Three new epipolythiodioxopiperazines, chaetocochins A (1), B (2), and C (3), along with dethio-tetra (methylthio) chetomin (4) and chetomin (5), were isolated from the ethyl acetate extract of the solid-state fermented rice culture of the fungus Chaetomium cochliodes. Their structures were elucidated on the basis of spectroscopic analysis. Compounds 1, 3, and 4 exhibited significant cytotoxicity in vitro against cancer cell lines Bre-04, Lu-04, and N-04.

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Brevianamide J (1), a new indole alkaloid dimer, was isolated together with four new diketopiperazine alkaloids (brevianamide K-N, 2-5) from the solid-state fermented culture of Aspergillus versicolor. Their structures were elucidated on the basis of spectral data. X-ray crystallographic analysis confirmed the structures of 1 and 4.Diketopiperazine alkaloids, a class of important secondary metabolites, are widely found in fungi such as Aspergillus, 1 Penicillium, 2 Pestalotiopsis, 3 and Chromocleista. 4 This class of alkaloids are derived from different amino acids and one or more isoprene units. Most of them are characteristic of diverse ring systems and possess diverse biological activities, 5 which attracted much attention of synthetic chemists. 6 Species of Aspergillus are important medically and commercially. Members of the genus are sources of natural products that can be potentially used to treat human diseases. 7 In the course to investigate the alkaloids from the fungus Aspergillus Versicolor, a new alkaloid dimer (1), together

Four new sesterterpenoids, terretonins A-D (1-4), and a new alkaloid, asterrelenin (5), together with five known compounds, were isolated from the ethyl acetate extract of a solid-state fermented culture of Aspergillus terreus. Their structures were elucidated on the basis of spectroscopic analysis. The structures of 1, 2, and 5 were confirmed by X-ray crystallographic analysis.

A series of epipolythiodioxopiperazines in the fungusEpipolythiodioxopiperazines (see the structure in Figure 1) are widely found as secondary metabolites of mold, with bioactivities including antitumor, antimicrobial, antinematodal, and cytotoxicity effects. 1-6 Some compounds produced from the genus Chaetomium, such as dethiotetra(methylthio)chetomin, chaetocochin A, and chaetocochin C, exhibit significant cytotoxicity in vitro against cancer cell lines such as Bre-04, Structural characterization of the epipolythiodioxopiperazines is the key for the study of their bioactivities. However, this has always been a challenge, especially for the characterization of those compounds and their metabolites that are of trace amounts. UV and IR spectroscopy only provide limited structural information. Nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography offer more structural information and have become important methods for structural characterization of epipolythiodioxopiperazines. 1,[8][9][10] However, NMR and X-ray crystallographic analyses require laborious purification and the production of monocrystals, respectively. Notably, some epipolythiodioxopiperazines are difficult to be identified even using NMR, since the numbers of S atoms in each piperazine ring are difficult to confirm.Mass spectrometry, especially tandem mass spectrometry, has been one of the most sensitive and rapid methods for identification of organic compounds. The fragmentation mechanisms of Na + adduct molecular ions, [M + Na] + for epipolythiodioxopiperazines were studied using low-energy collision-induced electrospray ionization quadrupole time-of-flight tandem spectrometry (ESI-QTOF-MS/MS) and ESI-IT-MS n . 11 Structures of biradical fragments in gas phase have attracted much scientific interest. [11][12][13] Two piperazine rings can be discriminated by the characteristic fragmentation pattern of McLafferty rearrangement when S-methyl groups are present. However, the number of sulfurs in each piperazine ring cannot be confirmed when only a S-S bond is present due to the loss of sulfide first. In addition, the abundances of low-mass fragment ions produced from [M + Na] + are very low, which make them unsuitable for serving as characteristic ions.

Nine new azaphilone alkaloids, penazaphilones A–I (1–9), were isolated from the solid fermented rice culture of Penicillium sclerotiorum cib-411. The structures of compounds 1–9 were elucidated based on HRESIMS, NMR, and CD spectroscopic data. The structures of 5 and 8 were confirmed by X-ray crystallographic analyses. Biological evaluation showed that compounds 1, 5, 6, and 8 inhibited the production of nitric oxide (NO) on RAW 264.7 cells stimulated by lipopolysaccharide with IC50 values of 15.29, 9.34, 9.50, and 7.05 μM, respectively. Meanwhile, they did not exhibit obvious cytotoxicity at a concentration of 50.0 μM.

Two new indole alkaloids chaetocochin J (1) and chaetoglobinol A (8), along with chetomin (2), chetoseminudin A (3), cochliodinol (9), and semicochliodinol (10), were isolated from the rice culture of the fungus Chaetomium globosum. Their structures were elucidated by spectral analysis. Three new epipolythiodioxopiperazines, chaetocochins G-I (5-7), were identified by the combination of UPLC and mass spectrometric analysis. Chaetocochin I contained two sulfur bridges, one formed by three sulfur atoms between C-3 and C-11a, and the other formed by four sulfur atoms between C-3' and C-6'. Chaetocochin I was readily transformed into chetomin (2), chetoseminudin A (3), chaetocochin D (4), chaetocochin G (5), and chaetocochin H (6) by losing sulfur atoms. Compounds 1-3, and 8 exhibited antibacterial activities against Bacillus subtilis with MICs of 25, 0.78, 0.78, and 50 μg/mL, respectively, but not against Gram-negative bacterium (Escherichia coli). Compounds 2 and 8 were inactive against Candida albicans, Fusarium graminearum, Fusarium vasinfectum, Saccharomyces cerevisiae, and Aspergillus niger even at the high concentrations of 200 and 100 μg/mL, respectively. Compound 8 showed free radical scavenging capacity against the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical (ABTS(+•)), with IC50 values of 143.6 and 45.2 μM, respectively. The free radical scavenging capacity rates of compounds 1-3 on the DPPH and ABTS(+•) were less than 20% at the test concentrations (89.9-108.3 μM). The superoxide anion radical scavenging assay indicated that compounds 1-3, and 8 showed 14.8% (90.9 μM), 18.1% (90.9 μM), 51.5% (88.3 μM), and 30.4% (61.3 μM) superoxide anion radical scavenging capacity, respectively.

Thunder god vine, the dried roots of Tripterygium wilfordii, is a widely used traditional Chinese medicine. More than 200 bioactive complex natural products have been isolated from this herb. Inspired by the diversity of chemical structures and bioactivities of the components of this herb, the investigation to mine new chemical entities as potential drug leads led to the identification of 36 nitrogen-containing compounds. Among them, 18 new dihydro-β-agarofuran alkaloids (tripterygiumines A-L (1-12), M-Q (22-26), and R (33)) were identified from the spectroscopic data and chemical degradation studies. Tripterygiumine Q (26) exhibited immunosuppressive activity against human peripheral mononuclear cells with an IC50 value of 8.67 μM and showed no cytotoxicity, even at 100 μM, indicating that 26 may represent a novel scaffold for the development of new immunosuppressants.