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High-Performance Liquid Chromatography
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Joel J. Kirschbaum, Adorjan Aszalos
Parasitism is almost universal in both animals and humans. It is debilitating and frequently disfiguring or fatal. In Africa alone, 1 million children are estimated to die each year from malaria, with 200 million people thought to be infected with schistosomes. The additional food intake required to maintain an infested organism can be equal to the usual daily intake, a quantity often impossible for some victims to maintain. For these reasons, research is continuing to discover more effective drugs. Anthelmintics, antimalarials, antitrichomoniasis, antitypanosamal, and antiprotozoan drugs are considered in the literature: allopurinal [31,32], berberine [33], cambendazole [34], chloroquine [35–37], ciclobendazole [38], dimetridazole [39], diminazene [40], emetine [41], levamisole [42], ivermectin (avermeetin) [43,44], mebendazole [45,46], mefloquine [47], metronidazole [48–50], ornidazole [51], oxfendazole [52], phenothiazine [53], preziquantel [54], primaquine [55], proquamil [56], pyrentel tartrate [57], pyrimethamine [58], quinine [59,60], salicylhydroxamic acid [61], tetramisole [62], thiabendazole [32,63,64], and tinidazole [65,66]. Figure 2 shows the separation of eight benzimidazoles after injecting 5 μg/ml of each compound [34].
Lipids of Aspergillus
Published in Rajendra Prasad, Mahmoud A. Ghannoum, Lipids of Pathogenic Fungi, 2017
P. Chakrabarti, M. Kundu, J. Basu
A respiratory-deficient acetate non-utilizing mutant, acwlO,44 with increased cyanide sensitivity has been isolated from the wild type strain V35 of A. niger by chemical mutagenesis.43,44 Respiration is less in the presence of glucose in the whole cells and cellular extract of the mutant, acu10. Hexokinase activity remains unaltered in the mutant. Cyanide-sensitive respiration is 3-fold greater in whole cells of acu10 than that in V35, but almost similar in their cellular extracts. Activities of some respiratory enzymes, viz. succinate dehydrogenase and cytochrome oxidase, are lower in acu\0 than that in V35 after 18 h of growth but almost the same at 41 h of growth. Mitochondrial lipid profile is almost unaltered in acu10. Salicylhydroxamic acid, a specific inhibitor of cyanide-insensitive respiration, inhibits the respiration of both strains. The extent of inhibition is lower in acu10 revealing that A. niger possesses two respiratory pathways: one sensitive to cyanide and the other to salicylhydroxamic acid. [14C]-cyanide uptake is much higher in acu10. This may be due to changes in cyanide permeability due to altered mycelial lipid composition of the mutant. Cyanide permeability and cyanide-insensitive respiration are affected in the mutant, acu10 of A. niger.
Recent development and biomedical applications of self-healing hydrogels
Published in Expert Opinion on Drug Delivery, 2018
Yinan Wang, Christian K. Adokoh, Ravin Narain
Complexation of diols and phenylboronic acid (PBA) can form a reversible boronate ester in an aqueous solution, and, therefore, can be introduced to polymer network to construct self-healing hydrogels. For example, Kiser and coworkers designed a self-healing hydrogel based on the reversible boronate ester complexation between polymers carrying PBA and salicylhydroxamic acid. The hydrogel can be tuned to display different mechanical properties at a wide range of pH, and can be potentially be exploited for drug delivery in acidic condition [64]. Messersmith’s group exploited self-healing hydrogels through complexation of a catechol-derived tetra-arm PEG (cPEG) with 1,3-benzenediboronic acid (BDBA) in phosphate buffer saline at 20°C under alkaline pH [65]. However, to make such self-healing hydrogels work at the physiological pH ranges, cytotoxic primary/secondary amines are usually introduced to the polymer backbones to adjust the PBA’s pKa values below the physiological pH ranges [45,47]. Replacing PBA with benzoxaborole group allow polymer network to be formed at neutral pH [66]. Very recently, our group has introduced a simple one-step method for the construction of self-healing hydrogel through the dynamic covalent diol-benzoxaborole complexation (Figure 8) [48]. The hydrogel was synthesized by mixing of glucose containing glycomonomer and benzoxaborole monomer at 2 M concentration followed by the in situ polymerization. The hydrogel showed excellent mechanical property and can achieve almost 100% recovery after healing in an aqueous solution at physiological pH. Moreover, due to the dynamic covalent nature, the hydrogels also showed shear thinning properties, which allowed this material being potentially used for 3D bioprinting.