Two new compounds, asperversin A (1) and 9ξ-O-2(2,3-dimethylbut-3-enyl)brevianamide Q (2), and nine known compounds, brevianamide K (3), brevianamide M (4), aversin (5), 6,8-di-O-methylnidurufin (6), 6,8-di-O-methylaverufin (7), 6-O-methylaverufin (8), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (9), ergosta-7,22-diene-3β,5α,6β-triol (10), and 6β-methoxyergosta-7,22-diene-3β,5α-diol (11), were obtained from the culture of Aspergillus versicolor, an endophytic fungus isolated from the marine brown alga Sargassum thunbergii. The structures of these compounds were established by spectroscopic techniques. Compounds 4, 7 and 8 exhibited antibacterial activities against Escherichia coli and Staphyloccocus aureus, and 7 also showed lethality against brine shrimp (Artemia salina) with an LC₅₀ value of 0.5 μg/mL.

Nitrogen heterocycles have drawn considerable attention due to of their significant biological activities. The marine fungi residing in extreme environments are among the richest sources of these basic nitrogen-containing secondary metabolites. As one of the most well-known universal groups of filamentous fungi, marine-derived Aspergillus species produce a large number of structurally unique heterocyclic alkaloids. This review attempts to provide a comprehensive summary of the structural diversity and biological activities of heterocyclic alkaloids that are produced by marine-derived Aspergillus species. Herein, a total of 130 such structures that were reported from the beginning of 2014 through the end of 2018 are included, and 75 references are cited in this review, which will benefit future drug development and innovation.

Two new antimicrobial bisabolane-type sesquiterpenoid derivatives, ent-aspergoterpenin C (compound 1) and 7-O-methylhydroxysydonic acid (2), and two new butyrolactone-type monoterpenoids, pestalotiolactones C (3) and D (4), along with a known monoterpenoid pestalotiolactone A (5) and four known bisabolane sesquiterpenoids (6−9), were isolated and identified from the deep-sea sediment-derived fungus Aspergillus versicolor SD-330. The structures of these compounds were elucidated on the basis of spectroscopic analysis, and the absolute configurations of the new compounds 1−4 were determined by the combination of NOESY and TDDFT-ECD calculations and X-ray crystallographic analysis. Additionally, we first determined and reported the absolute configuration of the known monoterpenoid pestalotiolactone A (5) through the X-ray crystallographic experiment. All of these isolated compounds were evaluated for antimicrobial activities against human and aquatic pathogenic bacteria. Compounds 1, 2, 6 and 9 exhibited selective inhibitory activities against zoonotic pathogenic bacteria such as Escherichia coli, Edwardsiella tarda, Vibrio anguillarum and V. harveyi, with MIC values ranging from 1.0 to 8.0 μg/mL.

Four new uncommon 20-nor-isopimarane diterpenoid epimers, aspewentins I−L (1–4), together with a new methylated derivative of 3, aspewentin M (5), were isolated from the deep sea sediment-derived fungus Aspergillus wentii SD-310. The very similar structures of these epimers made the separation and purification procedures difficult. The structures of compounds 1–5 were illustrated based on spectroscopic analysis, and the absolute configurations of compounds 1–5 were unambiguously determined by the combination of NOESY, time-dependent density functional (TDDFT)-ECD calculations, and X-ray crystallographic analysis. These metabolites represented the rare examples of 20-nor-isopimarane analogues possessing a cyclohexa-2,5-dien-1-one moiety. These compounds were tested for antimicrobial activities against human and aquatic pathogenic bacteria, as well as plant-pathogenic fungi. While compounds 1 and 2 exhibited inhibitory activities against zoonotic pathogenic bacteria such as Escherichia coli, Edwardsiella tarda, Vibrio harveyi, and V. parahaemolyticus, compound 5 showed potent activity against the plant pathogen Fusarium graminearum.

Marine-derived fungi are considered to be valuable producers of bioactive secondary metabolites used as lead compounds with medicinal importance. In this study, chemical investigation of the seawater-derived fungus Aspergillus sydowii SW9 led to the isolation and identification of one new quinazolinone alkaloid, 2-(4-hydroxybenzyl)-4-(3-acetyl)quinazolin-one (1), one new aromatic bisabolene-type sesquiterpenoid, (2) and one new chorismic acid analogue (3), as well as two known alkaloids (compounds 4 and 5). Their structures were determined by extensive 1D/2D NMR and mass spectrometric data, and the absolute configurations of 2 and 3 were assigned by the analysis of ECD spectra aided by quantum chemical computations. Compounds 1, 2, and 4 exhibited selective inhibitory activities against the human pathogenic bacteria Escherichia coli, Staphylococcus aureus, S. epidermidis, and Streptococcus pneumoniae, with MIC values ranging from 2.0 to 16 μg/mL.

A sample of the marine brown alga D. divaricata collected off the coast of Yantai (P.R. China) was dried, powdered, and extracted with the mixture of CHCl₃ and MeOH (1:1, v/v). By a combination of silica gel and Sephadex LH-20 column chromatography and preparative TLC, a new cadinane sesquiterpene 1,4-epoxymuurolan-5β-ol (1) was isolated from this species. Its structure was established by detailed MS and NMR spectroscopic analysis, as well as comparison with literature data.