| heterocyclic compounds, 2-ring | A class of organic compounds containing two ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic. (12 Dec 1998) |
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| heterocyclic compounds, 3-ring | A class of organic compounds containing three ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic (12 Dec 1998) |
| heterocyclic compounds, bridged-ring | A class of organic compounds which contain two rings that share a pair of bridgehead carbon atoms. (12 Dec 1998) |
| heterocyclic compounds with 4 or more rings | A class of organic compounds containing four or more ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic. (12 Dec 1998) |
| hexamethonium compounds | <chemical> Compounds containing the hexamethylenebis(trimethylammonium) cation. Members of this group frequently act as antihypertensive agents and selective ganglionic blocking agents. Pharmacological action: antihypertensive agents, ganglionic blockers. (12 Dec 1998) |
| high energy compounds | Classically, a group of phosphoric esters whose hydrolysis takes place with a standard free energy change of -5 to -15 kcal/mol (or, -20 to -63 kJ/mol) (in contrast to -1 to -4 kcal/mol or, -4 to -17 kJ/mol) for simple phosphoric esters like glucose-6-phosphate or alpha-glycerophosphates), thus being capable of driving energy-consuming reactions in living cells or reconstituted cell-free systems; adenosine 5'-triphosphate, with respect to the beta-and gamma-phosphates, is the best known and is regarded as the immediate energy source for most metabolic syntheses. The general types are acid anhydrides, phosphoric esters of enols, phosphamic acid (R-NH-PO3H2) derivatives, acyl thioesters (e.g., of coenzyme A), sulfonium compound's (R3-S+), and aminoacyl esters of ribosyl moieties. See: high energy phosphates. (05 Mar 2000) |
| selenium compounds | Inorganic compounds that contain selenium as an integral part of the molecule. (12 Dec 1998) |
| pyrvinium compounds | <chemical> Pharmacological action: antinematodal agent. (12 Dec 1998) |
| silicon compounds | Inorganic compounds that contain silicon as an integral part of the molecule. (12 Dec 1998) |
| silver compounds | Inorganic compounds that contain silver as an integral part of the molecule. (12 Dec 1998) |
| sodium compounds | Inorganic compounds that contain sodium as an integral part of the molecule. (12 Dec 1998) |
| spiro compounds | A group of compounds consisting in part of two rings sharing one carbon atom in common. (12 Dec 1998) |
| nitrogen compounds | Inorganic compounds that contain nitrogen as an integral part of the molecule. (12 Dec 1998) |
| nitrogen mustard compounds | <chemical> A group of alkylating agents derived from mustard gas, with the sulfur replaced by nitrogen. They were formerly used as toxicants and vesicants, but now function as antineoplastic agent. These compounds are also powerful mutagens, teratogens, immunosuppressants, and carcinogens. Pharmacological action: antineoplastic agent, alkylating, carcinogens, mutagens, teratogens. (12 Dec 1998) |
| sulfhydryl compounds | Compounds containing the -sh radical. (12 Dec 1998) |