Target type: biologicalprocess
The chemical reactions and pathways resulting in the formation of eye pigments, any general or particular coloring matter in living organisms, found or utilized in the eye. [GOC:ai]
Eye pigment biosynthesis is a complex and multifaceted process that involves the production and deposition of pigments within the eye, specifically in the retina and iris. These pigments play crucial roles in visual perception, protecting the eye from damaging light, and contributing to overall eye health. The process can be broadly divided into two main pathways: melanin biosynthesis and visual pigment biosynthesis.
**Melanin Biosynthesis**
Melanin biosynthesis is responsible for the production of melanins, a group of dark pigments responsible for the color of the iris, choroid, and retinal pigment epithelium (RPE). The key precursor for melanin is tyrosine, an amino acid. The biosynthesis pathway starts with the conversion of tyrosine to L-DOPA (L-3,4-dihydroxyphenylalanine) by the enzyme tyrosinase. L-DOPA is then further oxidized by tyrosinase to dopaquinone, which undergoes a series of enzymatic and non-enzymatic reactions to produce melanin. Two major types of melanin are produced: eumelanin (brown-black pigment) and pheomelanin (red-yellow pigment). The ratio of these two pigments determines the final eye color.
**Visual Pigment Biosynthesis**
Visual pigment biosynthesis involves the production of light-sensitive pigments found in photoreceptor cells of the retina. These pigments, called rhodopsin and cone pigments, are responsible for converting light energy into electrical signals that the brain can interpret. The synthesis of visual pigments is a complex process that involves multiple steps:
1. **Retinal Synthesis:** Retinal, a derivative of vitamin A, is the light-absorbing chromophore of visual pigments. It is synthesized from retinol (vitamin A alcohol) by a series of enzymatic reactions.
2. **Opsin Synthesis:** Opsin, a protein, is the other major component of visual pigments. It is synthesized in the photoreceptor cells and transported to the outer segments of the rods and cones.
3. **Retinal-Opsin Binding:** Retinal and opsin combine to form the complete visual pigment. This binding process is highly specific and ensures that the correct type of visual pigment is produced in each photoreceptor cell.
**Regulation and Importance**
The biosynthesis of eye pigments is tightly regulated by a complex interplay of genetic and environmental factors. Mutations in genes involved in the biosynthesis pathways can lead to various eye disorders, including albinism, oculocutaneous albinism, and retinitis pigmentosa. Proper eye pigment biosynthesis is essential for normal vision, light protection, and overall eye health. It plays a crucial role in visual perception, adaptation to different light conditions, and protecting the delicate structures of the eye from damage.
'"
| Protein | Definition | Taxonomy |
|---|---|---|
| Tyrosinase | A tyrosinase that is encoded in the genome of human. [PRO:DNx, UniProtKB:P14679] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| 4-hydroxybenzoic acid | 4-hydroxybenzoic acid : A monohydroxybenzoic acid that is benzoic acid carrying a hydroxy substituent at C-4 of the benzene ring. | monohydroxybenzoic acid | algal metabolite; plant metabolite |
| benzaldehyde | benzaldehydes | EC 3.1.1.3 (triacylglycerol lipase) inhibitor; EC 3.5.5.1 (nitrilase) inhibitor; flavouring agent; fragrance; odorant receptor agonist; plant metabolite | |
| benzoic acid | aromatic carboxylic acid : Any carboxylic acid in which the carboxy group is directly bonded to an aromatic ring. benzoic acid : A compound comprising a benzene ring core carrying a carboxylic acid substituent. Benzoic Acid: A fungistatic compound that is widely used as a food preservative. It is conjugated to GLYCINE in the liver and excreted as hippuric acid. | benzoic acids | algal metabolite; antimicrobial food preservative; drug allergen; EC 1.13.11.33 (arachidonate 15-lipoxygenase) inhibitor; EC 3.1.1.3 (triacylglycerol lipase) inhibitor; human xenobiotic metabolite; plant metabolite |
| cuminaldehyde | cuminaldehyde : A member of the class of benzaldehydes that is benzaldehyde substituted by an isopropyl group at position 4. It is a component of essential oils from Cumin and exhibits insecticidal activities. | benzaldehydes | insecticide; plant metabolite; volatile oil component |
| hydroquinone | benzenediol; hydroquinones | antioxidant; carcinogenic agent; cofactor; Escherichia coli metabolite; human xenobiotic metabolite; mouse metabolite; skin lightening agent | |
| hexylresorcinol | resorcinols | ||
| beta-thujaplicin | beta-thujaplicin : A monoterpenoid that is cyclohepta-2,4,6-trien-1-one substituted by a hydroxy group at position 2 and an isopropyl group at position 4. Isolated from Thuja plicata and Chamaecyparis obtusa, it exhibits antimicrobial activities. beta-thujaplicin: structure | cyclic ketone; enol; monoterpenoid | antibacterial agent; antifungal agent; antineoplastic agent; antiplasmodial drug; plant metabolite |
| kojic acid | 4-pyranones; enol; primary alcohol | Aspergillus metabolite; EC 1.10.3.1 (catechol oxidase) inhibitor; EC 1.10.3.2 (laccase) inhibitor; EC 1.13.11.24 (quercetin 2,3-dioxygenase) inhibitor; EC 1.14.18.1 (tyrosinase) inhibitor; EC 1.4.3.3 (D-amino-acid oxidase) inhibitor; NF-kappaB inhibitor; skin lightening agent | |
| resorcinol | resorcinol : A benzenediol that is benzene dihydroxylated at positions 1 and 3. resorcinol: RN given refers to parent cpd; structure in Merck Index, 9th ed, #7951 | benzenediol; phenolic donor; resorcinols | erythropoietin inhibitor; sensitiser |
| levodopa | L-dopa : An optically active form of dopa having L-configuration. Used to treat the stiffness, tremors, spasms, and poor muscle control of Parkinson's disease Levodopa: The naturally occurring form of DIHYDROXYPHENYLALANINE and the immediate precursor of DOPAMINE. Unlike dopamine itself, it can be taken orally and crosses the blood-brain barrier. It is rapidly taken up by dopaminergic neurons and converted to DOPAMINE. It is used for the treatment of PARKINSONIAN DISORDERS and is usually given with agents that inhibit its conversion to dopamine outside of the central nervous system. | amino acid zwitterion; dopa; L-tyrosine derivative; non-proteinogenic L-alpha-amino acid | allelochemical; antidyskinesia agent; antiparkinson drug; dopaminergic agent; hapten; human metabolite; mouse metabolite; neurotoxin; plant growth retardant; plant metabolite; prodrug |
| salicylaldehyde | o-hydroxybenzaldehyde: structure in first source | hydroxybenzaldehyde | nematicide; plant metabolite |
| xanthone | xanthone : The parent compound of the xanthone class consisting of xanthene bearing a single oxo substituent at position 9. | xanthones | insecticide |
| butylphen | 4-tert-butylphenol : A member of the class of phenols that is phenol substituted with a tert-butyl group at position 4. butylphen: irritant; structure | phenols | allergen |
| gamma-thujaplicin | 2-hydroxy-5-isopropyl- 2,4,6-cycloheptatrienone: a metal chelating agent | cyclic ketone | |
| 3-hydroxy-1-benzopyran-2-one | 3-hydroxycoumarin: Photoprotective from sea urchin gametes and embryonic cells; structure in first source hydroxycoumarin : Any coumarin carrying at least one hydroxy substituent. | hydroxycoumarin | |
| 2-tert-butylhydroquinone | 2-tert-butylhydroquinone : A member of the class of hydroquinones in which one of the ring hydrogens of hydroquinone is replaced by a tert-butyl group. 2-tert-butylhydroquinone: an anticarcinogenic and chemopreventive agent | hydroquinones | food antioxidant |
| 4-anisaldehyde | 4-anisaldehyde: RN given refers to cpd with specified locants for methoxy moieties; structure in Merck, 9th ed, #696 p-methoxybenzaldehyde : A member of the class of benzaldehydes consisting of benzaldehyde itself carrying a methoxy substituent at position 4. | benzaldehydes | bacterial metabolite; human urinary metabolite; insect repellent; plant metabolite |
| 2-hydroxy-4-methoxybenzaldehyde | 2-hydroxy-4-methoxybenzaldehyde: from African medicinal plants: Mondia whitei (Apocynaceae), Rhus vulagaris (Anacardiaceae), Sclerocarya caffra (Anacardiaceae) | methoxybenzenes; phenols | |
| 1-hydroxy-2(1h)-pyridinone | 1-hydroxy-2(1H)-pyridinone: structure in first source | ||
| 2-Methoxyxanthone | xanthones | ||
| alpha-thujaplicin | alpha-thujaplicin: structure in first source | ||
| arctiin | arctiin: from fruits of Arctium lappa L; RN given refers to (3R-trans)-isomer; RN for cpd without isomeric designation not avail 12/92 | glycoside; lignan | |
| glabridin | hydroxyisoflavans | antiplasmodial drug | |
| moracin m | moracin M: has been isolated from Morus alba L.; structure in first source | benzofurans | |
| 4-n-butylresorcinol | 4-n-butylresorcinol: structure in first source | resorcinols | |
| 4-methoxyxanthone | 4-methoxyxanthone: a vasodilator; structure in first source | ||
| mimosine | L-mimosine : An L-alpha-amino acid that is propionic acid substituted by an amino group at position 2 and a 3-hydroxy-4-oxopyridin-1(4H)-yl group at position 3 (the 2S-stereoisomer). It a non-protein plant amino acid isolated from Mimosa pudica. | 4-pyridones; amino acid zwitterion; non-proteinogenic L-alpha-amino acid | EC 1.14.18.1 (tyrosinase) inhibitor; plant metabolite |
| arbutin | hydroquinone O-beta-D-glucopyranoside : A monosaccharide derivative that is hydroquinone attached to a beta-D-glucopyranosyl residue at position 4 via a glycosidic linkage. | beta-D-glucoside; monosaccharide derivative | Escherichia coli metabolite; plant metabolite |
| resveratrol | trans-resveratrol : A resveratrol in which the double bond has E configuration. | resveratrol | antioxidant; phytoalexin; plant metabolite; quorum sensing inhibitor; radical scavenger |
| glabrene | glabrene: structure in first source | isoflavonoid | |
| glyasperin D | glyasperin D : A member of the class of hydroxyisoflavans that is (R)-isoflavan substituted by hydroxy groups at positions 2' and 4', methoxy groups at positions 5 and 7 and a prenyl group at position 6. It has been isolated from Glycyrrhiza uralensis. | aromatic ether; hydroxyisoflavans; methoxyisoflavan | plant metabolite |
| 6-hydroxyindole | 6-hydroxyindole: structure in first source | ||
| trans-4-coumaric acid | 4-coumaric acid : A coumaric acid in which the hydroxy substituent is located at C-4 of the phenyl ring. hydroxycinnamic acid : Any member of the class of cinnamic acids carrying one or more hydroxy substituents. trans-4-coumaric acid : The trans-isomer of 4-coumaric acid. | 4-coumaric acid | food component; mouse metabolite; plant metabolite |
| phenylthiourea | N-phenylthiourea : A member of the class of thioureas that is thiourea in which one of the hydrogens is replaced by a phenyl group. Depending on their genetic makeup, humans find it either very bitter-tasting or tasteless. This unusual property resulted in N-phenylthiourea being used in paternity testing prior to the advent of DNA testing. Phenylthiourea: Phenylthiourea is a THIOUREA derivative containing a phenyl ring. Depending on their genetic makeup, humans can find it either bitter-tasting or tasteless. | thioureas | EC 1.14.18.1 (tyrosinase) inhibitor |
| isoeugenol | trans-isoeugenol : The trans-stereoisomer of isoeugenol. | isoeugenol | plant metabolite |
| curcumin | curcumin : A beta-diketone that is methane in which two of the hydrogens are substituted by feruloyl groups. A natural dyestuff found in the root of Curcuma longa. Curcumin: A yellow-orange dye obtained from tumeric, the powdered root of CURCUMA longa. It is used in the preparation of curcuma paper and the detection of boron. Curcumin appears to possess a spectrum of pharmacological properties, due primarily to its inhibitory effects on metabolic enzymes. | aromatic ether; beta-diketone; diarylheptanoid; enone; polyphenol | anti-inflammatory agent; antifungal agent; antineoplastic agent; biological pigment; contraceptive drug; dye; EC 1.1.1.205 (IMP dehydrogenase) inhibitor; EC 1.1.1.21 (aldehyde reductase) inhibitor; EC 1.1.1.25 (shikimate dehydrogenase) inhibitor; EC 1.6.5.2 [NAD(P)H dehydrogenase (quinone)] inhibitor; EC 1.8.1.9 (thioredoxin reductase) inhibitor; EC 2.7.10.2 (non-specific protein-tyrosine kinase) inhibitor; EC 3.5.1.98 (histone deacetylase) inhibitor; flavouring agent; food colouring; geroprotector; hepatoprotective agent; immunomodulator; iron chelator; ligand; lipoxygenase inhibitor; metabolite; neuroprotective agent; nutraceutical; radical scavenger |
| 4-hydroxy-5-methyl-3(2h)-furanone | 4-hydroxy-5-methyl-3-furanone : A member of the class of furans that is 5-methyl-2,3-dihydrofuran with a hydroxy group at position 4 and a keto group at position 3. | cyclic ketone; enol; furans | metabolite |
| quercetin | 7-hydroxyflavonol; pentahydroxyflavone | antibacterial agent; antineoplastic agent; antioxidant; Aurora kinase inhibitor; chelator; EC 1.10.99.2 [ribosyldihydronicotinamide dehydrogenase (quinone)] inhibitor; geroprotector; phytoestrogen; plant metabolite; protein kinase inhibitor; radical scavenger | |
| luteolin | 3'-hydroxyflavonoid; tetrahydroxyflavone | angiogenesis inhibitor; anti-inflammatory agent; antineoplastic agent; apoptosis inducer; c-Jun N-terminal kinase inhibitor; EC 2.3.1.85 (fatty acid synthase) inhibitor; immunomodulator; nephroprotective agent; plant metabolite; radical scavenger; vascular endothelial growth factor receptor antagonist | |
| apigetrin | apigenin 7-O-beta-D-glucoside : A glycosyloxyflavone that is apigenin substituted by a beta-D-glucopyranosyl moiety at position 7 via a glycosidic linkage. apigetrin: structure given in first source | beta-D-glucoside; dihydroxyflavone; glycosyloxyflavone; monosaccharide derivative | antibacterial agent; metabolite; non-steroidal anti-inflammatory drug |
| quercetin 3-o-glucopyranoside | quercetin 3-O-beta-D-glucopyranoside : A quercetin O-glucoside that is quercetin with a beta-D-glucosyl residue attached at position 3. Isolated from Lepisorus contortus, it exhibits antineoplastic activityand has been found to decrease the rate of polymerization and sickling of red blood cells quercetin 3-O-glucopyranoside: structure in first source | beta-D-glucoside; monosaccharide derivative; quercetin O-glucoside; tetrahydroxyflavone | antineoplastic agent; antioxidant; antipruritic drug; bone density conservation agent; geroprotector; histamine antagonist; osteogenesis regulator; plant metabolite |
| kaempferol | 7-hydroxyflavonol; flavonols; tetrahydroxyflavone | antibacterial agent; geroprotector; human blood serum metabolite; human urinary metabolite; human xenobiotic metabolite; plant metabolite | |
| hispidol | hispidol : A hydroxyaurone that is aurone substituted by hydroxy groups at positions 6 and 4' respectively. | hydroxyaurone | plant metabolite |
| 7-hydroxycoumarin | 7-oxycoumarin: derivatives have anti-oxidant properties umbelliferone : A hydroxycoumarin that is coumarin substituted by a hydroxy group ay position 7. | hydroxycoumarin | fluorescent probe; food component; plant metabolite |
| euxanthone | euxanthone : A member of the class of xanthones that is 9H-xanthene substituted by hydroxy group at positions 1 and 7 and an oxo group at position 9. It has been isolated from Cratoxylum cochinchinense. | phenols; xanthones | metabolite; plant metabolite |
| trans-2,3',4,5'-tetrahydroxystilbene | trans-2,3',4,5'-tetrahydroxystilbene: hydroxystilbene oxyresveratrol | stilbenoid | |
| linarin | linarin: flavone glycoside isolated from leaves of Linaria japonica MIQ | ||
| methyl-p-coumarate | 4-coumaric acid methyl ester : A cinnamate ester that is the methyl ester of 4-coumaric acid. methyl-p-coumarate: structure in first source | 4-coumaric acid methyl ester | |
| tiliroside | tiliroside: isolated from seeds of Eremocarpus setigerus | cinnamate ester; glycosyloxyflavone; monosaccharide derivative; trihydroxyflavone | plant metabolite |
| tilianin | tilianin: from several medicinal plants including Agastache rugosa and Dracocephalum moldavia | ||
| 2,4,3',5'-tetramethoxystilbene | 2,4,3',5'-tetramethoxystilbene: potent inhibitor of human cytochrome P450 1B1; an antihypertensive agent; structure in first source | ||
| 1-hydroxyxanthone | 1-hydroxyxanthone: structure in first source | ||
| Norartocarpetin | flavones | ||
| 3,4-dihydroxy-xanthone | 3,4-dihydroxy-xanthone: structure given in first source | ||
| hylin | |||
| apigenin-7-o-rutinoside | |||
| morachalcone a | morachalcone A: tyrosinase inhibitor from the wood of Artocarpus heterophyllus; structure in first source | chalcones | |
| 2,4,2',4'-Tetrahydroxychalcone | chalcones | ||
| 4-(1-phenylethyl)resorcinol | 4-(1-phenylethyl)resorcinol: a depigmenting agent for treatment of solar lentigines; structure in first source | ||
| 3-hydroxyphloretin | 3-hydroxyphloretin: compound from Formosan apple that reduces tyrosinase activity in human epidermal melanocytes; structure in first source | chalcones | |
| subamolide a | subamolide A: cytotoxic constituent of the stems of Cinnamomum subavenium; structure in first source | ||
| feruloyldopamine | feruloyldopamine: a dopamine metabolite isolated from tomatoes after infection by Pseudomonas syringae; structure in first source | ||
| ascorbic acid | Ascorbic Acid: A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant. L-ascorbate : The L-enantiomer of ascorbate and conjugate base of L-ascorbic acid, arising from selective deprotonation of the 3-hydroxy group. Required for a range of essential metabolic reactions in all animals and plants. L-ascorbic acid : The L-enantiomer of ascorbic acid and conjugate acid of L-ascorbate. vitamin C : Any member of a group of vitamers that belong to the chemical structural class called butenolides that exhibit biological activity against vitamin C deficiency in animals. The vitamers include L-ascorbic acid and its salt, ionized and oxidized forms. | ascorbic acid; vitamin C | coenzyme; cofactor; flour treatment agent; food antioxidant; food colour retention agent; geroprotector; plant metabolite; skin lightening agent |