Ten undescribed eremophilane and guaiane sesquiterpenes from Penicillium roqueforti.

Nine undescribed eremophilane sesquiterpenes, one undescribed guaiane sesquiterpene, along with ten known analogues were isolated and identified from fungus Penicillium roqueforti, which was separated from the root soil of Hypericum beanii N. Robson collected from the Shennongjia Forestry District, Hubei Province. Their structures were elucidated on the basis of various spectroscopic analyses, mainly including NMR and HRESIMS data, 13C NMR calculations with DP4+ probability analyses, ECD calculations, and single-crystal X-ray diffraction experiments. Furthermore, all twenty compounds were evaluated for the in vitro cytotoxic activities against seven human tumor cell lines, and the result suggested that 14-hydroxymethylene-1(10)-ene-epi-guaidiol A exhibited considerable cytotoxic activity against the Farage (IC50 < 10 µM, 48 h), SU-DHL-2, and HL-60 cells. Further mechanism study demonstrated that 14-hydroxymethylene-1(10)-ene-epi-guaidiol A could significantly promote apoptosis by inhibiting tumor cell respiration and decreasing intracellular ROS levels, thereby inducing S-phase blockade in tumor cells.

New α-pyrone derivatives with herbicidal activity from the endophytic fungus Alternaria brassicicola.

Three pairs of undescribed enantiomeric α-pyrone derivatives (1a/1b-3a/3b) and six undescribed congeners (4-9), were obtained from the fungus Alternaria brassicicola that was isolated from the fresh leaves of Siegesbeckia pubescens Makino (Compositae). The structures of these new compounds were characterized by extensive NMR spectroscopic and HRESIMS data, and their absolute configurations were further elucidated by a modified Mosher's method, chemical conversion, single-crystal X-ray diffraction analysis, and ECD calculations. This is the first report of three pairs of enantiomeric α-pyrone derivatives from the fungus A. brassicicola, and these enantiomers were successfully acquired from scalemic mixtures via chiral HPLC. Compounds 1a/1b-3a/3b and 4-9 were evaluated for the herbicidal activity against Echinochloa crusgalli, Setaria viridis, Portulaca oleracea, and Taraxacum mongolicum. At a concentration of 100 µg/mL, compounds 1a and 1b could significantly inhibit the germination of monocotyledon weed seeds (E. crusgalli and S. viridis) with inhibitory ratios ranging from 68.6 ± 6.4% to 84.2 ± 5.1%, which was equivalent to that of the positive control (glyphosate). The potential structure-herbicidal activity relationship of these compounds was also discussed. To a certain extent, the results of this study will attract great interest for the potential practical application of promising fungal metabolites, α-pyrone derivatives, as ecofriendly herbicides.

Inducing new bioactive metabolites production from coculture of Pestalotiopsis sp. and Penicillium bialowiezense.

Coculturing two or more fungi is a useful strategy to awaken the silent genes to produce structurally diverse and bioactive natural products. Through the coculture of Pestalotiopsis sp. and Penicillium bialowiezense, six new isoprenylated chromane derivatives, including two pairs of enantiomeric ones (1a/1b-2a/2b) and two optical pure ones (3-4), two new isoprenylated phenol glucoside derivatives (6-7), as well as eight known structural analogues (5 and 8-14), were obtained. The structures of these new compounds were characterized by NMR spectroscopy, single-crystal X-ray crystallography, and ECD calculation. The Δ10,11 double bond of pestaloficin D (5) was revised to E-configurated based on the extensive spectroscopic analyses. Compounds 1a/1b and 2a/2b were the first examples of enantiomeric isoprenylated chromane derivatives, which were successfully separated by chiral HPLC. Additionally, all the isolated compounds were evaluated for the in vitro ß-glucuronidase (GUS) and butyrylcholinesterase (BChE) inhibitory activities. Compounds 1a and 1b showed significant ß-glucuronidase inhibitory potency with IC50 values of 7.6 and 10.3 µM, respectively. Compound 14 exhibited moderate BChE inhibitory activity with an IC50 value of 21.3 µM. In addition, the structure-enzyme inhibitory activity relationship of compounds 1-14 is discussed.