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Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Amino acids (AA) are organic nitrogenous compounds containing both an acidic carboxyl (-COOH) and a basic amino (-NH2) group attached to a central α-carbon. They are called α-amino acids and are classified as proteins (37–39). The first carbon is part of the carboxyl group. The second carbon, to which is attached the amino group, is called the α-carbon. The α-carbon of most amino acids is joined by covalent bonds to four different groups. Thus, the α-carbon in all the amino acids is asymmetric, except in glycine where the α-carbon is symmetric. In some amino acids, the amine group is attached to the β or γ-carbon, and these are therefore referred to as beta or gamma amino acids (38–39).
Antibiotics: The Need for Innovation
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
A single fluorine atom at position 6 greatly increased activity as well as uptake into the bacterial cell. Addition of a piperazine ring on position 7 is beneficial; improved oral adsorption, tissue distribution, metabolic stability, as well as improving the level and spectrum of activity are among the advantages. Presumably, the ability for the basic substituent to form a zwitterion with the carboxyl group is the reason for these improved drug properties. Further modifications include addition of an isopropyl ring to nitrogen 1, and replacement of pyridine with benzene. This leads to the development of ciprofloxacin, which is regarded as one of the most active broad spectrum antibiotics available. Furthermore, bacteria are slow to develop resistance to it, unlike nalidixic acid.
Components of Nutrition
Published in Christopher Cumo, Ancestral Diets and Nutrition, 2020
Ignoring the carboxyl group mentioned earlier and within a rectangle in Figure 2.7, each carbon forms two bonds with hydrogen atoms and the other two with adjacent carbons. Aside from the carboxyl group, no carbon has a double bond with another atom.
Hydrogels for localized chemotherapy of liver cancer: a possible strategy for improved and safe liver cancer treatment
Published in Drug Delivery, 2022
Jianyong Ma, Bingzhu Wang, Haibin Shao, Songou Zhang, Xiaozhen Chen, Feize Li, Wenqing Liang
pH-responsive hydrogels have widely been used in various applications, including wound healing and antimicrobial therapies, as well as tumor therapy (Qu et al., 2018, 2019; Wu et al., 2019). The primary reason for developing pH-sensitive hydrogels includes the extracellular pH (pHex) of tumors (5.8 and 7.2), and endosomal or lysosomal pH is roughly 5.5, both of which are more acidic than the normal tissue pH (∼7.40) (Ojugo et al., 1999). Thus, both the extracellular and intracellular endosome environments produce an acidic environment favorable to hydrogel degradation and drug release (Eckmann et al., 2014). Protonation of carboxyl groups (e.g. ionizable groups) or hydrolysis of acid-labile bonds can be attributed to pH sensitivity. pH-sensitive hydrogels have emerged as promising options to deliver drugs to tumor tissue due to their biocompatibility, biodegradability, and potential to selectively release the drug in an acidic environment. In the domain of hydrogels with pH-sensitive characteristics, pH-sensitive hydrogel theranostics and prodrugs are becoming increasingly popular. Chemotherapy medicines are conjugated with hydrogel monomers via acid-labile linkages to produce the prodrugs. They have little pharmacological activity at physiological pH (∼7.40), but in an acidic environment, they transform into chemotherapeutic agents that kill tumor cells. Under acidic conditions, pH-sensitive theranostics release both pharmaceuticals and diagnostic agents concurrently from the pH-responsive hydrogel to fulfill the aim of integrating diagnosis and therapy (Figure 5).
Advances in phosphoproteomics and its application to COPD
Published in Expert Review of Proteomics, 2022
Xiaoyin Zeng, Yanting Lan, Jing Xiao, Longbo Hu, Long Tan, Mengdi Liang, Xufei Wang, Shaohua Lu, Tao Peng, Fei Long
In strong cation exchange (SCX) chromatography, the stationary phase particles of SCX are negatively charged functional groups, and acidic conditions promote interaction between the positively charged tryptic peptides and the SCX particles. Beausoleil et al. [60] found that at pH = 2.7, the carboxyl group would be protonated. The phosphopeptide will retain the negative charge on the phosphate group, causing the tryptic peptide to change from a + 2 charge to a + 1 charge. Hence, the phosphopeptide interacts less with the stationary phase. It is therefore eluted from the column earlier, separating the phosphorylated peptide from the nonphosphorylated peptide (Figure 2a). However, the protein digestion process is prone to missing cleavage sites, affecting the charge number of peptides after digestion and resulting in some phosphopeptides not being eluted first but simultaneously being eluted down with nonphosphorylated peptides. Therefore, to increase the separation effect of SCX, some researchers are now using the SCX method in combination with IMAC, MOAC, and other chemical derivatization methods to improve the separation and identification of phosphopeptides. For example, Gruhler’s group [61] and Trinidad’s group [62] reported that the number of phosphopeptides identified was greatly improved by the total proteins being enzymatically cleaved into peptides by SCX during the first fractionating followed by further enrichment of phosphopeptides using IMAC.
Nutraceuticals-based therapeutic approach: recent advances to combat pathogenesis of Alzheimer’s disease
Published in Expert Review of Neurotherapeutics, 2021
Marjan Talebi, Eleni Kakouri, Mohsen Talebi, Petros A. Tarantilis, Tahereh Farkhondeh, Selen İlgün, Ali Mohammad Pourbagher-Shahri, Saeed Samarghandian
Biologically important molecules that have long attracted scientists’ interest are the carotenoids derived from the plant of Crocus sativus L, and specifically from its red stigmas, namely crocins (CRCs) and crocetin [150]. There are five different types of CRCs identified at the stigmas of the plant which differ at the sugar moiety attached at the terminals of the carbohydrate skeleton [151]. Because of their glycosylated ends, CRCs are water-soluble carotenoids. On the other hand, crocetin a dicarboxylic acid, basically the aglycon part of CRCs, is found in minor quantity with respect to CRCs. Each terminal part of the carbohydrate skeleton is occupied by a carboxyl group (-COOH). Both molecules are capable of delaying the progression of neurodegenerative disorders, such as Alzheimer’s disease [152]; as we describe below.