Mechanism and kinetics of the oxidative damage to ergosterol induced by peroxyl radicals in lipid media: a theoretical quantum chemistry study

Medina, Manuel E.; Iuga, Cristina; Trigos, Ángel

doi:10.1002/poc.3520

Cited by 14 publications

(18 citation statements)

References 62 publications

(61 reference statements)

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“…Yin et al suggested mechanisms involving abstraction of hydrogen atoms at either C‐9 or C‐14 of the sterol 24 . This was further confirmed for ergosterol with the C‐9 mechanism representing the highest contribution to ergosterol damage by peroxyl radicals 27 …”

Section: Resultssupporting

confidence: 94%

Detection of ergosterol using liquid chromatography/electrospray ionization mass spectrometry: Investigation of unusual in‐source reactions

Ory

Gentil

Kumla

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale:In the field of natural products, de-replication of complex mixtures has become a usual practice to annotate known compounds and avoid their re-isolation.For this purpose, many groups rely on liquid chromatography coupled to highresolution mass spectrometry (HPLC/MS) to deduce molecular formulae of compounds allowing comparison with public or in-house databases. Electrospray ionization (ESI) is usually considered as the method of choice for investigating a large panel of compounds but, in some cases, it may lead to unusual results as described in this article for ergosterol. Methods: Ergosterol and other fungal sterols in methanolic solution were analysed using various chromatographic gradients with HPLC/MS using both ion trap time-offlight MS and Orbitrap MS instruments fitted with an ESI source. Further flow injection analyses were performed to investigate the influence of the solvent composition. MS/MS fragmentation data were acquired to annotate the various ions observed.Results: Contrary to other fungal sterols, ergosterol was found to be highly sensitive to oxidation during ESI. Putative structures were proposed based on MS/MS studies and known oxidation mechanisms of ergosterol by reactive oxygen species that could be formed in the ESI process. The proportion of acetonitrile in the eluent was found to influence this in-source oxidation, with an increased proportion of oxidized sodium adducts with higher proportions of acetonitrile. Conclusions:While ergosterol is a major sterol found in fungi, this study investigates its ionization by electrospray for the first time. The results reported here will help further detection and annotation of this compound in fungal extracts after HPLC/ESI-MS analyses.

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Section: Resultssupporting

confidence: 94%

Detection of ergosterol using liquid chromatography/electrospray ionization mass spectrometry: Investigation of unusual in‐source reactions

Ory

Gentil

Kumla

et al. 2020

Rapid Comm Mass Spectrometry

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“…[48] However, β-sitosterol reacts with the • OOH radical slower than ergosterol (2.05 × 10 6 M −1 s −1 ). [49] Equally important, β-sitosterol also reacts with the peroxyl radical • OOH slightly faster than some known antioxidants, such as α-mangostin (7.8 × 10 3 M −1 s −1 ), [50] capsaicin (6.5 × 10 3 M −1 s −1 ), [51] and protocatechuic acid (5.1 × 10 3 M −1 s −1 ). [52]…”

Section: Resultsmentioning

confidence: 99%

On the peroxyl radical scavenging ability of β‐sitosterol in lipid media: A theoretical study

Ortiz‐Escarza

Medina

Trigos

2020

J of Physical Organic Chem

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Vegetable consumption was considered healthy, mainly because a large number and variety of antioxidants were identified from them. However, the main component in all vegetables is β‐sitosterol, and although its antioxidant capacity was reported, little is known about the reaction mechanism involved. In this study, thermodynamic and kinetic studies of the peroxyl radical scavenging activity of β‐sitosterol in lipid media were carried out, employing the density functional theory (DFT). The results showed that the hydrogen transfer (HT) reaction mechanism is the most important in the peroxyl radical scavenging activity of β‐sitosterol when peroxyl radicals with a medium reactivity such as •OOH and •OOCH3 were considered. However, when the peroxyl radical has significant reactivity, it could react through the radical adduct formation (RAF) mechanism. The calculated overall reaction rate constants of the peroxyl radical scavenging of β‐sitosterol were 8.76 × 103 and 1.54 × 102 M−1 s−1 for the peroxyl radicals •OOH and •OOCH3, respectively. According to the previous results, β‐sitosterol might be considered a modest antioxidant, which prevents oxidative damage to biological molecules such as cell membrane lipids. These results support the idea that vegetables could be considered antioxidants in the organism, and therefore, considering the consumption of vegetables in the daily diet could prevent cell aging by inhibiting oxidative damage.

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“…The results obtained on the radical scavenging activity from HMD with • OOH in lipid media could be employed to compare this activity with other antioxidants, according to this, the HMD is better antioxidant than tyrosol (7.13 × 10 2 M ‐1 s ‐1 ), capsaicin (6.54 × 10 3 M ‐1 s ‐1 ), sinapinic acid (1.66 × 10 4 M ‐1 s ‐1 ), fraxetin (2.43 × 10 4 M ‐1 s ‐1 ), esculetin (4.93 × 10 4 M ‐1 s ‐1 ), sesamol (3.33 × 10 4 M ‐1 s ‐1 ), trans‐Resveratrol (1.42 × 10 5 M ‐1 s ‐1 ), hydroxytyrosol (6.42 × 10 5 M ‐1 s ‐1 ), dopamine (8.16 × 10 5 M ‐1 s ‐1 ), canonol (6.80 × 10 5 M ‐1 s ‐1 ); since the HMD reacts lower than ergosterol (2.05 × 10 6 M ‐1 s ‐1 ) in lipid media.…”

Section: Resultsmentioning

confidence: 99%

On the primary and secondary antioxidant activity from hydroxy‐methylcoumarins: experimental and theoretical studies

Couttolenc

Díaz‐Porras

Espinoza

et al. 2019

J of Physical Organic Chem

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In this work, the experimental and theoretical study on the primary and secondary antioxidant activities of three hydroxy-4-methylcoumarins were carried out. According to the experimental results obtained in the TEAC test employing ABTS, DPPH and galvinoxyl radicals, coumarin with the most important radical scavenging activity was 7,8-dihydroxy-4-methylcoumarin (HMD), even observing a radical scavenging activity greater than that demonstrated by the Trolox antioxidant. The theoretical results on primary antioxidant capability shown that the HMD has a good radical scavenging activity in lipid media when compared to other molecules with known antioxidant activity. It was also highlighted that HMD showed an excellent radical scavenging capability in aqueous media considering the physiological pH, the results indicated that it even has a more important radical scavenging capability than others coumarins that are considered excellent antioxidants. Hence, HMD showed a great versatility to stabilize different kinds of important biological radicals, in these results were highlighted their great antioxidant activity. In addition to the previous results, the secondary antioxidant activity was studied, the results showed that HMD could inhibit the reduction of the copper and in this way avoid the Haber-Weiss reactions, which leads to the increase of the hydroxyl radical concentration, and then, to oxidative stress. Therefore, this study shows that the HMD is able to stabilize the radicals in the primary antioxidant activity and avoid the generation of radicals through the Fenton reaction in the secondary antioxidant activity.

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Mechanism and kinetics of the oxidative damage to ergosterol induced by peroxyl radicals in lipid media: a theoretical quantum chemistry study

Cited by 14 publications

References 62 publications

Detection of ergosterol using liquid chromatography/electrospray ionization mass spectrometry: Investigation of unusual in‐source reactions

Detection of ergosterol using liquid chromatography/electrospray ionization mass spectrometry: Investigation of unusual in‐source reactions

On the peroxyl radical scavenging ability of β‐sitosterol in lipid media: A theoretical study

On the primary and secondary antioxidant activity from hydroxy‐methylcoumarins: experimental and theoretical studies

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