Metabolic Profiles of Whole, Parotid and Submandibular/Sublingual Saliva

Abstract

The detection of salivary molecules associated with pathological and physiological alterations has encouraged the search of novel and non-invasive diagnostic biomarkers for oral health evaluation. While genomic, transcriptomic, and proteomic profiles of human saliva have been reported, its metabolic composition is a topic of research: metabolites in submandibular/sublingual saliva have never been analyzed systematically. In this study, samples of whole, parotid, and submandibular/sublingual saliva from 20 healthy donors, without dental or periodontal diseases, were examined by nuclear magnetic resonance. We identified metabolites which are differently distributed within the three saliva subtypes (54 in whole, 49 in parotid, and 36 in submandibular/sublingual saliva). Principal component analysis revealed a distinct cluster for whole saliva and a partial overlap for parotid and submandibular/sublingual metabolites. We found exclusive metabolites for each subtype: 2-hydroxy-3-methylvalerate, 3-methyl-glutarate, 3-phenylpropionate, 4-hydroxyphenylacetate, 4-hydroxyphenyllactate, galactose, and isocaproate in whole saliva; caprylate and glycolate in submandibular/sublingual saliva; arginine in parotid saliva. Salivary metabolites were classified into standard and non-proteinogenic amino acids and amines; simple carbohydrates; organic acids; bacterial-derived metabolites. The identification of a salivary gland-specific metabolic composition in healthy people provides the basis to invigorate the search for salivary biomarkers associated with oral and systemic diseases.

Monitoring of Lactate in Interstitial Fluid, Saliva and Sweat by Electrochemical Biosensor: The Uncertainties of Biological Interpretation

“…Though this is low in electrolyte, it is sufficient for undiluted electrochemical measurement Lactate is imported into the gland through acinar cell filtration activity, but the duct exchanges mean that its final concentration is altered radically and in a manner that is flow dependent. Moreover, the parotid gland, the main contributor of salivary metabolites [58] varies its secretory contribution depending on stimulation, adding further uncertainty to compositional evaluation. saliva is isotonic.…”

Spatially resolved sampling for untargeted metabolomics: A new tool for salivomics

“…Article for spatially resolved biochemical analysis of the human oral cavity. Finally, we compared our results with a similarly designed study where NMR rather than MS was used for metabolite identification (Meleti et al, 2020). Despite the difference in the number and nature of identified molecules, due to the different instrumentation implemented, comparable individual metabolomic profiles per location were observed including the more dilute fluid content of BT samples when compared with CC.…”

Updates and Original Case Studies Focused on the NMR-Linked Metabolomics Analysis of Human Oral Fluids Part III: Implementations for the Diagnosis of Non-Cancerous Disorders, Both Oral and Systemic

“…Since biomolecules present in submandibular/sublingual saliva samples were not previously systematically analysed, one study conducted by Meleti et al in 2020 [ 17 ] explored samples of whole, parotid, and submandibular/sublingual saliva collected from a total of 20 healthy human participants, who were free from any PDs and other dental conditions—samples were analysed by NMR analysis. These researchers successfully identified a series of metabolites which were differentially distributed amongst the three sub-types of saliva sample, specifically 54 in WMS, and 49 and 36 in parotid and submandibular/sublingual fluids, respectively.…”