Search results for "DPP"
showing 10 items of 168 documents
Antioxidant phenolic compounds recovery from Mangifera indica L. by-products by supercritical antisolvent extraction
2015
Abstract Supercritical Antisolvent Extraction (SAE) was used in the recovery of antioxidant compounds from mango by-products. The antioxidant extract was obtained by solid–liquid extraction using aqueous acetone (80% v/v) and subsequent adsorption/desorption in C18 cartridge. Recovery of antioxidants was performed by SAE using SC-CO 2 as antisolvent. The temperature and pressure parameters were varied in the range 35–45 °C and 8–15 MPa. The SAE process allowed the recovery of about 90% of the initial phenolic compounds, the best recovery was obtained at 40 °C and 10 MPa and the main compounds were mangiferin, isomangiferin, quercetin 3-O-galactoside, quercetin 3-O-glucoside, quercetin 3-O-x…
Synthèse de nouveaux agents bimodaux hydrosolubles pour l'IRM, l'imagerie nucléaire, l'imagerie biphotonique et la génération de second harmonique
2015
The goal of my PhD studies was to synthesize new compounds for possible medical imaging applications. The first part of my thesis focused on the synthesis of heteroleptic ligands to achieve the chelation of two different metals aimed at addressing two types of medical imaging. We first synthesized porphyrins, which are well-known for the chelation of numerous transition metals. We focused on copper, whose copper-64 isotope is a β+ emitter usable in Positron Emission Tomography (PET). These porphyrins have been coupled with a DOTA derivative. This molecule, metallated with gadolinium, is well-known in Magnetic Resonance Imaging (MRI). Our compounds display encouraging relaxivities for MRI ap…
Incretin-Based Therapies Role in COVID-19 Era: Evolving Insights
2020
The current coronavirus disease 2019 (COVID-19) pandemic has led the scientific community to breach new frontiers in the understanding of human physiology and disease pathogenesis. It has been hypothesized that the human dipeptidyl peptidase 4 (DPP4) enzyme receptor may be a functional target for the spike proteins of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Since DPP4-inhibitors are currently used for the treatment of patients with type-2 diabetes (T2DM), there is currently high interest in the possibility that these agents, or incretin-based therapies (IBTs) in general, may be of benefit against the new coronavirus infection. Diabetes is associated with increased COV…
Quantitative Structure-Antioxidant Activity Models of Isoflavonoids: A Theoretical Study
2015
Seventeen isoflavonoids from isoflavone, isoflavanone and isoflavan classes are selected from Dalbergia parviflora. The ChEMBL database is representative from these molecules, most of which result highly drug-like. Binary rules appear risky for the selection of compounds with high antioxidant capacity in complementary xanthine/xanthine oxidase, ORAC, and DPPH model assays. Isoflavonoid structure-activity analysis shows the most important properties (log P, log D, pKa, QED, PSA, NH + OH ≈ HBD, N + O ≈ HBA). Some descriptors (PSA, HBD) are detected as more important than others (size measure Mw, HBA). Linear and nonlinear models of antioxidant potency are obtained. Weak nonlinear relationship…
A new procedure for the Antioxidant capacity dpph assessment in small samples.
2018
The antioxidant capacity of a substance is its ability to prevent or slow down oxidation. This reaction is a transfer of electrons. The molecule catching electrons is the oxidative agent and the molecule giving electrons is the reducing agent. Oxidative stress is toxic for the cells, and it can be limited by different pathways: the inhibition of enzymes responsible of the production of oxidative species, the synthesis, activation or stabilization of antioxidant enzymes, and finally by direct scavenging of radical species. In living organisms, especially in association to the respiration process, free radicals are commonly produced. Antioxidant are naturally present to prevent damages, and t…
Assessment of the antioxidant and antibacterial activities of different olive processing wastewaters.
2017
Olive processing wastewaters (OPW), namely olive mill wastewater (OMW) and table-olive wastewaters (TOW) were evaluated for their antibacterial activity against five Gram-positive and two Gram-negative bacteria using the standard disc diffusion and thin layer chromatography (TLC)-bioautography assays. Disc diffusion screening and bioautography of OMW were compared to the phenolic extracts of table-olive brines. Positive activity against S. aureus was demonstrated. The optimization of chromatographic separation revealed that hexane/acetone in the ratio of 4:6 was the most effective for phenolic compounds separation. A HPLC-MS analysis was performed showing that only two compounds, hydroxytyr…
Supercritical carbon dioxide extraction of seed oil from yellow horn (Xanthoceras sorbifolia Bunge.) and its anti-oxidant activity
2010
Supercritical fluid carbon dioxide (SF-CO(2)) extraction (SFE) of seed oil from yellow horn and its anti-oxidant activity were investigated. The effects of CO(2) flow rate and particle size were firstly optimized, and a central composite design (CCD) combined with response surface methodology was used to study the effects of extraction pressure, temperature and time on the extraction yields. A maximal extraction yield of 61.28% was achieved under optimal conditions of extraction pressure 30 MPa at 45.68 degrees C, 2.08 h and CO(2) flow rate 12 kg/h with 0.5mm particle size. By analyzing the chemical composition of the seed oil, we found that the content of unsaturated fatty acids was approx…
Antioxidant activity and chemical composition of three Tunisian Cistus: Cistus monspeliensis Cistus villosus and Cistus libanotis
2015
The chemical composition of three rockrose Cistus species, Cistus monspeliensis, Cistus libanotis and Cistus villosus, collected in Tunisia, was studied by HPTLC, focusing on the terpenes and phenols constituents. Diterpenes of Cistus are important as the main constituents of the leaf sticky aromatic resin, known as labdanum, which are highly appreciated in perfumery. Polyphenols in the methanolic extracts of each species were identified, quantified as total and as flavonoids and tannins, and tested for antioxidant activity. Diterpenes were evident in C. libanotis and C. monspeliensis, whereas they were practically absent in C. villosus; C. libanotis had higher phenolic amount, whereas anti…
Effect of bioclimatic area on the composition and bioactivity of Tunisian Rosmarinus officinalis essential oils
2014
The chemical composition of eight Tunisian Rosmarinus officinalis L. populations (A-H) from different bioclimatic areas has been examined by gas chromatography (GC) and GC-mass spectrometry. The essential oils are characterised by high amounts of oxygenated monoterpenes (58.2-71.7%) followed by monoterpene hydrocabons (15.1-26.7%). 1,8-Cineole, camphor, α-pinene and borneol are the main representative components. The antioxidant activity was investigated by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), ferric reducing ability power assay and β-carotene bleaching test. Samples showed antiradical activity by inhibiting DPPH radical with IC50 values ranging from 375.3 to 592.8 μg mL(- 1) for s…
Invazīvo augu (Lupinus polyphyllus, Impatiens glandulifera, Echinocystis lobate) bioloģiski aktīvo vielu grupas un to izmantošanas potenciāls bioekon…
2022
Invazīvās augu sugas var veicināt ar ekosistēmu funkcionēšanu saistītas problēmas, radot ekonomiskus zaudējumus, kaitējumu cilvēka veselībai un samazinot rekreācijas resursu kvalitāti. Tās raksturo strauja un agresīva izplatīšanās, nomācot endēmiskās sugas. Pilnīgai invazīvo augu biomasas izmantošanai ir nepieciešams atrast ilgtspējīgus, bioekonomikā balstītus pārstrādes risinājumus, kas ļautu iegūt komponentus vai produktus ar augstu pievienoto vērtību. Darbā tika apskatītas dažādas daudzlapu lupīnas, puķu spriganes un adatainā dzeloņgurķa augu daļas. Augos tika noteikts kopējais polifenolu daudzums, novērtēta antiradikālā aktivitāte (DPPH), un lupīnās atrodamie alkaloīdi (GC-MS). Augstākā…