A gene cluster encoding a nonribosomal peptide synthetase-like enzyme catalyzes γ-aromatic butenolides.

Sea cucumber-derived fungi have attracted much attention due to their capacity to produce an incredible variety of secondary metabolites. Genome-wide information on Aspergillus micronesiensis H39 obtained using third-generation sequencing technology (PacBio-SMRT) showed that the strain contains nonribosomal peptide synthetase (NRPS)-like gene clusters, which aroused our interest in mining its secondary metabolites. 11 known compounds (1-11), including two γ-aromatic butenolides (γ-AB) and five cytochalasans, were isolated from A. micronesiensis H39. The structures of the compounds were determined by NMR and ESIMS, and comparison with those reported in the literature. From the perspective of biogenetic origins, the γ-butyrolactone core of compounds 1 and 2 was assembled by NRPS-like enzyme. All of the obtained compounds showed no inhibitory activity against drug-resistant bacteria and fungi, as well as compounds 1 and 2 had no anti-angiogenic activity against zebrafish.

[The study of the secondary metabolites from fungus Paecilomyces sp].

OBJECTIVE: To get active secondary metabolites from the fungus Paecilomyces sp.. METHODS: The strain Paecilomyces sp. was further grown in solid-substrate fermentation cultures, the metabolites were got by application of different separation techniques, such as silica gel, Sephadex LH-20 column chromatography, and reversed-phase high performance liquid chromatography. Their structures were identified by comprehensive spectroscopic methods. RESULTS: Four compounds were isolated and identified as Cerebroside C (1), Cerebroside D (2), 2-Hydroxybenzyl alcohol (3), 2-(4-Hydroxyphenyl) ethanol. CONCLUSION: Four compounds are isolated from Paecilomyces sp. for the first time.

The bioactive metabolites of the mangrove endophytic fungus Talaromyces sp. ZH-154 isolated from Kandelia candel (L.) Druce.

Bioactivity-directed fractionation of the extract of the mangrove endophytic fungus Talaromyces sp. ZH-154, which was isolated from the stem bark of Kandelia candel (L.) Druce, Rhizophoraceae, afforded two new metabolites, 7-epiaustdiol ( 1) and 8-O-methylepiaustdiol ( 2), together with the known compounds, stemphyperylenol ( 3), skyrin ( 4), secalonic acid A ( 5), emodin ( 6), and norlichexanthone ( 7). Their structures were elucidated on the basis of spectroscopic evidences including CD, MS, and 1D, 2D NMR techniques. The absolute configuration of 1 was unequivocally determined by single-crystal X-ray diffraction. All isolated compounds were evaluated for their antimicrobial and in vitro cytotoxic activities.

[The secondary metabolites of the HS-3 Alternaria sp. fungus associated with holothurians].

OBJECTIVE: The metabolites of HS-3 associated with holothurians were studied, which was identified by molecular biology as Alternaria sp.. METHODS: The holothurians were gathered from the Sea of Zhifu Islet, Shandong Province. HS-3 Alternaria sp. was culternitived in potato medium, and four compound was got by TLC, chromatography and HPLC, and 1-hydroxyl-3-methylanthracene-9,10-dione (1), chrysophanol (2), sterigmatocystin (3) and cerebroside (4) were elucated by modern spectrum. CONCLUSION: All of this provides scientific data for further study of holothurians, and the four coumpouns are isolated from the microbe associated with holothurians for the first time.

[Study on the second metabolisms from fungus HS-1 Epicoccum spp. from the sea cucumber in Yellow Sea].

OBJECTIVE: To get active metabolites from the microbes associated with sea cucumber. METHODS: Fungus was isolated from the sea cucumber, and the species was identified by molecular biology, and then was cultivated in GYP medium, and the metabolites were got by chromatography. Their structures were identified by comprehensive spectroscopic methods. RESULTS: Fungus HS-1 Epicocum sp. was isolated from the sea cucumber in Weihai, Yellow Sea. Four compounds were got as 5-methyl-6-hydroxy-8-methyoxy-3-methylisochroman (1), 8-hydroxy-3-methylisochroman-1-one (2), peroxy-ergosterol (3) and succinic acid (4). CONCLUSION: Fungus HS-1 Epicocum spp. is first isolated from the sea cucumber sample, this research provides new idea for further development of sea cucumber.

Structure elucidation of three diphenyl ether derivatives from the mangrove endophytic fungus SBE-14 from the South China Sea.

Two new natural products, tenelate A (1) and B (2), together with the known compound, tenellic acid C (3), were isolated from the mangrove endophytic fungus Talaromyces sp. (SBE-14), from the South China Sea. Their structures were elucidated by spectroscopic methods, mainly 1D and 2D NMR techniques.

[The secondary metabolites of the mangrove endophytic fungi ZZF13 and Guignardia sp. 4382 from the South China Sea].

OBJECTIVE: The secondary metabolites of the fungus ZZF13 isolated from the leaves of the mangrove sample Kandelia candel in Zhanjiang and Guignardia sp. 4382 isolated from bark of Kandelia candel (endophyte) of Mai Po, Hong Kong were studied. METHODS: The compounds were isolated by siliga gel, and their structures were identified by IR, MS and NMR. RESULTS: Four compounds were isolated from the culture of this strain. Their structures were identified as Bacillpsporin C (1), 5-carboxymellein (2), 5-methylmellein (3) and 1-(2,6-dihydroxyphenyl) butanone (4). CONCLUSION: The compounds 2 - 4 are isolated from the Guignardia sp. of Marine fungi for the first time.

1H and 13C NMR assignments for 6-demethylvermistatin and two penicillide derivatives from the mangrove fungus Guignardia sp. (No. 4382) from the South China Sea.

One new compound 6-demethylvermistatin (1), together with two known compounds, the penicillide derivatives (2) and (3) were isolated from the mangrove fungus Guignardia sp. No. 4382 obtained from the South China Sea. Their structures were assigned using high-resolution electron ionization mass spectrometry(HREIMS), (1)H and (13)C NMR spectra, DEPT, and by 2D COSY, HMQC, and HMBC experiments. The absolute configuration of 1 was established by comparison of its CD with that of vermistatin.

Three new C-27-carboxylated-lupane-triterpenoid derivatives from Potentilla discolor Bunge and their in vitro antitumor activities.

Three new lupane-triterpenoids (1-3) along with six known compounds (4-9) were isolated from the ethanolic extract of whole plant of Potentilla discolor Bunge. The structures of Compounds 1-3 were established by extensive 1D and 2D NMR together with other spectrum analysis, indicating that their C-27 positions were highly oxygenated, which were rarely found in nature. Their in vitro anti-proliferative activities against HepG-2, MCF-7 and T-84 cell lines were evaluated by Cell Counting Kit-8 (CCK-8) assay, and the results showed different activities for three cell lines with IC50 values ranging from 17.84 to 40.64 µM. In addition, the results from Hoechst 33258 and AO/EB staining as well as annexinV-FITC assays exhibited Compound 1 caused a markedly increased HepG-2 cellular apoptosis in a dose-dependent manner. The further mechanisms of Compound 1-induced cellular apoptosis were confirmed that 1 induced the production of ROS and the alteration of pro- and anti-apoptotic proteins, which led to the dysfunction of mitochondria and activation of caspase-9 and caspase-3 and finally caused cellular apoptosis. These results would be useful in search for new potential antitumor agents and for developing semisynthetic lupane-triterpenoid derivatives with high antitumor activity.

Antioxidant activity of chito-oligosaccharides on pancreatic islet cells in streptozotocin-induced diabetes in rats.

AIM: To investigate the antioxidant activity of chito-oligosaccharides (COSs) on pancreatic islet cells in diabetic rats induced by streptozotocin. METHODS: The antioxidant effect of COSs on pancreatic islet cells was detected under optical microscopy and with colorimetric assay and gel electrophoresis. The activities of glutathione peroxidase and superoxide dismutase, total antioxidant capacity, and content of malondialdehyde in serum and tissue slices of pancreas were examined after 60 d to determine the effect of COSs in streptozotocin-induced diabetes in rats. RESULTS: COSs can prohibit the apoptosis of pancreatic islet cells. All concentrations of COSs can improve the capability of total antioxidant capacity and activity of superoxide dismutase and decrease the content of malondialdehyde drastically. Morphological investigation in the pancreas showed that COSs have resulted in the reduction of islets, loss of pancreatic cells, and nuclear pyknosis of pancreatic cells. CONCLUSION: COSs possess various biological activities and can be used in the treatment of diabetes mellitus.

Secalonic acid D induced leukemia cell apoptosis and cell cycle arrest of G(1) with involvement of GSK-3beta/beta-catenin/c-Myc pathway.

The anticancer activities of secalonic acid D separated from the secondary metabolites of the mangrove endophytic fungus No. ZSU44 were investigated in this study. Secalonic acid D showed potent cytotoxicity to HL60 and K562 cells, and the IC(50) values were 0.38 and 0.43 mumol/L, respectively. Annexin V-FITC/PI assay and western blot indicated that secalonic acid D induced apoptosis in HL60 and K562 cells. In addition, secalonic acid D led to cell cycle arrest of G(1) phase related to downregulation of c-Myc. Moreover, our data indicated that downregulation of c-Myc and cell cycle arrest of G(1) phase were caused not by formation of G-quadruplex structures but by activation of GSK-3beta followed by degradation of beta-catenin.

Five nitro-phenyl compounds from the South China Sea mangrove fungus.

A novel nitro-phenyl glucoside (1) was isolated from mangrove endophytic fungus (fungus B60), collected from the Shenzhen mangrove Acanthus ilicifolius linn. Four related nitro-phenyl compounds (2-5) were also obtained, which were isolated for the first time as natural products. Their structures were established on the basis of NMR spectroscopic, mass spectrometric data and some chemical transformations. In the preliminary bioassay, compound 1 had a slight inhibitory effect on alpha-glucosidase with an IC(50) of 160.3 microM.

(1)H and (13)C NMR assignments for five anthraquinones from the mangrove endophytic fungus Halorosellinia sp. (No. 1403).

We report the unambiguous assignments of the (1)H and (13)C NMR spectra of two new natural products, namely, 1,4,5,6,7,9-hexahydroxy-2-methoxy-7-methyl-5beta,9beta,8abeta, 6alpha,10aalpha-hexahydroanthracen-10 (10aH)-one (1) and 1,4,6-trihydroxy-2-methoxy-7-methylanthracene-9, 10-dione (2), together with three known anthraquinones. These compounds were all isolated from the marine endophytic fungus No. 1403 collected from the South China Sea. Compounds 3 and 4 were isolated from the marine fungus for the first time. The structures were elucidated by the spectroscopic methods 1D and 2D NMR including COSY, HMQC, HMBC and NOE, and HREIMS. In our cytotoxicity assays, compound 5 showed cytotoxicity toward KB and KBv-200 cells with IC(50) of 1.40 and 2.58 microg/ml, respectively. In addition, the plausible biogenic relationship of compounds 1, 2, 3 and 4 is discussed.

Anthracenedione derivative 1403P-3 induces apoptosis in KB and KBv200 cells via reactive oxygen species-independent mitochondrial pathway and death receptor pathway.

Anthracenedione derivatives are potent cytotoxic agents to tumor cells. In this study, we investigated the anticancer activities of anthracenedione derivative 1403P-3 separated from the secondary metabolites of the mangrove endophytic fungus No. 1403. Our results demonstrated that 1403P-3 showed potent cytotoxicity not only to human epidermoid carcinoma drug-sensitive parental KB cells but also to multidrug resistant (MDR) KBv200 cells and the IC50 values were 19.66 and 19.27 muM, respectively. Further research indicated that 1403P-3 induced apoptosis in KB cells and KBv200 cells confirmed by Hoechst 33258 staining, detection of DNA fragmentation and cleavage of poly (ADP-ribose) polymerase (PARP). Furthermore, apoptosis triggered by 1403P-3 was characterized by the loss of mitochondrial membrane potential (DeltaPsi(m)), release of cytochrome c, cleavage of Bid, and activation of caspases-2, -3, -7, -8 and -9. Z-IETD-FMK, caspase-8 inhibitor could inhibit the activation of caspase-2 and cleavage of Bid induced by 1403P-3. However, activation of caspase-9 and cleavage of PARP caused by 1403P-3 were not inhibited by Z-IETD-FMK. Additionally, 1403P-3 did not influence the expression level of Bcl-2 and Bax. It is noteworthy that 1403P-3 decreased the generation of reactive oxygen species (ROS) in KB cells and KBv200 cells. DNA binding assay exhibited that apoptosis induced by 1403P-3 was not involved in intercalating to DNA. In summary, 1403P-3 induced apoptosis of KB cells and KBv200 cells through mitochondrial pathway and death receptor pathway. Furthermore, the mitochondrial pathway was independent of reactive oxygen species and activation of caspase-8.