s‐triazine (cyanuric chloride) based chiral derivatizing reagents. l ‐isoleucine and l ‐methionine were introduced as chiral auxiliary in s‐triazine and two new monochloro‐s‐triazine reagents were synthesized. These reagents were characterized and used for synthesis of diastereomeric derivatives of (RS)‐Ipn spiked in human plasma. (RS)‐Ipn was isolated (purified and characterized) from a commercial pharmaceutical formulation and was used as the standard racemic sample. Structures of the two diastereomeric derivatives were optimized for lowest energy using the Gaussian 09 Rev A. 02 program and hybrid density functional B3LYP with 6‐31G* basis set which showed the spatial orientation of hydrophobic groups on stereogenic centers in the diastereomeric derivatives. The results were correlated with the mechanism of separation and elution order. Limit of detection values were found to be 24.6 and 26.8 ng mL^?1 for the first and second eluting diastereomeric derivatives, respectively.     

Thin-Layer Chromatographic Enantioresolution of (RS)-Ketorolac Using L-Amino Acids as Chiral Additive in Stationary Phase

JPC – Journal of Planar Chromatography – Modern TLC - Direct resolution of enantiomers of (RS)-ketorolac was achieved by thin-layer chromatography on silica gel plates using...     

Detection and quantification of heavy metal elements in gallstones using X-ray fluorescence spectrometry

Gallbladder cancer, which is associated with the heavy metal toxicity, is one of the most dangerous malignancies. High occurrence of gallstones in the gallbladder is a well-recognized risk factor for gallbladder cancer. Accumulation of heavy and toxic metals in the biliary system is one of the main causes of gallstone formation and leads to gallbladder cancer if it remains untreated. In this work, we investigate heavy and toxic metals in gallstones to identify their association as potential risk factors for gallbladder cancer. Detection and quantification of the heavy and toxic chemicals present in gallstones are important to define etiopathogenic factors that, in turn, are useful to identify preventive and therapeutic strategies. We quantified the heavy metals in gallstones collected from patients of different age groups and dietary habits. We carried out chemical composition studies of trace and heavy metal elements present in gallstones by applying Fourier transform infrared (FTIR) spectroscopy and wavelength-dispersive X-ray fluorescence (WD-XRF) spectrometry. We also compared our experimental results with the results obtained from atomic absorption spectroscopy, as well as values previously reported in literature. These findings demonstrate the potential of WD-XRF spectrometry and FTIR spectroscopy as important emerging diagnostic tools in the field of gastroenterology.     

Comparative application of microwave,ultrasonication, ultracentrifugation and conventional heating for preparation of sample as dinitrophenyl derivative for direct enantioseparation of certain amino alcohols and 1-amino-2-propanol from vitamin B12 hydrolysate on α1-acid glycoprotein and β-cyclodextrin columns

Taking into account the structural similarities of amino alcohols with amino acids and in order to reduce time for derivatization unconventional approaches viz. microwave irradiation, ultrasonication and ultra centrifugation were applied for synthesis of dinitrophenyl derivatives of nine amino alcohols and to work out a method of choice for sample preparation for direct enantioseparation. The enantiomeric dinitrophenyl derivatives so synthesized were separated on α₁-acid glycoprotein and β-cyclodextrin columns with detection at 230 nm using photodiode array detection system. Derivatization methods and chromatographic parameters were optimized. β-Cyclodextrin column was found better compared to AGP column for enantioseparation. Limit of detection, quantification, accuracy and precision were also determined. The developed method was successfully applied to determine enantiomeric purity of 1-amino-2-propanol obtained from vitamin B₁₂ hydrolysate.     

Reversed-phase high-performance liquid chromatographic, gel electrophoretic and size exclusion chromatographic studies of subunit structure of arachin and its molecular species

Arachin and its molecular species (arachin I and arachin II) were separated and isolated. The number and kind of subunits of arachin, arachin I and arachin II were determined. Studies were carried out under different experimental conditions using slab gel electrophoresis, size-exclusion chromatography and reversed-phase high-performance liquid chromatography. Gel electrophoresis was done under varying concentrations of resolving gel. Tube gel as well as slab gel electrophoresis were used and continuous as well as discontinuous buffer systems were used for both types of electrophoresis. In addition, the subunits were separated by reversed-phase HPLC using a gradient program. Arachin and arachin II were found to have 12 subunits each while arachin I showed six subunits. The subunits of arachin I were allowed to reconstitute by removing SDS. Eight combinations were tried for studying the reconstitution pattern. Molecular weight and weight ratio in each case were also determined.