{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T17:46:36Z","timestamp":1784310396605,"version":"3.55.0"},"reference-count":53,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2023,1,23]],"date-time":"2023-01-23T00:00:00Z","timestamp":1674432000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National University Health System Seed Fund","award":["NR19MRF015"],"award-info":[{"award-number":["NR19MRF015"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Major depressive disorder (MDD) is a highly prevalent and disabling condition with a high disease burden. There are currently no validated biomarkers for the diagnosis and treatment of MDD. This study assessed serum amino acid metabolite changes between MDD patients and healthy controls (HCs) and their association with disease severity and diagnostic utility. In total, 70 MDD patients and 70 HCs matched in age, gender, and ethnicity were recruited for the study. For amino acid profiling, serum samples were analysed and quantified by liquid chromatography-mass spectrometry (LC-MS). Receiver-operating characteristic (ROC) curves were used to classify putative candidate biomarkers. MDD patients had significantly higher serum levels of glutamic acid, aspartic acid and glycine but lower levels of 3-Hydroxykynurenine; glutamic acid and phenylalanine levels also correlated with depression severity. Combining these four metabolites allowed for accurate discrimination of MDD patients and HCs, with 65.7% of depressed patients and 62.9% of HCs correctly classified. Glutamic acid, aspartic acid, glycine and 3-Hydroxykynurenine may serve as potential diagnostic biomarkers, whereas glutamic acid and phenylalanine may be markers for depression severity. To elucidate the association between these indicators and clinical features, it is necessary to conduct additional studies with larger sample sizes that involve a spectrum of depressive symptomatology.<\/jats:p>","DOI":"10.3390\/ijms24032231","type":"journal-article","created":{"date-parts":[[2023,1,25]],"date-time":"2023-01-25T03:21:54Z","timestamp":1674616914000},"page":"2231","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":36,"title":["The Utility of Amino Acid Metabolites in the Diagnosis of Major Depressive Disorder and Correlations with Depression Severity"],"prefix":"10.3390","volume":"24","author":[{"given":"Cyrus Su Hui","family":"Ho","sequence":"first","affiliation":[{"name":"Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gabrielle Wann Nii","family":"Tay","sequence":"additional","affiliation":[{"name":"Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2898-0648","authenticated-orcid":false,"given":"Hai Ning","family":"Wee","sequence":"additional","affiliation":[{"name":"Cardiovascular and Metabolic Disorders Programme, Duke-NUS Graduate Medical School, Singapore 169857, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1526-8459","authenticated-orcid":false,"given":"Jianhong","family":"Ching","sequence":"additional","affiliation":[{"name":"Cardiovascular and Metabolic Disorders Programme, Duke-NUS Graduate Medical School, Singapore 169857, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"178","DOI":"10.1016\/j.redox.2017.09.002","article-title":"Short overview on metabolomic approach and redox changes in psychiatric disorders","volume":"14","author":"Erjavec","year":"2018","journal-title":"Redox Biol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"316","DOI":"10.1038\/nbt.4101","article-title":"Metabolomics activity screening for identifying metabolites that modulate phenotype","volume":"36","author":"Guijas","year":"2018","journal-title":"Nat. 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