All articles A–Z

Dihydrocapsiate

Dihydrocapsiate (DHC, DCT) is a non-pungent capsinoid analog of capsaicin from CH-19 Sweet peppers, formula C18H28O4; human trials show a small thermogenic effect near 50 kcal/day, and it is GRAS in the US and an authorized EU novel food.

Dihydrocodeine

Dihydrocodeine (DHC), a semisynthetic opioid derivative of codeine used for moderate to severe pain and cough, metabolized via CYP2D6 and CYP3A4, with limited efficacy evidence and addiction and respiratory-depression risks.

Dihydrodipicolinate reductase

Dihydrodipicolinate reductase (DapB, EC 1.17.1.8, 4-hydroxy-tetrahydrodipicolinate reductase) is a bacterial NAD(P)-dependent homotetrameric enzyme catalyzing HTPA-to-tetrahydrodipicolinate reduction, the second step of the diaminopimelate/lysine pathway and an antibiotic target.

Dihydroergotamine

Dihydroergotamine (DHE) is a semi-synthetic ergot alkaloid drug used for the acute treatment of migraine and cluster headache, first synthesized in 1943 and approved in 1946.

Dihydroetorphine

Dihydroetorphine (二氢埃托啡, DHE), a Chinese-developed etorphine-family opioid agonist over 1,000 times stronger than morphine, approved 1991 for severe pain, later restricted for abuse and dependence.

Dihydrofolate reductase

Dihydrofolate reductase, also known as DHFR, is an enzyme that produces the folate cofactor required for synthesizing purines and thymidylate, making it a key drug target.

Dihydrogen monoxide parody

The dihydrogen monoxide parody, also called the DHMO hoax, presents water under its chemical-sounding name with true but alarming descriptions, famously fooling officials in Aliso Viejo, California, in 2004.

Dihydrolipoamide dehydrogenase

Dihydrolipoamide dehydrogenase (DLD, E3, EC 1.8.1.4) is a homodimeric mitochondrial FAD enzyme, encoded on chromosome 7, that reoxidizes lipoamide in the PDH, α-ketoglutarate, branched-chain keto acid, and 2-oxoadipate dehydrogenase complexes; DLD mutations cause rare autosomal recessive E3 deficiency.

Dihydroorotase

Dihydroorotase (DHOase, EC 3.5.2.3), zinc metalloenzyme of de novo pyrimidine biosynthesis catalyzing reversible carbamoyl aspartate to dihydroorotate conversion; TIM-barrel amidohydrolase, type I and II, CAD domain in mammals, binuclear or mononuclear zinc center.

Dihydroorotate dehydrogenase

Dihydroorotate dehydrogenase (DHODH, PyrD) is an FMN flavoenzyme catalyzing the fourth, redox step of de novo pyrimidine biosynthesis; Class 1 (fumarate/NAD+) and Class 2 (ubiquinone, mitochondrial) forms are drug targets in arthritis, cancer, and malaria via leflunomide, teriflunomide, and DSM265.

Dihydropteroate synthase

Dihydropteroate synthase (DHPS) is an enzyme that joins p-aminobenzoic acid to a pterin in bacterial folate biosynthesis, making it the target of sulfonamide antibiotics, the oldest class of synthetic antibacterial drugs.

Dihydropteroate synthase type-3

Dihydropteroate synthase type-3 (Sul3, gene sul3) is a plasmid-borne sulfonamide-resistant DHPS enzyme, characterized in 2003 from E. coli plasmid pVP440 in Swiss pigs, 263 amino acids, spread via IS15Δ/26-flanked segments.

Dihydropyridines

Dihydropyridines, first made by Arthur Hantzsch in 1881, are six-membered nitrogen heterocycles whose 1,4 isomer is the scaffold of calcium channel blocker drugs including nifedipine and amlodipine.

Dihydropyrimidine dehydrogenase deficiency

Dihydropyrimidine dehydrogenase deficiency (DPD deficiency, DPYD deficiency) is an autosomal recessive DPYD enzyme disorder causing neurological disease in some and severe, sometimes fatal fluoropyrimidine (5-FU, capecitabine) toxicity in others.

Dihydropyrimidinuria

Dihydropyrimidinuria, also called dihydropyrimidinase deficiency (DPYS deficiency, OMIM 222748), is a rare autosomal recessive pyrimidine metabolism disorder causing dihydrouracil and dihydrothymine accumulation, variable neurologic and gastrointestinal features, and fluoropyrimidine toxicity risk.

Dihydrostreptomycin

Dihydrostreptomycin is an aminoglycoside antibiotic, made by catalytic hydrogenation of streptomycin and introduced in 1946, later withdrawn from human use in the United States for ototoxicity.

Dihydrotachysterol

Dihydrotachysterol (DHT, A.T. 10) is a half-synthetic vitamin D analog from ergosterol, introduced in 1933 for hypoparathyroidism; it needs no renal hydroxylation and is no longer sold in the US.

Dihydrotestosterone

Dihydrotestosterone (DHT, androstanolone), the most potent androgen, made from testosterone by 5α-reductase in prostate, testes, hair follicles, and adrenals; key in male sex development, BPH, and hair loss, acting mainly as a paracrine hormone.

Dihydrouracil

Dihydrouracil is a saturated pyrimidine, uracil with the 5,6 double bond reduced, that is the first intermediate in pyrimidine catabolism and the base of the tRNA modification dihydrouridine.

Dihydroxy-acid dehydratase

Dihydroxy-acid dehydratase (DHAD, EC 4.2.1.9, gene ilvD/ILV3) is an Fe-S cluster enzyme of the IlvD/EDD superfamily that dehydrates dihydroxy acids into keto acid precursors of leucine, isoleucine, and valine, and is an antimicrobial drug target.

Dihydroxyacetone

Dihydroxyacetone (DHA) is the simplest ketose sugar, a three-carbon compound used almost universally in sunless tanning products, where it browns the skin through a reaction with surface amino acids.

Dihydroxyacetone phosphate

Dihydroxyacetone phosphate (DHAP), also called glycerone phosphate, is a three-carbon phosphorylated sugar with formula C3H7O6P that serves as a central intermediate in glycolysis, gluconeogenesis, and lipid biosynthesis.

Dihydroxyacetone phosphate acyltransferase

Dihydroxyacetone phosphate acyltransferase (DHAPAT, GNPAT, EC 2.3.1.42) is a peroxisomal membrane enzyme that acylates DHAP to start plasmalogen synthesis; its deficiency causes rhizomelic chondrodysplasia punctata type 2.

Sep 29, 2026

Dihydroxylation

Dihydroxylation is the addition of two hydroxyl groups across an alkene's double bond to give a vicinal diol, done syn with osmium tetroxide or anti via epoxidation and hydrolysis.

DIII-D

DIII-D is a tokamak fusion research facility in San Diego, California, operated by General Atomics and the largest magnetic fusion experiment in the United States.

Diimine (functional group)

Diimine, or diazene (diimide), HN=NH, is an unstable nitrogen hydride used as a reducing agent for alkenes, and by extension any compound bearing two imine (C=N) groups.

Diipa Buller-Khosla

Diipa Büller-Khosla, born 1991 in Delhi, is an Indian influencer and co-founder of Ayurvedic beauty brand Indē Wild (Ayurvedistry), first Indian influencer on the Cannes red carpet, Sephora US entrant.

Diisobutylene

Diisobutylene (DIB) is a colorless liquid mixture of two C8 olefin isomers, produced by dimerizing isobutylene over acid catalysts and used as a chemical intermediate and fuel blending component.

Diisononyl phthalate

Diisononyl phthalate (DINP) is a mixture of branched C9 phthalate esters, used mainly as a plasticizer for polyvinyl chloride in flooring, cable, and coated products.