Two new xanthone derivatives from the algicolous marine fungus Wardomyces anomalus

A marine fungal isolate, identified as Wardomyces anomalus, was cultivated and found to produce two new xanthone derivatives, 2,3,6,8-tetrahydroxy-1-methylxanthone (1) and 2,3,4,6,8-pentahydroxy-1-methylxanthone (2), in addition to the known xanthone derivative 3,6,8-trihydroxy-1-methylxanthone (3) and the known fungal metabolite 5-(hydroxymethyl)-2-furanocarboxylic acid (4). The structures of all compounds were determined on the basis of extensive spectroscopic measurements (1D and 2D NMR, MS, UV, and IR). Compounds 1 and 4 showed significant antioxidant activities. The total extract and 1, 3, and 4 were shown to be inhibitors of p56(lck)tyrosine kinase.     

Monodictyochromes A and B, dimeric xanthone derivatives from the marine algicolous fungus Monodictys putredinis

Investigations of the marine-derived fungus Monodictys putredinis led to the isolation of two novel dimeric chromanones (1, 2) that consist of two uniquely modified xanthone-derived units. The structures were elucidated by extensive spectroscopic measurements including NOE experiments and CD analysis to deduce the configuration. The compounds (1, 2) were examined for their cancer chemopreventive potential and shown to inhibit cytochrome P450 1A activity with IC(50) values of 5.3 and 7.5 μM, respectively. In addition, both compounds displayed moderate activity as inducers of NAD(P)H:quinone reductase (QR) in cultured mouse Hepa 1c1c7 cells, with CD values (concentration required to double the specific activity of QR) of 22.1 and 24.8 μM, respectively. Compound 1 was slightly less potent than compound 2 in inhibiting aromatase activity, with IC(50) values of 24.4 and 16.5 μM.     

海洋真菌Aspergillus sp.中的苯甲醛衍生物研究

目的 研究海洋真菌Aspergillus sp.的化学成分及其抗氧化活性.方法 采用硅胶柱色谱、高效液相色谱等方法进行分离纯化,以现代波谱技术和理化性质鉴定化合物的结构,并测定了所得化合物清除DPPH自由基的活性.结果 分离得到6个苯甲醛衍生物,分别鉴定为2-(E-3-庚烯基)-5-异戊烯基-3,6二羟基苯甲醛(1)、二氢金(色)灰绿曲霉素(2)、异二氢金(色)灰绿曲霉素(3)、曲霉素(4)、灰绿曲霉黄色素(5)和毛壳菌吡喃宁(6).结论 化合物1为新化合物,命名为异曲霉素,化合物1～6具有很强的清除DPPH自由基的活性.     

Potential cancer chemopreventive in vitro activities of monomeric xanthone derivatives from the marine algicolous fungus Monodictys putredinis

Investigation of the fungal strain Monodictys putredinis isolated from the inner tissue of a marine green alga led to the isolation of four new monomeric xanthones and a benzophenone. All structures were elucidated by extensive spectroscopic measurements. The relative configuration of compound 1 was determined by X-ray crystal structure analysis, while for 2 and 3 configurations were confirmed by NOE experiments. Absolute configurations for compounds 1-3 were deduced by comparing experimental circular dichroism spectroscopic data with those calculated employing quantum-chemical time-dependent density functional theory (TDDFT). The compounds were examined for their cancer chemopreventive potential. Xanthone 2 was shown to inhibit cytochrome P450 1A activity with an IC50 value of 3.0 microM. Compounds 2 and 3 displayed moderate activity as inducers of NAD(P)H:quinone reductase (QR) in cultured mouse Hepa 1c1c7 cells, with CD values (concentration required to double the specific activity of QR) of 12.0 and 12.8 microM, respectively. Compound 3 showed weak inhibition of aromatase activity.     

Phenolic glycosides from the filamentous fungus Acremonium sp. BCC 14080

New phenolic mono- and digalactopyranosides (1 and 2), their aglycone KS-501a (3), and a new phenolic 4-O-methylglucopyranoside (4) were isolated from the filamentous fungus Acremonium sp. BCC 14080. Structures of these compounds were elucidated by extensive MS and NMR spectroscopic analyses. Compound 1 displayed anti-HSV-1 activity with an IC(50) value of 7.2 microM. Compound 3 exhibited activity against Plasmodium falciparum K1 with an IC(50) value of 9.9 microM.     

Rare sesquiterpenes from the algicolous fungus Drechslera dematioidea

From the inner tissue of the marine red alga Liagora viscida the fungus Drechslera dematioidea was isolated. After mass cultivation, the fungus was investigated for its secondary metabolite content, and 10 new sesquiterpenoids [isosativenetriol (1), drechslerines A (2) and B (3), 9-hydroxyhelminthosporol (5), drechslerines C-G (6-10), and sativene epoxide (12)] were isolated. Compounds 8 and 10 exhibited antiplasmodial activity against Plasmodium falciparum strains K1 and NF54. The known compounds helminthosporol (4), cis-sativenediol (11), isocochlioquinone A (14), isocochlioquinone C (15), and cochlioquinone B (16) were also isolated. All structures were elucidated using spectroscopic methods, mainly 1D and 2D NMR and MS.     

Acremostrictin, a highly oxygenated metabolite from the marine fungus Acremonium strictum

The novel natural product acremostrictin was isolated from the culture broth of Acremonium strictum, a marine fungus collected from a Choristida sponge off the coast of Korea. Structurally, acremostrictin is a tricyclic lactone of an unprecedented skeletal class based on combined spectroscopic and X-ray crystallographic analyses. The new compound exhibited weak antibacterial and moderate antioxidant activities.     

Aromatic polyketides from marine algicolous fungi

The investigation of the marine-derived fungi Acremonium sp. and Nodulisporium sp. led to the isolation of the new natural products acremonisol A ( 1) and (3 R)-7-hydroxy-5-methylmellein ( 2). Both fungi are endophytes of marine algae. Compounds 1 and 2 are biosynthetically related by both being aromatic pentaketides belonging to the dihydroisocoumarins. All structures were elucidated by extensive spectroscopic measurements.     

Acremolides A-D, lipodepsipeptides from an Australian marine-derived fungus, Acremonium sp

An Australian estuarine isolate of an Acremonium sp. (MST-MF588a) yielded the two known compounds 19- O-acetylchaetoglobosin D ( 1) and 19- O-acetylchaetoglobosin B ( 2), as the sole cytotoxic principles, along with the known aromatic metabolite RKB 3564S ( 3), and a novel family of lipodepsipeptides, acremolides A-D ( 4- 7). Structures were assigned to 4- 7 on the basis of detailed spectroscopic analysis and chemical derivatization and by application of a new C 3 Marfey's method for amino acid analysis.     

New glycosides of the fungus Acremonium striatisporum isolated from a sea cucumber

Four new diterpene glycosides, virescenosides R (1), S (2), T (3), and U (4), have been isolated from a marine strain of Acremonium striatisporum KMM 4401 associated with the holothurian Eupentacta fraudatrix. Their structures have been elucidated on the basis of HRFABMS, 1D and 2D NMR (1H, 13C, DEPT, COSY-45, COSY-RCT, HSQC, HMBC, and NOESY spectra), and the results of acidic hydrolysis as 19-O-[beta-D-glucopyranosyl(1-->6)-beta-d-altropyranosyl]-isopimara-7,15-diene-2alpha,3beta-diol (1), 19-O-beta-D-altropyranosyl-3-oxo-isopimara-8(14),15-diene-7alpha-ol (2), 19-O-beta-D-altropyranosyl-3,7-dioxo-isopimara-8,15-diene (3), and 19-O-beta-D-altropyranosyl-3,7-dioxo-isopimara-8(14),15-diene (4). The cytotoxic activity of the virescenosides was examined.     

New communesin derivatives from the fungus Penicillium sp. derived from the Mediterranean sponge Axinella verrucosa

The ethyl acetate extract of Penicillium sp., derived from the Mediterranean sponge Axinella verrucosa, yielded the known compound communesin B (1) and its new congeners communesins C (2) and D (3), as well as the known compounds griseofulvin, dechlorogriseofulvin, and oxaline. All structures were unambiguously established by 1D and 2D NMR and MS data. In several bioassays performed on different leukemia cell lines, the communesins exhibited moderate antiproliferative activity.     

New diterpenic altrosides of the fungus Acremonium striatisporum isolated from a sea cucumber

Two new diterpenic glycosides, virescenosides M (1) and N (2), have been isolated from a marine strain of Acremonium striatisporum KMM 4401 associated with the holothurian Eupentacta fraudatrix. Their structures were determined on the basis of MS and NMR data as beta-D-altropyranosido-19-7-oxo-isopimara-8,15-diene-2alp ha, 3beta-diol (1) and beta-D-altropyranosido-19-isopimara-7, 15-diene-2alpha,3beta,6beta-triol (2). Three other altrosides (3-5), identified as virescenosides A, B, and C from the terrestrial strain Acremonium luzulae, were also isolated. The cytotoxic activity of the virescenosides was examined.     

New diterpene glycosides of the fungus Acremonium striatisporum isolated from a sea cucumber

Three new diterpene glycosides, virescenosides O (1), P (2), and Q (3), have been isolated from a marine strain of Acremonium striatisporum KMM 4401 associated with the holothurian Eupentacta fraudatrix. Their structures were determined on the basis of HRMALDIMS and NMR data as beta-D-altropyranosido-19-isopimara-8(14),15-diene-7alpha,3beta-diol (1), beta-D-altropyranosido-19-7-oxoisopimara-8(9),15-diene-3beta-ol (2), and beta-D-mannopyranosido-19-isopimara-7,15-diene-3beta-ol (3). The cytotoxic activity of the virescenosides was examined.     

Bioactive asterric acid derivatives from the Antarctic ascomycete fungus Geomyces sp

Five new asterric acid derivatives, ethyl asterrate (3), n-butyl asterrate (4), and geomycins A-C (6-8), have been isolated from cultures of an isolate of the Antarctic ascomycete fungus Geomyces sp. The structures of these metabolites were elucidated by NMR spectroscopy. The absolute configuration of 8 was determined by application of the CD excitation chirality method. Compound 7 displayed antifungal activity against Aspergillus fumigatus, whereas 8 showed antimicrobial activities against gram-positive and gram-negative bacteria.     

Chromone derivatives from the filamentous fungus Lachnum sp. BCC 2424

Five new chromones, named lachnones A-E (1-5), were isolated from the filamentous fungus Lachnum sp. BCC 2424 along with known (2E,6S)-2,6-dimethyl-2,7-octadiene-1,6-diol. Their structures were elucidated by spectroscopic methods. Lachnones B (2) and D (4) mildly inhibited the growth of Mycobacterium tuberculosis, both with MIC values of 200 microg/mL.     

Antibacterial anthraquinone derivatives from a sea anemone-derived fungus Nigrospora sp

Chemical investigation of a marine-derived fungus Nigrospora sp., isolated from an unidentified sea anemone, yielded two new hydroanthraquinone analogues, 4a-epi-9α-methoxydihydrodeoxybostrycin (1) and 10-deoxybostrycin (2), together with seven known anthraquinone derivatives (3-9). The structures of the two new compounds were established through extensive NMR spectroscopy as well as a single-crystal X-ray diffraction analysis using Cu Kα radiation. The antibacterial activities of compounds 1-9 and 10 acetyl derivatives (6a, 7a, 8a-8g, 9a) were evaluated in vitro. Compound 6a, the acetylated derivative of 6, exhibited promising activity against Bacillus cereus with an MIC value of 48.8 nM, which was stronger than that of the positive control ciprofloxacin (MIC = 1250 nM). Analysis of the antibacterial screening data for the metabolites and their acetyl derivatives revealed the key structural features required for this activity.     

Cytotoxic sterol derivatives from a marine sponge Homaxinella sp

A bioactivity-guided fractionation of a marine sponge Homaxinella sp. has led to the isolation of three new (1-3) highly degraded sterols and four new 6-O-alkylated (6-9) sterols, along with known sterol derivatives. The degraded sterols (1-5) belong to the class incisterols, previously isolated from the marine sponge Dictyonella incisa. Mainly NMR and MS spectroscopic analyses established the gross structures of the new compounds. The relationship between the stereoisomerism of the side chain and HPLC retention time has also been discussed. The compounds were tested against a panel of five human solid tumor cell lines, and especially the degraded sterols (1-4) displayed significant cytotoxicity.     

Botryane metabolites from the fungus Geniculosporium sp. isolated from the marine red alga Polysiphonia

Eleven new botryane metabolites (1-11) were isolated together with four known cytochalasins (12-15) from the mitosporic fungus Geniculosporium sp., which is associated with the red alga Polysiphonia sp. The structures of 1-11 differ from known botryanes in substitution pattern, degree of saturation, and altered sites of oxidation, alkylation, unsaturation, etc. They were determined by spectroscopic methods (mainly extensive 1D and 2D NMR experiments and mass spectral measurements) and X-ray single-crystal analysis. The herbicidal, antifungal, and antibacterial activities of these new natural products were evaluated.     

New secondary metabolites from the marine endophytic fungus Apiospora montagnei

The marine fungus Apiospora montagnei was isolated from the inner tissue of the North Sea alga Polysiphonia violacea. Cultivation of this fungal strain led to the isolation of several new secondary metabolites, including the diterpene myrocin A (1) and the polyketide apiosporic acid (2). Furthermore the new monomethyl ester of 9-hydroxyhexylitaconic acid (3) and the (-)-enantiomer (4) of the known (+)-hexylitaconic acid were found together with the known (+)-epiepoxydon (5), (+)-epoxydon monoacetate, R-mellein, R-8-methoxymellein, 5-hydroxymethylfuran-2-carboxylic acid, and the xanthone derivative anomalin A. The structures were elucidated mainly by 1D and 2D NMR, MS, UV, and IR spectral data. Compound 5 exhibited significant cytoxicity against human cancer cell lines.     

海洋真菌Penicillium sp．化学成分研究

从南海采集的海泥中分离得到的海洋真菌Penicillium sp．中分离得到4个化合物。通过理化性质和波谱数据分析鉴定了这4个化合物的结构。它们分别是：3-苄基-6-异丙基哌嗪-2,5-二酮（1）、3-苄基-6-异丁基哌嗪-2,5-二酮（2）、3-苄基-6-另丁基哌嗪-2,5-二酮（3）、3,6-二苄基哌嗪-2,5-二酮（4）。