Radiochemistry for Preclinical Imaging Studies
George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos in Handbook of Small Animal Imaging, 2018
99mTc-sestamibi with its isonitrile ligands belongs to the class of organometallic compounds. More recently carbonyl ligands have been employed as well. For this, pertechnetate is reduced by sodium borohydride (NaBH4) in the presence of CO (Alberto et al. 1998) or boranocarbonate Na2H3BCO2 is used as a combination of reducing agent and in situ source of CO (Alberto et al. 2001). This gives the intermediate complex fac-[99mTc(CO)3(H2O)3]+ (fac for facial isomer). The three carbonyl ligands coordinate strongly with the TcI center, which provides higher kinetical stability than technetium in other oxidation states. The three weakly bound water molecules easily undergo ligand exchange, for example, with a tridentate chelator such as histidine or cysteine (Alberto et al. 2004b). Each of these amino acids can also act as bidentate chelator if they are the terminal residue of a peptide. The first of many examples for this type of compounds involves a bidentate chelator and a single chloride ligand (Alberto et al. 1999) but tridentate chelators provide generally more stable complexes (Kluba and Mindt 2013). Also, click-chemistry-based synthetic routes have been explored more recently, for example, coupling chelator and targeting domain equipped with alkyne and azido functions into a triazole (Carroll et al. 2012).
Aspergillus spp.
Rossana de Aguiar Cordeiro in Pocket Guide to Mycological Diagnosis, 2019
The emergence of triazole resistance is increasingly reported around the world in the past decade, becoming a worrying public health problem. In a patient, this resistance is acquired through two distinct epidemiological routes. The first resistance cases were described following long-term treatment with medical azoles (Denning et al., 1997; Chryssanthou, 1997; Verweij et al., 2016). More recently, contamination of azole-naive patients by already resistant isolates from the environment has been reported, linked to the use of azole fungicides in agriculture, horticulture, and wood preservation (Alvarez-Moreno et al., 2017; Snelders et al., 2008; Verweij et al., 2016). This second route of acquisition of resistance was initially proposed in the Netherlands and then reported in the United States, Australia, and several other countries in Europe, Asia, Africa, and Latin America (Alvarez-Moreno et al., 2017; Kidd et al., 2015; Snelders et al., 2008; van der Linden et al., 2015; Verweij et al., 2016; Wiederhold et al., 2016). In Europe, a relationship was found between environmental azole use and the development of cross-resistance to medical triazoles through TR34/L98H and TR46/Y121F/T289A mutations in the CYP51A gene and its promoter region (Lavergne et al., 2015; Snelders et al., 2009) and more recently through TR53 in Latin America (Alvarez-Moreno et al., 2017).
Lipids of Candida Albicans
Rajendra Prasad, Mahmoud A. Ghannoum in Lipids of Pathogenic Fungi, 2017
No significant differences in triacylglycerol and nonesterified fatty acid fractions were detected in azole-sensitive and resistant strains. The azole resistant strains (AD and KB) contained more nonesterified sterols and, thus, the phospholipid:sterol ratio was approximately half that of azole- sensitive strains. The ratio correlated well with the permeability of triazoles.28 Resistant strain Darlington showed a higher uptake of triazole as compared to sensitive strain A. Recently, Hitchcock et al. observed that the mycelial form of C. albicans containing higher phospholipid/nonesterified sterols also had an enhanced ability to take up triazole as compared to the yeast form, which had a lower ratio.29
Genetic functional algorithm model, docking studies and in silico design of novel proposed compounds against Mycobacterium tuberculosis
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Shola Elijah Adeniji
Triazole compounds are the subject of many research studies due to its structural entities and their widespread potential in medicinal applications [2,6]. Triazole and its analogue among all other heterocyclic compounds are being considered in pharmacological fields due to its unique structure and properties [3,6]. Triazole is a five membered ring heterocyclic diunsaturated compound composed of two carbon atoms at and three nitrogen atoms non adjacent positions respectively. Recent researches have shown that triazole nucleus has gained huge attention among pharmacist, biochemist, biologist and chemists as it’s one of the major bioactive molecules in pharmaceuticals particularly in drug design and chemotherapeutical [7]. Triazole has been reported to show substantial and extensive kind of pharmacological activities such as analgesic and antitubercular [8,9], anti-neoplastic [10] and anti-malarial [11]. It is also reported as the most efficient molecules toward anti-TB activity [12].
DFT based QSAR study on quinolone-triazole derivatives as antibacterial agents
Published in Journal of Receptors and Signal Transduction, 2022
Niloofar Ghasedi, Shahin Ahmadi, Sepideh Ketabi, Ali Almasirad
Triazoles, including 1,2,3-triazole and 1,2,4-triazole, are one of the most important classes of nitrogen-containing heterocycles. Triazole derivatives exhibit a variety of biological activities, including anti-tumor, antibacterial, anti-malarial, anti-fungal, anti-HIV, and anti-tuberculous properties [4,5]. The triazole moiety can affect the molecule's lipophilicity, polarity, and hydrogen bonding capacity, improving the compounds' pharmacological, pharmacokinetic, toxicological, and physicochemical properties. Therefore, these derivatives play a significant role in developing new drugs [6,7]. Quinolone-triazole derivatives are a new class of hybrid molecules studied in recent years, and already synthesized samples have shown good antibacterial activity, mostly higher than the reference antibiotics [8–11].
Preparation and in vivo evaluation of a highly skin- and nail-permeable efinaconazole topical formulation for enhanced treatment of onychomycosis
Published in Drug Delivery, 2019
Byung Chul Lee, Rudra Pangeni, Jungtae Na, Kyo-Tan Koo, Jin Woo Park
To address the problems of drug solubility and stability, as well as improve the efficacy of conventional antifungal agents, different strategies have been utilized, such as chemical modification of antifungal agents, carrier-based delivery using penetration enhancers, preparation and application of nanoformulations, and combined treatment with physical methods to enhance drug delivery, including iontophoresis, photodynamic therapy, and lasers (Dutet & Delgado-Charro, 2009; Eichner et al., 2017). However, the composition of topical solutions may significantly affect drug release and skin and nail permeability (Brown et al., 2009). In addition, formulations containing active ingredients of triazole exhibit varying degrees of instability and solubility in solution during storage. Certain formulations are known to exhibit discoloration within storage periods as short as 1 or 2 days, resulting in solutions ranging in color from yellow to deep red or brown. This can discourage the use of prescribed formulations by patients.
Related Knowledge Centers
- Amide
- Click Chemistry
- Green Chemistry
- Imide
- Chemical Formula
- Half Sandwich Compound
- 1,2,3-Triazole
- 1,2,4-Triazole
- Hydrazide
- Hydrazines