Fungal metabolites. Part VI. Crystal and molecular structure of secalonic acid A

Howard, Colin C.; Johnstone, R. A. W.; King, Trevor J.; Lessinger, L.

doi:10.1039/p19760001820

Cited by 15 publications

(9 citation statements)

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“… By the recrystallization of 1a from CHCl 3 , single crystals suitable for X-ray measurements (Figure ) were produced. The obtained X-ray crystal structure of 1a appeared to be different from the previously deposited structures of secalonic acid A crystallized from acetic acid or methanol . In our case, X-ray diffraction clearly demonstrated a differently twisted conformation of 1a (Figure ).…”

Section: Resultscontrasting

confidence: 93%

Insights into Ergochromes of the Plant Pathogen Claviceps purpurea

et al. 2021

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Claviceps purpurea is an ergot fungus known for its neurotropic alkaloids, which have been identified as the main cause of ergotism, a livestock and human disease triggered by ergot consumption. Tetrahydroxanthone dimers, the so-called ergopigments, presumably also contribute to this toxic effect. Overexpression of the cluster-specific transcription factor responsible for the formation of these pigments in C. purpurea led to the isolation of three new metabolites (8−10). The new pigments were characterized utilizing HRMS, NMR techniques, and CD spectroscopy and shown to be xanthone dimers. Secalonic acid A and its 2,4′-and 4,4′-linked isomers were also isolated, and their absolute configuration was investigated. The contribution of secalonic acid A, its isomers, and new metabolites to the toxicity of C. purpurea was investigated in HepG2 and CCF-STTG1 cells. Along with cytotoxic properties, secalonic acid A was found to inhibit topoisomerase I and II activity.

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Section: Resultscontrasting

confidence: 93%

Insights into Ergochromes of the Plant Pathogen Claviceps purpurea

et al. 2021

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“…Only secalonic acid A ( 2 ) exhibited P388 cancer cell inhibitory activity (ED 50 3.5 μg/mL), and the supply was not sufficient for human cancer cell line evaluation. Secalonic acid A, isolated mainly from fungi, , was previously reported to inhibit growth of the murine L1210 lymphocytic leukemia cell line . The other six compounds were inactive against both P388 and human cancer cell lines.…”

Section: Resultsmentioning

confidence: 99%

Isolation and Structure of Ruprechstyril from Ruprechtia tangarana^†,1

et al. 2003

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Bioassay (P388 lymphocytic leukemia cell line and human cancer cell lines)-guided separation of an extract prepared from the stem bark and twigs of the previously uninvestigated Ruprechtia tangarana led to the isolation of a new isocarbostyril designated ruprechstyril (1), secalonic acid A (2), 2'-O-methylevernic acid (3), 3,3',4-tri-O-methylflavellagic acid (4), lichexanthone (5), methyl asterrate (6), and 3beta,22E,24S-stigmasta-5,22-dien-3-ol (7). Only secalonic acid A exhibited cancer cell and microbial growth inhibition. The structure of ruprechstyril (1) was determined by HRMS and 1D and 2D NMR spectra and confirmed by single-crystal X-ray analysis. The structures and absolute stereochemistry of five of the other compounds were also established by X-ray crystal structure determination.

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“…In contrast to cebetin B, most previously known dimeric xanthones and anthraquinones have two similar tricyclic units forming symmetric or pseudosymmetric structures. [36][37][38] The nature of the linkage of the two tricyclic systems of cebetin B is also unique. The molecule has one sp2-sp3 linkage, C(4)-C(2'), directly connecting rings A and A' and a bridging sp3-sp3 bond, C(11)-C(4'a), between the two rings.…”

Section: Resultsmentioning

confidence: 99%

Cercospora beticola phytotoxins: cebetins that are photoactive, magnesium ion-binding, chlorinated anthraquinone-xanthone conjugates

Jalal¹,

Hossain²,

Robeson³

et al. 1992

J. Am. Chem. Soc.

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Two Cercospora beticola toxins, isolated from cultures of the sugar beet pathogen, were identified as tautomeric compounds and named cebetin A (1) and cebetin B (2). The structure of cebetin B (2) and its absolute configuration were determined by single-crystal X-ray diffraction. The structure of cebetin A (1) was elucidated on the basis of UV-visible, NMR, and mass spectral data. The molecular backbone of cebetins is totally different from that of the known phytotoxin cercosporin and comprises partially hydrogenated xanthone and anthraquinone moieties connected through two seven-membered rings.The xanthone and anthraquinone systems contain respectively a chlorine atom and an epoxide function. Cebetin B crystallizes in the orthorhombic space group P22{2, with a = 14.449 (3) Á, b = 22.269 (2) A, c = 14.061 (2) A, V = 4524.3 A3, Z = 4, and Z), = 1.369 g/cm3. The structure was determined from 3670 diffractometer data and refined to a final R = 0.066.In the crystal, cebetin B molecules exist as a dimeric complex, (C3, 2 013€1•2£ 3 )2 £2, where the two molecules of cebetin B share two Mg2+ ions and are related by a 2-fold axis. Spectroscopic data showed that cebetin A is a metal-free keto-enol tautomer of cebetin B. Both cebetins A and B at a concentration of 1 ppm were lethal to sugar beet cells in suspension culture in the presence of light. This effect was not observed in the absence of light.

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Fungal metabolites. Part VI. Crystal and molecular structure of secalonic acid A

Cited by 15 publications

References 0 publications

Insights into Ergochromes of the Plant Pathogen Claviceps purpurea

Insights into Ergochromes of the Plant Pathogen Claviceps purpurea

Isolation and Structure of Ruprechstyril from Ruprechtia tangarana^†,1

Cercospora beticola phytotoxins: cebetins that are photoactive, magnesium ion-binding, chlorinated anthraquinone-xanthone conjugates

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Fungal metabolites. Part VI. Crystal and molecular structure of secalonic acid A

Cited by 15 publications

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Insights into Ergochromes of the Plant Pathogen Claviceps purpurea

Insights into Ergochromes of the Plant Pathogen Claviceps purpurea

Isolation and Structure of Ruprechstyril from Ruprechtia tangarana†,1

Cercospora beticola phytotoxins: cebetins that are photoactive, magnesium ion-binding, chlorinated anthraquinone-xanthone conjugates

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Isolation and Structure of Ruprechstyril from Ruprechtia tangarana^†,1