Chemical fingerprinting of Hoodia species and related genera: chemical analysis of oxypregnane glycosides using high-performance liquid chromatography with UV detection in Hoodia gordonii

Hoodia gordonii, family Asclepiadaceae, is a succulent plant and is traditionally used in southern Africa for its appetite-suppressant properties. A high-performance liquid chromatographic (HPLC) method with UV detection for analysis of 11 oxypregnane glycosides from H. gordonii has been developed. The simultaneous analysis of 11 oxypregnane glycosides was achieved with a Phenomenex (Torrance, CA) reversed-phase C18 column using gradient mobile phase of water and acetonitrile, both containing 0.025% trifluoroacetic acid. The developed method was applied to the identification of oxypregnane glycosides in 3 different species of Hoodia and 23 related genera. The HPLC profiles of various plant samples were compared for the presence of oxypregnane glycosides.     

Quantitative determination of pregnanes from aerial parts of Caralluma species using HPLC-UV and identification by LC-ESI-TOF

An HPLC method was developed for the quantitative determination of five pregnane derivatives from aerial parts of Caralluma species and dietary supplements. The method was validated for linearity, repeatability, LOD, and LOQ. The LOD and LOQ of five pregnane compounds were found to be in the range of 1-5 and 3-15 microg/mL, respectively, by HPLC using photodiode array detection. This method was applied to the identification of three plant materials of Caralluma species (C. fimbriata, C. umbellate, and C. attentuata) and seven dietary supplements claiming to contain C. fimbriata. An LCIMS coupled with electrospray ionization interface method was used for the identification of compounds and involved the use of [M+Na]+ ions in the positive ion mode with extracted ion chromatogram.     

HPTLC Quantitation of Camptothecin in Nothapodytes foetida (Wight) Sleumer Stem Powder

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive and reliable high-performance thin layer chromato-graphic method has been developed for quantitation of camp-tothecin...     

Rheological characterization of asphalt in a temperature-gradient combinatorial squeeze-flow setup

A new technique for parallel rheological characterization of asphalt in a combinatorial squeeze-flow array is described. The basis of the technique is a device that is capable of subjecting multiple samples simultaneously to constant volume (Type B) squeeze flow with application of a temperature gradient. The time-dependent sample dimensions, which are calculated from digital images taken through the transparent top plate, are used to derive the flow curves. The results obtained using the combinatorial setup compared favorably with those obtained using conventional parallel-plate torsional flow in a commercial rheometer. With the existing setup, the accessible shear rate range is limited to about one decade at a single temperature.

Diffusion of Cesium Ions Labeled with 134 Cs in Agar Gel Containing Alkali Metal Iodides: Obstruction Effect and Activation Energy

The effect of some alkali metal iodides on the obstruction effect and activation energy for tracer-diffusion of cesium ions in an agar gel medium was studied using the zone-diffusion technique. It to be observed that both the extent of obstruction (α) and the activation energy (E) decrease with the increasing charge density of the cation of the supporting electrolyte. These trends are explained on the basis of competitive hydration between ions and agar molecules and the relative distortion in the water structure that is brought about by these different ions and agar molecules, respectively.     

Identification and structural characterization of steroidal glycosides in Hoodia gordonii by ion-trap tandem mass spectrometry and liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry

Electrospray ion-trap tandem mass spectrometry (ESI-MS/MS) and high-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOFMS) were used to identify and characterize eight C-21 steroidal glycosides in Hoodia gordonii. A generalized fragmentation pathway was proposed by comparing the spectra acquired for eight C-21 steroidal glycosides. The steroidal glycosides in Hoodia gordonii have been classified into two major core groups: hoodigenin A and calogenin. Using the ESI-TOF method, the major core peak ions generated by hoodigenin A glycosides are m/z 313 and 295 and by calogenin glycosides are m/z 479, 461, 299 and 281, respectively. In the MS/MS spectra, fragmentation reactions of the [M+Na](+) ion were recorded to provide structural information about the glycosyl and aglycone moieties. The data illustrates the ability of positive mode ESI for the identification of hoodigenin A and calogenin glycosides, including the nature of the hoodigenin A and calogenin core, the number of sugar residues and the type of saccharide moiety.     

Production of succinate from glucose, cellobiose, and various cellulosic materials by the ruminai anaerobic bacteriaFibrobacter succinogenes andRuminococcus flavefaciens

The production of organic acids by two anaerobic ruminal bacteria,Fibrobacter succinogenes S85 andRuminococcus flavefaciens FD-1, was compared with glucose, cellobiose, microcrystalline cellulose, Walseth cellulose (acid swollen cellulose), pulped paper, and steam-exploded yellow poplar as substrates. The major end product produced byF. succinogenes from each of these substrates was succinate (69.5–83%), the principal secondary product was acetate (16–30.5%). Maximum succinate productivity ranged from 14.1 mg/L · h for steam-exploded yellow Poplar to 59.7 mg/L · h for pulped paper. ForR. flavefaciens, the major end product from cellobiose, microcrystalline cellulose, and acid-swollen Walseth cellulose was acetate (39–46%), pulped paper and steam-exploded yellow poplar yielded succinate (42–54%) as the major product. Maximum succinate productivity byR. flavefaciens ranged from 9.21 mg/L · h for cellobiose to 43.1 mg/L · h for pulped paper. In general, much less succinate was produced at a lower maximum productivity byR. flavefaciens than byF. succinogenes under similar fermentation conditions. The maximum succinate productivities by these two organisms are comparable to the previously reported value of 59 mg/L · h forAnderobiospirillum succiniciproducens grown on glucose and corn steep liquor.     

Application of NAA in diffusion studies

The diffusion of Mn₂+ ions in CoSO₄ , NiSO₄ and ZnSO₄ containing 1% agar gel as well as that of MnSO₄ in 1% agar gel was studied at 25 °C. The diffusion coefficientsat selected concentrations were determined by the zone diffusion techniqueand by measuring the concentration of diffusing ions using neutron activationanalysis.     

Trace element composition of atmospheric aerosols in Ankara,Turkey, determined by instrumental neutron activation analysis

Twenty six trace elements were determined by INAA in the aerosol samples collected at two stations in Ankara, Turkey. Industrially derived elements, Se, As, Sb, Zn and Au did not show seasonal dependence and they were not substantially enriched. Elements originating from coal combustion are highly enriched and have higher concentrations in the winter. Correlation factors indicate that motor vehicles, coal and oil combustion are the main sources of aerosols over the city.