Global and Local Reactivity Descriptors for Picloram Herbicide: A Theoretical Quantum Study

Mendoza-Huízar, Luis Humberto

doi:10.5935/0100-4042.20140283

Cited by 8 publications

(6 citation statements)

References 2 publications

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“…These two derivatives ( f + , f − ) are considered the local reactivity descriptors that indicates the preferred regions where a chemical species will change its density when the number of electrons is modified. Thus, it indicates the susceptibility of the electronic density to deform at a given position upon accepting or donating electrons . The sites in chemical species with the largest values of Fukui function ( f ( r )) are those with higher reactivity…”

Section: Resultsmentioning

confidence: 99%

In silico and in vitro degradation studies of isolated phloroglucinols eugenial C and eugenial D from Eugenia umbelliflora fruits

Farias

Amorin

Santos

et al. 2019

Phytochemical Analysis

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Introduction Eugenia umbelliflora fruits are an important source of phloroglucinols, as eugenial C and eugenial D, related to antimicrobial activity against Staphylococcus aureus. However, for the establishment of new antimicrobial substances, it is essential to know their stability profile, in view of driving the administration route and the release system development. Methodology The in silico approaches, based on the Fukui indices and bond dissociation analysis, were performed. Eugenial C and eugenial D, isolated from the green fruits of E. umbelliflora, with purity > 90%, were submitted to stress degradation including: acid (0.5 mM hydrochloric acid) and alkaline (0.5 mM sodium hydroxide) hydrolysis, and oxidation (0.25% hydrogen peroxide), in different periods, monitoring by high‐performance liquid chromatography with ultraviolet detector (HPLC‐UV). Eugenial C was also submitted to UV‐visible radiation (2,400 lux/h) and dry/humid heating (40°C, 75% relative humidity). Results In silico studies indicated that both molecules have regions of high susceptibility to nucleophilic and electrophilic attack as well as sites likely to suffer auto‐oxidation. Under in vitro tests, both phloroglucinols proved to be very unstable under hydrolysis (eugenial C and D were degraded 23.8% and 89.0% in acid and 78.4% and 97.8% in alkaline conditions, respectively) and oxidation (eugenial C and D degraded 31.9% and 28.6%, respectively), both during 5 min. Eugenial C degraded 12.6% and 63.8% under dry and humid heat, respectively, without photosensitivity. Conclusion The in vitro stress tests monitored by HPLC‐UV were in agreement with in silico degradation prediction. Phloroglucinols could be unstable if administered by oral route and also under environmental conditions demanding a protective release system.

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Section: Resultsmentioning

confidence: 99%

In silico and in vitro degradation studies of isolated phloroglucinols eugenial C and eugenial D from Eugenia umbelliflora fruits

Farias

Amorin

Santos

et al. 2019

Phytochemical Analysis

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“…(3) ) for radical attack we calculated as follows: f - j = q j (N) - q j (N - 1) f + j = q j (N + 1) - q j (N) f 0 j = ½ q j [(N +1) – q j (N - 1)] The possible regions of the molecule susceptible to degradation, under acid and alkaline conditions, were evaluated by the Fukui functions [ 20 ]. These functions indicate the susceptibility of the electronic density to deform at a given position upon accepting or donating electrons [ 21 ]. In this case, q j is the number of electrons (evaluated from NPA) at the j th atomic site in the neutral ( N ), anionic ( N + 1) or cationic ( N - 1) chemical species on the reference molecule.…”

Section: Methodsmentioning

confidence: 99%

Taxifolin stability: In silico prediction and in vitro degradation with HPLC-UV/UPLC–ESI-MS monitoring

Moura

Machado

Paula

et al. 2021

Journal of Pharmaceutical Analysis

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Taxifolin has a plethora of therapeutic activities and is currently isolated from the stem bark of the tree Larix gmelinni (Dahurian larch). It is a flavonoid of high commercial interest for its use in supplements or in antioxidant-rich functional foods. However, its poor stability and low bioavailability hinder the use of flavonoid in nutritional or pharmaceutical formulations. In this work, taxifolin isolated from the seeds of Mimusops balata , was evaluated by in silico stability prediction studies and in vitro forced degradation studies (acid and alkaline hydrolysis, oxidation, visible/UV radiation, dry/humid heating) monitored by high performance liquid chromatography with ultraviolet detection (HPLC-UV) and ultrahigh performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS). The in silico stability prediction studies indicated the most susceptible regions in the molecule to nucleophilic and electrophilic attacks, as well as the sites susceptible to oxidation. The in vitro forced degradation tests were in agreement with the in silico stability prediction, indicating that taxifolin is extremely unstable (class 1) under alkaline hydrolysis. In addition, taxifolin thermal degradation was increased by humidity. On the other hand, with respect to photosensitivity, taxifolin can be classified as class 4 (stable). Moreover, the alkaline degradation products were characterized by UPLC-ESI-MS/MS as dimers of taxifolin. These results enabled an understanding of the intrinsic lability of taxifolin, contributing to the development of stability-indicating methods, and of appropriate drug release systems, with the aims of preserving its stability and improving its bioavailability.

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“…However, the observed situation is not unique. In literature, there are cases, in which the order of reactivity according to different descriptors is generally consistent (e.g., μ, χ, S, ω in Table 4 in [7]), but the vast majority of papers also reports different sequences of reactivity of studied molecules, which depends on tested descriptors (like in [12,38,53,55,64,67]). More detailed research shows that both variants are natural-it was shown in [46] the reactivity order based on global reactivity descriptors obtained from experimental values for atoms could be very similar during the analysis of certain parameters set, e.g., χ, η for Li, Na, Al atoms shown in Table 1 in [46] or differs significantly when another set of parameters is chosen (e.g., I, A, χ for Li, Na, Al).…”

Section: Global Reactivity Descriptorsmentioning

confidence: 99%

1-Naphthols as components for multifunctional material systems (MFMS): the molecular modeling approach

Radkowska

Brągiel

2020

Struct Chem

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Increasing research interests have been paid to developing efficient multifunctional material systems (MFMS) by using various composite materials, owing to their useful properties and good stability. Here, we systematically studied 1-naphthols, especially how the type and position of a substituent influence the reactivity and properties, using different electron-directing groups. During computations, important preparation guidelines for thiol derivatives of 1-naphthol were obtained. It is very interesting to note that some molecules could exhibit intramolecular O–H–O interactions. Careful theoretical investigation reveals that all the tested compounds are stable and the molecules with substituents in positions 4 and 8 are the least reactive. It is also worth noting that for the stability and polarizability tensor values, it is more favorable when both substituents are in the same benzene ring. Among tested 1-naphthols, the greatest values of alpha, beta, and gamma are more than 5, 60, and 110 times better respectively, than in the urea molecule; the change of electron-withdrawing group (EWG) to electron-donating group (EDG) increases NLO effects. This study provided a new scope of 1-naphthols applicability by using them as anti-corrosion materials and as very good materials for NLO devices due to the high stability of the aromatic structure coupled with polarity given by the substituents. Also, the understanding of IR vibrations for more complex organic compounds with thiol substituent has been improved.

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Global and Local Reactivity Descriptors for Picloram Herbicide: A Theoretical Quantum Study

Cited by 8 publications

References 2 publications

In silico and in vitro degradation studies of isolated phloroglucinols eugenial C and eugenial D from Eugenia umbelliflora fruits

In silico and in vitro degradation studies of isolated phloroglucinols eugenial C and eugenial D from Eugenia umbelliflora fruits

Taxifolin stability: In silico prediction and in vitro degradation with HPLC-UV/UPLC–ESI-MS monitoring

1-Naphthols as components for multifunctional material systems (MFMS): the molecular modeling approach

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