Pholiotone A, a new polyketide derivative from Pholiota sp

Antibacterial insights into alternariol and its derivative alternariol monomethyl ether produced by a marine fungus

Alternaria alternata FB1 is a marine fungus identified as a candidate for plastic degradation in our previous study. This fungus has been recently shown to produce secondary metabolites with significant antimicrobial activity against various pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and the notorious aquaculture pathogen Vibrio anguillarum. The antibacterial compounds were purified and identified as alternariol (AOH) and its derivative, alternariol monomethyl ether (AME). We found that AOH and AME primarily inhibited pathogenic bacteria (MRSA or V. anguillarum) by disordering cell division and some other key physiological and biochemical processes. We further demonstrated that AOH could effectively inhibit the unwinding activity of MRSA topoisomerases, which are closely related to cell division and are the potential action target of AOH. The antibacterial activities of AOH and AME were verified by using zebrafish as the in vivo model. Notably, AOH and AME did not significantly affect the viability of normal human liver cells at concentrations that effectively inhibited MRSA or V. anguillarum. Finally, we developed the genetic operation system of A. alternata FB1 and blocked the biosynthesis of AME by knocking out omtI (encoding an O-methyl transferase), which facilitated A. alternata FB1 to only produce AOH. The development of this system in the marine fungus will accelerate the discovery of novel natural products and further bioactivity study.IMPORTANCEMore and more scientific reports indicate that alternariol (AOH) and its derivative alternariol monomethyl ether (AME) exhibit antibacterial activities. However, limited exploration of their detailed antibacterial mechanisms has been performed. In the present study, the antibacterial mechanisms of AOH and AME produced by the marine fungus Alternaria alternata FB1 were disclosed in vitro and in vivo. Given their low toxicity on the normal human liver cell line under the concentrations exhibiting significant antibacterial activity against different pathogens, AOH and AME are proposed to be good candidates for developing promising antibiotics against methicillin-resistant Staphylococcus aureus and Vibrio anguillarum. We also succeeded in blocking the biosynthesis of AME, which facilitated us to easily obtain pure AOH. Moreover, based on our previous results, A. alternata FB1 was shown to enable polyethylene degradation.

Koninginins X-Z, Three New Polyketides from Trichoderma koningiopsis SC-5

Koninginins X-Z (1-3), three novel polyketides, were isolated from the solid fermentation of the endophytic fungus Trichoderma koningiopsis SC-5. Their structures, including the absolute configurations, were comprehensively characterized by a combination of NMR spectroscopic methods, HRESIMS, 13C NMR, DFT GIAO 13C NMR, and electronic circular dichroism calculations as well as single crystal X-ray diffraction. In addition, all the compounds were evaluated for antifungal activity against Candida albicans.

Polyketides with Anti-Inflammatory Activity from Trichoderma koningiopsis, a Rhizosphere Fungus from the Medicinal Plant Polygonum paleaceum

Twelve new fungal polyketides, koningiopisins I-P (1-8) and trichoketides C-F (9-12), together with six known congeners (13-18), were isolated from Trichoderma koningiopsis, a rhizosphere fungus obtained from the medicinal plant Polygonum paleaceum. Their structures and absolute configurations were established by spectroscopic analysis, single-crystal X-ray diffraction, the modified Mosher's method, chemical derivatization, the octant rule, and ¹³C NMR and ECD calculations. Compounds 1-5 are tricyclic polyketides possessing an octahydrochromene framework with a 6,8-dioxabicyclo[3.2.1]octane core. Compounds 7 and 8 contain a unique ketone carbonyl group at C-7 and differ from other members of this group of compounds with the ketone carbonyl group at C-1. Compounds 1, 2, and 13 showed inhibitory activity on LPS-induced BV-2 cells on NO production with IC₅₀ values of 14 ± 1, 3.0 ± 0.5, and 8.9 ± 2.7 μM, respectively.

New polyketides from the basidiomycetous fungus Pholiota sp

Two new polyketides, pholiotones B and C (1 and 2), and four known compounds, trichodermatide D (3), vermistatin (4), dehydroaltenuene A (5) and terpestacin (6) were isolated from the crude extract of Pholiota sp. Their structures were identified by NMR and MS spectroscopic data. The absolute configurations of compounds 1 and 2 were elucidated by modified Mosher's method, electronic circular dichroism (ECD) calculations and ¹³C NMR calculations as well as DP4+ probability analyses. All the compounds were evaluated for their antifungal and cytotoxicity.

Pterygota alata (Roxb.) R.Br. Bark Fraction Induced Intrinsic Apoptotic Pathway in 4T1 Cells by Decreasing Bcl-2 and Inducing Bax Expression

BACKGROUND AND OBJECTIVE

Pterygota alata (Roxb.) R.Br. bark extract has been studied to have cytotoxic activity on 4T1 cells. This study was conducted to determine the cytotoxic activity of several fractions of Pterygota alata (Roxb.) R.Br. bark against 4T1 breast cancer cells and to investigate the most active fractions on Bcl-2 and Bax expressions.

MATERIALS AND METHODS

The bark of Pterygota alata (Roxb.) R.Br. was extracted using 80% methanol and was fractionated into fractions of n-hexane, chloroform, ethyl acetate, n-butanol and insoluble n-butanol with liquid-liquid partition. Cytotoxic tests were performed using the MTT method and expressions of Bax and Bcl-2 on 4T1 breast cancer cells were detected with immunocytochemical staining. Identification of compounds in the most active fraction using GC-MS.

RESULTS

The results showed that the most active fraction was the insoluble fraction of n-butanol (IFB) with an IC50 of 15.14 μg mL-1. IFB also decreases the expression of Bcl-2 and increases the expression of Bax.

CONCLUSION

It can be concluded that Pterygota alata (Roxb.) R.Br. bark has the potential to be developed for medical use, especially for breast cancer therapy.