Structural elucidation and NMR spectral assignments of paraconfuranones I-M from the insect-associated fungus Paraconiothyrium brasiliense

Aspercitrininone A, novel antibacterial polyketide featuring unusual spiral skeleton from Aspergillus cristatus

Aspercitrininone A (1), a novel polyketide featuring an unprecedented tetracyclic 6/6/6/5 spiral skeleton, was obtained from the rice fermentation cultures of the fungus Aspergillus cristatus together with five known compounds (2-6). Their structures were determined by HRESIMS data, 1D and 2D NMR spectroscopic analysis, and electronic circular dichroism (ECD) calculations. Aspercitrininone A was revealed as a new type of C/D cycle spiral structure and an unusual addition product of o-quinoid form citrinin with 2-methylterrefuranone. Compounds 1, 4, and 5 exhibited potent antibacterial activities with minimal inhibitory concentration (MIC) values from 13.2 to 67.3 μg/mL against four strains of human pathogenic bacteria in vitro.

The genus Paraconiothyrium: species concepts, biological functions, and secondary metabolites

The genus Paraconiothyrium has worldwide distribution with diverse host habitats and exhibits potential utilisation as biocontrol agent, bioreactor and antibiotic producer. In this review, we firstly comprehensively summarise the current taxonomic status of Paraconiothyrium species, including their category names, morphological features, habitats, and multigene phylogenetic relationships. Some Paraconiothyrium species possess vital biological functions and potential applications in medicine, agriculture, industry, and environmental protection. A total of 147 secondary metabolites have been reported so far from Paraconiothyrium, among which 95 are novel. This paper serves to provide an overview of their diverse structures with chemical classification and biological activities. To date, 27 species of Paraconiothyrium have been documented; however, only seven have been investigated for their secondary metabolites or biological functions. Our review is expected to draw more attention to this genus for providing a taxonomic reference, discovering extensive biological functions, and searching in-depth for new bioactive natural products.

Asperfuranones A-C, 3(2H)-furanone derivatives from the fungus Aspergillus sp. and the configuration reassignment of their eighteen analogues

Three undescribed 3(2H)-furanone derivatives, asperfuranones A-C (1-3), along with one known compound (4) were isolated from the Aspergillus sp. strain obtained from the intestines of centipede. Their structures were determined by NMR and MS spectroscopic analyses, and the absolute configurations were established by the Snatzke's sector rules, modified Mosher's method and electronic circular dichroism (ECD) calculation. Meanwhile, the application of the sector rules led to the reassignment of the absolute configurations of 4 and other seventeen previously reported analogues (5-21).