Eremophilane-Type Sesquiterpenoids From the Endophytic Fungus Rhizopycnis vagum and Their Antibacterial, Cytotoxic, and Phytotoxic Activities

Fourteen new eremophilane-type sesquiterpenoids, named rhizoperemophilanes A~N (1~14), together with eight known congeners, were isolated from the culture of the endophytic fungus Rhizopycnis vagum. The structures of the new compounds were elucidated by extensive spectroscopic analyses, as well as ECD calculations and the modified Mosher's method for the assignment of the absolute configurations. Rhizoperemophilane J (10) contains an uncommon C-4/C-11 epoxy ring, while rhizoperemophilane N (14) features an unprecedented 3-nor-eremophilane lactone-lactam skeleton. These metabolites were evaluated for their antibacterial, cytotoxic, and phytotoxic activities. Among them, compounds 11, 16, and 20 displayed antibacterial activities, while 14 showed selective cytotoxicity against NCI-H1650 and BGC823 tumor cells. Moreover, compounds 5, 6, 12, 13, 16, and 19 exhibited strong phytotoxic activities against the radicle elongation of rice seedlings.

Two New Anisic Acid Derivatives from Endophytic Fungus Rhizopycnis vagum Nitaf22 and Their Antibacterial Activity

Rhizopycnis acids A (1) and B (2), two new anisic acid derivatives, were obtained from the ethyl acetate extract of the fermentation cultures of Rhizopycnis vagum, an endophytic fungus isolated from the healthy tissues of Nicotiana tabacum. The structures of the two compounds were determined through a series of 1D and 2D NMR and HRMS spectral analyses. Both compounds were the first anisic acid derivatives containing methylbutanoic/methylbutenoic acid group found in fungi. 1 and 2 displayed antibacterial activity against six tested bacteria with IC₅₀ values in the range 16.1~81.3 μg/mL.

Diversity of sterile root-associated fungi of two Mediterranean plants

•  The diversity of dark sterile mycelia (DSM) associated with the roots of neighboring healthy ectomycorrhizal Pinus halepensis and endomycorrhizal Rosmarinus officinalis plants in a Mediterranean ecosystem in Italy was investigated to assess taxonomic affinities of these poorly known root endophytes. •  More than 260 fungal isolates were obtained and ascribed to distinct morphotypes based on their macro- and microscopic features. Polymerase chain reaction-restriction fragment length polymorphism and sequence analyses of the internal transcribed spacers (ITS1-5.8S-ITS2) and 18S rDNA regions were carried out for representatives of the morphotypes obtained from both hosts over an 11-yr period. •  Molecular evidence matched morphological group circumscription. Recognition of systematic affinities was possible with varying degrees of resolution for the different morphotypes. Morph 2 was closely related to Rhizopycnis vagum (within Dothideomycetidae), Morph 1 to Diaporthe / Phomopsis (within Sordariomycetidae), whereas Morphs 3a, 3b, 3c and 3d could only be given taxonomic placement at a higher level (Dothideomycetidae and Chaetothyriomycetidae). •  This peculiar systematic spectrum suggests that actual DSM diversity in nature is still largely underestimated. Morphophysiological convergence among morphotypes, and ecological traits possibly involved in interactions with plant hosts are discussed.