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Natural Products from the Amazon Region as Potential Antimicrobials
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Josiane E. A. Silva, Iasmin L. D. Paranatinga, Elaine C. P. Oliveira, Silvia K. S. Escher, Ananda S. Antonio, Leandro S. Nascimento, Patricia P. Orlandi, Valdir F. Veiga-Júnior
When looking for bioactive substances, the polarity of the extracting solvent is an important factor. Nonpolar substances are very commonly observed and not very active, such as fatty acids, waxes and sterols. On the other hand, very polar substances, extracted in water, are also sometimes less active and also easily observed very frequently among several species, such as polyphenols and sugars. Thus, medium polarity solvents are preferred when looking for new substances with biological activities that are unprecedented.
Current Perspectives and Methods for the Characterization of Natural Medicines
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Muthusamy Ramesh, Arunachalam Muthuraman, Nallapilai Paramakrishnan, Balasubramanyam I. Vishwanathan
The constituents with diverse polarity (polar/non-polar/low polar) can be studied; and (iii) multiple and a large quantity of samples can be handled (Kumar et al., 2013; Ciura et al., 2017). Roh et al. employed thin-layer chromatography for the separation of lycopene from Lycopersicon esculentum. Silica Gel 60 F254 (0.25mm) activated by warming of plates at 110°C for the period of 10 min to ascertain the purity of lycopene. The method was suggested to be useful in large-scale purification of lycopene (Kyun et al., 2013). The assembly of thin-layer chromatography is illustrated in Figure 2.2.
High-Performance Liquid Chromatography
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Joel J. Kirschbaum, Adorjan Aszalos
High-performance liquid chromatography (HPLC) is increasingly becoming the premier choice for analyzing antibiotics and anti-infective agents, according to regulatory agencies and compendia. The advantages of HPLC include simplicity, accuracy, precision, versatility, and, most importantly, selectivity, especially to distinguish between constituents of a multicomponent system. Columns of different polarity can be used to analyze a compound, thus enabling many interfering substances, such as those found in biological matrices, to be reduced or eliminated. HPLC is versatile enough to permit several methods of analysis to be developed starting with almost any type of separating column.
Aldehyde oxidase mediated drug metabolism: an underpredicted obstacle in drug discovery and development
Published in Drug Metabolism Reviews, 2022
Siva Nageswara Rao Gajula, Tanaaz Navin Nathani, Rashmi Madhukar Patil, Sasikala Talari, Rajesh Sonti
Metabolic stability data is essential for evaluating and optimizing the human therapeutic dose. Improved metabolic stability of the drug enhances its plasma half-life and reduces dosing frequency (Gajula et al. 2021). The knowledge of liable sites for metabolism aids in deciding structural changes to impart metabolic stability to the drug molecules. The specific structural features of drug molecules can be attributed to their susceptibility toward AO mediated metabolism. For instance, drugs with at least one aromatic nitrogen-containing heterocycle with an unsubstituted aromatic carbon atom adjacent to the nitrogen atom are potential substrates for AO (Pryde et al. 2010). The polarity of the drug can be increased by incorporating isosteric functional groups at the metabolic site, thereby reducing the AO mediated metabolism (Gajula et al. 2021). Medicinal chemists are attempting to reduce lipophilicity by introducing polar nitrogen-based heterocyclic rings. These heterocyclic rings are essential for binding kinase inhibitors to the ATP binding ‘hinge’ region of the kinase domain. However, this strategy in synthesizing kinase inhibitors alleviates P450 metabolism but increases the AO metabolism (Pryde et al. 2010). Furthermore, blocking or modification of metabolically liable groups enhances metabolic stability. For AO substrates, several strategies available to reduce AO susceptibility are direct blocking of the oxidation site, replacing the affected carbon with a heteroatom, removing nitrogen, and saturation of aromatic and unsaturated azaheterocycles (Manevski et al. 2019).
The Prominence of Self-referential Processing across ERP and Memory Consolidation in Children
Published in Developmental Neuropsychology, 2021
Anna Hudson, Emma S. Green, McLennon J.G. Wilson, Roxane J. Itier, Heather A. Henderson
Additionally, while we argue that the enhanced cortical activation is reflective of a parietal LPP in our developmental sample, it is important to note that there is both temporal and spatial overlap between the early LPP and the N400 waveform. The N400 is a negativity captured across centro-parietal sites between 200–600 ms in response to language, semantics, and memory processing (for review, see Kutas & Federmeier, 2011). The N400 is also thought to be involved in the bottom-up and top-down neurocognitive mechanisms with which to interpret incoming information, similarly to our understanding of the LPP. Indeed, previous work has demonstrated that adults displayed an increased positive frontal LPP and increased negative parietal N400 amplitude in response to reading social expectation violations (i.e., reading positive traits followed by consistent or inconsistent behaviors associated with that trait; Baetens et al., 2011).This was interpreted to reflect differential processing efforts from the N400 and LPP during social information processing, with the N400 being associated with the unanticipated behavior, while the LPP was involved in more evaluative processing. Moreover, Baetens and colleagues (2011) discuss the potential overlap between these two components of opposite polarity. It is therefore important to continue to monitor the developmental trajectory of the LPP and N400 components to determine when these two waveforms start diverging. Moreover, since this was the first study to examine referent and valence processing in response to trait adjectives across ERPs in children, replication is necessary.
Factors influencing lithium versus valproate prescription preference in the maintenance treatment of bipolar patients: a report from the Italian Early Career Psychiatrists (SOPSI-GG)
Published in International Journal of Psychiatry in Clinical Practice, 2021
Massimiliano Buoli, Eleonora Gattoni, Enrico Collantoni, Alessio Maria Monteleone, Marco Solmi, Luisa Longo, Michele Ribolsi, Jacopo Santambrogio, Francesco Saverio Bersani, Andrea Aguglia, Gianluca Serafini, Maria Salvina Signorelli, Bernardo Dell’Osso, Mario Luciano, Silvana Galderisi
The mainstay of treatment for BD is pharmacotherapy, which articulates in two fundamental phases with specific aims: (i) treatment of acute episodes, without increasing the risk of onset of symptoms of opposite polarity; (ii) the prevention of subsequent episodes, in order to progressively stabilise the clinical picture and avoid chronic course (Buoli et al. 2014). Mood stabilisers include a class of medications with the aforementioned indications and aims (Pisanu et al. 2018). Indeed, lithium was the first drug showing stabilising properties and it is considered the first line compound for both acute and maintenance phases of BD (Severus et al. 2018), with early reports on its efficacy dating back to the Fifties (Noack and Trautner 1951). In addition, lithium demonstrated to significantly reduce the risk of suicidal behaviour in subjects affected by major affective disorders including BD (Manchia et al. 2013; Tondo et al. 2019). Other drugs that fall into the category of mood stabilisers include anti-epileptics such as valproate, lamotrigine and carbamazepine. Furthermore, many second generation antipsychotics have proven efficacy on acute and maintenance therapy of BD and they are currently labelled for the treatment of this condition (Yatham et al. 2018).