Comparison of gas chromatography–mass spectrometry and gas chromatography–combustion–isotope ratio mass spectrometry analysis for in vivo estimates of metabolic fluxes

Gas chromatography–mass spectrometry (GC–MS) was compared with gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS) for measurements of cholesterol ¹³C enrichment after infusion of labeled precursor ([¹³C_1,2]acetate). Paired results were significantly correlated, although GC–MS was less accurate than GC–C–IRMS for higher enrichments. Nevertheless, only GC–MS was able to provide information on isotopologue distribution, bringing new insights to lipid metabolism. Therefore, we assessed the isotopologue distribution of cholesterol in humans and dogs known to present contrasted cholesterol metabolic pathways. The labeled tracer incorporation was different in both species, highlighting the subsidiarity of GC–MS and GC–C–IRMS to analyze in vivo stable isotope studies.     

Comparative metabolomics of Japanese Black cattle beef and other meats using gas chromatography–mass spectrometry

Progress in metabolomic analysis now allows the evaluation of food quality. This study aims to identify the metabolites in meat from livestock using a metabolomic approach. Using gas chromatography–mass spectrometry (GC/MS), many metabolites were reproducibly detected in meats, and distinct differences between livestock species (cattle, pigs, and chickens) were indicated. A comparison of metabolites between tissues types (muscle, intramuscular fat, and intermuscular fat) in marbled beef of Japanese Black cattle revealed that most metabolites are abundant in the muscle tissue. Several metabolites (medium-chain fatty acids, etc.) involved in triacylglycerol synthesis were uniquely detected in fat tissue. Additionally, the results of multivariate analysis suggest that GC/MS analysis of metabolites can distinguish between cattle breeds. These results provide useful information for the analysis of meat quality using GC/MS-based metabolomic analysis.

ABBREVIATIONS: GC/MS: gas chromatography-mass spectrometry; NMR: nuclear magnetic resonance; MS: mass spectrometry; IS: 2-isopropylmalic acid; MSTFA: N-Methyl-N-trimethylsilyltrifluoroacetamide; CV: coefficient of variation; TBS: Tris-buffered saline; MHC: myosin fast type; PCA: principal component analysis; OPLS-DA: orthogonal partial least-squares discriminant analysis; O2PLS: two-way orthogonal partial least-squares     

The consequence of genotype × environment interaction on high essential oil yield and its composition in clove basil (Ocimum gratissimum L.)

Clove basil (Ocimum gratissimum L.) is an aromatic, perennial herb belonging to the family Lamiaceae. The plant is indigenous to tropical areas especially India and West Africa. In Nigeria, it is found in the Savannah and coastal areas. The whole herbs of the plant contain essential oils and it is cultivated for various purposes. The plant is a rich source of eugenol in its essential oil. It is also used in the preparation of tea and infusions. It is also used in the treatment of fungal infections, fever, cold, and cough. Eugenol (4-allyl-2-methoxy phenol) is a phenolic compound from the class of phenylpropanoids. It is used in the food industry as a preservative, mainly due to its antioxidant property, and flavoring agent. The fresh herb × winter season/environment produced the highest essential oil 2.07 mL/plot with essential oil content 0.41% followed by fresh herb × summer season/environment (M1S2) = 1.68 mL. For the eugenol content, the autumn season/environment was found highly favorable = 74.52% (leaves = 69.024, stem = 74.531, and in inflorescence = 80.012) followed winter season/environment 72.30% (leaves = 71.841, stem 69.389, inflorescence 76.042, mean = 72.42%). These seasons are recommended for harvesting to obtain the optimum benefit for the quality essential oil yield.     

Composition of the essential oil from the lemon balm growing in the neighborhood of Krasnoyarsk as indicated by gas chromatography–mass spectrometry data

Essential oil has been isolated from the above-ground part of the lemon balm growing in the neighborhood of Krasnoyarsk by the method of exhaustive water and steam distillation. Forty seven components, each with a content of more than 0.1% of whole oil, have been identified by GC-MS. The main oil components are citronellol (36.71%) and geraniol (27.20%). The oil also contains ten components with a content of more than 1% of the sum of all oil components: benzyl alcohol (1.67%), linalool (1.75%), citronellal (1.44%), neral (3.33%), geranial (4.39%), caryophyllene (3.73%), caryophyllene oxide (1.40%), dibutyl phthalate (1.36%), butylisobutyl ester of phthalic acid (2.45%), and phytol (2.55%). The composition of lemon balm oils from different regions of the world has been compared.     

Volatile essential oil chemical composition of basil (<Emphasis Type="Italic">Ocimum basilicum</Emphasis> L. ‘Green’) cultivated in a greenhouse and micropropagated on a culture medium containing copper sulfate

The objective of this study was to determine the effects of copper sulfate (CuSO₄) on the chemical composition of basil (Ocimum basilicum L. ‘Green’) using static headspace extraction. The basil was cultivated in vitro and ex vitro. The sowing was completed in trays, and the seedlings were transplanted to pots and grown in a protected environment for 180 d. For in vitro cultivation, the seeds were placed on Murashige and Skoog (MS) medium enriched with growth regulators, sucrose, agar, and CuSO₄ (at 0 μM [control], 25 μM, or 75 μM). Volatile organic compounds emitted from the excised leaves were collected by the static headspace technique, and identified by gas chromatography coupled to mass spectrometry (GC/MS). Twenty-six compounds were identified in the leaves harvested from the plants cultivated in vitro, while 11 compounds were identified in the leaves sampled from the ex vitro plants. Oxygenated monoterpenes were the main compounds found in plants cultivated ex vitro. Phenylpropanoids predominated in the control and the 25 μM CuSO₄ treatments. The main compounds found were methyl eugenol (52.03%) and eugenol (20.66%). For the 75 μM CuSO₄ treatment, the major compounds detected were linalool (28.14%) and 1.8-cineole (15.7%). Volatile secondary metabolites of basil cultivated in vitro with CuSO₄ were easily isolated and rapidly obtained. The results of this study demonstrate the feasibility and potential of using copper treatments to reduce the impact of seasonality on essential oil production.     

Comparative metabolomic analysis of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> during the degradation of patulin using gas chromatography–mass spectrometry

A comparative metabolomic analysis was conducted on Saccharomyces cerevisiae cells with and without patulin treatment using gas chromatography–mass spectrometry-based approach. A total of 72 metabolites were detected and compared, including 16 amino acids, 29 organic acids and alcohols, 19 sugars and sugar alcohols, 2 nucleotides, and 6 miscellaneous compounds. Principle component analysis showed a clear separation of metabolome between the cells with and without patulin treatment, and most of the identified metabolites contributed to the separation. A close examination of the identified metabolites showed an increased level of most of the free amino acids, an increased level of the intermediates in the tricarboxylic acid cycle, a higher amount of glycerol, a changed fatty acid composition, and a decreased level of cysteine and glutathione in the cells with patulin treatment. This finding indicated a slower protein synthesis rate and induced oxidative stress in the cells with patulin treatment, and provided new insights into the effect of toxic chemicals on the metabolism of organisms.     

Isolation and measurement of urinary 8-iso-prostaglandin F2α by high-performance liquid chromatography and gas chromatography–mass spectrometry

8-iso-Prostaglandin F_2α (8-iso-PGF_2α) is a product of free radical-catalyzed peroxidation of arachidonic acid. Measurement of its urinary excretion has been proposed as an index of oxidative status in vivo. A stable isotope dilution method for its quantification by gas chromatography–electron capture chemical ionization mass spectrometry is described. Sample cleanup required the combined use of high-performance liquid chromatography and thin-layer chromatography. The inter-assay R.S.D. in two separate determinations was 1.6 (n=4) and 2.3% (n=4). The accuracy of the assay was evaluated through recovery experiments. The equation of the regression plot correlating the amounts added and recovered was y=0.91x−0.31, r=0.9916 (n=12). The pair of fragment ions ([M−181]⁻) at m/z 569 and m/z 573 was monitored for quantification. The mean 8-iso-PGF_2α excretion rate was 528±127 (S.D.) ng per day in five male volunteers and 730±305 ng per day in six females. Intake of 80 mg of lycopene per day by eleven volunteers for four weeks resulted in a non-significant reduction of 8-iso-PGF_2α excretion.