Four new chromone derivatives from the Arctic fungus Phoma muscivora CPCC 401424 and their antiviral activities

New fusidane-type nortriterpenoids from the Arctic marine-derived fungus Simplicillium lamellicola culture medium with their inhibitory effect on benign prostatic hyperplasia

Three new fusidane-type nortriterpenoids, simplifusinolide A, 24-epi simplifusinolide A, and simplifusidic acid L (1-3), were isolated from the EtOAc extract of the Arctic marine-derived fungus Simplicillium lamellicola culture medium, together with fusidic acid (4) and 16-O-deacetylfusicid acid (5). The structures of the isolated compounds were elucidated by NMR and MS analyses. The absolute configurations of compounds 1-3 were established by the quantum mechanical calculations of electronic circular dichroism and gauge-including atomic orbital NMR chemical shifts, followed by DP4 + analysis. Benign prostatic hyperplasia (BPH) is a major urological disorder in men worldwide. The anti-BPH potentials of the isolated compounds were evaluated using BPH-1 and WPMY-1 cells. Treatment with simplifusidic acid L (3) and fusidic acid (4) significantly downregulated the mRNA levels of the androgen receptor (AR) and its downstream effectors, inhibiting the proliferation of BPH-1 cells. Specifically, treatment with 24-epi simplifusinolide A (2) significantly suppressed the cell proliferation of both BPH-1 and DHT-stimulated WPMY-1 cells by inhibiting AR signaling. These results suggest the potential of 24-epi simplifusinolide A (2), simplifusidic acid L (3) and fusidic acid (4) as alternative agents for BPH treatment by targeting AR signaling.

Characterization of a Malabaricane-Type Triterpene Synthase from Astragalus membranaceus and Enzymatic Synthesis of Astramalabaricosides

Triterpenoids are a large and medicinally important group of natural products with a wide range of biological and pharmacological effects. Among them, malabaricane-type triterpenoids are a rare group of terpenoids with a 6,6,5-tricyclic ring system, and a few malabaricane triterpene synthases have been characterized to date. Here, an arabidiol synthase AmAS for the formation of the malabaricane-type 6,6,5-tricyclic triterpenoid skeleton in astramalabaricosides biosynthesis was characterized from Astragalus membranaceus. Multiple sequence alignment, site-directed mutagenesis, and molecular docking of AmAS reveal that residues Q256 and Y258 are essential for AmAS activity, and the triad motif IIH725-727 was the critical residue necessary for its product specificity. Mutation of IIH725-727 with VFN led to the formation of seven tricyclic, tetracyclic, and pentacyclic triterpenoids (1-7). Glycosylation of malabaricane-type triterpenoids in the biosynthesis of astramalabaricosides was also explored. Three triterpenoids (1, 5, and 6) displayed potent inhibitory effects against influenza A virus in vitro. These findings provide insights into malabaricane-type triterpenoids biosynthesis in A. membranaceus and access to diverse bioactive triterpenoids for drug discovery.