Byssochlamic Acid Research Articles

A New Dihydrochromone Dimer and Other Secondary Metabolites from Cultures of the Marine Sponge-Associated Fungi Neosartorya fennelliae KUFA 0811 and Neosartorya tsunodae KUFC 9213.

A previously unreported dihydrochromone dimer, paecilin E (1), was isolated, together with eleven known compounds: β-sitostenone, ergosta-4,6,8 (14), 22-tetraen-3-one, cyathisterone, byssochlamic acid, dehydromevalonic acid lactone, chevalone B, aszonalenin, dankasterone A (2), helvolic acid, secalonic acid A and fellutanine A, from the culture filtrate extract of the marine sponge-associated fungus Neosartorya fennelliae KUFA 0811. Nine previously reported metabolites, including a chromanol derivative (3), (3β, 5α, 22E), 3,5-dihydroxyergosta-7,22-dien-6-one (4), byssochlamic acid, hopan-3β,22-diol, chevalone C, sartorypyrone B, helvolic acid, lumichrome and the alkaloid harmane were isolated from the culture of the marine-sponge associated fungus Neosartorya tsunodae KUFC 9213. Paecilin E (1), dankasterone A (2), a chromanol derivative (3), (3β, 5α, 22E)-3,5-dihydroxyergosta-7,22-dien-6-one (4), hopan-3β,22-diol (5), lumichrome (6), and harmane (7) were tested for their antibacterial activity against Gram-positive and Gram-negative reference and multidrug-resistant strains isolated from the environment. While paecilin E (1) was active against S. aureus ATCC 29213 and E. faecalis ATCC 29212, dankastetrone A (2) was only effective against E. faecalis ATCC 29212 and the multidrug-resistant VRE E. faecalis A5/102. Both compounds neither inhibit biofilm mass production in any of the strains at the concentrations tested nor exhibit synergistic association with antibiotics.

A New Nonadride Derivative from the Co-Culture Broth of Two Mangrove Fungi

A new nonadride derivative, named (–)-byssochlamic acid imide (1), was isolated from the co-culture broth of two mangrove fungi (strain Nos. K38 and E33). Their structures were established by comprehensive spectroscopic analyses. Primary bioassays showed that 1 had moderate in vitro antifungal activities against Fusarium graminearum Schw. and Fusarium oxysporum Schlecht. f. sp. lycopersici (Sacc.) W. C. Snyder et H. N. Hansen, as compared with the positive control carbendazim.

Heterologous Production of Fungal Maleidrides Reveals the Cryptic Cyclization Involved in their Biosynthesis.

Fungal maleidrides are an important family of bioactive secondary metabolites that consist of 7, 8, or 9‐membered carbocycles with one or two fused maleic anhydride moieties. The biosynthesis of byssochlamic acid (a nonadride) and agnestadride A (a heptadride) was investigated through gene disruption and heterologous expression experiments. The results reveal that the precursors for cyclization are formed by an iterative highly reducing fungal polyketide synthase supported by a hydrolase, together with two citrate‐processing enzymes. The enigmatic ring formation is catalyzed by two proteins with homology to ketosteroid isomerases, and assisted by two proteins with homology to phosphatidylethanolamine‐binding proteins.

Novel nonadride, heptadride and maleic acid metabolites from the byssochlamic acid producer Byssochlamys fulva IMI 40021 - an insight into the biosynthesis of maleidrides.

The filamentous fungus Byssochlamys fulva strain IMI 40021 produces (+)-byssochlamic acid 1, its novel dihydroanalogue 2 and four related secondary metabolites. Agnestadrides A, 17 and B, 18 constitute a novel class of seven-membered ring, maleic anhydride-containing (hence termed heptadride) natural products. The putative maleic anhydride precursor 5 for both nonadride and heptadride biosynthesis was isolated as a fermentation product for the first time and its structure confirmed by synthesis. Acid 5 undergoes facile decarboxylation to anhydride 6. The generic term maleidrides is proposed to encompass biosynthetically-related compounds containing maleic anhydride moieties fused to an alicyclic ring, varying in size and substituents.

In vitro cytotoxicity of fungi spoiling maize silage

Penicillium roqueforti, Penicillium paneum, Monascus ruber, Alternaria tenuissima, Fusarium graminearum, Fusarium avenaceum, Byssochlamys nivea and Aspergillus fumigatus have previously been identified as major fungal contaminants of Danish maize silage. In the present study their metabolite production and in vitro cytotoxicity have been determined for fungal agar and silage extracts. All 8 fungal species significantly affected Caco-2 cell viability in the resazurin assay, with large variations for each species and growth medium. The 50% inhibition concentrations (IC50) of the major P. roqueforti metabolites roquefortine C (48μg/mL), andrastin A (>50μg/mL), mycophenolic acid (>100μg/mL) and 1-hydroxyeremophil-7(11),9(10)-dien-8-one (>280μg/mL) were high. Fractionating of agar extracts identified PR-toxin as an important cytotoxic P. roqueforti metabolite, also detectable in maize silage. The strongly cytotoxic B. nivea and P. paneum agar extracts contained patulin above the IC50 of 0.6μg/mL, however inoculated onto maize silage B. nivea and P. paneum did not produce patulin (>371μg/kg). Still B. nivea infected maize silage containing mycophenolic acid (∼50mg/kg), byssochlamic acid and other metabolites, was cytotoxic. In contrast hot-spots of P. roqueforti, P. paneum, M. ruber and A. fumigatus were not more cytotoxic than uninoculated silage.

A new diimide derivative from the co-culture broth of two mangrove fungi (strain no. E33 and K38)

A new diimide derivative, named ( − )-byssochlamic acid bisdiimide (1), was isolated from the mixed broth of two mangrove fungi (strain no. K38 and E33) from the South China sea coast. The structure of 1 was determined by comprehensive spectroscopic methods, including 1D and 2D NMR (COSY, HMQC, and HMBC) and semi-synthesis. Primary bioassays showed that 1 had weak cytotoxic activity against Hep-2 and HepG2 cells.

Polyphasic taxonomy of the heat resistant ascomycete genus <I>Byssochlamys</I> and its <I>Paecilomyces</I> anamorphs

Byssochlamys and related Paecilomyces strains are often heat resistant and may produce mycotoxins in contaminated pasteurised foodstuffs. A comparative study of all Byssochlamys species was carried out using a polyphasic approach to find characters that differentiate species and to establish accurate data on potential mycotoxin production by each species. Phylogenetic analysis of the ITS region, parts of the beta-tubulin and calmodulin genes, macro- and micromorphological examinations and analysis of extrolite profiles were applied. Phylogenetic analyses revealed that the genus Byssochlamys includes nine species, five of which form a teleomorph, i.e. B. fulva, B. lagunculariae, B. nivea, B. spectabilis and B. zollerniae, while four are asexual, namely P. brunneolus, P. divaricatus, P. formosus and P. saturatus. Among these, B. nivea produces the mycotoxins patulin and byssochlamic acid and the immunosuppressant mycophenolic acid. Byssochlamys lagunculariae produces byssochlamic acid and mycophenolic acid and thus chemically resembles B. nivea. Some strains of P. saturatus produce patulin and brefeldin A, while B. spectabilis (anamorph P. variotii s.s.) produces viriditoxin. Some micro- and macromorphological characters are valuable for identification purposes, including the shape and size of conidia and ascospores, presence and ornamentation of chlamydospores, growth rates on MEA and CYA and acid production on CREA. A dichotomous key is provided for species identification based on phenotypical characters.

A new nonadride derivative from mangrove fungus (strain No. k38)

A new nonadride derivative, ( − )-1-hydroxybyssochlamic acid (1) and the known ( − )-byssochlamic acid (2) were isolated from mangrove fungus (strain No. k38) collected from the South China Sea coast. The structure and relative configuration of 1 were elucidated by spectral data and X-ray diffraction analysis. Primary bioassays showed that 2 had medium cytotoxic activity against HEp-2 and HepG2 Cells, and 1 exhibited weak activity.

Isolation and crystal structure of (−)-byssochlamic acid from mangrove fungus (strain no. k38)

(−)-Byssochlamic acid (1) was isolated from mangrove fungus (strain No. k38) from the South China Sea coast. This is the first time that 1 was found in nature. Its structure was confirmed by spectra data and X-ray diffraction analysis.

Enantiospecific Synthesis of (+)-Byssochlamic Acid, a Nonadride from the Ascomycete Byssochlamys fulva

A photoaddition−cycloreversion strategy applicable to enantiospecific synthesis of natural byssochlamic acid and its enantiomer was developed in which porcine liver esterase (PLE) catalyzed hydrolysis of 24 was used to desymmetrize this dimethyl ester to give (R)-25. Analogous PLE catalyzed hydrolysis of dimethyl ester 32 and bis(methylthio)methyl ester 48, while highly regioselective, gave racemic half acids 33 and 49, respectively. Stepwise coupling of (±)-49 and (R)-46, the latter derived from 25, afforded diolide 52, which upon irradiation gave exo,exo and exo,endo [2 + 2] photoadducts 53 and 54, respectively. The photoadducts underwent thermal cycloreversion to produce nine-membered bislactones 55 and 56. Conversion of these lactones via 1,5-cyclononadienes 57 and 58 to (+)-byssochlamic acid (3) was accompanied by acid-catalyzed epimerization of the n-propyl substituent. Stepwise coupling of (S)-60 (the enantiomer of 46) with (±)-49 led to diolide 63, which upon photoaddition−cycloreversion gave bis-...

Heat-resistant fungi of importance to the food and beverage industry.

Spoilage of pasteurized and canned fruit and fruit products caused by heat-resistant molds have been reported repeatedly in recent years. Species most commonly implicated in fruit and fruit product disintegration are Byssochlamys fulva, Byssochlamys nivea, Neosartorya fischeri, Talaromyces flavus, and Eupenicillium brefeldianum. These organisms are saprophytic rather than parasitic and usually contaminate fruits on or near the ground. They can survive heat treatments used for fruit processing and can grow and spoil the products during storage at room temperature, which results in great economic losses. Mold heat resistance is attributed to the formation of sexual spores, ascospores. Ascospores have a wide range of heat resistance, depending on species, strain, age of organism, heating medium, pH, presence of sugars, fats, and acids in heating medium, growth conditions, etc. The mechanism(s) of thermoresistance are not clear; probably some very stable compound(s) critical to germination and outgrowth are present in the heat-resistant ascospores. Besides spoilage, the heat-resistant molds produce a number of toxic secondary metabolites, such as byssotoxin A; byssochlamic acid; the carcinogen, patulin, the tremorgenic substances, fumitremorgin A and C, and verruculogen; fischerin, which caused fatal peritonitis in mice; and eupenifeldin, a compound possessing cytotoxicity as well as in vivo antitumor activity. Growth of heat-resistant fungi can be controlled by lowering the water activity, adding sulfur dioxide, sorbate, or benzoate; washing of fruits in hypochlorite solution before heat treatment reduces the number of ascospores and makes the heat destruction more successful. More research is needed to elucidate the mechanism(s) of thermoresistance and develop new methods for the complete inactivation of resistant ascospores.

Total synthesis of (.+-.)-byssochlamic acid

Total synthesis of (.+-.)-byssochlamic acid

Structural role of an unsaturated lactone in acute toxicity of rubratoxin B isolated from Penicillium rubrum

AbstractRubratoxin B is a substituted higher homolog of byssochlamic acid in which the ethyl group is replaced by a six‐membered ring containing an unsaturated lactone. Hydrogenation of the unsaturated lactone greatly reduces the acute toxixity of the compound. The acute median lethal doses of rubratoxin B and hydrogenated rubratoxin in male mice were 5.6 and 31 mg/kg, respectively. Pretreatment with phenobarbital (60 rag/kg × 4 days) or with SKF 525A (40 mg/kg) failed to significantly alter the toxicity of either compound. Histopathological examination of mice treated with rubratoxin B (3.5 mg/kg) revealed areas of hepatic zonal necrosis and marked necrosis of kidney tubules. No necrosis was observed in mice treated with hydrogenated rubratoxin (20 mg/kg). Hepatic microsomal mixed function oxidase activity was significantly reduced in mice pretreated with rubratoxin B (0.5 mg/kg × 4 days), while pretreatment with hydrogenated rubratoxin (2.5 mg/kg × 4 days) failed to depress microsomal activity. Our studies document the requirement of an alpha, beta unsaturated lactone ring for rubratoxin B toxicity. Based on the results from these studies the mechanism for rubratoxin B induced toxicity is postulated to be due to its electrophilic properties and subsequent alkylating activity.

1H‐ und 13C‐NMR.‐Spektroskopie der Nonadride

1H‐ and 13C‐NMR. Spectroscopy of the NonadridesThe 1H‐ and 13C‐NMR. spectra of the nonadrides glaucanic acid (1), glauconic acid (2), heveadride (3), byssochlamic acid (4), scytalidin (5), rubratoxin A (6), and rubratoxin B (7) have been measured. Partial decoupling experiments permitted assignment of the majority of the signals.

Survey of selected mycotoxins in food.

The contamination of a variety of foods with the mycotoxins aflatoxins B1, B2, G1, M1, ochratoxin A, patulin, and byssochlamic acid was investigated. With the developed methods, the identification was made possible by in situ fluorescence spectral analysis with a far reaching exclusion of substances which simulate sycotoxins. Aflatoxin B1 was detected in 2 samples of 105 spontaneously moulded food specimens and only in 1 of a group of 198 food samples that were obviously not moulded. Aflatoxin M1 was identified in 4 of 60 samples of the so-called wintermilk. Investigated dairy products did not contain aflatoxin M1. Ochratoxin A could be detected twice in 49 spontaneously moulded corn samples, aflatoxin, however, was not found. Further investigations of 50 samples of moulded food revealed ochratoxin A in 2 samples of raw coffee. Food samples obviously not moulded did not contain ochratoxin A. Patulin was detected in 19 of 110 samples of fruit and fruit products, especially in commercial apple juice, in rotten parts of apples, and in moulded fruit products. Byssochlamic acid was not detected in fruit juices or in fruit. The toxicological consequences of mycotoxins in food and possibilities to reduce mycotoxins are discussed.

Significance of byssochlamic acid in fruit juice mold

The authors describe a method for the determination of byssochlamic acid in fruit juice. After extraction and purification, byssochlamic acid is separated by thin-layer chromatography on HF 254 silica gel. The quenching of fluorescence of byssochlamic acid is estimated quantitatively on the plate by means of the thin-layer attachment of a fluorescence spectrophotometer using reference substances. For fruit juices the recovery rate is 80%; the limit of detection lies at 0.5 p.p.m. Byssochlamic acid could not be detected in commercially-available fruit juice and neither in juices produced of fruits which had spontaneously got mouldy.

Antibiose manifest�e par une souche de Byssochlamys nivea Westling, 1909. II. Spectre d'activit�

A strain of Byssochlamys nivea cultivated in a liquid medium (Saccharose: 50 g: NaNo3: 2 g; KH2PO4: 1 g; KCL: 0.5 g; MgSO4, 7H2O: 0.5 g; water to 1000 ml) produces, at 24 degrees C, an antibiotic substance which appears after several days of growth (10-12 days). Among 43 strains of Bacteria Gram (minus) belonging to 10 genera none was resistant. The most was susceptible, save Pseudomonas aeruginosa, Serratia marcescens, Moraxella glucidolytica. On the the great bulk of the Bacteria (Gram +) tested was little influenced, except certain strains of Bacillus. The filtrate is ineffectual against Mycobacteria and Fungi (yeast or mould) at the concentration used. This substance seemed to be different of those produced by Byssochlamys fluva (byssochlamic acid) and by some species of Paecilomyces (P. varioti, P. persicinus, P. elegans, P. variabilis, P. fusidioides).

Total synthesis of (+-)-byssochlamic acid

Total synthesis of (+-)-byssochlamic acid

The structure of byssochlamic acid.

Die Struktur desp-Bromphenylhydrazids der Byssochlamsäure, des charakteristischen Stoffwechselproduktes vonByssochlamys fulva, wurde durch dreidimensionale Röntgenanalyse bestimmt. Die Resultate stellen eine Bestimmung der Konstitution und Stereochemie (abgesehen von der absoluten Konfiguration) desp-Bromphenylhydrazids als (I) und demnach der Byssochlamsäure als (II) dar.