Analysis of the volatiles in the headspace above the plasmodium and sporangia of the slime mould (Physarum polycephalum) by SPME-GCMS

Solid phase micro-extraction (SPME) coupled with Gas Chromatography Mass Spectrometry (GC-MS) was used to extract and analyse the volatiles in the headspace above the plasmodial and sporulating stages of the slime mould Physarum Polycephalum. In total 115 compounds were identified from across a broad range of chemical classes. Although more (87) volatile organic compounds (VOCs) were identified when using a higher incubation temperature of 75oC, a large number of compounds (79) were still identified at the lower extraction temperature of 30oC and where the plasmodial stage was living. Far fewer compounds were extracted after sporulation at the two extraction temperatures. There were some marked differences between the VOCs identified in the plasmodial stage and after sporulation. In particular the nitrogen containing compounds acetonitrile, pyrrole, 2, 5-dimethyl-pyrazine and trimethyl pyrazine seemed to be associated with the sporulating stage. There were many compounds associated predominantly with the plasmodial stage including a number of furans and alkanes. Interestingly, a number of known fungal metabolites were identified including 1-octen-3-ol, 3-octanone, 1-octen-3 one, 3-octanol. In addition known metabolites of cyanobacteria and actinobacteria in particular geosmin was identified in the headspace. Volatile metabolites that had previously been identified as having a positive chemotactic response to the plasmodial stage of P. polycephalum were also identified including {\beta} farnesene, {\beta}-myrcene, limonene and 3-octanone. This study constitutes the first comprehensive analysis of the headspace volatiles emitted from Physarum Polycephalum. Further work to understand the origin and function of the volatiles identified is required

The effect of air-drying on the volatiles composition of lemon thyme (Thymus citriodorus) and lemon verbena (Aloysia triphylla)

The research investigates the effect of air-drying on the volatile composition of infusions prepared from Thymus citriodorus (Pers.) Schreb and lemon verbena (Aloysia triphylla (L'Herit)). The fresh and the dried herbs were analysed over a period of one month for lemon thyme and ten months for lemon verbena. Both herbs lost 75% of their moisture within 5 days of picking and subsequently showed no further loss during storage. Drying and different periods of storage had a considerable effect on the aroma composition of lemon thyme and lemon verbena. Marked losses of many important aroma volatiles were observed on drying and this would be expected to give rise to different sensory properties of teas made from the fresh and dried herbs. The loss of compounds contributing to the lemon characteristics was marked, especially in lemon verbena

Metabolism of androstenone, 17β-estradiol and dihydrotestosterone in primary cultured pig hepatocytes and the role of 3β-hydroxysteroid dehydrogenase in this process

© 2015 Chen et al. Steroids metabolism plays an important role in mammals and contributes to quality of pig meat. The main objective of this study was to identify metabolites of androstenone, 17β-estradiol and dihydrotestosterone using primary cultured pig hepatocytes as a model system. The role of 3β-hydroxysteroid dehydrogenase (3βHSD) in regulation of steroid metabolism was also validated using trilostane, a specific 3βHSD inhibitor. Steroid glucuronide conjugated metabolites were detected by liquid chromatography time of flight mass spectrometry (LC-TOF-MS). 3βHSD enzyme was essential for metabolism of androstenone to 5α-androst-16-en-3β-ol, which then formed androstenone glucuronide conjugate. Metabolism of 17β-estradiol was accompanied by formation of glucuronide-conjugated estrone and glucuronide-conjugated estradiol. The ratio of the two metabolites was around 5:1. 3βHSD enzyme was not involved in 17β-estradiol metabolism. 5α-Dihydrotestosterone-17β-glucuronide was identified as a dihydrotestosterone metabolite, and this metabolism was related to 3βHSD enzyme activity as demonstrated by inhibition study

Urinary volatile organic compounds for the detection of prostate cancer

© 2015 Khalid et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The aim of this work was to investigate volatile organic compounds (VOCs) emanating from urine samples to determine whether they can be used to classify samples into those from prostate cancer and non-cancer groups. Participants were men referred for a trans-rectal ultrasound-guided prostate biopsy because of an elevated prostate specific antigen (PSA) level or abnormal findings on digital rectal examination. Urine samples were collected from patients with prostate cancer (n = 59) and cancer-free controls (n = 43), on the day of their biopsy, prior to their procedure. VOCs from the headspace of basified urine samples were extracted using solid-phase micro-extraction and analysed by gas chromatography/mass spectrometry. Classifiers were developed using Random Forest (RF) and Linear Discriminant Analysis (LDA) classification techniques. PSA alone had an accuracy of 62-64% in these samples. A model based on 4 VOCs, 2,6-dimethyl-7-octen-2-ol, pentanal, 3-octanone, and 2-octanone, was marginally more accurate 63-65%. When combined, PSA level and these four VOCs had mean accuracies of 74% and 65%, using RF and LDA, respectively. With repeated double cross-validation, the mean accuracies fell to 71% and 65%, using RF and LDA, respectively. Results from VOC profiling of urine headspace are encouraging and suggest that there are other metabolomic avenues worth exploring which could help improve the stratification of men at risk of prostate cancer. This study also adds to our knowledge on the profile of compounds found in basified urine, from controls and cancer patients, which is useful information for future studies comparing the urine from patients with other disease states

Aroma characteristics of some lemon-flavoured herbs

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Ion chromatograms and mass spectra (inset) of 17β-estradiol and its metabolites.

<p>(<b>A</b>) 17β-estradiol in the medium in absence of isolated hepatocytes; (<b>B</b>) 17β-estradiol in the medium in the presence of isolated hepatocytes. No 17β-estradiol was found after 6 h of cell culture; (<b>C</b>) identified 17β-estradiol metabolite estrone-3-glucuronide (m/z− = 445.2190). The samples were analyzed in ESI– ionization mode; (<b>D</b>) identified 17β-estradiol metabolite β-estradiol-3-glucuronide (m/z− = 447.2298) in ESI– ionization mode; (<b>E</b>) a mixture of authentic standards β-estradiol-17-glucuronide and β-estradiol-3-glucuronide.</p

Ion chromatograms and mass spectra (inset) of dihydrotestosterone and its metabolite.

<p>(<b>A</b>) dihydrotestosterone in the medium in absence of isolated hepatocytes; (<b>B</b>) dihydrotestosterone in the medium in the presence of isolated hepatocytes. No dihydrotestosterone was found after 6 h of cell culture; (<b>C</b>) identified dihydrotestosterone metabolite dihydrotestosterone-17-glucuronide (m/z− = 465.2554). The samples were analyzed in ESI– ionization mode.</p

Peak heights (cps) of the ion chromatograms of steroids metabolites in cell culture medium.

<p>Data are presented as Mean ± SD. (**) presents statistical significance of differences between groups at p<0.01. The peak height values are presented after division by 1000 (cps/1000).</p><p>C = steroid metabolites analyzed after 48 h incubation of cell culture in absence of enzyme inhibitors. Apigenin = steroid metabolites analyzed after 48 h of cell culture in the presence of apigenin, the specific inhibitor of 17βHSD. Trilostane = steroid metabolites analyzed after 48 h of incubation of cell culture in the presence of trilostane, the specific inhibitor of 3βHSD. The cell density was approx. 5×10⁶ cells/plate. The experiments were conducted in three independent batches with triplicate repeats for each experiment.</p><p>Peak heights (cps) of the ion chromatograms of steroids metabolites in cell culture medium.</p