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Five new stilbene oligomers, laetevirenol A-E (4-8), were isolated from Parthenocissus laetevirens, together with three known stilbene oligomers (2, 3, and 9). The structures of the new compounds were elucidated by spectroscopic analysis, including 1D and 2D NMR experiments. Afterward the absolute configurations were determined. Biomimetic transformations revealed a possible biogenetic route, where stilbene trimers were enzymatically synthesized for the first time. In addition, their antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The results showed that stilbene oligomers with an unusual phenanthrene moiety exhibited much stronger antioxidant activities. Thus, the photocatalyzed cyclization of stilbenes was supposed to be an antioxidant activity promoting transformation, which was hypothesized to play a role in the antioxidative defense system of the plant.

Nowadays, various drugs on the market are becoming more and more resistant to numerous diseases, thus declining their efficacy for treatment purposes in human beings. Antibiotic resistance is one among the top listed threat around the world which eventually urged the discovery of new potent drugs followed by an increase in the number of deaths caused by cancer due to chemotherapy resistance as well. Accordingly, marine cyanobacteria, being the oldest prokaryotic microorganisms belonging to a monophyletic group, have proven themselves as being able to generate pharmaceutically important natural products. They have long been known to produce distinct and structurally complex secondary metabolites including peptides, polyketides, alkaloids, lipids, and terpenes with potent biological properties and applications. As such, this review will focus on recently published novel compounds isolated from marine cyanobacteria along with their potential bioactivities such as antibacterial, antifungal, anticancer, anti-tuberculosis, immunosuppressive and anti-inflammatory capacities. Moreover, various structural classes, as well as their technological uses will also be discussed.

Auranofin, an FDA-approved arthritis drug, has recently been repurposed as a potential antimicrobial agent; it performed well against many Gram-positive bacteria, including multidrug resistant strains. It is, however, inactive toward Gram-negative bacteria, for which we are in dire need of new therapies. In this work, 40 auranofin analogues were synthesized by varying the structures of the thiol and phosphine ligands, and their activities were tested against ESKAPE pathogens. The study identified compounds that exhibited bacterial inhibition (MIC) and killing (MBC) activities up to 65 folds higher than that of auranofin, making them effective against Gram-negative pathogens. Both thiol and the phosphine structures influence the activities of the analogues. The trimethylphosphine and triethylphosphine ligands gave the highest activities against Gram-negative and Gram-positive bacteria, respectively. Our SAR study revealed that the thiol ligand is also very important, the structure of which can modulate the activities of the AuI complexes for both Gram-negative and Gram-positive bacteria. Moreover, these analogues had mammalian cell toxicities either similar to or lower than that of auranofin.

We report the modular formulation of ciprofloxacin-based pure theranostic nanodrugs that display enhanced antibacterial activities, as well as aggregation-induced emission (AIE) enhancement that was successfully used to image bacteria. The drug derivatives, consisting of ciprofloxacin, a perfluoroaryl ring, and a phenyl ring linked by an amidine bond, were efficiently synthesized by a straightforward protocol from a perfluoroaryl azide, ciprofloxacin, and an aldehyde in acetone at room temperature. These compounds are propeller-shaped, and upon precipitation into water, readily assembled into stable nanoaggregates that transformed ciprofloxacin derivatives into AIE-active luminogens. The nanoaggregates displayed increased luminescence and were successfully used to image bacteria. In addition, these nanodrugs showed enhanced antibacterial activities, lowering the minimum inhibitory concentration (MIC) by more than one order of magnitude against both sensitive and resistant Escherichia coli. The study represents a strategy in the design and development of pure theranostic nanodrugs for combating drug-resistant bacterial infections.nanodrugs | aggregation-induced emission | fluoroquinolones

An unusual polyketide with a new carbon skeleton, lindgomycin (1), and the recently described ascosetin (2) were extracted from mycelia and culture broth of different Lindgomycetaceae strains, which were isolated from a sponge of the Kiel Fjord in the Baltic Sea (Germany) and from the Antarctic. Their structures were established by spectroscopic means. In the new polyketide, two distinct domains, a bicyclic hydrocarbon and a tetramic acid, are connected by a bridging carbonyl. The tetramic acid substructure of compound 1 was proved to possess a unique 5-benzylpyrrolidine-2,4-dione unit. The combination of 5-benzylpyrrolidine-2,4-dione of compound 1 in its tetramic acid half and 3-methylbut-3-enoic acid pendant in its decalin half allow the assignment of a new carbon skeleton. The new compound 1 and ascosetin showed antibiotic activities with IC50 value of 5.1 (±0.2) µM and 3.2 (±0.4) μM, respectively, against methicillin-resistant Staphylococcus aureus.

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