Epoxy Compounds: Organic compounds that include a cyclic ether with three ring atoms in their structure. They are commonly used as precursors for POLYMERS such as EPOXY RESINS.Epoxide Hydrolases: Enzymes that catalyze reversibly the formation of an epoxide or arene oxide from a glycol or aromatic diol, respectively.Epoxy Resins: Polymeric resins derived from OXIRANES and characterized by strength and thermosetting properties. Epoxy resins are often used as dental materials.7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide: 7,8,8a,9a-Tetrahydrobenzo(10,11)chryseno (3,4-b)oxirene-7,8-diol. A benzopyrene derivative with carcinogenic and mutagenic activity.Vitamin K Epoxide Reductases: OXIDOREDUCTASES which mediate vitamin K metabolism by converting inactive vitamin K 2,3-epoxide to active vitamin K.Stereoisomerism: The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Chrysenes: 1,2-Benzphenanthrenes. POLYCYCLIC COMPOUNDS obtained from coal tar.Heptachlor Epoxide: An oxidation product of HEPTACHLOR formed by many plants and animals, including humans, after exposure to HEPTACHLOR. It has been shown to remain in soil treated with HEPTACHLOR for over fifteen years and is toxic to animals and humans. (From ATSDR Public Heath Statement, April 1989)Benzopyrenes: A class of chemicals that contain an anthracene ring with a naphthalene ring attached to it.PhenanthrenesStructure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Sulfur Compounds: Inorganic or organic compounds that contain sulfur as an integral part of the molecule.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Ethers, Cyclic: Compounds of the general formula R-O-R arranged in a ring or crown formation.8,11,14-Eicosatrienoic Acid: A 20-carbon-chain fatty acid, unsaturated at positions 8, 11, and 14. It differs from arachidonic acid, 5,8,11,14-eicosatetraenoic acid, only at position 5.Volatile Organic Compounds: Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.Microsomes, Liver: Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.Polycyclic Compounds: Compounds consisting of two or more fused ring structures.Biotransformation: The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Mutagens: Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.Carcinogens: Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.Benz(a)Anthracenes: Four fused benzyl rings with three linear and one angular, that can be viewed as a benzyl-phenanthrenes. Compare with NAPHTHACENES which are four linear rings.Dihydroxydihydrobenzopyrenes: Benzopyrenes saturated in any two adjacent positions and substituted with two hydroxyl groups in any position. The majority of these compounds have carcinogenic or mutagenic activity.DNA Adducts: The products of chemical reactions that result in the addition of extraneous chemical groups to DNA.Leukotriene A4: (2S-(2 alpha,3 beta(1E,3E,5Z,8Z)))-3-(1,3,5,8-Tetradecatetraenyl)oxiranebutanoic acid. An unstable allylic epoxide, formed from the immediate precursor 5-HPETE via the stereospecific removal of a proton at C-10 and dehydration. Its biological actions are determined primarily by its metabolites, i.e., LEUKOTRIENE B4 and cysteinyl-leukotrienes. Alternatively, leukotriene A4 is converted into LEUKOTRIENE C4 by glutathione-S-transferase or into 5,6-di-HETE by the epoxide-hydrolase. (From Dictionary of Prostaglandins and Related Compounds, 1990)Phenols: Benzene derivatives that include one or more hydroxyl groups attached to the ring structure.Bay-Region, Polycyclic Aromatic Hydrocarbon: A concave exterior region on some POLYCYCLIC AROMATIC HYDROCARBONS that have three phenyl rings in a non-linear arrangement.Kinetics: The rate dynamics in chemical or physical systems.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Adamantane: A tricyclo bridged hydrocarbon.Alkenes: Unsaturated hydrocarbons of the type Cn-H2n, indicated by the suffix -ene. (Grant & Hackh's Chemical Dictionary, 5th ed, p408)Inhibitory Concentration 50: The concentration of a compound needed to reduce population growth of organisms, including eukaryotic cells, by 50% in vitro. Though often expressed to denote in vitro antibacterial activity, it is also used as a benchmark for cytotoxicity to eukaryotic cells in culture.Drug Evaluation, Preclinical: Preclinical testing of drugs in experimental animals or in vitro for their biological and toxic effects and potential clinical applications.Mixed Function Oxygenases: Widely distributed enzymes that carry out oxidation-reduction reactions in which one atom of the oxygen molecule is incorporated into the organic substrate; the other oxygen atom is reduced and combined with hydrogen ions to form water. They are also known as monooxygenases or hydroxylases. These reactions require two substrates as reductants for each of the two oxygen atoms. There are different classes of monooxygenases depending on the type of hydrogen-providing cosubstrate (COENZYMES) required in the mixed-function oxidation.Cyclohexenes: Six-carbon alicyclic hydrocarbons which contain one or more double bonds in the ring. The cyclohexadienes are not aromatic, in contrast to BENZOQUINONES which are sometimes called 2,5-cyclohexadiene-1,4-diones.Spiro Compounds: A group of compounds consisting in part of two rings sharing one atom (usually a carbon) in common.Sulfhydryl Compounds: Compounds containing the -SH radical.Vitamin K 1: A family of phylloquinones that contains a ring of 2-methyl-1,4-naphthoquinone and an isoprenoid side chain. Members of this group of vitamin K 1 have only one double bond on the proximal isoprene unit. Rich sources of vitamin K 1 include green plants, algae, and photosynthetic bacteria. Vitamin K1 has antihemorrhagic and prothrombogenic activity.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Aflatoxin B1: A potent hepatotoxic and hepatocarcinogenic mycotoxin produced by the Aspergillus flavus group of fungi. It is also mutagenic, teratogenic, and causes immunosuppression in animals. It is found as a contaminant in peanuts, cottonseed meal, corn, and other grains. The mycotoxin requires epoxidation to aflatoxin B1 2,3-oxide for activation. Microsomal monooxygenases biotransform the toxin to the less toxic metabolites aflatoxin M1 and Q1.Cytochrome P-450 Enzyme System: A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.Carbamazepine: An anticonvulsant used to control grand mal and psychomotor or focal seizures. Its mode of action is not fully understood, but some of its actions resemble those of PHENYTOIN; although there is little chemical resemblance between the two compounds, their three-dimensional structure is similar.Benzo(a)pyrene: A potent mutagen and carcinogen. It is a public health concern because of its possible effects on industrial workers, as an environmental pollutant, an as a component of tobacco smoke.Heterocyclic Compounds: Ring compounds having atoms other than carbon in their nuclei. (Grant & Hackh's Chemical Dictionary, 5th ed)Molecular Conformation: The characteristic three-dimensional shape of a molecule.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Biphenyl CompoundsSmall Molecule Libraries: Large collections of small molecules (molecular weight about 600 or less), of similar or diverse nature which are used for high-throughput screening analysis of the gene function, protein interaction, cellular processing, biochemical pathways, or other chemical interactions.Mutagenicity Tests: Tests of chemical substances and physical agents for mutagenic potential. They include microbial, insect, mammalian cell, and whole animal tests.Enzyme Inhibitors: Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.Cyclization: Changing an open-chain hydrocarbon to a closed ring. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Solubility: The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Organotin Compounds: Organic compounds which contain tin in the molecule. Used widely in industry and agriculture.Lauric Acids: 12-Carbon saturated monocarboxylic acids.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.