INTRODUCTION
Metabolomics is the assessment of all the low-molecular-weight molecules called metabolites (with a molecular mass <1,500 Da in any organism (from fish to humans)) by advanced analytical chemistry techniques in a cell, tissue, organ, organism or biofluid. This approach is relatively new and more comprehensive, cheaper and faster than clinical chemistry. This field of life science in conjunction with statistical methods, examines the metabolome and used in a wide range of research, including animal health studies, biomedical research, food and nutritional analysis and drug testing.
The metabolome is a set of all the low-molecular-weight metabolites that can demonstrate biological disorders in the host. Perturbations in metabolic pathways in an organism, causes these disorders. Metabolites are the end products of genes, proteins, and enzymes and are specific to each cell or tissue. These small molecules provide the chemical fuel for cellular processes, are essential to life and cellular signaling pathways. Metabolites can be primary, such as lipids, amino acids, nucleic acids, sugars, short peptides, or organic acids that are endogenous, their synthesis is encoded by the host genome and are highly conserved, or can be secondary, such as plant/food phytochemicals, food additives, microbial products, chemical contaminants, and pesticides that are exogenous, highly variable and depend on environmental exposures, dietary patterns and gut microflora. Primary metabolites are essential for growth and physiological functions. Deficiency of essential metabolites leads to various types of diseases such as pellagra (lack of vitamin B3), rickets (lack of vitamin D), kwashiorkor (lack of protein or essential amino acids), and scurvy (lack of vitamin C). Each person’s metabolome is unique and depends on various factors such as genetics, age, gender, geographical location, diet and environmental factors.
Methods of measuring metabolites
The metabolome is complex and large, and its evaluation requires more advanced tools and equipment than the genome and proteome. The various techniques used to measure metabolites include the following:
- Nuclear magnetic resonance (NMR)
- Spectrometers, mass spectrometers (MS)
- Gas chromatography (GC)
- Liquid chromatography (LC)
- Ion mobility systems (IMS)
- Capillary electrophoresis (CE) systems
- Integrated liquid chromatography-mass spectrometry (LC-MS)
- Integrated capillary electrophoresis-mass spectrometry (CE-MS)
- Integrated ion mobility spectrometry-mass spectrometry (IMS-MS)
- Gas chromatography-mass spectrometry (GC-MS)
- LC-MS/NMR
Samples used to measure metabolites are a cell culture, an organ, a tissue biopsy or biofluid such as urine, blood, cerebrospinal fluid (CSF), sweat and saliva.
Today, there are well-equipped laboratories in this field with a complete set of accurate analytical tools, various types of databases and software to measure metabolites globally.
Metabolomics and diseases
The primary use of metabolomics has been to diagnosis of diseases and identifying pathological conditions. Metabolic diseases fall into 13 general categories, which are diseases related to:
- Carbohydrate metabolism
- Amino acid metabolism
- Organic acid metabolism
- Fatty acid oxidation
- Nucleotide metabolism
- Porphyrin metabolism
- Urea cycle metabolism
- Steroid metabolism
- Mitochondrial function
- Peroxisomal function
- Lipid metabolism
- Metal storage
- Lysosomal storage
Hundreds to thousands of metabolites can be measured simultaneously using metabolomic techniques. For this reason, the most widely used of these techniques is for newborn screening and the detection of inborn errors of metabolism (IEMs) such as alkoptunuria, phenylketonuria or PKU, Lesch-Nyhan syndrome and Gaucher’s disease. Metabolomics is also used in personalized medicine for diagnosis and the follow-up treatment of metabolomic diseases such as autoimmune diseases, diabetes mellitus, atherosclerosis, hypertension, hypothyroidism, chronic inflammation, chronic kidney disease (CKD), canser, allergies, inflammatory bowel disease (IBD), obesity, metabolic syndrome, Tay-Sachs and albinism.
Prepared by: Parvin Zarei
References
- Challenges and Opportunitiesof Metabolomics
- Metabolomics for Investigating Physiological and Pathophysiological Processes
