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Alkaloids potential health Benefits and toxicity
Published in Quan V. Vuong, Utilisation of Bioactive Compounds from Agricultural and Food Waste, 2017
Renée A. Street, Gerhard Prinsloo, Lyndy J. McGaw
Obesity is a complex chronic condition in which excess body fat accumulates into adipocytes, leading to adverse metabolic effects on blood pressure, cholesterol, an increased risk for type 2 diabetes T2DM, coronary heart disease and hypertension (Choi et al. 2014, WHO 2016). In obesity, there is an increase in the number of differentiated mature cells, which are regulated by genetic and environmental factors. The prevalence of obesity has been increasing in both the developed and developing world (Choi et al. 2014). In 2014, nearly 2 billion adults worldwide were overweight (39 per cent of adults 18+) and, of these, more than half a billion were obese. In Americas, Europe and Eastern Mediterranean regions, 50 per cent of women are overweight and 25 per cent of these are obese. Obesity is, however, more prevalent in low and lower middle-income countries with more women obese than men (WHO 2016). Screening natural products for anti-obesity potential is important in the search for treatment of this worldwide disease (Choi et al. 2014). The fruits of Piper retrofractum have been used for their anti-flatulent, expectorant, antitussive, antifungal and appetizing properties in traditional medicine, and they are reported to possess gastroprotective and cholesterol-lowering properties. Piperidine alkaloids from Piper retrofractum, namely piperine, pipernonaline and dehydropipernonaline were isolated as anti-obesity constituents of this plant (Kim et al. 2011).
Functionalization of Graphite and Graphene
Published in Titash Mondal, Anil K. Bhowmick, Graphene-Rubber Nanocomposites, 2023
Akash Ghosh, Simran Sharma, Anil K. Bhowmick, Titash Mondal
Amine-based graphene functionalization seeks attention in various fields like polymer solar cell, sensor, drug delivery, and energy storage. The epoxy and carboxylic groups were mainly used to react with the amine for surface anchoring. A similar strategy was utilized by Mondal et al. to modify the surface of the graphene oxide with blocked amine. 1-Methyl imidazole-based ionic liquid was used as the modifier for the graphene oxide. The ionic liquid modified graphene was further utilized in polyurethane-based foam composition to generate pores with uniformity (Mondal, Basak, and Bhowmick 2017). Bourlinos et al. used different amines and amino acids to modify the surface of graphene oxide. The epoxy group on the graphene oxide undergoes the substitution and nucleophilic reaction to modify the properties (Bourlinos et al. 2003). Using microwaves, Caliman et al. (2018) proposed a direct method to prepare amine functionalized graphene oxide. They produced four different amine functionalized graphenes by the use of dibenzyl amine, p-phenylenediamine, diisopropylamine, and piperidine. It was reported that the diisopropylamine and piperidine functionalized graphenes exhibit a better life cycle and specific capacitance of 290 F g−1 leading to its usage in the field of supercapacitors. Aguilar-Bolados and his co-workers reported the reductive amination of graphene oxide using the Leuckart reaction. Ammonium formate is used to reduce the carbonyl group present on the graphene oxide surface with simultaneous addition of amine (Aguilar-Bolados et al. 2017). Jeyaseelan et al. (2021) anchored the ethylenediamine molecule on graphene oxide for fluoride removal application.
Major Classes of Conjugated Polymers and Synthetic Strategies
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
Poly(aryleneethynylene)s (PAEs), including Poly(phenyleneethynylene)s (PPE), poly(thienyleneethynylene)s (PTE) and other heterocyclic poly(aryleneethynylene)s, are synthesized mainly by the Pd-catalyzed coupling of terminal alkynes to aromatic bromides or iodides in amine solvents [50], as shown in Scheme 6.22. Both bromo- and iodoaromatic compounds can be used in this reaction. In comparison with aryl bromides, the iodides react much faster, and the reaction can be carried out under a lower temperature. As a consequence, the polymerization can be performed under mild conditions when iodides are used, so that problems including cross-linking and formation of defects can be minimized. Therefore, if available, iodoarenes are the preferred substance for the reaction. The reaction is also dramatically influenced by the substituent on aryl halides. Electron-withdrawing group, such as nitro, on the halide improves the rate and the yield of the coupling reaction, while the electron-pushing group, such as alkoxy, reduces the reaction. The electron-withdrawing substituents on ortho- or para-position are more efficient than that on the meta-position. Most frequently 0.1–5 mol% (Ph3P)2PdCl2 and varying amounts of CuI are used in both organic and polymer-forming reactions. In the cases where the haloarenes are sufficiently active (typically iodoarenes), much smaller amounts (0.1%–0.3%) should be sufficient. An organic amine, such as tributylamine, triethylamine, and piperidine mixed with toluene or THF, is used as solvent. Suzuki coupling as that of synthesis of PFs and PTs (Scheme 6.23) can also be used to prepare PPEs.
Plant responses to per- and polyfluoroalkyl substances (PFAS): a molecular perspective
Published in International Journal of Phytoremediation, 2023
Ayesha Karamat, Rouzbeh Tehrani, Gregory D. Foster, Benoit Van Aken
Liu et al. (2022) analyzed gene expression in the alga C. pyrenoidosa exposed to PFBS and FBSA, which revealed downregulation of SOD (SOD2) and peroxidase genes (PRDX5), and upregulation of glutathione peroxidase genes (GPX). The authors then proposed that these changes would increase H2O2 and decrease free glutathione in exposed tissues, explaining the phytotoxic effect of PFAS. The downregulation of SOD2 was consistent with a decrease of the SOD activity in exposed plants. However, results at the transcriptomic level were not always in agreement with the recorded enzymatic activities. In their experiment with E. crassipes exposed to PFOS, Li et al. (2020c) observed downregulation of a SOD gene (Mn-SOD) in plants exposed to high level of PFOS (10 mg L−1), while no significant change in SOD activity was measured. In another transcriptomic analysis, exposure of soil-grown soybean (Glycine max) plants to the short-chain PFBA did not result in significant changes in the level of expression of SOD and CAT, although the activities of these enzymes decreased in plants exposed to even low concentration (100 ng/L), suggesting posttranslational inhibition of the enzymes by PFBA (Omagamre et al. 2022). In this study, enrichment of pathways involved in alkaloid biosynthesis (e.g., isoquinoline, tropane piperidine, and pyridine) led the authors to suggest a non-enzymatic response to ROS.
Supramolecular structural influences from remote functionality in coordination complexes of 4-picolylamine ligands
Published in Journal of Coordination Chemistry, 2022
V. D. Slyusarchuk, B. J. O’Brien, C. S. Hawes
In keeping with previous studies on silver(I) complexes with cyclic amine ligands [30], in all cases L1 and L2 coordinate to silver ions through both the pyridine and piperidine/morpholine nitrogen atoms. Combination of AgSbF6 with L1 or L2 in THF gave structurally related one-dimensional coordination polymers, allowing for direct comparison of the ligand backbones and their contribution to the extended structure. As shown in Figure 7, both complexes take the empirical formula poly-[Ag(L)]SbF6·0.5THF, though poly-[AgL1]SbF6·0.5THF (6) crystallizes with a single formula unit within the asymmetric unit, while the asymmetric unit of poly-[Ag(L2)]SbF6·0.5THF (7) contains two unique ligand molecules, silver ions and hexafluoroantimonate counterions. In both cases the silver ions adopt linear two-coordinate geometries bound by one pyridine and one tertiary amine, with the pyridine typically giving the shorter Ag-N distance (2.114(3) − 2.121(3) Å vs. 2.170(3) − 2.181(3) Å), and no significant difference between the two complexes in these values.
The Knoevenagel reaction: a review of the unfinished treasure map to forming carbon–carbon bonds
Published in Green Chemistry Letters and Reviews, 2020
Koen van Beurden, Steffijn de Koning, Dennis Molendijk, Jack van Schijndel
In Knoevenagel condensation reactions, the use of secondary amines is extensively researched. Especially piperidine is a catalyst often wanted after, usually accompanied by pyridine. Such is the case with the Knoevenagel condensation reported by Simpson et al., resulting in an E-factor of 16.3 (65). The calculation of this E-factor is as follows: E-factor equals [((3.9 g malonic acid + 3.05 g 1,5-dimethoxy-4-hydroxybenzaldehyde + 8.5 g piperidine + 20 g pyridine) – 2.05 g product) / 2.05 g product]. Other reported Knoevenagel reactions with piperidine had calculated values for the E-factor of 7.0 (64), 8.1 (6), and 22.6 (66), both dependent on the quantity of pyridine added as a solvent for this reaction. In an attempt by Pawar et al. to give a “greener” alternative, triethylamine was used to substitute the solvent pyridine in these reactions, and this resulted in an E-factor of 9.7 (48). A more unusual approach using the classic piperidine/pyridine combination is the application of imidazole. The imidazole molecule combines an aromatic tertiary amine and a secondary amine. The Knoevenagel reactions with imidazole reach an E-factor of 19.1 (67). But this is owing to the required addition of the solvent dichloromethane.