Molecular Knowledge Base
A scientific reference for bioactive compounds, organized by class and not tied to any product.
The content on this page is provided for information only. It is not medical advice.
GHK-Cu
PeptidesCopper-binding tripeptide (glycyl-L-histidyl-L-lysine)
Overview
GHK-Cu (Glycyl-L-Histidyl-L-Lysine Copper) is a naturally occurring human copper-binding tripeptide. In cell-based systems it influences matrix protein and glycosaminoglycan synthesis, together with antioxidant and anti-inflammatory activity at the cellular level.
Mechanism of action
GHK-Cu (glycyl-histidyl-lysine-copper) is a tripeptide-copper complex derived from the collagen alpha chain. Acting as a copper chaperone, it delivers copper to fibroblasts, activating lysyl oxidase, an enzyme that forms cross-links in tropocollagen. It also modulates expression of over 1,000 genes, including genes of antioxidant defense and anti-inflammatory signaling.
Key characteristics
Scientific references
For information only; not medical advice.
BPC-157
PeptidesSynthetic pentadecapeptide derived from a gastric protein sequence
Overview
BPC-157 is a 15-amino acid synthetic peptide derived from a protective gastric juice protein. In preclinical systems it has been reported to upregulate growth factor receptor expression and VEGF signaling.
Mechanism of action
BPC-157 is a synthetic 15-amino-acid gastropeptide stable in human gastric juice. It has been reported to upregulate growth hormone receptor expression and VEGF signaling, with downstream effects on the GH/IGF-1 axis. It has also been reported to suppress pro-inflammatory cytokines and to modulate nitric oxide synthase.
Key characteristics
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TB-500
PeptidesSynthetic fragment related to thymosin beta-4
Overview
TB-500 is a synthetic peptide analog of Thymosin Beta-4, an actin-sequestering protein abundant in platelets and extracellular fluids. It binds actin and influences actin polymerization and cell migration in cell-based systems.
Mechanism of action
Thymosin β-4 (TB-500) binds actin with high affinity, regulating the intracellular G-actin pool and controlling actin polymerization. It interacts with integrin-linked kinase (ILK) to activate the Akt2 pathway and metalloproteinase production, triggering migration of epithelial and endothelial cells. It has been reported to influence migration and differentiation of progenitor cells, to modulate VEGF-related signaling and to influence apoptotic and inflammatory signaling.
Key characteristics
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CJC-1295
PeptidesSynthetic analog of growth hormone-releasing hormone
Overview
CJC-1295 is a modified analog of growth hormone-releasing hormone (GHRH) engineered for extended bioavailability. It stimulates the anterior pituitary to secrete growth hormone in a physiological pulsatile pattern; its effects on the GH/IGF-1 axis are studied in research settings.
Mechanism of action
CJC-1295 is a synthetic analog of the hypothalamic growth hormone-releasing factor (GHRH) 1-29 fragment. In circulation, it covalently binds endogenous albumin, extending its half-life substantially; it binds GHRH receptors on pituitary somatotrophs to increase GH synthesis and secretion. It maintains GH pulsatility while sustaining elevated IGF-1 levels.
Key characteristics
Scientific references
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MOTS-c
PeptidesMitochondrial-derived peptide of 16 amino acids
Overview
MOTS-c is a 16-amino acid peptide encoded within the mitochondrial 12S rRNA gene. It translocates to the nucleus during metabolic stress, activating AMPK-dependent pathways that regulate metabolic homeostasis and stress-response signaling.
Mechanism of action
MOTS-c is a 16-amino-acid mitochondria-derived peptide encoded by the 12S rRNA region of the mitochondrial genome. It targets the folate cycle to trigger AICAR accumulation and activate AMPK, thereby increasing glucose utilization. Under metabolic stress, it translocates to the nucleus and regulates nuclear gene expression via PGC-1α-dependent mechanisms.
Key characteristics
Scientific references
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Selank
PeptidesSynthetic heptapeptide analog of tuftsin
Overview
Selank is a synthetic analog of the immunomodulatory tetrapeptide Tuftsin. It modulates GABA-A receptors and serotonergic signaling and upregulates BDNF expression in experimental systems.
Mechanism of action
Selank is a heptapeptide analog of the endogenous immunomodulator tuftsin. It has been reported to act as a positive allosteric modulator at GABA-A receptors, while also regulating BDNF levels in the hippocampus and prefrontal cortex. It modulates dopaminergic, serotonergic and monoaminergic signaling, and has been reported to influence cytokine expression.
Key characteristics
Scientific references
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Epitalon
PeptidesSynthetic tetrapeptide (Ala-Glu-Asp-Gly)
Overview
Epitalon (AEDG) is a synthetic tetrapeptide originally derived from pineal gland extract. In cell-based systems it has been reported to affect hTERT expression, telomerase activity and antioxidant gene expression.
Mechanism of action
Epitalon (AEDG) is a tetrapeptide originally derived from pineal gland extract. In cell studies it has been reported to upregulate hTERT mRNA expression and telomerase enzyme activity. It has also been described as modifying chromatin structure through heterochromatin changes and as regulating antioxidant gene expression.
Key characteristics
Scientific references
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Thymosin Alpha-1
Peptides28-amino-acid peptide first isolated from thymus tissue
Overview
Thymosin Alpha-1 is a 28-amino-acid peptide isolated from the thymus. It activates TLR receptors to accelerate T cell maturation and stimulate natural killer cells, and its effects on immune responses have been described in the published literature.
Mechanism of action
Thymosin Alpha-1 (Tα1) is a 28-amino-acid peptide isolated from the thymus. It binds TLR3/4/9 receptors, activating IRF3 and NF-κB signaling pathways; it accelerates T cell maturation into CD4+/CD8+ subtypes and stimulates natural killer cells. It suppresses pro-inflammatory cytokines while increasing IL-2 receptor expression, thereby regulating immune homeostasis.
Key characteristics
Scientific references
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Semax
PeptidesSynthetic heptapeptide analog of an ACTH fragment
Overview
Semax is a synthetic neuropeptide combining the ACTH(4-7) fragment with the Pro-Gly-Pro tripeptide. In experimental systems it increases BDNF and NGF expression in the hippocampus and modulates pro-inflammatory cytokine gene expression.
Mechanism of action
Semax is a synthetic neuropeptide combining the ACTH(4-7) fragment with the Pro-Gly-Pro tripeptide. In experimental systems it increases BDNF, NGF and TrkB mRNA and protein levels in the rat hippocampus and frontal cortex, reduces pro-inflammatory cytokine gene expression and modulates dopaminergic and serotonergic signaling.
Key characteristics
Scientific references
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Ipamorelin
PeptidesSynthetic pentapeptide growth hormone secretagogue
Overview
Ipamorelin is a pentapeptide selective agonist at the GHSR-1a (growth hormone secretagogue receptor). By mimicking ghrelin it triggers GH release from the pituitary without significantly elevating ACTH or cortisol, distinguishing it from other GHRPs.
Mechanism of action
Ipamorelin is a pentapeptide selective agonist at the GHSR-1a (ghrelin/growth hormone secretagogue receptor). By mimicking ghrelin, it triggers GH release from the pituitary without significantly elevating ACTH or cortisol levels—unlike GHRP-6. This selectivity allows GH release without corticoadrenal activation.
Key characteristics
Scientific references
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Tesamorelin
PeptidesSynthetic analog of growth hormone-releasing hormone (44 amino acids)
Overview
Tesamorelin is a synthetic 44-amino-acid GHRH analog engineered for resistance to enzymatic degradation. It binds GHRH receptors on pituitary somatotrophs to stimulate endogenous GH synthesis and secretion.
Mechanism of action
Tesamorelin is a synthetic 44-amino-acid GHRH analog engineered for resistance to enzymatic degradation. It binds the G protein-coupled GHRH receptor on pituitary somatotrophs, raising intracellular cAMP signaling that drives endogenous GH synthesis and secretion; the resulting GH/IGF-1 axis signaling is studied in endocrine research.
Key characteristics
Scientific references
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Superoxide Dismutase
EnzymesMetalloenzyme that catalyses the dismutation of superoxide
Overview
Superoxide dismutase (SOD) is a metalloenzyme that catalyzes the conversion of the superoxide radical into oxygen and hydrogen peroxide, forming the primary cellular defense against reactive oxygen species. Three isoforms exist: cytoplasmic CuZn-SOD, mitochondrial Mn-SOD, and extracellular EC-SOD.
Mechanism of action
Superoxide Dismutase (SOD) is a metalloenzyme that catalyzes the dismutation of superoxide anion (O₂•⁻) into oxygen and hydrogen peroxide. This reaction proceeds via the redox cycling of copper (Cu,Zn-SOD) or manganese (Mn-SOD) ions at the active site. SOD constitutes the primary tier of intracellular antioxidant defense.
Key characteristics
Scientific references
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Catalase
EnzymesHeme enzyme that converts hydrogen peroxide to water and oxygen
Overview
Catalase is one of the most catalytically efficient enzymes known, decomposing millions of hydrogen peroxide molecules per second. Present predominantly in peroxisomes, it limits H2O2 accumulation, a source of oxidative damage, and works together with SOD.
Mechanism of action
Catalase is a heme-enzyme that catalyzes the reaction 2H₂O₂ → 2H₂O + O₂. The reaction proceeds when H₂O₂ oxidizes the enzyme's iron center to Compound I, a high-valent iron intermediate; a second H₂O₂ molecule then reduces this intermediate. Operating at an exceptionally high turnover, catalase limits accumulation of H₂O₂, which could otherwise generate hydroxyl radicals.
Key characteristics
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Glutathione Peroxidase
EnzymesSelenium-dependent peroxidase enzyme family
Overview
Glutathione peroxidase (GPx) is a selenium-containing enzyme family that reduces lipid hydroperoxides and H₂O₂ using a reduced thiol tripeptide as the electron donor. GPx acts on membrane lipid hydroperoxides and contributes to intracellular redox balance.
Mechanism of action
Glutathione peroxidase (GPx) is a selenoprotein containing selenocysteine at its active site. It reduces H₂O₂ and lipid hydroperoxides to their corresponding alcohols, using a reduced thiol cofactor as the electron donor. The GPx4 isoform directly reduces complex lipid peroxides and has been identified as a regulator of ferroptosis.
Key characteristics
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Bromelain
EnzymesMixture of cysteine proteases from pineapple
Overview
Bromelain is a cysteine protease complex derived from pineapple stem (Ananas comosus). It inhibits NF-κB and COX-2 pathways (anti-inflammatory activity in experimental models), displays fibrinolytic activity and has proteolytic digestive activity.
Mechanism of action
Bromelain is a cysteine protease complex derived from pineapple stem (Ananas comosus). It inhibits NF-κB and MAPK signaling pathways, suppressing iNOS and COX-2 expression and reducing production of pro-inflammatory cytokines. It also modulates the arachidonate cascade, inhibits platelet aggregation, and displays fibrinolytic activity.
Key characteristics
Scientific references
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Lysozyme
EnzymesEnzyme that hydrolyzes peptidoglycan in bacterial cell walls
Overview
Lysozyme (muramidase) is a glycoside hydrolase enzyme that disrupts bacterial peptidoglycan layers, causing bacterial lysis. Abundantly present in tears, saliva, and human milk, it is a key antimicrobial component of the innate immune system.
Mechanism of action
Lysozyme (muramidase) is a glycoside hydrolase enzyme that cleaves β-(1,4)-glycosidic bonds between N-acetylmuramic acid and N-acetylglucosamine. This disrupts bacterial peptidoglycan layers, compromising cell wall integrity and causing bacterial lysis. As a cationic antimicrobial peptide, it also provides a second defense mechanism independent of its muramidase activity.
Key characteristics
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Glutathione-S-Transferase
EnzymesEnzyme family of phase II xenobiotic conjugation
Overview
Glutathione-S-Transferase (GST) is an enzyme family that conjugates a reduced thiol tripeptide to electrophilic xenobiotics, increasing their water solubility and facilitating excretion. It is studied in xenobiotic metabolism research.
Mechanism of action
Glutathione-S-Transferase (GST) is a family of enzymes that catalyze the conjugation of a reduced thiol tripeptide to electrophilic xenobiotics generated by cytochrome P450 metabolism. An active-site residue activates the thiol to its nucleophilic thiolate form; this nucleophile forms conjugates with reactive xenobiotics and environmental pollutants, increasing water solubility and facilitating excretion.
Key characteristics
Scientific references
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Telomerase
EnzymesRibonucleoprotein enzyme that extends telomeric DNA
Overview
Telomerase is a ribonucleoprotein complex consisting of the TERT reverse transcriptase subunit and the RNA component TERC. It adds TTAGGG repeats to chromosome ends; it is active in progenitor cells, and its activity is investigated in cell-proliferation biology.
Mechanism of action
Telomerase is a ribonucleoprotein complex consisting of the TERT (reverse transcriptase subunit) and the RNA component TERC. It adds TTAGGG repeats to chromosome ends, preserving chromosome-end integrity through successive cell divisions. Regulation of TERT expression, including through promoter variants or epigenetic activation, is investigated in cell-proliferation research.
Key characteristics
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Vitamin C
VitaminsWater-soluble vitamin and cofactor in collagen hydroxylation
Overview
Vitamin C (L-ascorbic acid) is an essential micronutrient with wide-ranging physiological roles. As a water-soluble antioxidant it scavenges reactive oxygen species and recycles vitamin E; as an enzyme cofactor it is indispensable for collagen hydroxylation, carnitine synthesis, and catecholamine biosynthesis.
Mechanism of action
Vitamin C (ascorbic acid) acts as an essential cofactor for prolyl hydroxylase and lysyl hydroxylase enzymes, hydroxylating proline and lysine residues in procollagen to enable proper folding of the stable collagen triple helix. As an electron donor, it neutralizes superoxide, hydroxyl, and peroxyl radicals and reduces vitamin E radicals back to vitamin E.
Key characteristics
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Vitamin B12
VitaminsCobalt-containing vitamin (cobalamin)
Overview
Vitamin B12 (cobalamin) is a water-soluble, cobalt-containing vitamin that serves as a cofactor for two enzymes: methionine synthase, involved in DNA methylation and homocysteine metabolism, and L-methylmalonyl-CoA mutase, involved in fatty acid metabolism.
Mechanism of action
Vitamin B12 (cobalamin) is a cofactor for methionine synthase, catalyzing the synthesis of methionine from homocysteine and thereby contributing to production of S-adenosylmethionine (SAM), the universal methyl donor. SAM is essential for virtually all transmethylation reactions including DNA, RNA, histone, and neurotransmitter methylation.
Key characteristics
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Vitamin D3
VitaminsSecosteroid vitamin (cholecalciferol)
Overview
Vitamin D3 (cholecalciferol) is a fat-soluble prohormone synthesized endogenously upon UV-B exposure. After two hydroxylation steps (25-hydroxylation, then 1α-hydroxylation) it becomes active calcitriol, a steroid hormone that binds nuclear vitamin D receptors and regulates expression of over 1,000 genes across virtually all tissues.
Mechanism of action
Vitamin D3 (cholecalciferol) is hydroxylated to 25(OH)D3, then to the active form 1,25(OH)₂D3 (calcitriol), including in immune cells. Calcitriol binds the vitamin D receptor (VDR), heterodimerizes with the retinoid X receptor, and regulates transcription of thousands of genes; it increases intestinal calcium absorption and modulates immune pathways.
Key characteristics
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B-Complex
VitaminsGroup of eight water-soluble B vitamins
Overview
The B-complex encompasses eight water-soluble vitamins — B1, B2, B3, B5, B6, B7, B9, and B12 — that collectively act as coenzymes in cellular energy metabolism, DNA synthesis, neurotransmitter production, and one-carbon metabolic pathways.
Mechanism of action
The B vitamin complex (B1, B2, B3, B5, B6, B7, B9, B12) is a group of water-soluble vitamins functioning as coenzymes in mitochondrial aerobic respiration. Their active forms (thiamine pyrophosphate, FAD, NAD+, coenzyme A) catalyze critical steps in the citric acid cycle and electron transport chain for ATP production.
Key characteristics
Scientific references
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Vitamin A
VitaminsFat-soluble retinoid vitamin
Overview
Vitamin A regulates cell differentiation and proliferation genes through its active form all-trans retinoic acid (atRA) via RAR/RXR nuclear receptors. In its 11-cis-retinal form it is essential for photoreceptor function, and it plays critical roles in immune development and epithelial integrity.
Mechanism of action
Vitamin A regulates gene expression through its active form all-trans retinoic acid (atRA) via nuclear receptors (RAR/RXR heterodimers). This complex binds retinoic acid response elements in DNA to modulate transcription of genes governing cell differentiation and proliferation. Retinol in its 11-cis-retinal form is also essential for photoreceptor function.
Key characteristics
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Vitamin E
VitaminsFat-soluble tocopherol and tocotrienol group
Overview
Vitamin E (α-tocopherol) acts as a chain-breaking antioxidant within lipophilic biological membranes and lipoproteins. It terminates lipid peroxidation chain reactions and is recycled by vitamin C, completing the antioxidant cycle.
Mechanism of action
Vitamin E (α-tocopherol) acts as a chain-breaking antioxidant within lipophilic biological membranes and lipoproteins. It terminates lipid peroxidation chain reactions by donating a hydrogen atom to lipid peroxyl radicals; the resulting tocopheroxyl radical is recycled by vitamin C.
Key characteristics
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Vitamin K2
VitaminsMenaquinone form of vitamin K
Overview
Vitamin K2 (menaquinone, especially MK-7) activates osteocalcin and matrix Gla protein as a cofactor for gamma-glutamyl carboxylase. Osteocalcin binds calcium in the bone matrix while matrix Gla protein inhibits calcification of soft-tissue matrices.
Mechanism of action
Vitamin K2 (menaquinone, especially MK-7) is a cofactor for gamma-glutamyl carboxylase, which γ-carboxylates glutamate residues of vitamin K-dependent proteins. This carboxylation activates the calcium-binding capacity of osteocalcin and matrix Gla protein; osteocalcin binds calcium in the bone matrix, while matrix Gla protein inhibits calcification of soft-tissue matrices.
Key characteristics
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Folate (B9)
VitaminsVitamin B9 in its folate and folic acid forms
Overview
Folate (vitamin B9) is the central cofactor of one-carbon metabolism. Its tetrahydrofolate form participates in purine and thymidine synthesis and methionine recycling, providing methyl groups for DNA and histone methylation via SAM production.
Mechanism of action
Folate (vitamin B9) is the central cofactor of one-carbon metabolism. Its tetrahydrofolate (THF) form carries single-carbon units used in thymidine and purine synthesis and methionine recycling, thereby generating SAM to provide methyl groups for DNA and histone methylation. Inadequate folate disrupts the nucleotide pool and leads to DNA hypomethylation.
Key characteristics
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Glutamine
Amino acidsConditionally essential amino acid
Overview
L-Glutamine is the most abundant free amino acid in circulation, becoming conditionally essential during catabolic states such as illness, surgery, or intense exercise. It is the principal fuel for rapidly dividing cells including intestinal enterocytes and immune cells.
Mechanism of action
Glutamine is the most abundant free amino acid in the human body and the primary energy substrate for small intestinal enterocytes. It maintains gut barrier integrity by regulating tight junction protein expression. In immune cells it serves as a critical nitrogen source for proliferation and cytokine production, and as a nitrogen donor for nucleotide biosynthesis.
Key characteristics
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Arginine
Amino acidsAmino acid and nitric oxide precursor
Overview
L-Arginine is a semi-essential amino acid and the exclusive precursor for nitric oxide synthesis via nitric oxide synthase enzymes. NO regulates vascular tone, platelet aggregation, and immune function. Arginine also stimulates growth hormone secretion and serves as a key intermediate in the urea cycle.
Mechanism of action
L-Arginine is the direct precursor for nitric oxide (NO) synthesis as the substrate for endothelial nitric oxide synthase (eNOS). eNOS converts L-arginine to L-citrulline, generating NO; NO activates guanylate cyclase to increase cGMP, leading to smooth muscle relaxation. It also inhibits platelet aggregation and participates in the urea cycle.
Key characteristics
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Taurine
Amino acidsSulfur-containing amino sulfonic acid
Overview
Taurine is a conditionally essential sulfur-containing amino acid abundantly present in skeletal muscle, the retina and the central nervous system. It regulates intracellular calcium signaling, osmotic balance, and bile acid conjugation, while exerting broad antioxidant and anti-inflammatory effects.
Mechanism of action
Taurine participates in mitochondrial protein synthesis by forming 5-taurinomethyluridine on mitochondrial tRNA, which influences electron transport chain activity. It scavenges hypochlorous acid directly, modulates intracellular calcium, and has been studied for effects on nitric oxide bioavailability.
Key characteristics
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Glycine
Amino acidsSimplest proteinogenic amino acid
Overview
Glycine is the simplest amino acid, constituting approximately 33% of all collagen residues. It acts as an inhibitory neurotransmitter at glycine receptors in the brainstem and spinal cord, and plays essential roles in one-carbon metabolism, creatine synthesis, and bile acid and xenobiotic conjugation.
Mechanism of action
Glycine is the dominant amino acid in the collagen Gly-X-Y repeat motif, determining triple helix stability; adequate glycine is essential for cartilage and connective tissue synthesis. It also acts as a co-agonist at NMDA receptors and, as an inhibitory neurotransmitter, participates in spinal cord inhibition.
Key characteristics
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Carnosine
Amino acidsDipeptide of beta-alanine and L-histidine
Overview
Carnosine is an endogenous dipeptide (beta-alanine + L-histidine) highly concentrated in muscle and brain. It serves as an intracellular pH buffer during high-intensity exercise, a carbonyl scavenger inhibiting advanced glycation end-product formation, and a zinc and copper chelator.
Mechanism of action
Carnosine (β-alanyl-L-histidine) is a dipeptide found at high concentrations in skeletal muscle. The pKa of histidine's imidazole ring provides muscle pH buffering, buffering pH changes during intense exercise. Through non-enzymatic reaction with protein carbonyl groups it inhibits advanced glycation end product (AGE) formation and chelates metal ions.
Key characteristics
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Lysine
Amino acidsEssential amino acid
Overview
Lysine is an essential amino acid that contributes to the indispensable post-translational modification enabling collagen fibril formation by generating hydroxylysine in procollagen. It is also the precursor for carnitine synthesis; carnitine transports fatty acids for mitochondrial oxidation.
Mechanism of action
Lysine serves as the substrate for prolyl hydroxylase and lysyl hydroxylase enzymes, generating hydroxylysine in procollagen; this post-translational modification is essential for collagen cross-linking and fibril formation. Lysine is also a precursor amino acid for carnitine synthesis; carnitine transports fatty acids for mitochondrial oxidation.
Key characteristics
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Cysteine
Amino acidsSulfur-containing proteinogenic amino acid
Overview
Cysteine is a thiol-containing amino acid whose side chain participates in disulfide bonds, metal binding and redox signaling. Its N-acetylcysteine (NAC) form is widely used in research as a cysteine source. Through the redox state of protein thiol groups it regulates enzyme activities, signaling pathways, and cellular redox homeostasis.
Mechanism of action
The thiol side chain of cysteine cycles between reduced and oxidized states, forming disulfide bonds and other reversible redox modifications. The redox state of protein thiol groups determines their tertiary structure and function. Cysteine is also a metabolic precursor of taurine and inorganic sulfate.
Key characteristics
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Tyrosine
Amino acidsAromatic amino acid and precursor of catecholamines
Overview
Tyrosine is the central precursor for catecholamine neurotransmitter synthesis, converted by tyrosine hydroxylase to dopamine, then norepinephrine and epinephrine. It also serves as the building block for thyroid hormone synthesis.
Mechanism of action
Tyrosine is the central precursor for catecholamine neurotransmitter synthesis, converted by tyrosine hydroxylase to L-DOPA and then to dopamine, norepinephrine, and epinephrine. It is also used in thyroid hormone synthesis; iodination forms the building blocks of thyroxine (T4) and triiodothyronine (T3).
Key characteristics
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Tryptophan
Amino acidsEssential aromatic amino acid and precursor of serotonin and niacin
Overview
Tryptophan is the sole dietary precursor for serotonin and melatonin biosynthesis. It is also converted to NAD+ precursor nicotinamide nucleotides via the kynurenine pathway; it participates in gut-brain axis signaling and immune responses.
Mechanism of action
Tryptophan converts a portion of dietary intake to serotonin (5-HT) and then melatonin via the serotonin/melatonin pathway, and the majority to nicotinamide nucleotides (NAD+ precursors) via the kynurenine pathway. Serotonin signaling is involved in the gut-brain axis and gut motility.
Key characteristics
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Proline
Amino acidsCyclic amino acid abundant in collagen
Overview
Proline frequently occupies the X and Y positions of the Gly-X-Y motif in collagen and is converted to hydroxyproline by prolyl 4-hydroxylase to increase collagen triple helix thermal stability. It also modulates oxidative stress responses via the proline cycle.
Mechanism of action
Proline frequently occupies the X and Y positions of the Gly-X-Y motif in collagen and is converted to hydroxyproline in procollagen by prolyl 4-hydroxylase. This hydroxylation increases the thermal stability of the collagen triple helix and reinforces tissue integrity. Proline also modulates cellular responses to oxidative stress via the 'proline cycle.'
Key characteristics
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NAD+
AntioxidantsRedox coenzyme (nicotinamide adenine dinucleotide)
Overview
Nicotinamide adenine dinucleotide (NAD+) is a coenzyme found in all living cells and central to oxidative phosphorylation and the TCA cycle. Beyond redox chemistry, NAD+ is a critical substrate for sirtuins, PARP enzymes, and CD38, linking cellular energy status to DNA repair, epigenetic regulation and cellular signaling.
Mechanism of action
NAD+ (nicotinamide adenine dinucleotide) serves a dual function as an electron-carrying coenzyme in redox reactions and as a substrate for NAD+-consuming enzymes (sirtuins SIRT1-7, PARPs, CD38). Sirtuins consume NAD+ in deacylation reactions to deacetylate histones and transcription factors; NAD+ availability depends on the balance between biosynthesis and consumption.
Key characteristics
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FAD
AntioxidantsFlavin adenine dinucleotide, a redox cofactor
Overview
Flavin adenine dinucleotide (FAD) is a redox-active coenzyme synthesized from riboflavin (vitamin B2). It serves as a prosthetic group for flavoproteins and participates in the mitochondrial electron transport chain, beta-oxidation of fatty acids, and the TCA cycle.
Mechanism of action
FAD (flavin adenine dinucleotide) is a riboflavin (B2)-derived coenzyme that catalyzes single- or two-electron redox reactions via its isoalloxazine ring. As a component of mitochondrial Complex II, it catalyzes the oxidation of succinate to fumarate and transfers electrons to coenzyme Q10, linking fatty acid β-oxidation to the respiratory chain.
Key characteristics
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Coenzyme Q10
AntioxidantsLipid-soluble quinone in the mitochondrial respiratory chain
Overview
Coenzyme Q10 (ubiquinone) is a fat-soluble molecule present in virtually every cell. As a mobile electron carrier in the mitochondrial inner membrane it shuttles electrons between respiratory complexes; in its reduced form (ubiquinol) it is a membrane-bound antioxidant.
Mechanism of action
Coenzyme Q10 (ubiquinone/ubiquinol) is a lipophilic quinone molecule in the mitochondrial respiratory chain that transfers electrons from Complexes I and II to Complex III. The Q-cycle between its fully oxidized and fully reduced forms sustains the proton gradient to feed ATP synthase. The reduced form ubiquinol is an antioxidant that breaks membrane lipid peroxidation.
Key characteristics
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Alpha-Lipoic Acid
AntioxidantsSulfur-containing fatty acid cofactor
Overview
Alpha-lipoic acid (ALA) is a natural cofactor for mitochondrial dehydrogenase complexes and a distinctive antioxidant. The ALA/DHLA redox couple scavenges reactive oxygen species and recycles vitamins E and C; its solubility in both fat and water sets it apart among antioxidants.
Mechanism of action
Alpha-lipoic acid (ALA) is a natural cofactor for mitochondrial pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes. The ALA/DHLA redox couple scavenges reactive oxygen species including superoxide, hydroxyl, and singlet oxygen, chelates metal ions, and recycles vitamin E and vitamin C. Its activity in both lipophilic and hydrophilic environments distinguishes it among antioxidants.
Key characteristics
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Resveratrol
AntioxidantsPlant polyphenol of the stilbene class
Overview
Resveratrol is a stilbene-class polyphenolic compound synthesized in grapes and other plants. It activates SIRT1, modulates NF-κB and AMPK pathways in studies of anti-inflammatory signaling, and stimulates mitochondrial biogenesis.
Mechanism of action
Resveratrol is a stilbene-class polyphenolic compound synthesized in grapes and other plants. It activates SIRT1, increasing NAD+-dependent deacetylase activity. It also modulates NF-κB and AMPK pathways and stimulates mitochondrial biogenesis.
Key characteristics
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Astaxanthin
AntioxidantsXanthophyll carotenoid
Overview
Astaxanthin is a unique carotenoid with hydroxyl and keto groups at both ends. Its membrane-spanning structure quenches singlet oxygen within the lipid bilayer and upregulates intrinsic antioxidant defense genes through Nrf2 activation.
Mechanism of action
Astaxanthin is a unique carotenoid with hydroxyl and keto groups at both ends. Its membrane-spanning structure quenches singlet oxygen and breaks peroxyl chain reactions within the lipid bilayer. It also activates the Nrf2 transcription factor, upregulating the cell's intrinsic antioxidant defense genes.
Key characteristics
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NMN
AntioxidantsNicotinamide mononucleotide, a precursor of NAD+
Overview
NMN (nicotinamide mononucleotide) is a critical intermediate in the salvage pathway of NAD+ biosynthesis. After cellular uptake it is converted to NAD+ by NMNAT enzymes, raising cellular NAD+ levels; effects on sirtuin and PARP activity are studied in research settings.
Mechanism of action
In the salvage pathway, nicotinamide phosphoribosyltransferase (NAMPT) forms NMN from nicotinamide, and NMNAT enzymes then convert NMN to NAD+. In studies, NMN supplementation has been reported to raise tissue NAD+ levels; effects on sirtuin and PARP activity, metabolic function and mitochondrial biogenesis are under investigation.
Key characteristics
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