Guang-Ying Chen

Bioactive Phenylalanine Derivatives and Cytochalasins from the Soft Coral-Derived Fungus, Aspergillus elegans

One new phenylalanine derivative 4′-OMe-asperphenamate (1), along with one known phenylalanine derivative (2) and two new cytochalasins, aspochalasin A1 (3) and cytochalasin Z24 (4), as well as eight known cytochalasin analogues (5–12) were isolated from the fermentation broth of Aspergillus elegans ZJ-2008010, a fungus obtained from a soft coral Sarcophyton sp. collected from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods. The absolute configuration of 1 was determined by chemical synthesis and Marfey’s method. All isolated metabolites (1–12) were evaluated for their antifouling and antibacterial activities. Cytochalasins 5, 6, 8 and 9 showed strong antifouling activity against the larval settlement of the barnacle Balanus amphitrite, with the EC50 values ranging from 6.2 to 37 μM. This is the first report of antifouling activity for this class of metabolites. Additionally, 8 exhibited a broad spectrum of antibacterial activity, especially against four pathogenic bacteria Staphylococcus albus, S. aureus, Escherichia coli and Bacillus cereus.

Aspergicin, a new antibacterial alkaloid produced by mixed fermentation of two marine-derived mangrove epiphytic fungi

A new alkaloid designated as aspergicin (1), together with a previous secondary metabolite, neoaspergillic acid (2), and a common compound, ergosterol (3), were isolated from the mixed cultured mycelia of two marine-derived mangrove epiphytic Aspergillus sp. fungi. Extensive application of 1D and 2D NMR techniques was made to characterize the structure and to establish the 1H and 13 C assignments of compound 1. In the antibacterial assays, both compounds 1 and 2 showed significant antibacterial activity against some selected Gram bacteria.

A new isochroman from the marine endophytic fungus 1893

A new isochroman, 6-hydroxy-3-methylisochroman-5-carboxylic acid, and six known compounds were isolated from the culture of marine-derived mangrove fungus 1893#. Their structures were elucidated by analysis of spectroscopic data.

A new fungicide produced by a Streptomyces sp. GAAS7310

Directed bioassay guided fraction led to a new macrodiolide antimycin A17 (1), isolated from a Streptomyces sp. GAAS7310, which showed significant antimicrobial activity against eleven fungal species, including Curvularia lunata (Wakker) Boed, Rhizopus nigrtcans Ehrb and Colletotrichum nigrum EL. et Halst. The structure was unambiguously established by interpretation of 1D and 2D NMR data and comparison with the known antimycin A1a.

Bioactive Anthraquinone Derivatives from the Mangrove-Derived Fungus Stemphylium sp. 33231

Four new anthraquinone derivatives (1-4) and four new alterporriol-type anthranoid dimers (14-17), along with 17 analogues, were isolated from the solid rice fermentation of the fungus Stemphylium sp. 33231 obtained from the mangrove Bruguiera sexangula var. rhynchopetala collected from the South China Sea. Their structures were elucidated using comprehensive spectroscopic methods. The absolute configurations of 1, 3, and 4 were determined by single-crystal X-ray diffraction of their derivatives (1a, 3b, and 4a). The absolute configurations of the chiral 17-19 were determined by comparing their CD spectra with 21. The inhibitory activities of most of the compounds against seven terrestrial pathogenic bacteria and two cancer cell lines were evaluated.

Antibacterial α-pyrone derivatives from a mangrove-derived fungus Stemphylium sp. 33231 from the South China Sea

Two new α-pyrone derivatives, infectopyrones A (1) and B (2), were obtained from the EtOAc extract of the endophytic fungus Stemphylium sp. 33231 isolated from the mangrove Brguiera sexangula var. rhynchopetala collected in the South China Sea. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. Compounds 1 and 2 were evaluated for their antibacterial activities, and they had a broad spectrum of antibacterial activity against five terrestrial pathogenic bacteria.

Isolation, 1H, 13C NMR Assignments, and crystal structure of chrodrimanin B from A marine fungus Aspergillus sp.

A terrestrial fungal metabolite, chrodrimanin B (1), has been isolated for the first time from the fermentation broth of a marine-derived fungus Aspergillus sp. collected from the South China Sea. Detailed assignments for the proton and carbon of 1 have been unambiguously elucidated by combined spectroscopic methods including 1D and 2D NMR spectral data, and the relative configurations were also confirmed by single- crystal X-ray data.

Bioactive Phenanthrene and Bibenzyl Derivatives from the Stems of Dendrobium nobile

A new enantiomeric pair of spirodiketones, (+)- and (-)-denobilone A (1 and 2), three new phenanthrene derivatives (3-5), and three new biphenanthrenes (22-24), along with 11 known phenanthrene derivatives (6-16), five known bibenzyl derivatives (17-21), and four known biphenanthrenes (25-28), were isolated from Dendrobium nobile. The structures of 1-5 and 22-24 were elucidated using comprehensive spectroscopic methods. (+)-Denobilone and (-)-denobilone A (1 and 2) were isolated as a pair of enantiomers by chiral HPLC. The absolute configurations of (+)- and (-)-denobilone A (1 and 2) were determined by comparing their experimental and calculated electronic circular dichroism spectra. The absolute configuration of denobilone B (3) was determined by X-ray crystallographic analysis. The inhibitory activities of all compounds against nine phytopathogenic fungi and three cancer cell lines were evaluated.

3'-O, 4'-O-aromatic acyl substituted 7,8-pyranocoumarins: a new class of P-glycoprotein modulators.

Objectives  P‐glycoprotein (Pgp) overexpression in tumour cells leads to multidrug resistance (MDR) and causes failure in cancer chemotherapy. We have previously identified (±)‐praeruptorin A (PA) as a potential lead compound for Pgp modulators. In this study we investigated the MDR‐reversing activities of PA derivatives.

Xanthones from the roots of Calophyllum membranaceum

0009-3130/11/4606-0976 2011 Springer Science+Business Media, Inc. 1) Key Laboratory of Tropical Medicinal Plant Chemistry of Hainan Province, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, P. R. China, fax: 0086 898 65889422, e-mail:hchr116@hainnu.edu.cn; 2) Institute of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002, P. R. China; 3) College of Chemistry and Life Science, China Three Gorges University, Yichang 443002, P. R. China. Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 830–831, November–December, 2010. Original article submitted July 7, 2009. Chemistry of Natural Compounds, Vol. 46, No. 6, 2011