Abstract:The redox electrode potential of cyanidin was determined both by experimental (cyclic voltammetry) and theoretical methods, at the HF/6--311G(d) level of theory. An isodesmic reaction scheme, involving 1,2-benzoquinone as reference molecules, was proposed for the computation of the electrode potential of cyanidin. The results of the ab initio computations were in reasonable agreement with the available experimental measurements; the differences between experiment and theory were within the range of 0.02-0.05 V… Show more
“…The molecule of reference (catechol) with its four-electron redox potential value is presented in Figure 1 b, while the reduced form of tryptanthrin is shown in Figure 1 c. Integral equation formalism polarizable continuum model (IEF-PCM) [ 49 , 50 ] was adopted for the solvent-phase computation using water as solvent. The standard reduction potential of I had been calculated using a modified literature procedure [ 51 , 52 ]. Scheme 2 Isodesmic redox-conversion of compound ( I ) by catechol ( II ).…”
Section: Methodsmentioning
confidence: 99%
“…Using the thermodynamic cycle outlined in Scheme 3 , the change in free energies of the gas and solution phase reactions are defined according to Eqs. (2) and (3) [ 51 , 52 ]: where is the standard Gibbs energy of the reaction in the gas phase and is the net solvation energy of the reaction in solution phase ( Table 7 ). The overall change in Gibbs energy ( ) for this system is given by Eq.…”
Section: Methodsmentioning
confidence: 99%
“…The overall change in Gibbs energy ( ) for this system is given by Eq. (4) [ 51 , 52 ]: Scheme 3 Thermodynamic cycle employed to obtain compound I redox potential. …”
Section: Methodsmentioning
confidence: 99%
“…The redox potential of I can be obtained according to Eq. (5) [ 51 , 52 , 53 ]: where n is the number of electrons transferred ( n = 4 in this case), F is the Faraday constant and is the four-electron redox potential value for cyclohex-3-en-5-yne-1,2-dione/catechol (reference molecule) which was extrapolated from the experimental one-electron redox potential of catechol [ 54 ].…”
Tryptanthrin is a potent natural alkaloid with good in vitro pharmacological properties. Herein, we report the synthesis of the compound via a new method involving the reduction of isatin with solid-state-supported sodium borohydride under microwave irradiation. The title compound has been tested for its analgesic and antiinflammatory activity. The results showed that tryptanthrin dose dependently inhibits oedema and pain formation in all the models used. The agent also exhibited significant higher effects in its anti-inflammatory and analgesic activities better than positive drugs (aspirin and indomethacin) being currently used in the treatment and in the management of acute and chronic forms of pain and inflammatory disorders. The inhibitory potential of the compound was investigated by molecular docking using the software AutoDock Vina. The docking results were used to better rationalize the action and prediction of the binding affinity of tryptanthrin. Density Functional Theory (DFT) calculations at the B3LYP/6-311þþG (2df, 2pd) level of theory showed that compared to ascorbic acid, tryptanthrin shows higher antioxidant activity which may be improved upon by functionalizing the aromatic core to enhance its solubility in polar solvents. The calculated electronic and thermodynamic properties obtained for tryptanthrin compete well with the standard ascorbic acid.
“…The molecule of reference (catechol) with its four-electron redox potential value is presented in Figure 1 b, while the reduced form of tryptanthrin is shown in Figure 1 c. Integral equation formalism polarizable continuum model (IEF-PCM) [ 49 , 50 ] was adopted for the solvent-phase computation using water as solvent. The standard reduction potential of I had been calculated using a modified literature procedure [ 51 , 52 ]. Scheme 2 Isodesmic redox-conversion of compound ( I ) by catechol ( II ).…”
Section: Methodsmentioning
confidence: 99%
“…Using the thermodynamic cycle outlined in Scheme 3 , the change in free energies of the gas and solution phase reactions are defined according to Eqs. (2) and (3) [ 51 , 52 ]: where is the standard Gibbs energy of the reaction in the gas phase and is the net solvation energy of the reaction in solution phase ( Table 7 ). The overall change in Gibbs energy ( ) for this system is given by Eq.…”
Section: Methodsmentioning
confidence: 99%
“…The overall change in Gibbs energy ( ) for this system is given by Eq. (4) [ 51 , 52 ]: Scheme 3 Thermodynamic cycle employed to obtain compound I redox potential. …”
Section: Methodsmentioning
confidence: 99%
“…The redox potential of I can be obtained according to Eq. (5) [ 51 , 52 , 53 ]: where n is the number of electrons transferred ( n = 4 in this case), F is the Faraday constant and is the four-electron redox potential value for cyclohex-3-en-5-yne-1,2-dione/catechol (reference molecule) which was extrapolated from the experimental one-electron redox potential of catechol [ 54 ].…”
Tryptanthrin is a potent natural alkaloid with good in vitro pharmacological properties. Herein, we report the synthesis of the compound via a new method involving the reduction of isatin with solid-state-supported sodium borohydride under microwave irradiation. The title compound has been tested for its analgesic and antiinflammatory activity. The results showed that tryptanthrin dose dependently inhibits oedema and pain formation in all the models used. The agent also exhibited significant higher effects in its anti-inflammatory and analgesic activities better than positive drugs (aspirin and indomethacin) being currently used in the treatment and in the management of acute and chronic forms of pain and inflammatory disorders. The inhibitory potential of the compound was investigated by molecular docking using the software AutoDock Vina. The docking results were used to better rationalize the action and prediction of the binding affinity of tryptanthrin. Density Functional Theory (DFT) calculations at the B3LYP/6-311þþG (2df, 2pd) level of theory showed that compared to ascorbic acid, tryptanthrin shows higher antioxidant activity which may be improved upon by functionalizing the aromatic core to enhance its solubility in polar solvents. The calculated electronic and thermodynamic properties obtained for tryptanthrin compete well with the standard ascorbic acid.
“…The animals used were divided into three classes: a control group (control: n = 3) on which the UG induction procedure was not performed and an untreated group on which a gastric ulcer induction protocol (n = 3) a group on which a gastric ulcer production protocol was performed (n = 3) [7][8][9][10].…”
It can be observed that oxidative stress initiates and aggravates many diseases, including peptic ulcers and gastric carcinoma. An increase in rat mucosal glandular lipid peroxidation (LPO) and superoxide dismutase (SOD) and a decrease in catalase (CAT) levels in gastric ulceration induced by cold retention stress were observed, whereas in patients with ulcerated clinical peptic and gastric carcinoma LPO serum is associated with a decrease in SOD and CAT. It was intended to determine the parameters of oxidative stress in the blood and brain in rats after induction of gastric ulcer, the effect of antioxidant treatment on these parameters and on the appearance of gastric ulcer, determination of correlation between oxidative stress and severity of gastric ulcer in rats and also evaluation of vascular endothelial function by in vitro studies in the organ bath, from rat aortic rings with gastric ulcer vs. normal and others under treatment vs. untreated.
Anthocyanidins, leucoanthocyanidins, and flavonols are natural compounds mainly known due to their reported biological activities, such as antiviral, antifungal, anti-inflammatory activities, and antioxidant activity. In the present study, we performed a comparative structural, conformational, electronic, and nuclear magnetic resonance analysis of the reactivity of the chemical structure of primary anthocyanidins, leucoanthocyanidins, and flavonoids. We focused our analysis on the following molecular questions: (i) differences in cyanidin catechols ( +)-catechin, leucocyanidin, and quercetin; (ii) the loss of hydroxyl presents in the R1 radical of leucoanthocyanidin in the functional groups linked to C4 (ring C); and (iii) the electron affinity of the 3-hydroxyl group (R7) in the flavonoids delphinidin, pelargonidin, cyanidin, quercetin, and kaempferol. We show unprecedented results for bond critical point (BCP) of leucopelargonidin and leucodelphirinidin. The BCP formed between hydroxyl hydrogen (R2) and ketone oxygen (R1) of kaempferol has the same degrees of covalence of quercetin. Kaempferol and quercetin exhibited localized electron densities between hydroxyl hydrogen (R2) and ketone oxygen (R1). Global molecular descriptors showed quercetin and leucocyanidin are the most reactive flavonoids in electrophilic reactions. Complementary, anthocyanidins are the most reactive in nucleophilic reactions, while the smallest gap occurs in delphinidin.Local descriptors indicate that anthocyanidins and flavonols are more prone to electrophilic attacks, while in leucoanthocyanidins, the most susceptible to attack are localized in the ring A. The ring C of anthocyanidins is more aromatic than the same found in flavonols and leucoanthocyanidins. Methods For the analysis of the molecular properties, we used the DFT to evaluate the formation of the covalent bonds and intermolecular forces. CAM-B3LYP functional with the def2TZV basis set was used for the geometry optimization. A broad analysis of quantum properties was performed using the assessment of the molecular electrostatic potential surface, electron localization function, Fukui functions, descriptors constructed from frontier orbitals, and nucleus independent chemical shift.
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