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Two new cytochalasin derivatives, peniotrinins A ( 1 ) and B ( 2 ), three new citrinin derivatives, peniotrinins C-E ( 4 , 5 , 7 ), and one new tetramic acid derivative, peniotrinin F ( 12 ), along with nine structurally related known compounds, were isolated from the solid culture of Peniophora sp. SCSIO41203. Their structures, including the absolute configurations of their stereogenic carbons, were fully elucidated based on spectroscopic analysis, quantum chemical calculations, and the calculated ECD. Interestingly, 1 is the first example of a rare 6/5/5/5/6/13 hexacyclic cytochalasin. We screened the above compounds for their anti-prostate cancer activity and found that compound 3 had a significant anti-prostate cancer cell proliferation effect, while compounds 1 and 2 showed weak activity at 10 μM. We then confirmed that compound 3 exerts its anti-prostate cancer effect by inducing methuosis through transmission electron microscopy and cellular immunostaining, which suggested that compound 3 might be first reported as a potential anti-prostate methuosis inducer.

Based on the marine natural products piperafizine B, XR334, and our previously reported compound 4m , fourteen novel 3,6-diunsaturated 2,5-diketopiperazine (2,5-DKP) derivatives ( 1 , 2 , 4 - 6 , 8 - 16 ), together with two known ones ( 3 and 7 ), were designed and synthesized as anticancer agents against the A549 and Hela cell lines. The MTT assay results showed that the derivatives 6 , 8 - 12, and 14 had moderate to good anticancer capacities, with IC 50 values ranging from 0.7 to 8.9 μM. Among them, compound 11, with naphthalen-1-ylmethylene and 2-methoxybenzylidene functions at the 3 and 6 positions of 2,5-DKP ring, respectively, displayed good inhibitory activities toward both A549 (IC 50 = 1.2 μM) and Hela (IC 50 = 0.7 μM) cancer cells. It could also induce apoptosis and obviously block cell cycle progression in the G2/M phases in both cells at 1.0 μM. The electron-withdrawing functions might not be favorable for the derivatives with high anticancer activities. Additionally, compared to piperafizine B and XR334, these semi- N -alkylated derivatives have high liposolubilities (>1.0 mg mL -1 ). Compound 11 can be further developed, aiming at the discovery of a novel anticancer candidate.

The mangrove-sediment-derived actinomycete strain Streptomyces   psammoticus SCSIO NS126 was found to have productive piericidin metabolites featuring anti-renal cell carcinoma activities. In this study, in order to explore more diverse piericidin derivatives, and therefore to discover superior anti-tumor lead compounds, the NS126 strain was further fermented at a 300-L scale under optimized fermentation conditions. As a result, eight new minor piericidin derivatives (piericidins L-R ( 1 - 7 ) and 11-demethyl-glucopiericidin A ( 8 )) were obtained, along with glucopiericidin B ( 9 ). The new structures including absolute configurations were determined by spectroscopic methods coupled with experimental and calculated electronic circular dichroism. We also proposed plausible biosynthetic pathways for these unusual post-modified piericidins. Compounds 1 and 6 showed selective cytotoxic activities against OS-RC-2 cells, and 2 - 5 exhibited potent cytotoxicity against HL-60 cells, with IC 50 values lower than 0.1 μM. The new piericidin glycoside 8 was cytotoxic against ACHN, HL-60 and K562, with IC 50 values of 2.3, 1.3 and 5.5 μM, respectively. The ability to arrest the cell cycle and cell apoptosis effects induced by 1 and 6 in OS-RC-2 cells, 2 in HL-60 cells, and 8 in ACHN cells were then further investigated. This study enriched the structural diversity of piericidin derivatives and confirmed that piericidins deserve further investigations as promising anti-tumor agents.

Four undescribed polyketide derivatives, named arthproliferins A-D (1-4), and one undescribed phenylspirodrimane derivative, named arthproliferin E (7), along with 11 known metabolites (5, 6, 8-16) were isolated from the soft coral-associated fungus Stachybotrys chartarum SCSIO41201. Their structures were determined through spectroscopic methods, X-ray crystallography, and ECD analysis. Compounds 1 and 3-15 were evaluated for their cytotoxic, and antibacterial activities. Among them, compounds 1 and 15 displayed moderate inhibitory activity against methicillin-resistant Staphylococcus aureus ATCC 29213 with an MIC value of 78 and 39 µg/mL, respectively. Furthermore, compound 15 displayed strong cytotoxic activities against the tested cell line with IC 50 values less than 39 nM.

Two novel sorbicillinoid adducts containing bicyclo[2.2.2]octane and tetrahydrofuran moieties, named sorbicillfurans A and B (1 and 2), were isolated from the static culture of the marine-derived fungus Penicillium citrinum SCSIO41402. Their structures including absolute configurations were determined by spectroscopic and calculated ECD analyses. Sorbicillfurans A and B (1 and 2) are the first examples of sorbicillinoids possessing a tetrahydrofuran unit. In the proposed biosynthetic pathway, sorbicillfuran B (2), harboring a rare and complex polycyclic framework, is probably formed by two Diels-Alder reactions. Both isolates were evaluated for the cytotoxicity against six human cancer cell lines, only sorbicillfuran B (2) showed weak cytotoxicity against HL-60 cells with an IC 50 value of 9.6 μM.

Iakyricidins A-D ( 1 - 4 ), a carbonyl-containing piericidin derivative and three novel piericidin analogues bearing cyclic skeletons, were isolated from the mangrove sediment derived strain Streptomyces iakyrus SCSIO NS104. These structures were established by spectroscopic techniques, Mosher's method, and ECD calculations. Compounds 2 - 4 represent a novel skeleton of piericidins with branched chain C-C cyclization, and their biosynthetic pathways are proposed. Compound 1 , the first natural carbonyl-containing piericidin derivate, exhibited potent antiproliferative activity against ACHN with an IC 50 value of 20 nM.

The marine fungus Emericella sp was isolated from the deep sea sediments. The fungus was identified by its morphology and ITS region. A new emerixanthone E ( 1 ) together with four ( 2-5 ) known emodin derivatives were isolated from the metabolites of the fungus Emericella SCSIO05240. The structures were elucidated on the basis of NMR spectroscopic analysis and mass spectrometry. The biological properties of those compounds ( 1-5 ) were explored for antimicrobial, antifungal and antitumor activity.

Seven new secondary metabolites classified as two perylenequinone derivatives ( 1 and 2 ), an altenusin derivative ( 3 ), two phthalide racemates ( 4 and 5 ), and two phenol derivatives ( 6 and 7 ), along with twenty-one known compounds ( 8 ⁻ 28 ) were isolated from cultures of the sponge-derived fungus, Alternaria sp. SCSIO41014. The structures and absolute configurations of these new compounds ( 1 ⁻ 7 ) were determined by spectroscopic analysis, X-ray single crystal diffraction, chiral-phase HPLC separation, and comparison of ECD spectra to calculations. Altertoxin VII ( 1 ) is the first example possessing a novel 4,8-dihydroxy-substituted perylenequinone derivative, while the phenolic hydroxy groups have commonly always substituted at C-4 and C-9. Compound 1 exhibited cytotoxic activities against human erythroleukemia (K562), human gastric carcinoma cells (SGC-7901), and hepatocellular carcinoma cells (BEL-7402) with IC 50 values of 26.58 ± 0.80, 8.75 ± 0.13, and 13.11 ± 0.95 μg/mL, respectively. Compound 11 showed selectively cytotoxic activity against K562, with an IC 50 value of 19.67 ± 0.19 μg/mL. Compound 25 displayed moderate inhibitory activity against Staphylococcus aureus with an MIC value of 31.25 μg/mL.

Three new 4-hydroxy-2-pyridone alkaloids, arthpyrones A-C (1-3), were isolated from the sponge-derived fungus Arthrinium arundinis ZSDS1-F3. Their structures were elucidated on the basis of spectroscopic analysis, CD spectra, quantum chemical calculation, and X-ray single-crystal diffraction analysis. Compounds 1 and 2 possessed a 2-pyridone core featured with a decalin moiety linked via a carboxide bridge bearing a novel oxabicyclo[3.3.1]nonane ring system rarely discovered in nature. A possible biosynthetic pathway for them was proposed.

Four new cytochalasins, arthriniumnins A-D (1-4), a new natural product, ketocytochalasin (5), as well as five known cytochalasin analogues (6-10) were isolated and identified from the fungus Arthrinium arundinis ZSDS1-F3 from the sponge Phakellia fusca. Their structures were elucidated by NMR spectroscopic and mass spectrometric analyses, as well as single crystal X-ray diffraction. Compounds 6 and 9 showed cytotoxicity against K562, A549, Huh-7, H1975, MCF-7, U937, BGC823, HL60, Hela, and MOLT-4 cell lines, with IC50 values ranging from 1.13 to 47.4 µM., (Georg Thieme Verlag KG Stuttgart · New York.)

Non-protected 2,5-diketopiperazine derivatives have poor solubility thus with negative impact on their bioavailability. In the present study, twenty-one novel soluble mono-protected, and three non-protected 2,5-diketopiperazine derivatives were designed and synthesized. Their anticancer activity to ten cell lines were evaluated by using CCK8 assay, and the results showed that about half of the mono-protected derivatives had broad-spectrum anticancer activity. Among allyl-protected derivatives, compound 4m had strong activity to all the cell lines (IC50 = 0.5-4.5 μM), especially to the cancer cell lines U937 (IC50 = 0.5 μM) and K562 (IC50 = 0.9 μM). Compound 4m could become a lead compound for further development for anticancer agents., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Chemical investigation of the fungus Xylariaceae sp. DPZ-SY43 has led to the isolation of a new compound, xylaolide A (1) together with three known compounds (2-4). The structures were established by analysing the spectroscopic data. Compound 1 was evaluated for its cytotoxicity.

A new actinomycete strain, isolated from soil in China, strongly inhibited in vitro proliferation of human hepatoma, chronic myelogenous leukemia, and colonic carcinoma cell lines. The strain, designated L033, was identified as a strain of Streptomyces avermitilis based on cultural property, morphology, carbon source utilization, 16s rRNA gene analysis, and DNA-DNA relatedness studies. The anticancer component from L033 was purified to homogeneity by preparative positive-phase high-performance liquid chromatography and crystallization. Nuclear magnetic resonance and mass spectrometric analysis showed that this compound had the same structure as oligomycin A. Different with other reported naturally occurring strains of S. avermitilis, L033 produced high quantity of oligomycin A (maximal 1,461 microg/ml). Therefore, L033 was considered of great potential as an industrial oligomycin-A-producing strain.