The Effects of Continuous Exposure of Animals to Ethanolamine Vapor

Ethanolamine: A Potential Promoiety with Additional Effects in the Brain

Ethanolamine is a bioactive molecule found in several cells, including those in the central nervous system (CNS). In the brain, ethanolamine and ethanolamine-related molecules have emerged as prodrug moieties that can promote drug movement across the blood-brain barrier. This improvement in the ability to target drugs to the brain may also mean that in the process ethanolamine concentrations in the brain are increased enough for ethanolamine to exert its own neurological ac-tions. Ethanolamine and its associated products have various positive functions ranging from cell signaling to molecular storage, and alterations in their levels have been linked to neurodegenerative conditions such as Alzheimer's disease. This mini-review focuses on the effects of ethanolamine in the CNS and highlights the possible implications of these effects for drug design.

Virtual screening, ADME/Tox predictions and the drug repurposing concept for future use of old drugs against the COVID-19

The new Coronavirus (SARS-CoV-2) is the cause of a serious infection in the respiratory tract called COVID-19. Structures of the main protease of SARS-CoV-2 (M^pro), responsible for the replication of the virus, have been solved and quickly made available, thus allowing the design of compounds that could interact with this protease and thus to prevent the progression of the disease by avoiding the viral peptide to be cleaved, so that smaller viral proteins can be released into the host's plasma. These structural data are extremely important for in silico design and development of compounds as well, being possible to quick and effectively identify potential inhibitors addressed to such enzyme's structure. Therefore, in order to identify potential inhibitors for M^pro, we used virtual screening approaches based with the structure of the enzyme and two compounds libraries, targeted to SARS-CoV-2, containing compounds with predicted activity against M^pro. In this way, we selected, through docking studies, the 100 top-ranked compounds, which followed to subsequent studies of pharmacokinetic and toxicity predictions. After all the simulations and predictions here performed, we obtained 10 top-ranked compounds that were again in silico analyzed inside the M^pro catalytic site, together some drugs that are being currently investigated for treatment of COVID-19. After proposing and analyzing the interaction modes of these compounds, we submitted one molecule then selected as template to a 2D similarity study in a database containing drugs approved by FDA and we have found and indicated Apixaban as a potential drug for future treatment of COVID-19.

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The new coronavirus (SARS-CoV-2) is the cause of a serious infection in the respiratory tract called COVID-19.

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The main protease SARS-CoV-2 (M^pro) is essential in the process of maturation and infectivity of the virus.

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In silico methodologies are extremely important to identify potential inhibitors for the target structure quickly and effectively.

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The drug repurposing is an important concept for future use of old drugs.

8 Final Report on the Safety Assessment of Triethanolamine, Diethanolamine, and Monoethanolamine

Triethanolamine (TEA), Diethanolamine (DEA), and Monoethanolamine (MEA) are amino alcohols used in cosmetic formulations as emulsifiers, thickeners, wetting agents, detergents, and alkalizing agents. The nitrosation of the etha-nolamines may result in the formation of N-nitrosodiethanolamine (NDELA) which is carcinogenic in laboratory animals.

In single-dose oral toxicity for rats, TEA was practically nontoxic to slightly toxic, and DEA and MEA were slightly toxic. Long-term oral ingestion of the ethanolamines by rats and guinea pigs produced lesions limited mainly to the liver and kidney. Long-term cutaneous applications to animals of the ethanolamines also produced evidence of hepatic and renal damage. TEA and DEA showed little potential for rabbit skin irritation in acute and subchronic skin irritation tests. MEA was corrosive to rabbit skin at a 30% concentration in a single semioccluded patch application and at a >10% concentration in 10 open applications over a period of 14 days.

The ethanolamines were nonmutagenic in the Ames test and TEA is also nonmutagenic to Bacillus subtilis. TEA did not cause DNA-damage inducible repair in an unscheduled DNA synthesis test. TEA had no carcinogenic or cocarcinogenic activity when dermally applied to mice for 18 months.

Clinical skin testing of TEA and cosmetic products containing TEA and DEA showed mild skin irritation in concentrations above 5%. There was very little skin sensitization. There was no phototoxicity or photosensitization reactions with products containing up to 20.04% TEA. A formulation containing 11.47% MEA and a formulation containing 1.6% DEA and 5.9% MEA were irritating to human skin in patch tests.

The Panel concludes that TEA, DEA, and MEA are safe for use in cosmetic formulations designed for discontinuous, brief use followed by thorough rinsing from the surface of the skin. In products intended for prolonged contact with the skin, the concentration of ethanolamines should not exceed 5%. MEA should be used only in rinse-off products. TEA and DEA should not be used in products containing N-nitrosating agents.

Effects of inhaled monoethanolamine on bronchoconstriction

We previously reported a 65-year-old man who aspirated an alkaline detergent containing 3.3% w/v (weight of solute per volume of solution) monoethanolamine (MEA) into his lungs, causing asthma-like symptoms. We presently describe the mechanism of MEA-induced bronchoconstriction according to findings in guinea pigs. In anesthetized, artificially ventilated animals, changes in airway opening pressure (P(ao)) were measured as an index of bronchoconstriction. An aerosol of 3.3% MEA solution (0.1 ml kg(-1)) inhaled through a tracheal cannula induced significantly stronger bronchoconstriction than an aerosol of potassium hydroxide (KOH) solution (0.1 ml kg(-1)) at the same pH. MEA-induced bronchoconstriction was significantly suppressed by premedication with intravenously injected atropine sulfate (3 mg kg(-1)), a muscarinic receptor antagonist, or diphenhydramine hydrochloride (10 mg kg(-1)), a histamine-H(1) receptor antagonist. MEA-induced bronchoconstriction was not enhanced by premedication with an intravenous injection of neostigmine (0.1 mg kg(-1)), an acetylcholinesterase inhibitor. When bronchoconstriction was induced by MEA, histamine concentrations in bronchoalveolar lavage fluid (BALF) were not significantly greater than in BALF after KOH-induced bronchoconstriction or in BALF after inhalation of physiologic saline. In vitro, contraction of trachea denuded of epithelium during superfusion with MEA (10 mm) was suppressed by premedication with pyrilamine maleate, a histamine-H(1) receptor antagonist, at 10 and 100 microm. Contraction of trachea denuded of epithelium during superfusion with MEA (10 mm) was suppressed by premedication with atropine sulfate at 10 and 100 microm. These results suggest that asthma-like symptoms may result partly from agonistic MEA effects at histamine-H(1) receptors and muscarinic receptors.

Toxicology of mono-, di-, and triethanolamine

The chemistry, biochemistry, toxicity, and industrial use of monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) are reviewed. The dual function groups, amino and hydroxyl, make them useful in cutting fluids and as intermediates in the production of surfactants, soaps, salts, corrosion control inhibitors, and in pharmaceutical and miscellaneous applications. In 1995, the annual U.S. production capacity for ethanolamines was 447,727 metric tons. The principal route of exposure is through skin, with some exposure occurring by inhalation of vapor and aerosols. MEA, DEA, and TEA in water penetrate rat skin at the rate of 2.9 x 10(-3), 4.36 x 10(-3) and 18 x 10(-3) cm/hr, respectively. MEA, DEA, and TEA are water-soluble ammonia derivatives, with pHs of 9-11 in water and pHa values of 9.3, 8.8, and 7.7, respectively. They are irritating to the skin, eyes, and respiratory tract, with MEA being the worst irritant, followed by DEA and TEA. The acute oral LD50s are 2.74 g/kg for MEA, 1.82 g/kg for DEA, and 2.34 g/kg for TEA (of bw), with most deaths occurring within 4 d of administration. MEA is present in nature as a nitrogenous base in phospholipids. These lipids, composed of glycerol, two fatty acid esters, phosphoric acid, and MEA, are the building blocks of biomembranes in animals. MEA is methylated to form choline, another important nitrogenous base in phospholipids and an essential vitamin. The rat dietary choline requirement is 10 mg kg-1 d-1; 30-d oral administration of MEA (160-2670 mg kg-1 d-1) to rats produced "altered" liver and kidney weights in animals ingesting 640 mg kg-1 d-1 or greater. Death occurred at dosages of 1280 mg kg-1 d-1. No treatment-related effects were noted in dogs administered as much as 22 mg kg-1 d-1 for 2 yr. DEA is not metabolized or readily eliminated from the liver or kidneys. At high tissue concentrations, DEA substitutes for MEA in phospholipids and is methylated to form phospholipids composed of N-methyl and N, N-dimethyl DEA. Dietary intake of DEA by rats for 13 wk at levels greater than 90 mg kg-1 d-1 resulted in degenerative changes in renal tubular epithelial cells and fatty degeneration of the liver. Similar effects were noted in drinking water studies. The findings are believed to be due to alterations in the structure and function of biomembranes brought about by the incorporation of DEA and methylated DEA in headgroups. TEA is not metabolized in the liver or incorporated into phospholipids. TEA, however, is readily eliminated in urine. Repeated oral administration to rats (7 d/wk, 24 wk) at dose levels up to and including 1600 mg kg-1 d-1 produced histopathological changes restricted to kidney and liver. Lesions in the liver consisted of cloudy swelling and occasional fatty changes, while cloudy swelling of the convoluted tubules and loop of Henle were observed in kidneys. Chronic administration (2 yr) of TEA in drinking water (0, 1%, or 2% w/v; 525 and 1100 mg kg-1 d-1 in males and 910 and 1970 mg kg-1 d-1 in females) depressed body and kidney weights in F-344 rats. Histopathological findings consisted of an "acceleration of so-called chronic nephropathy" commonly found in the kidneys of aging F-344 rats. In B6C3F1 mice, chronic administration of TEA in drinking water (0, 1%, or 2%) produced no significant change in terminal body weights between treated and control animals or gross pathological changes. TEA was not considered to be carcinogenic. Systemic effects in rats chronically administered TEA dermally (0, 32, 64, or 125 mg kg-1 d-1 in males; 0, 63, 125, or 250 mg kg-1 d-1 in females) 5 d/wk for 2 yr were primarily limited to hyperplasia of renal tubular epithelium and small microscopic adenomas. In a companion mouse dermal study, the most significant change was associated with nonneoplastic changes in livers of male mice consistent with chronic bacterial hepatitis.

Organic acids and bases: review of toxicological studies

Organic acids and bases are among the most frequently used chemicals in the manufacturing industries. However, the toxicology of only a number of them has been fully characterized, and for fewer still have occupational exposure limits been established. This paper reviews the acute and chronic toxicity data of the organic acids and bases, and considers the mechanism by which these chemicals produce their effects. A methodology for establishing preliminary occupational exposure limits based on the physicochemical properties of these chemicals is presented. Workplace exposure limits for 20 organic acids and bases which currently have no exposure guidelines are suggested. Advice regarding appropriate medical treatment of exposure to these materials is discussed.

Studies on the embryopathic effects of ethanolamine in Long-Evans rats: preferential embryopathy in pups contiguous with male siblings in utero

The embryopathic effects of high doses of ethanolamine were evaluated in pregnant Long-Evans rats during the "critical period" or organogenesis. Ethanolamine was given by gavage at levels of 0, 500, 300, or 50 mg/kg/day (24%, 14.4%, or 2.4% of the LD50 value). Ethanolamine caused dose-dependent increases in intrauterine deaths, malformations, and intrauterine growth retardation. Embryolethality caused by 500 mg/kg of ethanolamine was not random: male pups contiguous to two male siblings (designated mMm) were almost quantitatively replaced by resorptions that were contiguous to two live male pups (designated mRm) (mMm pups constituted 6.7% of control implants and decreased to only 0.9% of group II implants while mRm resorptions increased from 0.3% in controls to 5.6% in group II dams). Intrauterine growth retardation and increases in gross structural anomalies (considered indicative of depressed fetal growth) more severely affected male than female offspring at all dose levels. Pups of either sex who were contiguous to male siblings were more adversely affected than those offspring contiguous to one or more female siblings. As ethanolamine was given prior to the period of greatest fetal growth and fetal sex steroidogenesis, it is suggested that intrauterine levels of female sex steroids (estradiol) enhance fetal repair of cellular damage while testosterone inhibits fetal repair or exacerbates previous embryonic damage by some unknown mechanism. Such interaction furthers the concept that intrauterine position affects the endpoints of developmental toxicity, as expressed at parturition.