Double perovskites Cs2AgSbCl6 have been synthesized via the solution state for applications as a promising photovoltaic absorber. Considering TiO2 as an electron transport layer (ETL), Cs2AgSbCl6/TiO2 heterojunction nanoparticles have also been prepared by the hydrothermal process to study the interface effect. Experimental measurements show that Cs2AgSbCl6 has a cubic structure with the lattice constant of 10.699 Å. The absorption peaks in the optical spectrum of the Ag and Sb-based double perovskites agree well with our density functional theory calculations. The Cs2AgSbCl6/TiO2 heterostructure exhibits enhanced optical absorption in the visible-light region compared to that of Cs2AgSbCl6, which is caused by the formation of the interface states and the decreased bandgap, thus facilitating the photo-induced optical transition in the visible-light region. From the charge transfer analysis of two interfaces (Ag2Sb2Cl8/TiO2 and Cs4Cl4/TiO2 interfaces), we find that the efficient separation of photo-induced carriers can be achieved at the Cs4Cl4/TiO2 interface, with electron flowing from the double perovskite layer to the TiO2 ETL, which is beneficial for improving the power conversion efficiency of solar cells. The combined study of theory and experiments indicates that the double perovskites Cs2AgSbCl6 would be a promising light-absorbing material in contact with TiO2 for the lead-free perovskite-based solar cell devices.

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Aspergillus versicolor Y10 is an endophytic fungus isolated from Huperzia serrata, which showed inhibitory activity against acetylcholinesterase. An investigation of the chemical constituents of Y10 led to the isolation of four new prenylated asteltoxin derivatives, named avertoxins A-D (2-5), together with the known mycotoxin asteltoxin (1). In the present study, we report structure elucidation for 2-5 and the revised NMR assignments for asteltoxin and demonstrated that avertoxin B (3) is an active inhibitor against human acetylcholinesterase with the IC50 value of 14.9 μM (huperzine A as the positive control had an IC50 of 0.6 μM). In addition, the cytotoxicity of asteltoxin (1) and avertoxins A-D (2-5) against MDA-MB-231, HCT116, and HeLa cell lines was evaluated.

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Tubercularia sp. TF5 is an endophytic fungal strain isolated from the medicinal plant Taxus mairei. Previously, taxol has been detected in the fermentation products of this strain. However, it lost the capability of producing taxol after long-term laboratory culture. Herein, we tried to reactivate the production of taxol by protoplast mutations and genome shuffling. The protoplasts of Tub. sp. TF5 were prepared from its mycelia, and mutated by UV and NTG. The mutant strains regenerated from the mutated protoplasts were selected and classified into four groups on the basis of their phenotypes, the profile of their metabolites analyzed by TLC, MS, and bioassay data. Then, genome shuffling was subsequently carried out with eight mutant strains, with two representatives from each protoplast mutant group, and genome shuffling mutant strains were obtained and screened using the same screening procedure. Although taxol has not been detected in any mutant, two important mutants, M-741 and G-444 were selected for metabolites isolation and determination due to their phenotypes, and differences in TLC analysis result from TF5 and other mutants. Three new sesquiterpenoids, namely tuberculariols A-C (1-3), and a known dihydroisocoumarin (4) were obtained from M-741. Eighteen novel compounds were isolated from G-444, including five new sesquiterpenoids (5-9), two new dihydroisocoumarins (10, 11), one new tetralone (12), together with 10 known compounds (13-20, 1, and 2). The compounds isolated from the M-741 and G-444 were different in structure types and substitutions from those of TF5 (15, 21-29). The results showed, for the first time, that protoplast mutations and genome shuffling are efficient approaches to mining natural products from endophytic fungi. Understanding the mechanisms of unlocking the biosynthesis of new metabolites will facilitate the manipulation of the secondary metabolism in fungi.