Table 2 Metabolic and physiological functions tested for the metabolic network

1. Carbohydrates

● Monosaccharides

Glucose and fructose metabolism

Energy production

[28, 29]

Glycogen formation

short-term energy storage

[22]

Ribose

Energy production

[30, 31]

Formation of ribonucleotides

2. Carboxylic acids

Degradation of ketone bodies

Energy production during fasting

[32, 33]

and diabetes

3. Lipids

● Cholesterol

De novo synthesis (cytosol, peroxisome)

Membrane synthesis

[34, 35]

● Fatty acids

Formation of (semi)-essential fatty acids

Membrane synthesis

[36, 37]

β-oxidation of (non)-essential fatty acids

Energy production

[38–40]

● Triacylglycerides

De novo synthesis/ degradation of Mono-,

Membrane synthesis

[41, 42]

Di- and Triacylglycerides

● Phospholipids

De novo synthesis/ degradation of:

Membrane formation

[15, 16, 41, 43–45]

∘ Phosphatidylserines

∘ Phosphatidylcholines

∘ Lysophosphatidylcholines

∘ Phosphatidylethanolamines

∘ Phosphatidylinositol

∘ Sphingomyelin

∘ Cardiolipin

● Sphingolipids

Ceramides

Membrane formation, apoptosis

[46]

4. Proteins

● Amino acids

Formation of (non)-essential amino acids

Precursors of cellular proteins, nucleic acids,

[47, 48]

glutathione and thioredoxin

Degradation of (non)-essential amino acids

Amino acid homoeostasis,

[49]

anaplerotic reactions of TCA cycle

Glutamine formation

Ammonia detoxification, Protein

[50]

de novo synthesis

De novo synthesis of L-Carnitine

Transport of fatty acids from cytosol into

[51, 52]

mitochondria during β-oxidation

● Tripeptide

De novo synthesis of Glutathione

Prevention of cellular damage due to ROS

[53]

● Polyamines

Formation/ degradation of Prutescine and Spermidine

Cell growth and division

[54, 55]

● Proteins

De novo synthesis of:

Myosin, Titin, α-Sarcoglycan, Tropomyosin, Troponin T

Contractile apparatus, enabling muscular contraction

[56, 57]

De novo synthesis of Thioredoxin

Prevention of cellular damage due to ROS

[47, 48]

5. Nucleic acids

● Nucleobases

De novo synthesis/ degradation of purine

Precursors of nucleosides, deoxy-ribonulceotides

[58, 59]

and pyrimidine nucleotides

and ribonucleotides

Salvage of purine and pyrimidine nucleotides

Maintaining energy state

[60]

De novo synthesis/ rephosphorylation of:

∘ nucleosides (ATP, CTP, GTP, TTP, UTP)

Energy production for muscular contraction

[59, 61–63]

∘ NADH, NADPH

Energy production and providing redox-state

[64, 65]