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Epigallocatechin-3-Gallate in Alzheimer’s Disease
Published in Atanu Bhattacharjee, Akula Ramakrishna, Magisetty Obulesu, Phytomedicine and Alzheimer’s Disease, 2020
Khaleel Pasha Md, Magisetty Obulesu
EGCG attenuates in vitro fibril formation through decreased Carboxymethylated kappa-casein (RCMkappa-CN) by averting RCMkappa-CN fibril formation (Hudson et al., 2009; Polito et al., 2018). Metal-chelating efficacy of EGCG substantially attenuated fibril formation (Polito et al., 2018). The oxidized EGCG formed Schiff bases by interacting with free amines of the amyloid fibrils, thus reducing the toxicity (Palhano et al., 2013; Polito et al., 2018). NMR studies also showed that EGCG conjugated nonspecifically to the Aβ monomer (Sinha et al., 2012; Polito et al., 2018).
Carbonyl Toxification Hypothesis of Biological Aging
Published in Alvaro Macieira-Coelho, Molecular Basis of Aging, 2017
DMaldehydes react readily, even at neutral pH and room temperature, with many important biochemical groups such as amino, thiol, or hydroxyl.30 Reversible reactions between carbonyls and amino groups form Schiff bases. A secondary functional group in aldehydes increases the reactivity potential and may induce further irreversible reaction products, or result in cross-linking reactions.3 Napetschnig33 has shown that 4-hydroxylalkenals can react with nearly all amino acids under appropriate conditions. Reactions between 4-hydroxylalkenals and amino groups in proteins34 and nucleic acids has been demonstrated as well.35 Reactions between carbonyls and thiol compounds have received particular attention since the addition of some DMcarbonyls (e.g., 4-hydroxylalkenals) to tissues, cells, or cell fractions causes a rapid loss of SH groups.30 Glutathione and cysteine easily react in neutral solutions with 4-hydroxylalkenal36,37 with the formation of a five-membered cyclic hemiacetal. Although the thiol-ether linkage that binds aldehydes to the protein-SH group is stable, it is reversible and, thus, may be removed from the protein by an excess of low molecular weight thiols, such as glutathione and cysteine.
Affinity Modification — Organic Chemistry
Published in Dmitri G. Knorre, Valentin V. Vlassov, Affinity Modification of Biopolymers, 1989
Dmitri G. Knorre, Valentin V. Vlassov
Reactive aldehyde groups scattered over the DNA molecule may be introduced by methylation of purines with dimethylsulfate and subsequent elimination of 7-methylguanines and 3-methyladenines. In the specific complexes with proteins, e.g., in chromatin, Schiff bases may be formed with a subsequent splitting of the DNA chain. The reduction of Schiff bases with NaBH4 as shown in Scheme 84 results in a stable covalent adduct.287 R1, R2 — polynuceotide chains.
Thio- and selenosemicarbazones as antiprotozoal agents against Trypanosoma cruzi and Trichomonas vaginalis
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Alexandra Ibáñez-Escribano, Cristina Fonseca-Berzal, Mónica Martínez-Montiel, Manuel Álvarez-Márquez, María Gómez-Núñez, Manuel Lacueva-Arnedo, Teresa Espinosa-Buitrago, Tania Martín-Pérez, José Antonio Escario, Penélope Merino-Montiel, Sara Montiel-Smith, Alicia Gómez-Barrio, Óscar López, José G. Fernández-Bolaños
Herein, we have accomplished the preparation of an ample panel of thiosemicarbazones with the aim of developing antiprotozoal agents with a different mechanism of action than that exhibited by nitroheterocyclic derivatives. This type of Schiff bases analogues has been reported to be endowed with a broad spectrum of relevant biological properties, like inhibitors of aldose reductase30, tyrosinase31, urease32 cholinesterases33, or β-amyloid aggregation34, and also as antimicrobial35, or anticancer agents36‒38, the latter being the most widely studied. Although there are some reports on the use of thiosemicarbazones as antiprotozoal agents against Toxoplasma gondii39‒41 or T. cruzi42‒45, studies on T. vaginalis are very scarce and limited to nitrofurane derivatives and bisthiosemicarbazones46–49.
MAO inhibitors and their wider applications: a patent review
Published in Expert Opinion on Therapeutic Patents, 2018
Simone Carradori, Daniela Secci, Jacques P. Petzer
Schiff bases are common structures in medicinal chemistry, despite their susceptibility to hydrolytic cleavage. In one patent [58], 16 new Schiff bases containing the 4-hydroxycoumarin nucleus were synthesized and fully characterized as outlined in Figure 6. MAO inhibition data for these compounds revealed low micromolar/high nanomolar inhibitors of both isoforms with a slight preference for MAO-B. Compound 43, which is functionalized with 2ʹ,3ʹ,4ʹ-OH, was the most potent toward both isoforms, whereas compound 53 (R1 = R3 = Br) was endowed with the highest B-selectivity (SI: 5.84) and a very promising IC50 MAO-B value of 0.851 ± 0.047 µM (Table 3). Its mechanism of action resulted to be noncompetitive (mixed) by Lineweaver-Burk plot analysis.
Potential multifunctional agents with anti-hepatoma and anti-inflammation properties by inhibiting NF-кB activation
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Chang-Ming Su, Gui-Ge Hou, Chun-Hua Wang, Hong-Qin Zhang, Cheng Yang, Mei Liu, Yun Hou
Schiff-base compounds with active –C=N groups exhibit a range of biological activities, including antibacterial, antiviral, anti-cancer and anti-inflammatory properties22,23. We tried to incorporate of amino-substituted BAPs and aromatic aldehydes substituted by -X or -OH to construct novel symmetric18 (such as BAP 5c) or dissymmetric Schiff-base substituted BAPs with desired anti-cancer and anti-inflammation activity. In this study, a series of novel dissymmetric BAPs 83–102 were synthesized, characterized and evaluated as potential anti-hepatoma and anti-inflammatory agents.