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Metal Hyperaccumulator Plants: A Review of the Ecology and Physiology of a Biological Resource for Phytoremediation of Metal-Polluted Soils
Published in Norman Terry, Gary Bañuelos, of Contaminated Soil and Water, 2020
Alan J. M. Baker, S. P. McGrath, Roger D. Reeves, J. A. C. Smith
Phytochelatins are low-molecular-weight, cysteine-rich peptides (Rauser, 1995; Zenk, 1996) now designated class III metallothioneins, as they can be regarded generically as nontranslationally synthesized metal-thiolate polypeptides (Robinson et al., 1993). They are synthesized by representatives of the whole plant kingdom upon exposure to heavy metals (Grill et al., 1987), and they are especially produced by plants growing in metal-enriched ecosystems (Grill et al., 1988). Phytochelatins are believed to be functionally analogous to the metallothioneins produced by animals and fungi (Tomsett and Thurman, 1988; Robinson et al., 1993) and consequently to be involved in cellular homeostasis of metal ions. They have the ability to bind a wide range of metals and it has been suggested by some researchers (Jackson et al., 1987; Salt et al., 1989) that phytochelatins are directly involved in heavy metal tolerance. However, there is considerable evidence to contradict this view. Metal induction of phytochelatins has been observed in both metal-resistant and metal-sensitive plants (Schultz and Hutchinson, 1988; Verkleij et al., 1991; Harmens et al., 1993). Furthermore, buthionine sulfoximine (BSO), an inhibitor of phytochelatin synthesis, has been shown not to decrease zinc tolerance (Reese and Wagner, 1987; Davies et al., 1991), while sulfur deficiency was seen to have no effect on copper tolerance of Deschampsia cespitosa (Schultz and Hutchinson, 1988). It is therefore questionable what exact role phytochelatins play in cellular metal-tolerance mechanisms.
Xenobiotic Metabolism
Published in Lorris G. Cockerham, Barbara S. Shane, Basic Environmental Toxicology, 2019
Larry G. Hansen, Barbara S. Shane
Compounds that alter protein synthesis will obviously inhibit the synthesis of biotransformation enzymes. Some inhibitors are more specific than others in that they inhibit the synthesis of cytochrome P450 but not the synthesis of proteins in general. Two chemicals that are known to inhibit the synthesis of heme, a coenzyme of cytochrome P450, and its precursor porphyrin are, respectively, cobalt and 3-amino-1,2,3-triazole. Some compounds are known to affect the tissue levels of certain cofactors. Both L-methionine-S-sulfoximine and buthionine sulfoximine inhibit the synthesis of glutathione, while diethyl maleate rapidly reduces the tissue stores of glutathione. The synthesis of UDP-glucuronic acid is inhibited by galactosamine. As a result of this depletion or reduction in concentration of these cofactors, the formation of glutathione and glucuronide conjugates may be inhibited.
Validation of Recovery and Purification Processes
Published in James Agalloco, Phil DeSantis, Anthony Grilli, Anthony Pavell, Handbook of Validation in Pharmaceutical Processes, 2021
Mammalian production systems also can contain media components whose removal must be validated prior to product licensure. Selective pressure is sometimes required to maintain genetic stability; components such as methotrexate, methionine sulfoximine, or gentamycin may be included in the production bioreactor. Antifoam is often used to reduce foaming and prevent clogging of the air filters, and Pluronic-F68 is added to media to provide shear protection to the cells.78 Proteins such as recombinant insulin, transferrin, or albumin may be used in cell culture media to support high density cell growth, although their use has decreased dramatically over the last ten years due to the development of chemically defined media.
Synthesis and characterization of new bis(fluoroalkyl) phosphoramidates bearing sulfoximine groups
Published in Journal of Sulfur Chemistry, 2021
Hanen Mechi, M.A.K. Sanhoury, F. Laribi, M. T. Ben Dhia
Sulfoximines are considered as the monoaza analogs of sulfones and their stability has led to versatile chemistry [17,18]. In synthetic organic chemistry [19,20], the acidic α-hydrogen is one of the properties they share but the nitrogen atom offers the possibility for functionalization of molecules through nucleophilic reactions [21]. The widespread interest in the chemistry of sulfoximines is mainly due to the versatility of their applications in stereochemical studies [22–24]; they have been explored as building blocks in bioactive molecules [25,26] and often have very high efficiency in asymmetric metal catalysis [27]. In the literature some patents can be found on substituted sulfoximines for use as agrochemicals [28], detergents, additives, bacterial, antifungal compounds and auspicious bioisosteres in medicinal chemistry [29]. Some sulfoximine phosphoramidates are known for their important biological role [30–34]. For example, the active form of methionine sulfoximine, which efficiently inhibits glutamine synthetase, is methionine sulfoximine phosphate [30]. In addition, two nucleoside sulfoximine-containing phosphoramidates were shown to be potent inhibitors of human asparagine synthetase (hASNS) [31–33]. However, research studies on N-phosphorylated sulfoximines are still relatively rare and limited to a few examples [34,35–37]. As far as we are aware and despite the above mentioned interest in sulfoximine derived phosphoramidates and the versatile influence of inclusion of fluorine atoms on molecule properties [38–40], no reports on fluoroalkyl analogs have been yet described.
3-Functional substituted 4-trifluoromethyl tetrahydrothiophenes via [3 + 2]-cycloaddition reactions
Published in Journal of Sulfur Chemistry, 2019
Yuriy M. Markitanov, Vadim M. Timoshenko, Tymofii V. Rudenko, Eduard B. Rusanov, Yuriy G. Shermolovich
Functionalization of sulfide moiety in thiolanes 4 was carried out by the oxidation and oxidative imination reactions. Tetrahydrothiophene 4d was converted to corresponding S-oxide 5, as a mixture of diastereomers (1.05:1), and S,S-dioxide 6 using meta-chloroperoxybenzoic acid as an oxidant (Scheme 1). Next we examined oxidative imination of the obtained tetrahydrothiophenes, which opened access to cyclic sulfoximines. A straightforward procedure for the preparation of NH-sulfoximines applied for 4a,d, via simultaneous transfer of O and NH group [26] involving diacetoxyiodobenzene as an oxidant and ammonium carbamate as ammonia source (Scheme 1), gave 4-(trifluoromethyl)tetrahydrothiophen-3-yl-S-imino-S-oxides 7a,b in 57%–65% isolated yields. Since an oxidative imination reaction of sulfides generates new stereogenic center, we expected the formation of two diastereomers for compounds 7a,b. Indeed, sulfoximine 7a was isolated as a mixture of diastereomers (1.25:1) with different stereochemistry of sulfur atom. In the case of sulfoximine 7b one diastereomer precipitated directly from the reaction mixture, while an isolation of another isomer from the mother liquor was complicated. The structures of both sulfoximines 7a,b were successfully confirmed by NMR spectra, mass spectroscopy data and elemental analysis.
Transition-metal-catalyzed C–N cross-coupling reactions of N-unsubstituted sulfoximines: a review
Published in Journal of Sulfur Chemistry, 2018
Akram Hosseinian, Leila Zare Fekri, Aazam Monfared, Esmail Vessally, Mohammad Nikpassand
Sulfoximines are mono-aza analogues of sulfones where one of the oxygen atoms of the sulfonyl group is substituted by a nitrogen atom [1]. The chemistry of these compounds started at the early of 1950s with the discovery of (2S,5S)-methionine sulfoximine as a toxic factor of the disease canine hysteria [2,3]. Due to their unique properties, sulfoximines have attracted significant attention from the medicinal chemistry community. Such compounds are responsible for the variety of pharmacological activities (e.g. anti-cancer, anti-asthmatic, anti-HIV, and anti-microbial) [4]. Although several compounds contain this privileged unit are in clinical trials (Figure 1), to date no sulfoximine has been approved for a therapeutic application [5,6–9]. This class of organosulfur compounds has also found a number of applications in agricultural chemistry [6–9]. Moreover, they have been employed most widely as chiral auxiliaries, ligands, and catalysts in asymmetric syntheses [10–12]. Furthermore, the sulfoximine functional group is a directing group for activation of aromatic C–H bonds for construction of new carbon–carbon [13–15] and carbon–heteroatom [16–17] bonds by metal-catalyzed cross-coupling reactions. Considering the widespread synthetic applications and biological activities of sulfoximines, the development of novel synthetic methodologies for their preparation and functionalization is extremely desirable.