scholarly journals The Antioxidant Capability of Higenamine: Insights from Theory

Antioxidants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 358
Author(s):  
Isabella Romeo ◽  
Angela Parise ◽  
Annia Galano ◽  
Nino Russo ◽  
Juan Raúl Alvarez-Idaboy ◽  
...  
Keyword(s):  
Density Functional ◽  
Water Solution ◽  
Protective Action ◽  
Molar Fraction ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Ros Scavenging ◽  
Working Mechanism ◽  
Functional Theory ◽  
Ph Values

Density functional theory was employed to highlight the antioxidant working mechanism of higenamine in aqueous and lipid-like environments. Different reaction mechanisms were considered for the reaction of higenamine with the •OOH radical. The pH values and the molar fraction at physiological pH were determined in aqueous solution. The results show that the preferred reaction mechanism was the hydrogen atom transfer from the catecholic ring. The computed kinetic constants revealed that, in order to obtain reliable results, it is important to consider all the species present in water solution derived from acid–base equilibria. From the present investigation, it emerges that at physiological pH (7.4), the scavenging activity of higenamine against the •OOH radical is higher than that of Trolox, chosen as a reference antioxidant. Furthermore, higenamine results to be more efficient for that purpose than melatonin and caffeine, whose protective action against oxidative stress is frequently associated with their reactive oxygen species (ROS) scavenging activity.

Density Functional Theory Calculations of the Radical Scavenging Activity of Alkannin Derivatives

2012 ◽  
Vol 189 ◽  
pp. 225-231
Author(s):  
Xiang Peng Guo ◽  
Rui Fa Jin
Keyword(s):  
Density Functional ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Density Functional Theory Calculations ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Structural And Electronic Properties ◽  
The One

The structural and electronic properties of alkannin and its derivatives and their radicals were investigated at density functional level. It turned out that the presence of the dihydroxy functionality increases the radical stability through hydrogen bond formation. The hydrogen atom transfer for alkannin derivatives is difficult to occur compared with zero compound phenol. However, alkannin derivatives appear to be good candidates for the one-electron-transfer, particularly for alkannin derivatives with –OCOCH=CH(CH3)2 and –OCOCH2CH(CH3)2 groups. It suggests that 1–7 are expected to be the promising candidates for radical scavenging activity compounds because The ionization potential (IP) values of 1–7 are lower than that of the zero compound phenol.

Exploring chemistry features of favipiravir in octanol/water solutions

2021 ◽  
pp. 1-12
Author(s):  
Halimeh Rajabzadeh ◽  
Ayla Sharafat ◽  
Maryam Abbasi ◽  
Maryam Eslami Gharaati ◽  
Iraj Alipourfard
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Partition Coefficients ◽  
Density Functional ◽  
Water Solution ◽  
Peptide Group ◽  
Functional Theory ◽  
Water Solutions ◽  
Group Rotations ◽  
Heterocyclic Structure

Favipiravir (Fav) has become a well-known drug for medication of patients by appearance of COVID-19. Heterocyclic structure and connected peptide group could make changes for Fav yielding different features from those required features. Therefore, it is indeed a challenging task to prepare a Fav compound with specific features of desired function. In this work, existence of eight Fav structures by tautomeric formations and peptide group rotations were obtained using density functional theory (DFT) optimization calculations. Gas phase, octanol solution, and water solution were employed to show impact of solution on features of Fav besides obtaining partition coefficients (LogP) for Fav compounds. Significant impacts of solutions were seen on features of Fav with the obtained LogP order: Fav-7 >  Fav-8 >  Fav-4 >  Fav-3 >  Fav-2 >  Fav-5 >  Fav-1 >  Fav-6. As a consequence, internal changes yielded significant impacts on features of Fav affirming its carful medication of COVID-19 patients.

scholarly journals Н-комплексы 1,2-нафтохинона с молекулами воды в водном растворе и их влияние на сдвиги полос поглощения

2021 ◽  
Vol 129 (5) ◽  
pp. 599
Author(s):  
С.Н. Цеплина ◽  
E.E. Цеплин
Keyword(s):  
Quantum Chemical ◽  
Continuum Model ◽  
Density Functional ◽  
Water Solution ◽  
Polarizable Continuum Model ◽  
Water Molecules ◽  
Absorption Bands ◽  
Functional Theory ◽  
Polarizable Continuum ◽  
Polar Water

Optical absorption spectra of 1,2-naphthoquinone in non-polar (n-hexane) and polar (water) solvents were obtained. It is shown that the use of quantum chemical calculations based on time-dependent density functional theory (TDDFT B3LYP/6-311+G(d, p)) with the polarizable continuum model (PCM) for calculating 1,2-naphthoquinone in a solution of n-hexane and hydrogen complex of 1,2-naphthoquinone with two water molecules in an aqueous medium describes well the shifts of the absorption bands of 1,2-naphthoquinone in a water solution compared to a solution in n-hexane. Based on the analysis of deviations of the calculated band shifts from the experimental ones, the question of the formation of 1,2-naphthoquinone hydrogen complexes with n water molecules (n = 1-4) in an aqueous solution is considered.

scholarly journals Radical-Scavenging and UV-Radiation Absorption Activities of Aaptamine Derivatives: DFT and TD-DFT Studies

2021 ◽  
Author(s):  
Thi Hoai Nam Doan ◽  
Thi Le Anh Nguyen ◽  
Nguyen Thi Ai Nhung ◽  
Duong Tuan Quang ◽  
Duy Quang Dao
Keyword(s):  
Density Functional ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Radiation Absorption ◽  
Functional Theory ◽  
Radical Adduct ◽  
Td Dft ◽  
Potential Applications

Antioxidant and UV absorption activities of three aaptamine derivatives including piperidine[3,2-b]demethyl(oxy)aaptamine (C1), 9-amino-2-ethoxy-8-methoxy-3H-benzo[de][1,6]naphthyridine-3-one (C2), and 2-(sec-butyl)-7,8-dimethoxybenzo[de]imidazo[4,5,1-ij][1,6]-naphthyridin-10(9H)-one (C3) were theoretically studied by density functional theory (DFT). Optimized geometries of C1C3 and theirs intrinsic thermochemical properties such as bond dissociation energy, proton affinity, and ionization potential were calculated at DFT/M05-2X/6-311++G(d,p) level of theory in vacuo and in water. The results show that C1C3 exhibited similar potent antioxidant activities, which are comparable to well-known antioxidants such as Trolox or cembrene. The radical scavenging activity of the antioxidants were then investigated by evaluation the Gibbs free energy (ΔrG0) of the reaction between C1C3 and the HOO●/HO● radicals via four mechanisms, including: hydrogen atom transfer (HAT), single electron transfer (SET), proton loss (PL) and radical adduct formation (RAF). Kinetic calculation reveals that HOO● scavenging in water is occurred via HAT mechanism with C1@C19 while RAF is more dominant with C2 and C3. Antioxidant activity of aaptamine derivatives can be classified as C1 > C3 > C2. In addition, all compounds are active in UV-Vis absorption; the excitations of which are determined as π-π* transition. Overall, the results suggest the potential applications of the aaptamines in pharmaceutics and cosmetics, i.e. as sunscreen and antioxidant ingredient<br>

scholarly journals Silver-Catalyzed Enantioselective Propargylic C–H Bond Amination Through Rational Ligand Design

2020 ◽  
Author(s):  
minsoo ju ◽  
Emily Zerull ◽  
Jessica Roberts ◽  
Minxue Huang ◽  
Jennifer Schomaker
Keyword(s):  
Density Functional ◽  
Ligand Design ◽  
Building Blocks ◽  
Hydrogen Atom Transfer ◽  
Enantioselective Synthesis ◽  
Functional Theory ◽  
Nitrene Transfer ◽  
Structure Activity ◽  
Rational Ligand Design ◽  
Sar Analysis

Asymmetric C–H amination via nitrene transfer (NT) is a powerful tool for the preparation of enantioenriched amine building blocks from abundant C–H bonds. Herein, we report a highly regio- and enantioselective synthesis of -alkynyl -amino alcohol motifs via a silver-catalyzed propargylic C–H amination. The protocol was enabled by development of a new bis(oxazoline) (BOX) ligand through a rapid structure-activity relationship (SAR) analysis. The method utilizes readily accessible carbamate ester substrates bearing -propargylic C–H bonds and furnishes versatile products in good yields and with excellent enantioselectivity (90–99% ee). A putative Ag–nitrene intermediate is proposed to undergo an enantiodetermining hydrogen-atom transfer (HAT) during the C–H amination event. Density functional theory (DFT) calculations were performed to investigate the origin of enantioselectivity in the HAT step.

scholarly journals Silver-Catalyzed Enantioselective Propargylic C–H Bond Amination Through Rational Ligand Design

2020 ◽  
Author(s):  
minsoo ju ◽  
Emily Zerull ◽  
Jessica Roberts ◽  
Minxue Huang ◽  
Jennifer Schomaker
Keyword(s):  
Density Functional ◽  
Ligand Design ◽  
Building Blocks ◽  
Hydrogen Atom Transfer ◽  
Enantioselective Synthesis ◽  
Functional Theory ◽  
Nitrene Transfer ◽  
Structure Activity ◽  
Rational Ligand Design ◽  
Sar Analysis

Asymmetric C–H amination via nitrene transfer (NT) is a powerful tool for the preparation of enantioenriched amine building blocks from abundant C–H bonds. Herein, we report a highly regio- and enantioselective synthesis of -alkynyl -amino alcohol motifs via a silver-catalyzed propargylic C–H amination. The protocol was enabled by development of a new bis(oxazoline) (BOX) ligand through a rapid structure-activity relationship (SAR) analysis. The method utilizes readily accessible carbamate ester substrates bearing -propargylic C–H bonds and furnishes versatile products in good yields and with excellent enantioselectivity (90–99% ee). A putative Ag–nitrene intermediate is proposed to undergo an enantiodetermining hydrogen-atom transfer (HAT) during the C–H amination event. Density functional theory (DFT) calculations were performed to investigate the origin of enantioselectivity in the HAT step.

scholarly journals Scavenging of hydroxyl radical by kinsenoside originated from anoectochilus roxburghii: A DFT approach

2020 ◽  
pp. 72-76
Author(s):  
Nguyen Minh Thong Nguyen
Keyword(s):  
Hydroxyl Radical ◽  
Density Functional ◽  
Energy Surface ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Single Electron Transfer ◽  
Functional Theory ◽  
Anoectochilus Roxburghii ◽  
Radical Scavenging Properties

- A density functional theory (DFT) study on the hydroxyl radical scavenging properties of Kinsenoside originated from Anoectochilus roxburghii is presented. Two mechanisms, single electron transfer (SET) and hydrogen atom transfer (HAT) are considered. The thermochemical results demonstrate that the SET mechanism is not plausible to occur. With respect to the HAT, the interaction of OH• radical with Kinsenoside is also studied in detail by establishing potential energy surface (PES). This result strongly confirms that the C8H bond decides the radical scavenging activity of Kinsenoside with activation Gibbs free energy (∆G≠) and rate constants (k) of 1.1 kcal/mol and 5.9×10-8 cm3/molecules, respectively

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