Polycyclic Aromatic Hydrocarbon Metabolites: Their Reactions with Nucleic Acids
Philip L. Grover in Chemical Carcinogens and DNA, 2019
These early observations gave rise to the concept that since the hydrocarbons do not possess reactive groups, their metabolic activation was necessary before they could react with nucleic acids. Attempts were therefore made to link the metabolism of hydrocarbons in cells to the levels of their reactions with cellular DNA. The enzymes thought most likely to be involved in this metabolic activation were the mono-oxygen-ases present in the endoplasmic reticulum of most cells, and this idea was supported by the results of experiments in which [3H]-labeled hydrocarbons were incubated with rat liver microsomal systems (which contain the mono-oxygenase) in the presence of DNA.6,7 Thus, studes on the metabolism of the hydrocarbons seemed essential if an understanding of the way in which the compounds react, both with DNA and with other cellular macromolecules, was to be gained. It is the purpose of this chapter to review those pathways of polycyclic hydrocarbon metabolism that give rise to reactive intermediates and to consider the nature of the products that are formed as a consequence of the reactions of those intermediates with nucleic acids, together with the biological events induced by the hydrocarbons and their derivatives that probably occur because of these reactions. So far the activation of only one polycyclic hydrocarbon, benzo[a]pyrene, has been studied in depth, but some information on the activation of others is available. The structural formulas of the hydrocarbons considered in this review are shown in Figure 1.
Aliphatic and Aromatic Hydrocarbons
Frank A. Barile in Barile’s Clinical Toxicology, 2019
Hydrocarbons (HCs) are composed of carbon and hydrogen molecules whose carbon–carbon (C–C) bonds are composed of either all single (saturated) bonds or combinations of single and multiple (unsaturated) bonds. Aliphatic HCs, the term usually pertaining to fats or oils, applies to straight, open chains of carbon atoms, rather than ring structures, the simplest of which are the saturated HCs (alkanes). In addition, alkanes exist as unbranched straight chains or branched (for butane or longer chains), depending on the structural isomerism. Multiple C–C bonds result when hydrogens are removed from the alkanes, yielding unsaturated HCs such as alkenes (double C–C bonds) and alkynes (triple C–C bonds). Alicyclic HCs are saturated ring structures consisting of three or more carbon atoms. Unlike the aromatic chemicals (see next subsection), cyclopropane, cyclobutane, cyclopentane, and cyclohexane, for example, have three-, four-, five-, and six-membered rings, respectively, but do not exhibit double bonds within the rings.
Guideline for Analyzing Intermolecular Forces and Calculating Phase Change Enthalpies
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk in Survival Guide to General Chemistry, 2019
Example: List the order of solubility from most soluble to least soluble for the following solutes in water as a solvent: C3H7—OH; C4H9—OH; C5H11—OH; C6H13—OH Step ( 1): The — OH portion of each molecule contributes to strong dipole and hydrogen bonding. The CxHy (hydrocarbon) portion of each molecule contributes to dispersion forces.Step ( 2): Water has strong dipole/hydrogen bonding with a very small contribution from dispersion forces.Step ( 3): The strong dipole/hydrogen bonding (—OH) portion of the solutes is a very good match to the solvent water but the hydrocarbon/dispersion portion is a very poor match with water. As the dispersion (hydrocarbon) portion of the solute molecule increases in proportion to the strong dipole/hydrogen bonding portion, the solubility in water decreases. The hydrocarbon contribution is indicated by the number of carbons and hydrogens in the molecule while the
Biological effects of inhaled crude oil vapor. III. Pulmonary inflammation, cytotoxicity, and gene expression profile
Published in Inhalation Toxicology, 2023
Tina M. Sager, Pius Joseph, Christina M. Umbright, Ann F. Hubbs, Mark Barger, Michael L. Kashon, Jeffrey S. Fedan, Jenny R. Roberts
This is the third study in a series of tandem papers that focuses on examining toxicity following in vivo inhalation exposure to crude oil vapor (COV) in upstream oil operations (McKinney et al. 2022; Fedan 2023). Crude oil is a complex mixture of chemicals consisting primarily of normal alkanes and hydrocarbons. The hydrocarbons are structurally defined in three groups as aromatic, naphthenic or cycloparaffinic (cycloalkanes or naphthenes), and aliphatic/paraffinic (alkanes) compounds that exist in gaseous, liquid, and solid form, and which contain low concentrations of sulfur, nitrogen, and oxygen compounds and trace amounts of metal-containing components (Hawley 1981; IARC 1989; Lin and Tjeerdema 2008). The aromatic hydrocarbon group contains some of the most toxic constituents of crude oil including benzene and its derivatives, naphthalenes, phenanthrenes, pyrenes, xylenes, and toluene. Benzene, toluene, ethylbenzene, and xylenes, referred to as BTEX, are frequently measured together to represent the VOC fraction of COV exposure, as well as other exposures that may contain VOCs (ATSDR 2004).
Lipid–drug conjugates and associated carrier strategies for enhanced antiretroviral drug delivery
Published in Pharmaceutical Development and Technology, 2020
Funanani Takalani, Pradeep Kumar, Pierre P. D. Kondiah, Yahya E. Choonara, Viness Pillay
Fatty acids are made up of long aliphatic chains (4–28 carbon atoms) which may be saturated or unsaturated. Since they produce ATP (adenosine triphosphate) in large quantities during metabolism, they are regarded as important sources of fuel. Fatty acids are the most utilized lipid carriers because they grant high lipophilicity during the development of drug conjugation (Rajabi and Mousa 2016). They consist of a carboxylic acid and a hydrocarbon chain. Two ways through which fatty acids can be conjugated to drugs are: (i) through direct attachment of a drug to the carboxylic end of a lipid with hydroxyl or amino function to yield an ester or amide linkage (Zaro 2015). Herein, the most executed method is one whereby the -OH group is converted to a better leaving group by activating agents like carbodiimide. Then a drug containing an amine or alcohol group is added. (ii) Through keeping the carboxylic group free to allow fatty acids to bind serum albumin and gain recognition from transporters in the cell membrane while the drug attaches to the ω-atom that has been altered (Markovic et al. 2019). It is worth mentioning that fatty acids with longer chains (>14) result in higher absorption and circulation stability in contrast to shorter chains. Therefore, fatty acid chain length has impact on drug properties which may affect drug delivery (Zaro 2015).
Letter to the editor, regarding the publication by Pirow and colleagues “Mineral oil in food, cosmetic products, and in products regulated by other legislations”
Published in Critical Reviews in Toxicology, 2020
Juan-Carlos Carrillo, Dirk Danneels
This is indeed the case and the key to understand the association between MOSH composition and the results of toxicological evaluations. The term MOSH (mineral oil saturated hydrocarbons), as pointed out in the review, was originally intended to describe mineral oil contamination of vegetable oil (Biedermann and Grob 2009) and as indicated on page 5, interferences with the chromatographic MOSH fraction (hump) may result from n-alkanes of plant origin. Unfortunately, the term MOSH has been extrapolated to all types of hydrocarbons of petroleum and synthetic origin, and it inevitably eliminated the distinction between oils and waxes which are compositionally very different products; the latter composed exclusively of n-alkanes and mono substituted alkanes. This chemical distinction is crucial when comparing the “MOSH” term used in rat studies of oils and waxes, and the “MOSH” term used to describe results in human tissues. There are dedicated chapters that review these differences, but we highlight some important associations between hydrocarbon composition and effect which should be reflected in future hazard and risk assessment.
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