Non-targeted metabolomics analysis reveals distinct metabolic profiles between positive and negative emotional tears of humans

BACKGROUND Although the chemical components of basal, reflex, and emotional tears are different, the presence of distinctions in the tears of different emotions is still unknown. The present study aimed to address the biochemical basis behind emotional tears through non-targeted metabolomics analysis between positive and negative emotional tears of humans. METHODS Samples of reflex (C), negative (S), and positive (M) emotional tears were collected from healthy college participants. Untargeted metabolomics was performed to identify the metabolites in the different types of tears. The differentially altered metabolites were screened and assessed using univariate and multivariate analyses. RESULTS The global metabolomics signatures classified the C, S, and M emotional tears. A total of 133 significantly differential metabolites of ESI- mode were identified between negative and positive emotional tears. The top 50 differential metabolites between S and M were highly correlated. The significantly altered pathways included porphyrin & chlorophyll metabolism, bile secretion, biotin metabolism, arginine & proline metabolism and among others. CONCLUSION The metabolic profiles between reflex, positive, and negative emotional tears of humans are distinct. Secretion of positive and negative emotional tears are distinctive biological activities. Therefore, the present study provides a chemical method to detect human emotions which may become a powerful tool for diagnosis of mental disease and identification of fake tears.