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A member of the class of 2-nitrophenols that is phenol in which one of the hydrogens that is ortho to the hydroxy group has been replaced by a nitro group." []

3-Hydroxy picolinic acid is a picolinic acid derivative and is a member of the pyridine family. Picolinic acid is an isomer of nicotinic acid, which has the carboxyl side chain at the 3-position. It is a catabolite of the amino acid tryptophan.

A member of the class of 3-nitrophenols that is phenol in which one of the hydrogens that is meta to the hydroxy group has been replaced by a nitro group." []

4-Nitrophenol (also called p-nitrophenol or 4-hydroxynitrobenzene) is a phenolic compound that has a nitro group at the opposite position of the hydroxyl group on the benzene ring. It belongs to the class of organic compounds known as nitrophenols. Nitrophenols are compounds containing a nitrophenol moiety, which consists of a benzene ring bearing both a hydroxyl group and a nitro group on two different ring carbon atoms. 4-Nitrophenol shows two polymorphs in the crystalline state. The alpha-form is colorless pillars, unstable at room temperature, and stable toward sunlight. The beta-form is yellow pillars, stable at room temperature, and gradually turns red upon irradiation of sunlight. Usually 4-nitrophenol exists as a mixture of these two forms. 4-Nitrophenol can be used as a pH indicator and as an intermediate in the synthesis of paracetamol. Itis also used as the precursor for the preparation of phenetidine and acetophenetidine, indicators, and raw materials for fungicides. Bioaccumulation of this compound rarely occurs. In peptide synthesis, carboxylate ester derivatives of 4-nitrophenol may serve as activated components for construction of amide moieties. 4-Nitrophenol is a potentially toxic compound: it can cause eyes, skin, and respiratory tract irritations. It may also cause inflammation of those parts. It has a delayed interaction with blood and forms methaemoglobin which is responsible for methemoglobinemia -which is characterized by tissue hypoxia, as methemoglobin cannot bind oxygen-, potentially causing cyanosis, confusion, and unconsciousness. When ingested, it causes abdominal pain and vomiting. Prolonged contact with skin may cause allergic response. Genotoxicity and carcinogenicity of 4-nitrophenol are not known. The LD50 in mice is 282 mg/kg and in rats is 202 mg/kg. Outside of the human body, 4-Nitrophenol has been detected, but not quantified in cow milk. Conjugates are more polar than the parent compounds and therefore are easier to excrete in the urine.

6-Hydroxynicotinic acid (6-OHNA) is exploited in the use of NMR spectroscopy or gas chromatography--mass spectrometry for the diagnosis of Pseudomonas aeruginosa in urinary tract infection. Among the common bacteria causing urinary infection, only P. aeruginosa produces 6-hydroxynicotinic acid from nicotinic acid. Pseudomonas aeruginosa infection has been reported to be the third leading cause of urinary infection, accounting for 11% of such infections, the first and second being Escherichia coli and Klebsiella pneumonia, respectively. Analyses of the NMR spectra of the bacterial media with variable cell count of P. aeruginosa, shows that the intensity of the signals of the 6-hydroxynicotinic acid increases with increasing number of bacterial cells (PMID:3926801, 15759292). 6-hydroxynicotinic acid can also be found in Achromobacter and Serratia.

2-Hydroxynicotinic acid, also known as 2-hydroxypyridine-3-carboxylic acid, is a member of the class of compounds known as pyridinecarboxylic acids. Pyridinecarboxylic acids are compounds containing a pyridine ring bearing a carboxylic acid group. 2-Hydroxynicotinic acid is soluble (in water) and a weakly acidic compound (based on its pKa). 2-Hydroxynicotinic acid can be found in urine. 2-Hydroxynicotinic acid is a white to light yellow powder soluble in water. Its melting point is 258-261°C.

Oxiniacic acid is an aromatic carboxylic acid and a member of pyridines. Oxiniacic Acid is a nicotinic acid derivative.

A nitrophenol that is phenol carrying a single nitro substituent at unspecified position." []

Basidalin is a butenolide. Basidalin has been reported in Leucoagaricus leucothites and Leucoagaricus naucinus with data available.