HPLC‐ECD and TDDFT‐ECD study of hexahydropyrrolo[1,2‐a]quinoline derivatives

Tóth, László; Mándi, Attila; Váradi, Dániel; Kovács, Tibor; Szabados, Anna; Kiss‐Szikszai, Attila; Gong, Qihuang; Zhang, Haiyan; Mátyus, Péter; Antus, Sándor; Kurtán, Tibor

doi:10.1002/chir.22969

Cited by 10 publications

(13 citation statements)

References 33 publications

(64 reference statements)

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“…It is interesting to note that for 2 the BH&HLYP functional reproduced the 265 nm shoulder while the B3LYP and PBE0 functionals performed better in the low-wavelength region and gave no shoulder at 265 nm. 41 For both compounds, the computed first and fourth high-wavelength transitions were found to be π-π* ones while the second and the third ones are of n-π* origin (Fig. 3 and 4).…”

Section: Resultsmentioning

confidence: 86%

Induced secondary metabolites from the endophytic fungus Aspergillus versicolor through bacterial co-culture and OSMAC approaches

Abdelwahab

Kurtán

Mándi

et al. 2018

Tetrahedron Letters

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Two new cryptic 3,4-dihydronaphthalen-(2H)-1-one (1-tetralone) derivatives, aspvanicin A(1) and its epimer aspvanicin B (2), as well as several known cryptic metabolites (3-8), were obtained from the ethyl acetate extract of the co-culture of the endophytic fungus Aspergillus versicolor KU258497 with the bacterium Bacillus subtilis 168 trpC2 on solid rice medium.When A. versicolor was cultured axenically in liquid Wickerham medium supplemented with 3.5% DMSO, an additional three known secondary metabolites (9-11) were isolated that were lacking when the fungus was fermented on rice medium. The structures of the new compounds were elucidated using one-and two-dimensional NMR spectroscopy as well as HRESIMS. The relative and absolute configurations of 1 and 2 were determined by the combination of NMR and electronic circular dichroism (ECD) analysis aided by DFT conformational analysis and TDDFT-ECD calculations. The ECD calculations revealed that although the sign of the blueshifted overlapping n-π* ECD transition follows the helicity rule of cyclic aryl ketones, the calculation of low-energy conformers and ECD spectra was necessary to determine the stereochemistry. All metabolites were assessed for their antibacterial and cytotoxic activities; one of the new diastereomers, compound 2, showed moderate cytotoxic activity against the mouse lymphoma cell line L5178Y.

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Section: Resultsmentioning

confidence: 86%

Induced secondary metabolites from the endophytic fungus Aspergillus versicolor through bacterial co-culture and OSMAC approaches

Abdelwahab

Kurtán

Mándi

et al. 2018

Tetrahedron Letters

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“…The BH&HLYP and CAM-B3LYP functionals on the other hand gave better results for this transition but were not successful in the low-wavelength region. 48 It is possible that the real conformational distribution is somewhat different from the estimated one (results not shown). Based on the approximate overall ECD agreement, the absolute configuration was determined as (3S,4R,7S,9R,13S,16S).…”

Section: Journal Of Natural Productsmentioning

confidence: 90%

Indole Diterpenoids from an Endophytic Penicillium sp.

et al. 2019

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A chemical investigation of the endophyte Penicillium sp. (strain ZO-R1-1), isolated from roots of the medicinal plant Zingiber officinale, yielded nine new indole diterpenoids (1–9), together with 13 known congeners (10–22). The structures of the new compounds were elucidated by 1D and 2D NMR analysis in combination with HRESIMS data. The absolute configuration of the new natural products 1, 3, and 7 was determined using the TDDFT-ECD approach and confirmed for 1 by single-crystal X-ray determination through anomalous dispersion. The isolated compounds were tested for cytotoxicity against L5178Y, A2780, J82, and HEK-293 cell lines. Compound 1 was the most active metabolite toward L5178Y cells, with an IC50 value of 3.6 μM, and an IC50 against A2780 cells of 8.7 μM. Interestingly, 1 features a new type of indole diterpenoid scaffold with a rare 6/5/6/6/6/6/5 heterocyclic system bearing an aromatic ring C, which is suggested to be important for the cytotoxic activity of this natural product against L5278Y and A2780 cells.

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“…6 and Table 2 ) was determined to have the same planar structure as 7 and the (1 R ,2 R ,3 R ) absolute configuration of 8 was assigned by comparison of the experimental and calculated ECD spectra carried out on the (1 R ,2 R ,3 R ) stereoisomer (Supplementary Fig. 7 ) 39 . In order to distinguish the two stereoisomers of FST B, 7 and 8 were named FST B1 and FST B2 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Flavin-enabled reductive and oxidative epoxide ring opening reactions

Zhang

Yang

et al. 2022

Nat Commun

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Epoxide ring opening reactions are common and important in both biological processes and synthetic applications and can be catalyzed in a non-redox manner by epoxide hydrolases or reductively by oxidoreductases. Here we report that fluostatins (FSTs), a family of atypical angucyclines with a benzofluorene core, can undergo nonenzyme-catalyzed epoxide ring opening reactions in the presence of flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide (NADH). The 2,3-epoxide ring in FST C is shown to open reductively via a putative enol intermediate, or oxidatively via a peroxylated intermediate with molecular oxygen as the oxidant. These reactions lead to multiple products with different redox states that possess a single hydroxyl group at C-2, a 2,3-vicinal diol, a contracted five-membered A-ring, or an expanded seven-membered A-ring. Similar reactions also take place in both natural products and other organic compounds harboring an epoxide adjacent to a carbonyl group that is conjugated to an aromatic moiety. Our findings extend the repertoire of known flavin chemistry that may provide new and useful tools for organic synthesis.

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HPLC‐ECD and TDDFT‐ECD study of hexahydropyrrolo[1,2‐a]quinoline derivatives

Cited by 10 publications

References 33 publications

Induced secondary metabolites from the endophytic fungus Aspergillus versicolor through bacterial co-culture and OSMAC approaches

Induced secondary metabolites from the endophytic fungus Aspergillus versicolor through bacterial co-culture and OSMAC approaches

Indole Diterpenoids from an Endophytic Penicillium sp.

Flavin-enabled reductive and oxidative epoxide ring opening reactions

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