Biological Properties and Absolute Configuration of Flavanones From Calceolariathyrsiflora Graham

Valdés, Ernesto Garzón; González, César; Díaz, Katy; Vásquez-Martínez, Yesseny; Mascayano, Carolina; Torrent, Claudia; Cabezas, Francisco; Mejias, Sophia; Montoya, Margarita; Martı́n, Marcelo Cortez-San; Muñoz, Marcelo A.; Joseph‐Nathan, Pedro; Osorio, Mauricio; Taborga, Lautaro

doi:10.3389/fphar.2020.01125

Cited by 11 publications

(13 citation statements)

References 40 publications

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“…The selection of this level is consequent to our previous study of both enantiomers of flavanone having natural isotopic abundances 27 for which we explored four levels of theory and found that all attempted calculations provided successful calculated spectra for good data comparison. By the way, the F I G U R E 1 Formulas of flavanones originally published VCD spectra of the flavanones with natural isotopic distribution were inadvertently wrong labeled in our initial study, 27 as it was recently already mentioned, 24 because the (S) labeled spectrum in reality corresponded to the (R) enantiomer and vice versa.…”

Section: Comparison Of Calculated and Experimental Vcd Spectramentioning

confidence: 79%

“…Flavanone is the parent molecule of a well‐known series of aromatic secondary metabolites and is characteristic of citric fruits. It is mostly found in nature as the ( S ) enantiomer and only in a recent case a plant derived flavanone has been studied by VCD 24 …”

Section: Introductionmentioning

confidence: 99%

“…It is mostly found in nature as the (S) enantiomer and only in a recent case a plant derived flavanone has been studied by VCD. 24…”

Section: Introductionmentioning

confidence: 99%

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Deuterium effects on the vibrational circular dichroism spectra of flavanone

Muñoz

Joseph‐Nathan

2020

Chirality

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The minimum chemical modification that can be incorporated into an organic molecule is the replacement of a hydrogen atom for a deuterium atom. This change is not altering the pharmacological properties of a molecule, although it provides the possibility of making specific spectroscopic evaluations. Thus, in the present study, we explore how a stereogenic center is influenced by such an isotopic labeling. The studies were conducted on both enantiomers of flavanone (1 and 2) which is the parent molecule of a large group of pharmacologically active natural occurring secondary metabolites. Flavanone comprised 12 carbon atoms forming two benzene rings, a carbonyl group, an ethereal oxygen atom, a methylene group, and only one C–H stereogenic center, so it seems to be an ideal candidate for such studies. Density functional theory (DFT) calculations were used for the accurate prediction of vibrational circular dichroism (VCD) spectra of (R)‐(3) and (S)‐flavanone‐2‐d (4), of (R)‐(5) and (S)‐flavanone‐3,3‐d2 (6), and of (R)‐(7) and (S)‐flavanone‐2′,3′,4′,5′,6′‐d5 (8). To gain compounds that provide experimental VCD spectra for comparative purposes, the calculated spectra of both enantiomers of the corresponding flavanones, obtained after HPLC separation of the racemates by means of a chiral column, were contrasted, thereby revealing excellent agreements when using the CompareVOA software. In addition, the VCD spectra of both unlabeled enantiomeric flavanones (1 and 2) were also compared to the labeled molecules, revealing that the VCD spectra show significant variations induced by the deuterium incorporation.

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Section: Comparison Of Calculated and Experimental Vcd Spectramentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

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Deuterium effects on the vibrational circular dichroism spectra of flavanone

Muñoz

Joseph‐Nathan

2020

Chirality

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“…The structural characteristic that differentiates these compounds from the rest of the structures is the catechol group (1,2-dihydroxybenzene) in Ring B. Many known inhibitors of 5-LOX possess the catechol group that is a relevant characteristic for their inhibitory properties [ 44 ].…”

Section: Resultsmentioning

confidence: 99%

Prenylated Flavonoids with Potential Antimicrobial Activity: Synthesis, Biological Activity, and In Silico Study

Osorio

Carvajal

Vergara

et al. 2021

IJMS

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Prenylated flavonoids are an important class of naturally occurring flavonoids with important biological activity, but their low abundance in nature limits their application in medicines. Here, we showed the hemisynthesis and the determination of various biological activities of seven prenylated flavonoids, named 7–13, with an emphasis on antimicrobial ones. Compounds 9, 11, and 12 showed inhibitory activity against human pathogenic fungi. Compounds 11, 12 (flavanones) and 13 (isoflavone) were the most active against clinical isolated Staphylococcus aureus MRSA, showing that structural requirements as prenylation at position C-6 or C-8 and OH at positions C-5, 7, and 4′ are key to the antibacterial activity. The combination of 11 or 12 with commercial antibiotics synergistically enhanced the antibacterial activity of vancomycin, ciprofloxacin, and methicillin in a factor of 10 to 100 times against drug-resistant bacteria. Compound 11 combined with ciprofloxacin was able to decrease the levels of ROS generated by ciprofloxacin. According to docking results of S enantiomer of 11 with ATP-binding cassette transporter showed the most favorable binding energy; however, more studies are needed to support this result.

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“…Consequently, the spectra were carefully recorded several times over different days using correct operation conditions and the identity and purity of the samples were always checked by H-NMR measurements, so the mainly mono-signated spectra shapes seem to own the sample. In fact, the VCD spectra of 1 and 2 remember the spectra of 7- O - β -D-glucopyranosylchrysin, 21 of ( S )-5-hydroxy-7-methoxy-4’-acetyloxyflavanone, 22 and of podocephalol acetate. 23 For the later compound supramolecular studies could be done.…”

Section: Resultsmentioning

confidence: 99%

Vibrational Circular Dichroism Similarity-Guided Absolute Configuration Determination of 11-Acyloxytremetones

Muñoz

Simirgiotis

Joseph‐Nathan

2022

Natural Product Communications

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Although tremetone [5-acetyl-2-(1-methylvinyl)-2,3-dihydrobenzofuran] has only one stereogenic center, the absolute configuration (AC) determination of its naturally occurring 11-acyloxy derivatives 1 and 2 by vibrational circular dichroism (VCD) turned out to be difficult. Similarity-based comparison of the experimental VCD spectrum of 11-coumaryloxytremetone (1), isolated from Parastrephia quadrangularis, with spectra calculated using popular density functional theory (DFT) levels of theory, provided poor enantiomeric similarity indices ( ESI), even when the p-coumaroyl ester group of 1 was replaced by the acetyl group in 2. In search for a better understanding of these results, IR-guided individual scaling factors (ISFs), recently introduced as part of the Vibrational Spectra Similarity and Analysis Tool (VISSAT) software, were used to correct DFT frequencies, while a VCD-guided conformational analysis was developed to explore conformational preferences. These studies showed that for both molecules 72% of the individual conformations gave ESI values in favor of the ( R) enantiomer. Likewise, when conformer abundances were optimized to produce the best possible similarity for each enantiomer, the obtained ESI values were always larger for the ( R) isomer than for the ( S) isomer. These results point toward the ( R) AC in both compounds and highlight the incorrect conformer abundance prediction by DFT calculations as the potential source of the initial difficulties. In addition, the AC of 1 was independently verified using the Flack and Hooft parameters gained after a single-crystal x-ray diffraction (XRD) study.

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Biological Properties and Absolute Configuration of Flavanones From Calceolariathyrsiflora Graham

Cited by 11 publications

References 40 publications

Deuterium effects on the vibrational circular dichroism spectra of flavanone

Deuterium effects on the vibrational circular dichroism spectra of flavanone

Prenylated Flavonoids with Potential Antimicrobial Activity: Synthesis, Biological Activity, and In Silico Study

Vibrational Circular Dichroism Similarity-Guided Absolute Configuration Determination of 11-Acyloxytremetones

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