Investigation on the antidepressant effect of sea buckthorn seed oil through the GC-MS-based metabolomics approach coupled with multivariate analysis.

Depression is one of the prevalent and serious mental disorders and the number of depressed patients has been on the rise globally during the recent decades. Sea buckthorn seed oil from traditional Chinese medicine (TCM) is edible and has been widely used for treatment of different diseases for a long time. However, there are few published reports on the antidepressant effect of sea buckthorn seed oil. With the objective of finding potential biomarkers of the therapeutic response of sea buckthorn seed oil in chronic unpredictable mild stress (CUMS) rats, urine metabolomics based on gas chromatography-mass spectrometry (GC-MS) coupled with multivariate analysis was applied. In this study, we discovered a higher level of pimelic acid as well as palmitic acid and a lower level of suberic acid, citrate, phthalic acid, cinnamic acid and Sumiki's acid in urine of rats exposed to CUMS procedures after sea buckthorn seed oil was administered. These changes of metabolites are involved in energy metabolism, fatty acid metabolism and other metabolic pathways as well as in the synthesis of neurotransmitters and it is helpful to facilitate the efficacy evaluation and mechanism elucidating the effect of sea buckthorn seed oil for depression management.

Azelaic and pimelic acids: metabolic intermediates or artefacts?

Azelaic and pimelic acids are excreted in elevated amounts in urine in disorders of mitochondrial beta-oxidation and disorders of peroxisomal beta-oxidation, for which they are of significant diagnostic value. We have detected the presence of azelaic, pimelic and even-chain-length dicarboxylic acids (adipic, suberic and sebacic acids) arising artefactually as a result of storage of small sample volumes in plastic containers. Storage of samples for organic acid analysis in glass containers is recommended.

Preliminary studies of a dicarboxylic acid as an energy substrate in man.

Azelaic acid (Az), a straight saturated chain nine carbon dicarboxylic acid, was administered in saline form to six healthy male volunteers by iv route. Serum levels of Az and urinary amounts of both azelaic and pimelic (C7) acids were measured by an improved gas liquid chromatographic method. Stoichiometric analysis of Az metabolism was compared with that of glucose and palmitic acid. The respiratory quotient (RQ) as well as the ATP/CO2 ratio of Az were quite similar to that of palmitic acid. Therefore, Az oxidation is associated with a low cost of ATP synthesis in terms of carbon dioxide production. At the infusion rate used (7.5 g/hr) more than 50% of the administered dose was excreted in the urine. However, the remaining portion was cleared from the plasma in 200 min suggesting an uptake by body tissues which was also confirmed by indirect calorimetric analysis.

The analysis of thiodiglycollic acid by selected ion monitoring.

A selected ion monitoring assay for thiodiglycollic acid in urine is described. Urine samples are analysed by combined gas chromatography-mass spectrometry as their dibutyl esters using pimelic acid as an internal standard. Rapid analysis was achieved by the simplification of sample preparation. The assay has proved to be reliable, with a detection limit of less than 0.5 mumol/l. The excretion of large amounts of thiodiglycollic acid in premature babies urine has been confirmed, with the greatest excretion occurring from those neonates born with a gestational age of 30 wk or less.

Identification of methyl-branched chain dicarboxylic acids in amniotic fluid and urine in propionic and methylmalonic acidemia.

3-Methyladipic, 4-methylpimelic, 4-methylsuberic, pimelic, and azeleic acids were identified by gas chromatography-mass spectrometry in the amniotic fluid of fetuses with propionic acidemia. These compounds were virtually undetectable in normal amniotic fluid. Concentrations much higher than those of the amniotic fluid were found in the urine of neonatal infants with propionic acidemia and methylmalonic acidemia. It appears that the accumulation of these compounds is a consequence of the accumulation of propionyl-CoA. Evidence was obtained for the presence of other methyl-branched chain dicarboxylic acids. 4-Methylpimelic acid and 4-methylsuberic acid have not previously been identified in human physiological fluids.