Epiequisetin

Advanced prostate cancer has a poor prognosis, and it is urgent to develop new effective drugs. 5'-Epiequisetin is a tetramic acid derivative which was isolated from a marine sponge-derived fungusFusarium equisetiin our previous study. In this study, 5'-epiequisetin showed cytotoxicity against four prostate cancer cell lines, namely, LNCaP, 22Rv1, DU145, and PC-3 cells, with the lowest IC50value of 4.43 ± 0.24 μM in PC-3 cells. Further studies showed that it could dramatically regulate the clonal colony formation, apoptosis, and migration of PC-3 cells. In addition, flow cytometry data showed that 5'-epiequisetin could block the cell cycle at the G1 phase. Proteome profiler array and Western blot revealed that 5'-epiequisetin could regulate the expression of proteins responsible for cell proliferation, apoptosis, and migration. 5'-Epiequisetin regulated the expression of PI3K, Akt, phosphorylated Akt, and proteins which control the cell cycle. Meanwhile, 5'-epiequisetin upregulated expression of DR5 and cleave-caspase 3, which play important roles in the process of apoptosis. Moreover, when DR5 was silenced by small interfering RNA, the proportion of apoptotic cells induced by 5'-epiequisetin remarkably declined. In addition, 5'-epiequisetin downregulated the expression of survivin which plays a key role in the process of survival and apoptosis. 5'-Epiequisetin also impacted beta-catenin and cadherins, which were associated with cell migration. In addition, 5'-Epiequisetin significantly inhibited the progression of prostate cancer in mice, accompanied by regulating the protein expression of DR5, caspase 8, survivin, and cadherinsin vivo. Taken together, these findings indicated that 5'-epiequisetin showed an anti-prostate cancer effect by inducing apoptosis and inhibiting cell proliferation and migration bothin vitroandin vivo, suggesting a promising lead compound for the pharmacotherapy of prostate cancer.

Sixty-four corn silages were characterized for chemicals, bacterial community, and concentrations of several fungal metabolites. Silages were grouped in five clusters, based on detected mycotoxins, and they were characterized for being contaminated by (1) low levels ofAspergillus- andPenicillium-mycotoxins; (2) low levels of fumonisins and otherFusarium-mycotoxins; (3) high levels ofAspergillus-mycotoxins; (4) high levels of non-regulatedFusarium-mycotoxins; (5) high levels of fumonisins and their metabolites. Altersetin was detected in clusters 1, 3, and 5. Rugulusovin or brevianamide F were detected in several samples, with the highest concentration in cluster 3. Emodin was detected in more than 50.0% of samples of clusters 1, 3 and 5, respectively. Kojic acid occurred mainly in clusters 1 and 2 at very low concentrations. RegardingFusariummycotoxins, high occurrences were observed for FB3, FB4, FA1, whereas the average concentrations of FB6 and FA2 were lower than 12.4 µg/kg dry matter. EmergingFusarium-produced mycotoxins, such as siccanol, moniliformin, equisetin, epiequisetin and bikaverin were detected in the majority of analyzed corn silages. Pestalotin, oxaline, phenopirrozin and questiomycin A were detected at high incidences. Concluding, this work highlighted that corn silages could be contaminated by a high number of regulated and emerging mycotoxins.

The Beibu Gulf harbors abundant underexplored marine microbial resources, which are rich in diversified secondary metabolites. The generaVibriois a well-known pathogenic bacterium of aquatic animals. In this study, 22 fungal strains were isolated and identified from the Beibu Gulf coralviathe serial dilution method and internal transcribed spacer (ITS) sequence analysis, which were further divided into three branches by phylogenetic tree analysis. The crude extracts of themviasmall-scale fermentation were selected for the screening of inhibitory activity againstVibrio alginalyticus,Vibrio coralliilyticus,Vibrio harveyi,Vibrio parahaemolyticus,Vibrio owensii, andVibrio shilonii. The results showed that eight fungal extracts displayed anti-Vibrioactivityviathe filter paper disk assay. Several of them showed strong inhibitory effects. Then, two tetramic acid alkaloids, equisetin (1) and 5'-epiequisetin (2), were identified fromFusarium equisetiBBG10 by bioassay-guided isolation, both of which inhibited the growth ofVibriospp. with the MIC values of 86-132 μg/ml. The scanning electron microscope results showed that cell membranes ofVibriobecame corrugated, distorted or ruptured after treatment with1and2. Taken together, this study provided eight fungal isolates with anti-Vibriopotentials, and two alkaloid-type antibiotics were found with anti-Vibrioeffects from the bioactive strainF. equisetiBBG10. Our findings highlight the importance of exploring promising microbes from the Beibu Gulf for the identification of anti-Vibriofor future antibiotic development.