A review of the volatiles from the healthy human body

Abstract

A compendium of all the volatile organic compounds (VOCs) emanating from the human body (the volatolome) is for the first time reported. 1840 VOCs have been assigned from breath (872), saliva (359), blood (154), milk (256), skin secretions (532) urine (279), and faeces (381) in apparently healthy individuals. Compounds were assigned CAS registry numbers and named according to a common convention where possible. The compounds have been grouped into tables according to their chemical class or functionality to permit easy comparison. Some clear differences are observed, for instance, a lack of esters in urine with a high number in faeces. Careful use of the database is needed. The numbers may not be a true reflection of the actual VOCs present from each bodily excretion. The lack of a compound could be due to the techniques used or reflect the intensity of effort e.g. there are few publications on VOCs from blood compared to a large number on VOCs in breath. The large number of volatiles reported from skin is partly due to the methodologies used, e.g. collecting excretions on glass beads and then heating to desorb VOCs. All compounds have been included as reported (unless there was a clear discrepancy between name and chemical structure), but there may be some mistaken assignations arising from the original publications, particularly for isomers. It is the authors' intention that this database will not only be a useful database of VOCs listed in the literature, but will stimulate further study of VOCs from healthy individuals. Establishing a list of volatiles emanating from healthy individuals and increased understanding of VOC metabolic pathways is an important step for differentiating between diseases using VOCs.

Application of Fecal Volatile Organic Compound Analysis in Clinical Practice: Current State and Future Perspectives

“…Next to identification of pathophysiological VOCs, it is first key to determine the spectrum of VOCs still considered to reflect a healthy state This leads us to the third hurdle needed to be taken before VOCs could be implemented as clinical biomarker in daily practice. To date, a total of 1840 VOCs have been identified as volatiles deriving from a healthy human body, of which 381 individual VOCs are linked to feces [84]. Presumably, factors including age, gender, body weight, gut microbiota composition, and life style, as well as variation in sampling techniques, all may significantly influence VOC composition.…”

Precursors for cytochrome P450 profiling breath tests from an in silico screening approach

“…The training set of 488 organic chemicals (2) must be an oxygen O (2) flanked by any atom X (1) except hydrogen or carbonyls and an alkyl rest (3) which has an abstractable hydrogen atom H. After addition of an oxygen atom O (4) the molecules is transformed into an alcohol and a ketone or aldehyde. X (1) as well as the further rests R′ and R″ are not affected by the encoded transformation. The corresponding SMIRKS formulation also considers amines and aromatic nitrogen atoms at index (2) for the volatility prediction was retrieved from the work of Raventos-Duran et al in SMILES notation [33].…”

“…This compilation provided CAS numbers (Chemical Abstract Services index) and names for 874 chemicals detected in breath. SMILES were automatically extracted via the Chemical Identifier Resolver hosted by the NCI cactus server 1 for the provided CAS numbers where possible. Two wrong assignments were identified and corrected manually (CAS 3855-78-5 and 7239-23-8).…”

“…Exhaled breath analysis is based on volatile organic compounds (VOCs) which are produced through various biochemical pathways [1][2][3]. The family of cytochrome P450 enzymes (CYPs) metabolizes many endogenously produced biochemical substances as well as drugs and xenobiotics.…”

“…Especially volatile ketones or aldehydes are suitable as marker molecules which do not occur as natural composites of human exhaled breath [1]. Those VOCs can be detected without being isotopelabeled using different mass spectrometric techniques for detection.…”