scholarly journals Theoretical study via DFT for prediction of 13C and 1H NMR data of two diterpenoids derived from the root of salvia grandifolia

2019 ◽  
Vol 84 (6) ◽  
pp. 591-598 ◽  
Author(s):  
Costa da ◽  
Sebastião Silva ◽  
O. de ◽  
Jorddy Cruz ◽  
Costa da ◽  
...  
Keyword(s):  
Experimental Data ◽  
Natural Products ◽  
1H Nmr ◽  
Computational Methods ◽  
Theoretical Study ◽  
Theoretical Data ◽  
Dft Method ◽  
Promising Alternative ◽  
Nmr Data ◽  
Linear Correlations

The DFT method has become a promising alternative in the support of traditional NMR experimental techniques, comparing experimental data with theoretical data, thereby achieving accurate and satisfactory results. In the present study, the experimental data of two diterpenes were compared to the theoretical data obtained by the GIAO method, applying DFT at the B3LYP/cc-pVDZ and B3PW91/DGDZVP levels to verify the degree of correlation, significance and predictability of the models obtained with the purpose of proving which of the computational methods is the most efficient for this class of substances. The theoretical NMR values obtained at B3LYP/cc-pVDZ were the more satisfactory, showing better linear correlations, presenting greater degrees of adjustments, significance and predictability compared to the B3PW91/DGDZVP method. Thus, these values were used to define H? and H? 1, 2, 3, 6 and 7 for diterpene 1 and 1, 2, 3, 6 and 7 for diterpene 2, which was not possible using experimental data. This showed that the quantum method used could help in the structural elucidation of natural products.

scholarly journals Uso de Cálculos de RMN de 13C e 1H e Redes Neurais no Auxilio da Determinação Estrutural da Savinina

2020 ◽  
Author(s):  
Evani Ferreira Cardoso ◽  
Rodrigo de Souza Miranda ◽  
Roberto Carlos Campos Martins ◽  
Gunar Vingre da Silva Mota ◽  
Antônio Maia de Jesus Chaves Neto ◽  
...  
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Immune System ◽  
1H Nmr ◽  
Theoretical Calculations ◽  
Human Colon ◽  
Human Colon Carcinoma ◽  
Nmr Data ◽  
The Neural Network ◽  
Hct116 Cells

This is a theoretical-experimental work, where the focus molecule of the study is savinine, a lignan of the dibenzylbutyrolactonic type, substances that can be found in several genera, one of which has a greater occurrence is the genus Acanthopanax (Araliaceae) which is traditionally used as an analgesic and immune system stimulant, in addition to exhibiting a potent insecticidal and cytotoxic activity for human colon carcinoma HCT116 cells. It was isolated and here we present its experimental and theoretical characterization by means of 13C and 1H NMR data and the possible confirmation of the structure using the neural network tool (ANN-PRA). The objective of this work is to use theoretical calculations of 13C and 1H NMR and experimental data for the resolution of the savinine structure, and the use of the neural network tool (ANN-PRA) to confirm the structure of the molecule.

scholarly journals Cinnamoylphenethylamine 1H-NMR Chemical Shifts: A Concise Reference for Ubiquitous Compounds

2010 ◽  
Vol 5 (8) ◽  
pp. 1934578X1000500 ◽  
Author(s):  
Hans A. Pedersen ◽  
Stine K. Steffensen ◽  
Carsten Christophersen
Keyword(s):  
Natural Products ◽  
1H Nmr ◽  
Spectroscopic Data ◽  
Uv Light ◽  
Chemical Shifts ◽  
Rapid Identification ◽  
Upfield Shift ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nmr Data

1H-NMR data of 25 cinnamoylphenethylamine derivates were recorded and compared in order to assign signals unequivocally without additional spectroscopic data. The spectra provide a key for the rapid identification of these ubiquitous natural products. The compounds isomerize rapidly in UV light, producing a characteristic upfield shift of the olefinic protons consistent with distorted planarity of the Cis cinnamate, and this requires special attention during preparative work.

Unexpected Keto-enol Tautomerism in the Cyclopyridinophane Class Direct and indirect proofs

2008 ◽  
Vol 59 (10) ◽  
Author(s):  
Paul Ionut Dron ◽  
Neculai Doru Miron ◽  
Gheorghe Surpateanu
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Stable Conformer ◽  
Ph Measurements ◽  
Theoretical Methods ◽  
Nmr Data ◽  
Tautomeric Forms ◽  
New Compounds

The paper presents the synthesis of cyclo (bis-paraquat p-phenylene p-phenylene-carbonyl) tetrakis (hexafluorophosphate), named �CETOBOX�, and the closely related structural determinations. This compound exists in three tautomeric forms. These forms were evidentiated by NMR-data (1H-NMR, TOCSY, COSY, NOESY), UV-Vis spectra coupled with pH measurements and by synthesis. As the �CETOBOX� gives �in situ� only the corresponding monoylide, the synthesis of a new fluorescent indolizine cyclophane has been performed by a 3+2 cycloaddition. All structures of the new compounds presented herein have been established by NMR spectroscopy. Also, theoretical methods (MM3, AM1, AM1-COSMO and B88LYPDFT) have been used to determine the most stable conformer structures.

scholarly journals Oxidation of Terpenoids to Achieve High-Value Flavor and Fragrances—Questioning Microalgae Oxidative Capabilities in the Biotransformation of the Sesquiterpene Valencene and of Selected Natural Apocarotenoids

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 821-830
Author(s):  
Davide De Simeis ◽  
Stefano Serra ◽  
Alessandro Di Fonzo ◽  
Francesco Secundo
Keyword(s):  
Experimental Data ◽  
Natural Products ◽  
Aqueous Medium ◽  
Photochemical Reaction ◽  
Substrate Oxidation ◽  
Market Size ◽  
Chlorella Sp ◽  
General Opinion ◽  
Natural Way

Natural flavor and fragrance market size is expected to grow steadily due to the rising consumer demand of natural ingredients. This market request is guided by the general opinion that the production of natural compounds leads to a reduction of pollution, with inherent advantages for the environment and people’s health. The biotransformation reactions have gained high relevance in the production of natural products. In this context, few pieces of research have described the role of microalgae in the oxidation of terpenoids. In this present study, we questioned the role of microalgal based oxidation in the synthesis of high-value flavors and fragrances. This study investigated the role of three different microalgae strains, Chlorella sp. (211.8b and 211.8p) and Chlorococcum sp. (JB3), in the oxidation of different terpenoid substrates: α-ionone, β-ionone, theaspirane and valencene. Unfortunately, the experimental data showed that the microalgal strains used are not responsible for the substrate oxidation. In fact, our experiments demonstrate that the transformation of the four starting compounds is a photochemical reaction that involves the oxygen as oxidant. Even though these findings cast a shadow on the use of these microorganisms for an industrial purpose, they open a new possible strategy to easily obtain nootkatone in a natural way by just using an aqueous medium, oxygen and light.

scholarly journals Three-Dimensional Structures of Carbohydrates and Where to Find Them

2020 ◽  
Vol 21 (20) ◽  
pp. 7702 ◽  
Author(s):  
Sofya I. Scherbinina ◽  
Philip V. Toukach
Keyword(s):  
Experimental Data ◽  
Molecular Modeling ◽  
Computational Methods ◽  
Three Dimensional ◽  
Structural Diversity ◽  
Structural Data ◽  
Structural Features ◽  
Data Validation ◽  
Data Generation ◽  
Efficient Treatment

Analysis and systematization of accumulated data on carbohydrate structural diversity is a subject of great interest for structural glycobiology. Despite being a challenging task, development of computational methods for efficient treatment and management of spatial (3D) structural features of carbohydrates breaks new ground in modern glycoscience. This review is dedicated to approaches of chemo- and glyco-informatics towards 3D structural data generation, deposition and processing in regard to carbohydrates and their derivatives. Databases, molecular modeling and experimental data validation services, and structure visualization facilities developed for last five years are reviewed.

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

Conformational study of a strained tolanophane by dynamic 1H NMR spectroscopy and computational methods

2008 ◽  
Vol 139 (10) ◽  
pp. 1185-1189 ◽  
Author(s):  
Hossein Reza Darabi ◽  
Marjan Azimzadeh Arani ◽  
Mohsen Tafazzoli ◽  
Mina Ghiasi
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Computational Methods ◽  
1H Nmr Spectroscopy ◽  
Conformational Study ◽  
Dynamic 1H Nmr

scholarly journals A study of computational methods for wake structure and base pressure prediction of a generic SUV model with fixed and rotating wheels

2017 ◽  
Vol 231 (9) ◽  
pp. 1222-1238 ◽  
Author(s):  
David Forbes ◽  
Gary Page ◽  
Martin Passmore ◽  
Adrian Gaylard
Keyword(s):  
Experimental Data ◽  
Computational Methods ◽  
Large Scale ◽  
Ground Plane ◽  
Computational Cost ◽  
Rear Wheel ◽  
Base Pressure ◽  
Detached Eddy Simulation ◽  
Wake Structure ◽  
Wake Interactions

This study is an evaluation of the computational methods in reproducing experimental data for a generic sports utility vehicle (SUV) geometry and an assessment on the influence of fixed and rotating wheels for this geometry. Initially, comparisons are made in the wake structure and base pressures between several CFD codes and experimental data. It was shown that steady-state RANS methods are unsuitable for this geometry due to a large scale unsteadiness in the wake caused by separation at the sharp trailing edge and rear wheel wake interactions. unsteady RANS (URANS) offered no improvements in wake prediction despite a significant increase in computational cost. The detached-eddy simulation (DES) and Lattice–Boltzmann methods showed the best agreement with the experimental results in both the wake structure and base pressure, with LBM running in approximately a fifth of the time for DES. The study then continues by analysing the influence of rotating wheels and a moving ground plane over a fixed wheel and ground plane arrangement. The introduction of wheel rotation and a moving ground was shown to increase the base pressure and reduce the drag acting on the vehicle when compared to the fixed case. However, when compared to the experimental standoff case, variations in drag and lift coefficients were minimal but misleading, as significant variations to the surface pressures were present.

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