All articles starting with P

Pyridoxamine

Pyridoxamine is one of the three naturally occurring forms of vitamin B6 and a transient intermediate in enzymatic transamination; as the drug Pyridorin, it inhibits advanced glycation end products.

Pyridoxamine-5-phosphate deficiency-developmental and epileptic encephalopathy

Pyridoxamine-5-phosphate deficiency-developmental and epileptic encephalopathy (PNPO-DEE), also called PNPO deficiency or pyridoxal phosphate-responsive seizures, is a rare autosomal recessive PNPO-gene disorder causing drug-resistant neonatal seizures that respond to vitamin B6.

Pyridoxine

Pyridoxine, one of the six vitamin B6 vitamers, is the common supplement and medicinal form of vitamin B6, a coenzyme in over 100 enzyme reactions; high doses cause sensory neuropathy, and US and EU upper limits differ sharply.

Pyridoxine 5′-phosphate oxidase

Pyridoxine 5′-phosphate oxidase (PNPO, EC 1.4.3.5, PdxH) is an FMN-dependent homodimeric enzyme oxidizing PNP and PMP to pyridoxal 5′-phosphate; human gene defects cause PLP-responsive neonatal epileptic encephalopathy.

Pyridoxine-dependent epilepsy

Pyridoxine-dependent-developmental and epileptic encephalopathy (PD-DEE), also known as pyridoxine-dependent epilepsy, is a rare autosomal recessive disorder whose seizures respond to vitamin B6, not anti-epileptic drugs.

Pyrifluquinazon

Pyrifluquinazon (CAS 337458-27-2), a pyridine azomethine insecticide, IRAC Group 9B chordotonal organ TRPV channel modulator sold as PQZ; registered in the US since 2013, not EU-approved, JMPR ADI 0-0.005 mg/kg bw.

Pyriftalid

Pyriftalid (CGA 279233), CAS 135186-78-6, is a Syngenta ALS-inhibitor herbicide for grass weeds in rice, used in Japan and South Korea, not EU-approved, with low mammalian but high Daphnia toxicity.

Pyrilamine

Pyrilamine, also known as mepyramine, is a first-generation H1 antihistamine of the ethylenediamine class, introduced in 1944 and used today chiefly in creams for insect bites and stings.

Pyrimethamine

Pyrimethamine, sold as Daraprim, is an antiparasitic medicine developed by Gertrude Elion and George Hitchings in the early 1950s, the standard therapy for toxoplasmosis and, with sulfadoxine, a malaria treatment.

Pyrimethanil

Pyrimethanil (CAS 53112-28-0) is an anilinopyrimidine fungicide, FRAC Group 9, inhibiting methionine biosynthesis in Botrytis and Venturia; EU approval renewed 2026-2041, with post-harvest citrus use and noted bee and fish risks.

Pyrimidifen

Pyrimidifen (CAS 105779-78-0, Miteclean) is a pyrimidinamine METI acaricide and insecticide, IRAC group 21A, inhibiting mitochondrial complex I; used against mites on fruit and vegetables, commercialized 1995, not EU-approved.

Pyrimidine

Pyrimidine is an aromatic heterocyclic compound with a six-membered ring of four carbons and two nitrogens, the core of the DNA and RNA bases cytosine, thymine, and uracil.

Pyrimidine biosynthesis

Pyrimidine biosynthesis (orotate pathway): six-step de novo route from glutamine, bicarbonate, and aspartate to UMP via CAD, DHODH, and UMPS; regulated by feedback inhibition and targeted by drugs such as leflunomide.

Pyrimidine catabolism

Pyrimidine catabolism, also called the reductive pathway of pyrimidine degradation, breaks down uracil to beta-alanine and thymine to beta-aminoisobutyrate via DPD, dihydropyrimidinase, and beta-ureidopropionase, mainly in liver.

Pyrimidine dimer

A pyrimidine dimer, also called a thymine dimer, is a DNA lesion in which ultraviolet light covalently joins two adjacent pyrimidine bases, most often two thymines, blocking replication.

Pyrimidine salvage

Pyrimidine salvage recovers pyrimidine nucleosides and bases from DNA/RNA breakdown via kinases (UCK1/2, DCK, TK1/TK2) and phosphorylases (TYMP, UPP), feeding nucleotide monophosphates back into biosynthesis; relevant to cancer, antiviral, and mitochondrial disease therapy.

Pyrimidinone

A pyrimidinone is a six-membered heterocyclic compound derived from pyrimidine in which one ring carbon carries a carbonyl group, widely used in medicinal chemistry in drugs such as lamivudine.

Pyrimisulfan

Pyrimisulfan (KUH-021, CAS 221205-90-9) is a Kumiai-discovered sulfonanilide ALS-inhibitor herbicide for paddy rice (Best Partner, 50–75 g a.i./ha) and turf (Vexis); not EU-approved.

Pyriofenone

Pyriofenone (IKF-309; Property, PROLIVO) is an aryl phenyl ketone, FRAC Group 50 fungicide by Ishihara Sangyo Kaisha that disrupts fungal actin to control powdery mildew on cereals, grapes, and vegetables.

Pyriproxyfen

Pyriproxyfen (CAS 95737-68-1), a juvenile hormone mimic insect growth regulator developed by Sumitomo, used against crop pests and Aedes mosquito larvae; EU-approved to 2035, WHO drinking-water assessed.

PyRIT

PyRIT (Python Risk Identification Toolkit for generative AI) is an open-source Python framework from Microsoft for automating red-teaming of generative AI systems, released publicly in 2024.

Pyrite

Pyrite, also called iron pyrite, is a common iron disulfide mineral (FeS₂) with a brass-yellow metallic luster nicknamed fool's gold; its oxidation causes acid mine drainage.

Pyrithiobac sodium

Pyrithiobac sodium (Staple) is a pyrimidinylthiobenzoate ALS-inhibiting herbicide for post-emergence broadleaf weed control in cotton, first US-registered in 1995, with widespread ALS resistance documented in Amaranthus weeds.

Pyritinol

Pyritinol, also known as pyrithioxin or pyridoxine disulfide, is a synthetic nootropic drug synthesized from vitamin B6 in 1961, used in Europe for cognitive disorders and dementia.

Pyrmont Bridge

Pyrmont Bridge is an electric swing bridge of 1902 crossing Darling Harbour in Sydney, designed by Percy Allan and one of the world's oldest surviving electrically operated swing bridges.

Pyro (Marvel Comics)

Pyro (St. John Allerdyce) is a Marvel Comics mutant created by Claremont and Byrne in Uncanny X-Men #141 (1981) who controls but cannot create fire, served in Mystique's Brotherhood and Freedom Force, died of the Legacy Virus, and returned in the Krakoa era.