101
|
Sun P, Yu Q, Li J, Riccio R, Lauro G, Bifulco G, Kurtán T, Mándi A, Tang H, Li TJ, Zhuang CL, Gerwick WH, Zhang W. Bissubvilides A and B, Cembrane-Capnosane Heterodimers from the Soft Coral Sarcophyton subviride. JOURNAL OF NATURAL PRODUCTS 2016; 79:2552-2558. [PMID: 27704808 DOI: 10.1021/acs.jnatprod.6b00453] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two new biscembranoid-like compounds, bissubvilides A (1) and B (2), were isolated together with sarsolilide B (3), the proposed biogenetic precursor to 1, from the soft coral Sarcophyton subviride. The structures and absolute configurations were solved by spectroscopic analysis and TDDFT/ECD and DFT/NMR calculations. The bissubvilides represent a novel biscembranoid-like skeleton presumed to derive from a cembrane-type diene and a capnosane-type dienophile via a Diels-Alder reaction. These two molecules exerted no cytotoxicity against MG-63 or A549 tumor cells or HuH7 tumor stem cells.
Collapse
|
102
|
Akone SH, Mándi A, Kurtán T, Hartmann R, Lin W, Daletos G, Proksch P. Inducing secondary metabolite production by the endophytic fungus Chaetomium sp. through fungal–bacterial co-culture and epigenetic modification. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.08.022] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
103
|
Zhou ZF, Kurtán T, Mándi A, Gu YC, Yao LG, Xin GR, Li XW, Guo YW. Novel and Neuroprotective Tetranortriterpenoids from Chinese Mangrove Xylocarpus granatum Koenig. Sci Rep 2016; 6:33908. [PMID: 27658619 PMCID: PMC5034266 DOI: 10.1038/srep33908] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/02/2016] [Indexed: 11/23/2022] Open
Abstract
Eight new tetranortriterpenoids (1–8) were isolated from the twigs and leaves of the Chinese mangrove plant Xylocarpus granatum, together with four related known ones (9–12). The structures of new compounds were elucidated by detailed spectroscopic analysis. The absolute configuration of 9-epixylogranatin A (1) was determined by time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) calculations of the solution conformers. Xylogranatumin A (2) represents the first example of the 9, 10-seco limonoid with an unprecedented oxygen-bridged B ring (2,7-dioxabicyclo[2.2.1]-heptane). All the isolates were evaluated for the in vitro neuroprotective activity, both compounds 11 and 12 displayed moderate effects against H2O2-induced neurotoxicity in PC12 cells at the concentration of 10 μM, with an increase in cell viability of 12.0% and 11.6%, respectively.
Collapse
|
104
|
Liu S, Dai H, Makhloufi G, Heering C, Janiak C, Hartmann R, Mándi A, Kurtán T, Müller WEG, Kassack MU, Lin W, Liu Z, Proksch P. Cytotoxic 14-Membered Macrolides from a Mangrove-Derived Endophytic Fungus, Pestalotiopsis microspora. JOURNAL OF NATURAL PRODUCTS 2016; 79:2332-2340. [PMID: 27556865 DOI: 10.1021/acs.jnatprod.6b00473] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Seven new 14-membered macrolides, pestalotioprolides C (2), D-H (4-8), and 7-O-methylnigrosporolide (3), together with four known analogues, pestalotioprolide B (1), seiricuprolide (9), nigrosporolide (10), and 4,7-dihydroxy-13-tetradeca-2,5,8-trienolide (11), were isolated from the mangrove-derived endophytic fungus Pestalotiopsis microspora. Their structures were elucidated by analysis of NMR and MS data and by comparison with literature data. Single-crystal X-ray diffraction analysis was used to confirm the absolute configurations of 1, 2, and 10, while Mosher's method and the TDDFT-ECD approach were applied to determine the absolute configurations of 5 and 6. Compounds 3-6 showed significant cytotoxicity against the murine lymphoma cell line L5178Y with IC50 values of 0.7, 5.6, 3.4, and 3.9 μM, respectively, while compound 5 showed potent activity against the human ovarian cancer cell line A2780 with an IC50 value of 1.2 μM. Structure-activity relationships are discussed. Coculture of P. microspora with Streptomyces lividans caused a roughly 10-fold enhanced accumulation of compounds 5 and 6 compared to axenic fungal control.
Collapse
|
105
|
Zhang P, Li XM, Mao XX, Mándi A, Kurtán T, Wang BG. Varioloid A, a new indolyl-6,10b-dihydro-5a H-[1]benzofuro[2,3- b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291. Beilstein J Org Chem 2016; 12:2012-2018. [PMID: 27829905 PMCID: PMC5082447 DOI: 10.3762/bjoc.12.188] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/26/2016] [Indexed: 11/23/2022] Open
Abstract
A new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative, varioloid A (1), was isolated from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291. Its structure was elucidated on the basis of extensive analysis of 1D and 2D NMR data and the absolute configuration was determined by time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) calculations. A similar compound, whose planar structure was previously described but the relative and absolute configurations and 13C NMR data were not reported, was also identified and was tentatively named as varioloid B (2). Both compounds 1 and 2 exhibited cytotoxicity against A549, HCT116, and HepG2 cell lines, with IC50 values ranging from 2.6 to 8.2 µg/mL.
Collapse
|
106
|
Zhou H, Li L, Wu C, Kurtán T, Mándi A, Liu Y, Gu Q, Zhu T, Guo P, Li D. Penipyridones A-F, Pyridone Alkaloids from Penicillium funiculosum. JOURNAL OF NATURAL PRODUCTS 2016; 79:1783-1790. [PMID: 27359163 DOI: 10.1021/acs.jnatprod.6b00218] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Six new pyridone alkaloids, named penipyridones A-F (1-6), were isolated from the fermentation broth of an Antarctic moss-derived fungus, Penicillium funiculosum GWT2-24. Their structures were elucidated from extensive NMR and MS data. Although they possess the same major chromophore and some of them presented almost mirror ECD spectra, their absolute configurations were found to be uniformly S, as evidenced by X-ray single-crystal diffraction analysis, stereocontrolled total synthesis, and chemical conversions. TDDFT-ECD calculations of compounds 3 and 6 revealed that subtle conformational changes are responsible for the significantly different ECD curves. None of the compounds were cytotoxic (IC50 > 50 μM), while compounds 1, 2, 5, and 7 elicited lipid-lowering activity in HepG2 hepatocytes.
Collapse
|
107
|
Meng LH, Mándi A, Li XM, Liu Y, Kurtán T, Wang BG. Isolation, Stereochemical Study, and Antioxidant Activity of Benzofuranone Derivatives from a Mangrove-derived FungusEurotium rubrumMA-150. Chirality 2016; 28:581-4. [DOI: 10.1002/chir.22613] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 04/11/2016] [Accepted: 05/03/2016] [Indexed: 12/29/2022]
|
108
|
Zhang H, Saurav K, Yu Z, Mándi A, Kurtán T, Li J, Tian X, Zhang Q, Zhang W, Zhang C. α-Pyrones with Diverse Hydroxy Substitutions from Three Marine-Derived Nocardiopsis Strains. JOURNAL OF NATURAL PRODUCTS 2016; 79:1610-1618. [PMID: 27300427 DOI: 10.1021/acs.jnatprod.6b00175] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Eight new α-pyrones 1-8 and three known α-pyrones 9-11 were isolated from three marine-derived Nocardiopsis strains SCSIO 10419, SCSIO 04583, and SCSIO KS107. The structures of compounds 1-8 were elucidated by comprehensive spectral analyses. The absolute configurations of 4-deoxyphomapyrone C (1), 4-deoxy-11-hydroxyphomapyrone C (3), 4-deoxy-7R-hydroxyphomapyrone C (5), and phomapyrone C (11) were determined by TDDFT-ECD calculations for the solution conformers, which revealed that the conformation of the side chain was decisive for the sign of the characteristic high-wavelength ECD transition. (-)-4-Deoxy-8-hydroxyphomapyrone C (4) was isolated from SCSIO 10419 and was deduced as a diastereomeric mixture containing (8S)- and (8R)-4-deoxy-8-hydroxyphomapyrone C in a ratio of 2.6:1 (8R:8S), by chiral-phase HPLC analysis and Mosher's ester analysis. Interestingly, 7-hydroxymucidone (9) was isolated from both SCSIO 04583 and SCSIO KS107, as an enantiomeric mixture containing (7S)-hydroxymucidone (major in 9 from SCSIO 04583) and (7R)-hydroxymucidone (major in 9 from SCSIO KS107). α-Pyrones 3-5 were identified as three isomers of phomapyrone C (11) with diverse hydroxy substitutions. α-Pyrones 10-hydroxymucidone (6), 4-hydroxymucidone (8), and 9, differed in the position of the hydroxy group. Several α-pyrones exhibited moderate growth inhibitory activity against Micrococcus luteus and Bacillus subtilis.
Collapse
|
109
|
Elnaggar MS, Ebada SS, Ashour ML, Ebrahim W, Müller WE, Mándi A, Kurtán T, Singab A, Lin W, Liu Z, Proksch P. Xanthones and sesquiterpene derivatives from a marine-derived fungus Scopulariopsis sp. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.03.073] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
110
|
Liu Y, Kurtán T, Yun Wang C, Han Lin W, Orfali R, Müller WE, Daletos G, Proksch P. Cladosporinone, a new viriditoxin derivative from the hypersaline lake derived fungus Cladosporium cladosporioides. J Antibiot (Tokyo) 2016; 69:702-6. [PMID: 26905758 DOI: 10.1038/ja.2016.11] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/14/2016] [Accepted: 01/20/2016] [Indexed: 02/05/2023]
Abstract
A new cytotoxic viriditoxin derivative, cladosporinone (1), along with the known viriditoxin (2) and two viriditoxin derivatives (3 and 4) were obtained from the fungus Cladosporium cladosporioides isolated from the sediment of a hypersaline lake in Egypt. The structure of the new compound (1) was determined by 1D and 2D NMR measurements as well as by high-resolution ESIMS and electronic circular dichroism spectroscopy. All isolated compounds were studied for their cytotoxicity against the murine lymphoma cell line L5187Y and for their antibiotic activity against several pathogenic bacteria. Viriditoxin (2) was the most active compound in both bioassays. Compound 1 also exhibited strong cytotoxicity against the murine lymphoma cell line L5187Y with an IC50 value of 0.88 μm, whereas its antibiotic activity was weak.
Collapse
|
111
|
Wu G, Yu G, Kurtán T, Mándi A, Peng J, Mo X, Liu M, Li H, Sun X, Li J, Zhu T, Gu Q, Li D. Versixanthones A-F, Cytotoxic Xanthone-Chromanone Dimers from the Marine-Derived Fungus Aspergillus versicolor HDN1009. JOURNAL OF NATURAL PRODUCTS 2015; 78:2691-2698. [PMID: 26506221 DOI: 10.1021/acs.jnatprod.5b00636] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Six unusual xanthone-chromanone dimers, versixanthones A-F (1-6), featuring different formal linkages of tetrahydroxanthone and 2,2-disubstituted chroman-4-one monomers, were isolated from a culture of the mangrove-derived fungus Aspergillus versicolor HDN1009. The absolute configurations of 1-6, representing the central and axial chirality elements or preferred helicities, were established by a combination of X-ray diffraction analysis, chemical conversions, and TDDFT-ECD calculations. The interconversion of different biaryl linkages between 1 and 4 and between 2 and 3 in DMSO by a retro-oxa-Michael mechanism provided insight into the formation of the xanthone-chromanone dimers and supported the assignments of their absolute configurations. Compounds 1-6 exhibited cytotoxicities against the seven tested cancer cell lines, with the best IC50 value of 0.7 μM. Compound 5 showed further inhibitory activity against topoisomerase I.
Collapse
|
112
|
Mándi A, Mudianta IW, Kurtán T, Garson MJ. Absolute Configuration and Conformational Study of Psammaplysins A and B from the Balinese Marine Sponge Aplysinella strongylata. JOURNAL OF NATURAL PRODUCTS 2015; 78:2051-2056. [PMID: 26237370 DOI: 10.1021/acs.jnatprod.5b00369] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The absolute configuration of psammaplysin A (1) has been assigned as (6R,7R) using experimental and calculated electronic circular dichroism (ECD) data and NMR analysis of MPA esters prepared from the acetamide derivative of 1. Detailed conformational analyses of a truncated model compound of 1 with an in vacuo method and with the PCM solvent model for MeOH have identified the major conformers and factors governing the ECD spectrum of 1. The correlation of the ECD data with the stereochemistry of 1 allows configurational assignment of related psammaplysin analogues on the basis of their ECD spectra.
Collapse
|
113
|
Turcsi E, Murillo E, Kurtán T, Szappanos Á, Illyés TZ, Gulyás-Fekete G, Agócs A, Avar P, Deli J. Isolation of β-Cryptoxanthin-epoxides, Precursors of Cryptocapsin and 3'-Deoxycapsanthin, from Red Mamey (Pouteria sapota). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:6059-6065. [PMID: 26057604 DOI: 10.1021/acs.jafc.5b01936] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
From an extract of red mamey (Pouteria sapota) β-cryptoxanthin-5,6-epoxide, β-cryptoxanthin-5',6'-epoxide, 3'-deoxycapsanthin, and cryptocapsin were isolated and characterized by UV-vis spectroscopy, electronic circular dichroism (ECD), nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry (MS). Epoxidation of β-cryptoxanthin delivered the β-(5'R,6'S)- and (5'S,6'R)-cryptoxanthin-5',6'-epoxides, which were identified by HPLC-ECD analysis. These carotenoids among others are quite common in the fruits of Central America, and as they are natural provitamins A, they should play an important role in the diet of the mostly vitamin A deficient population of this region.
Collapse
|
114
|
Pérez Hemphill CF, Daletos G, Hamacher A, Kassack MU, Lin W, Mándi A, Kurtán T, Proksch P. Absolute configuration and anti-tumor activity of torrubiellin B. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.03.126] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
115
|
Zhu J, Ye Y, Ning M, Mándi A, Feng Y, Zou Q, Kurtán T, Leng Y, Shen J. Corrigendum: Design, Synthesis, and Structure-Activity Relationships of 3,4,5-Trisubstituted 4,5-Dihydro-1,2,4-oxadiazoles as TGR5 Agonists. ChemMedChem 2015. [DOI: 10.1002/cmdc.201500054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
116
|
Liu Y, Marmann A, Abdel-Aziz MS, Wang CY, Müller WEG, Lin WH, Mándi A, Kurtán T, Daletos G, Proksch P. Tetrahydroanthraquinone Derivatives from the Endophytic FungusStemphylium globuliferum. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500079] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
117
|
Zhang P, Meng LH, Mándi A, Li XM, Kurtán T, Wang BG. Correction: structure, absolute configuration, and conformational study of resorcylic acid derivatives and related congeners from the fungus Penicillium brocae. RSC Adv 2015. [DOI: 10.1039/c5ra90054a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Correction for ‘Structure, absolute configuration, and conformational study of resorcylic acid derivatives and related congeners from the fungus Penicillium brocae’ by Peng Zhang et al., RSC Adv., 2015, 5, 39870–39877.
Collapse
|
118
|
Zhang P, Meng LH, Mándi A, Li XM, Kurtán T, Wang BG. Structure, absolute configuration, and conformational study of resorcylic acid derivatives and related congeners from the fungus Penicillium brocae. RSC Adv 2015. [DOI: 10.1039/c5ra02203g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A new resorcylic acid derivative (4) and five new loop-opened resorcylic acid-related congeners (5–9), were identified from the marine mangrove-derived endophyte Penicillium brocae MA-192. All compounds were evaluated for the antioxidant activity against DPPH and ABTS radicals.
Collapse
|
119
|
Macabeo APG, Martinez FPA, Kurtán T, Tóth L, Mándi A, Schmidt S, Heilmann J, Alejandro GJD, Knorn M, Dahse HM, Franzblau SG. Tetrahydroxanthene-1,3(2H)-dione derivatives from Uvaria valderramensis. JOURNAL OF NATURAL PRODUCTS 2014; 77:2711-5. [PMID: 25372601 DOI: 10.1021/np500538c] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Two tetrahydroxanthene-1,3(2H)-dione metabolites, valderramenols A (1) and B (2), were isolated from the Philippine endemic Annonaceous species Uvaria valderramensis. Planar structures of the rac-xanthene-1,3-(2H)-diones 1 and 2 were established by MS and NMR measurements. Their enantiomers were separated by chiral HPLC, and the absolute configurations of the separated enantiomers were determined by comparison of the HPLC-ECD spectra with computed TDDFT-generated spectra. A TDDFT-ECD study of the known grandiuvarone (3) allowed the revision of its absolute configuration as S. Compound 1 showed antitubercular activity (MIC 10 μg/mL), while 3 and 4 had weaker activities (MIC 32 μg/mL). Oxepinone 3 exhibited cytotoxic activity against KB-562, a chronic myeloid leukemia cell line.
Collapse
|
120
|
Tóth L, Fu Y, Zhang HY, Mándi A, Kövér KE, Illyés TZ, Kiss-Szikszai A, Balogh B, Kurtán T, Antus S, Mátyus P. Preparation of neuroprotective condensed 1,4-benzoxazepines by regio- and diastereoselective domino Knoevenagel-[1,5]-hydride shift cyclization reaction. Beilstein J Org Chem 2014; 10:2594-602. [PMID: 25550721 PMCID: PMC4273254 DOI: 10.3762/bjoc.10.272] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 10/16/2014] [Indexed: 11/23/2022] Open
Abstract
Condensed O,N-heterocycles containing tetrahydro-1,4-benzoxazepine and tetrahydroquinoline moieties were prepared by a regio- and diastereoselective domino Knoevenagel–[1,5]-hydride shift cyclization reaction of a 4-aryl-2-phenyl-1,4-benzoxazepine derivative obtained from flavanone. The relative configuration of products were determined by the correlation of 3JH,H coupling data with the geometry of major conformers accessed by DFT conformational analysis. Separated enantiomers of the products were characterized by HPLC-ECD data, which allowed their configurational assignment on the basis of TDDFT-ECD calculation of the solution conformers. Two compounds showed neuroprotective activities against hydrogen peroxide (H2O2) or β-amyloid25–35 (Aβ25–35)-induced cellular injuries in human neuroblastoma SH-SY5Y cells in the range of those of positive controls.
Collapse
|
121
|
Zhang P, Mándi A, Li XM, Du FY, Wang JN, Li X, Kurtán T, Wang BG. Varioxepine A, a 3H-Oxepine-Containing Alkaloid with a New Oxa-Cage from the Marine Algal-Derived Endophytic Fungus Paecilomyces variotii. Org Lett 2014; 16:4834-7. [DOI: 10.1021/ol502329k] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
122
|
Luan Y, Wei H, Zhang Z, Che Q, Liu Y, Zhu T, Mándi A, Kurtán T, Gu Q, Li D. Eleganketal A, a highly oxygenated dibenzospiroketal from the marine-derived fungus Spicaria elegans KLA03. JOURNAL OF NATURAL PRODUCTS 2014; 77:1718-1723. [PMID: 24967847 DOI: 10.1021/np500458a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Eleganketal A (1), a naturally occurring aromatic polyketide possessing a rare highly oxygenated spiro[isobenzofuran-1,3'-isochroman] ring system, was isolated from the fungus Spicaria elegans KLA03 by culturing it in a modified mannitol-based medium. The structure of 1 including the absolute configuration was determined by combining spectroscopic analysis, synthesis of the racemic permethylated analogue, chiral-phase HPLC separation, and TDDFT-ECD analysis.
Collapse
|
123
|
Zhou ZF, Kong LY, Kurtán T, Liu HL, Mándi A, Li J, Gu YC, Guo YW. Four phragmalin orthoesters from the Chinese mangrove Xylocarpus granatum. PLANTA MEDICA 2014; 80:949-954. [PMID: 25029177 DOI: 10.1055/s-0034-1382840] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Four new 8,9,30-phragmalin orthoesters (1-4), along with six related known compounds, namely xyloccensins O-S (5-9) and V (10), were isolated and characterized from the twigs and leaves of the Chinese mangrove Xylocarpus granatum. The structures of the new compounds were determined on the basis of extensive spectroscopic analysis and by comparison with those of related known compounds in the literature. The absolute configuration of xyloccensin Q (7) was revised as its enantiomer by X-ray diffraction analysis employing graphite monochromated Cu Kα radiation (λ=1.54178 Å) with a Flack parameter of -0.04 and was further secured by a time-dependent density functional theory electronic circular dichroism (TDDFT ECD) calculation. Consequently, the absolute configurations of xyloccensins O (5), P (6), R (8), S (9), and V (10) were all corrected as their corresponding enantiomers, respectively. Xyloccensin S (9) exhibited inhibitory activity against protein tyrosine phosphatase 1B, a potential drug target for the treatment of type II diabetes and obesity, with an IC50 value of 8.72 µg/mL.
Collapse
|
124
|
Németh I, Kiss-Szikszai A, Illyés TZ, Mándi A, Komáromi I, Kurtán T, Antus S. Oxidative Rearrangement of Flavanones with Thallium(III) Nitrate, Lead Tetraacetate and Hypervalent Iodines in Trimethyl Orthoformate and Perchloric or Sulfuric Acid. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2014. [DOI: 10.5560/znb.2012-0214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
An HPLC monitoring protocol has been developed to follow the reaction of flavanone [(±)-1] with thallium(III) nitrate, lead tetracetate, phenyliodonium diacetate (PIDA) or [hydroxyl( tosyloxy)iodo]benzene in trimethyl orthoformate. Besides the major ring-contraction product, the 2,3-dihydrobenzo[b]furan derivative (±)-4a, minor components were also identified, and their structures including the relative stereochemistry and a plausible mechanism of formation are reported and compared with literature data. The oxidation reactions were monitored by HPLC at different conditions, and the structure and the ratio of the products were determined and compared. The preferred formation of flavone (5) from (±)-flavanone (1) by PIDA is explained by quantum-chemical calculations on the intermediate formed by the addition of this reagent to the enol ether derivative of (±)-1.
Collapse
|
125
|
Xu DX, Sun P, Kurtán T, Mándi A, Tang H, Liu B, Gerwick WH, Wang ZW, Zhang W. Polyhydroxy cyclohexanols from a Dendrodochium sp. fungus associated with the sea cucumber Holothuria nobilis Selenka. JOURNAL OF NATURAL PRODUCTS 2014; 77:1179-1184. [PMID: 24749951 DOI: 10.1021/np500024r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Four cyclohexanol analogues, dendrodochols A-D (1-4), were isolated from a Dendrodochium sp. fungus associated with the sea cucumber Holothuria nobilis Selenka collected from the South China Sea. The structures were elucidated by means of detailed spectroscopic analysis. The absolute configurations were assigned using a solution TDDFT/ECD calculation approach and the modified Mosher's method. In an in vitro bioassay, these compounds exhibited no growth inhibition activity against the A549 and MG63 cell lines. Dendrodochols 1 and 3 exhibited modest antifungal activity against Candida strains, Cryptococcus neoformans, and Trichophyton rubrum, whereas 2 and 4 showed no activity against the tested strains.
Collapse
|