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Tocopheryl Acetate
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Tocopheryl acetate is the acetate ester of tocopherol (vitamin E). Being a strong antioxidant, tocopherol is unstable and is usually esterified to facilitate stability; tocopheryl acetate is the most widely used form. The primary health-related use for which tocopheryl acetate is formally indicated is as a dietary supplement for patients who demonstrate a genuine vitamin E deficiency. At the same time, vitamin E deficiency is generally quite rare but may occur in premature babies of very low birth weight (< 1500 grams), individuals with fat-malabsorption disorders (as fat is required for the digestive tract to absorb vitamin E), or individuals with a-β-lipoproteinemia, which is a rare, inherited disorder that causes poor absorption of dietary fat (1).
Principles of Radioiodination and Iodine-Labeled Tracers in Biomedical Investigation †
Published in Garimella V. S. Rayudu, Lelio G. Colombetti, Radiotracers for Medical Applications, 2019
Mrinal K. Dewanjee, Shyam A. Rao
The synthesis of NP-59 and 19-iodocholesterol is shown in Figure 27. The authors synthesized cholest-5-ene-3,19-diol-3-acetate (I) by multistep synthesis described by Kalvoda et al.218 Treatment of this compound with p-toluene sulfonyl chloride in pyridine yielded the desired tosylate (II). The acetate ester (II) was subjected to selective hydrolysis with an aqueous methanolic alkali solution under mild conditions to obtain compound III. Cholest-5-ene-3,19-diol tosylate (III) was refluxed with Nal and absolute alcohol under a stream of nitrogen for 4 hr. The alcohol was evaporated under vacuum, extracted with ether, and dried over anhydrous Na2SO4. The resulting products were ⋍90% NP-59 (6β-iodomethyl-19-nor-cholest-5[10]-en-3β-ol) and ⋍10% 19-iodocholesterol. When the mixture containing 19-iodocholesterol and ⋍30% NP-59 was refluxed under nitrogen in isopropanol or absolute ethanol with Nal, the resulting products contained 90% NP-59 and 10% 19-iodocholesterol.
Experimental Colon Carcinogens and Their Mode of Action
Published in Herman Autrup, Gary M. Williams, Experimental Colon Carcinogenesis, 2019
John H. Weisburger, Emerich S. Fiala
The proximate carcinogen derived from DMH is MAM, which occurs as the natural product cycasin in the nut of certain species of the cycad tree, in the form of the β-glucoside of methylazoxymethanol.8,9 As described above, the chemical synthesis is complex. The compound itself is rather unstable in aqueous solution or in vivo, but is available commercially as a stable acetate ester, methylazoxymethyl acetate. Tissue esterases split the acetate ester in vivo and make MAM available.9,58,67 MAM and MAM acetate are carcinogens specific for the colon of many species and can cause tumors in the duodenum and in the ear duct of some species such as rats. These compounds, also capable of inducing hepatomegaly, are generally toxic to the liver and kidney. When administered as the acetate ester, it is able to cause cancer after a single dose.
In silico evaluation of multispecies toxicity of natural compounds
Published in Drug and Chemical Toxicology, 2021
Sripriya N., Ranjith Kumar M., Ashwin Karthick N., Bhuvaneswari S., Udaya Prakash N. K.
Bioaccumulation factor is the ratio of the concentration of a chemical in fish due to absorption via the respiratory surface with respect to water at steady state. In general, a compound is termed bioaccummulative, if its BF value is greater than 2000 and very bioaccummulative if its value is greater than 5000 (Burden et al. 2014). In the present study, the bioaccumulation factor for all the compounds was less than 2000, and hence, non-bioaccummulative in nature. Developmental toxicity defines whether a particular chemical causes any effect that hinders normal development, both before and after birth. Most of the compounds i.e., 15 out of 27 studied from the plants – C. angustifolium, C. carandas, and E. oxypetalum were developmental toxicants. Compounds that are positive to Ames mutagenicity test are regarded as potential carcinogens (Griffiths et al. 2000). The non-mutagenicity of the 27 compounds studied, except for Dasycarpidan-1-methanol, acetate (ester), suggests that the compounds can be explored in different industries.
A metabolic pathway for the prodrug nabumetone to the pharmacologically active metabolite, 6-methoxy-2-naphthylacetic acid (6-MNA) by non-cytochrome P450 enzymes
Published in Xenobiotica, 2020
Kaori Matsumoto, Tetsuya Hasegawa, Kosuke Ohara, Chihiro Takei, Tomoyo Kamei, Junichi Koyanagi, Tamiko Takahashi, Masayuki Akimoto
Despite its long-term use in routine clinical practice, the mechanisms underlying the conversion of the prodrug nabumetone to its active metabolite 6-MNA have not yet been elucidated. Nabumetone was recently shown to be efficiently oxidized in vitro by FMO5 to the corresponding acetate ester as a metabolic intermediate with high selectivity (Fiorentini et al., 2017). Recent study has shown that FMO5 specifically catalyzes the BVO of piperidine-4-one in the same way as nabumetone (Lai et al., 2011). To clarify this biotransformation, we synthesized a series of potential intermediates and used them to compare the products formed in the metabolism of nabumetone by cDNA-expressed hFMO5 and human liver subcellular fractions. We also used various prototypical inhibitors to identify the enzymes responsible for the formation of metabolites related to the formation of 6-MNA. The results obtained demonstrated that the hydrolysis of 6-MNEA to 6-MNE-ol, the oxidation of 6-MNE-ol to its aldehyde, 6-MN-CHO, and the oxidation of 6-MN-CHO to 6-MNA occurred in subcellular fractions and cDNA-expressed FMO systems, which supported the proposed pathway advocated by Fiorentini et al. (2017). However, they only revealed the formation of an acetate compound by a GC/MS analysis.
Comprehensive overview of the recently FDA-approved contraceptive vaginal ring releasing segesterone acetate and ethinylestradiol: A new year-long, patient controlled, reversible birth control method
Published in Expert Review of Clinical Pharmacology, 2019
The most critical component that accounts for the success of this new CVR is the new progestin segesterone acetate. Segesterone acetate is a 19-nor-progesterone derivative, known as 19-norpregn-4-ene-3,20-dione, 17-hydroxy-16-methylene-19-nonpregn-4-ene-3,20-dione acetate ester and 16-methylene-17α-acetoxy-19-nor-pregn-4-ene-3,20-dione (see Figure 3). Its molecule formula is C23H3004 (see Figure 3). It is a white or yellowish-white powder with a molecular weight of 370.5 Dalton. This compound has significant potency; only low doses are needed for ovulation suppression. However, it is rapidly metabolized when administered orally, so a slow release, transdermal or transmucosal delivery system, such as the contraceptive vaginal ring, represents an excellent delivery system to utilize its strengths [11].