[20(22)E]-Lanostane Triterpenes from the Fungus Ganoderma australe

Penidaleodiolides A and B, Cage-Like Polyketides with Neurotransmission-Regulating Activity from the Soil Fungus Penicillium daleae L3SO

Penicillium daleae L3SO is a fungus isolated from the rhizospheric soil of the chloroplast-deficient plant Monotropa uniflora. A chemical study on the rice fermentation of this fungus led to the isolation and identification of two cage-like polyketides, penidaleodiolide A (1) and its biosynthetic-related congener penidaleodiolide B (2). The structures of 1 and 2 were determined by a combination of extensive spectroscopic analysis, biosynthetic consideration, chemical derivatization, and computational methods. Compound 1 harbors an unusual tricyclo[4.3.04,9]nonane scaffold, unprecedented in polyketide natural products. The hypothetical biosynthetic pathways for 1 and 2 were postulated and were supported by CRISPR/Cas9 genome editing results. Penidaleodiolide A (1) showed a significant inhibitory effect on the action potentials of murine hippocampal basket neurons and decreased the frequency of spontaneous excitatory postsynaptic currents in a concentration-dependent manner (the inhibition ratios were 0.30 ± 0.02 for 1 μM, 0.37 ± 0.03 for 10 μM, and 0.50 ± 0.07 for 20 μM) while being devoid of cytotoxicity against the nerve cells.

Ganoaustralins A and B, Unusual Aromatic Triterpenes from the Mushroom Ganoderma australe

Two triterpenes, ganoaustralins A (1) and B (2), featuring unprecedented 6/6/6/5/6 scaffolds were isolated from the fruiting bodies of the mushroom Ganoderma australe. The structures were determined by extensive NMR and HRESIMS spectroscopic analysis. The absolute configuration of the C-25 in ganoaustralin A was assigned by the phenylglycine methyl ester (PGME) method. The relative and absolute configurations of the polycyclic backbones were determined by NMR and ECD calculations, respectively. The plausible biosynthetic pathways of ganoaustralins A and B were proposed. Ganoaustralin B showed weak inhibition against β-secretase 1.

Secondary Metabolites from Fungi-In Honor of Prof. Dr. Ji-Kai Liu's 60th Birthday

It is our pleasure and privilege to serve as Guest Editors for this Special Issue of the Journal of Fungi in honor of Professor Ji-Kai Liu's 60th birthday [...].

Tetra-, penta-, and hexa-nor-lanostane triterpenes from the medicinal fungus Ganoderma australe

Chemical investigation on the medicinal fungus Ganoderma australe led to the identification of ten new nor-lanostane triterpenes, namely two hexa-nor ones, ganoaustratetraenones A (1) and B (2), five penta-nor ones, ganoaustraldehydes A-E (3-7), and three tetra-nor ones ganoaustrenoic acids A-C (8-10). The chemical structures along with the absolute configurations were determined by extensive spectroscopic analysis of 1D & 2D NMR and HRESIMS data. The postulated biosynthesis pathways of these compounds were proposed. Ganoaustraldehydes A (3) and B (4) showed moderate inhibition against nitric oxide production in RAW264.7 macrophage cells with the respective IC₅₀ values of 32.5, 34.2 µM (the IC₅₀ of positive control pyrrolidine dithiocarbamate was 20.0 µM).