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Rationale: 4,7-Dichloroquinoline (DCQ) represents a group of synthetic molecules inspired by natural products with important roles in biological and biomedical areas. This work aimed to characterize DCQ and its derivatives by high-resolution electrospray ionization (ESI) mass spectrometry and tandem mass spectrometry (ESI-MS/MS), supported by theoretical calculations. Biological assays were carried out with DCQ and its derivatives to determine LC 50 values against Aedes aegypti larvae., Methods: Five DCQ derivatives were synthesized by using previously described protocols. ESI-MS/MS analyses were carried out with a quadrupole/time-of-flight and ion-trap instrument. The proposed gas-phase protonation sites and fragmentation were supported by density functional theory calculations. The larvicidal tests were performed with the Ae. aegypti Rockefeller strain, and the LC 50 values were determined by employing five test concentrations. Larval mortality was determined after treatment for 48 h., Results: DCQ bromides or aldehydes (C-3 or C-8 positions), as well as the trimethylsilyl derivative (C-3 position), were prepared. Detailed ESI-MS/MS data revealed heteroatom elimination through an exception to the even-electron rule, to originate open-shell species. Computational studies were used to define the protonation sites and fragmentation pathways. High activity of DCQ and its derivatives against Ae. aegypti larvae was demonstrated., Conclusion: Our results provided a well-founded characterization of the fragmentation reactions of DCQ and its derivatives, which can be useful for complementary studies of the development of a larvicidal product against Ae. aegypti., (© 2024 John Wiley & Sons Ltd.)

Peptides from skin secretions of amphibians are considered important components of their immune system and also play a relevant role in their defense mechanism against predators. Herein, by using mass spectrometry (MS), we characterize the sequence of 13 peptides from the gland secretion of the hylid tree frog, Boana punctata . Using in situ matrix-assisted laser desorption ionization imaging MS of a transverse section of the skin tissue, we show that some peptides are stored as longer molecules that are cleaved after being secreted, whereas others do not undergo any modification. Sequence comparison with peptides from other Boana species and analysis of the three-dimensional theoretical structure indicate that this cleavage depends on both the presence of a specific sequence motif and the secondary structure. The fact that peptides undergo a rapid cleavage upon secretion suggests that stored and secreted peptides may have distinct roles for anuran survival, including defense against pathogens and predators., Competing Interests: The authors declare no competing financial interest.

This work describes the structural elucidation of the sex pheromone of the soybean stink bug, Pallantia macunaima. The biological activity of the synthetic pheromone was demonstrated by behavioral and EAD experiments. Furthermore, the absolute configuration of the natural pheromone was determined as (6R,10S)-6,10,13-trimethyltetradecan-2-one. This is the first ketone identified as a male-produced sex pheromone in Pentatomidae, and the trivial name, pallantione, was assigned to this novel pheromone molecule.

Phthia picta is part of a complex of true bugs (Heteroptera) in Brazil that attack tomatoes, being particularly damaging because nymphs and adults feed on both leaves and fruit. Gas chromatography (GC) of aeration extracts of adult males vs. females revealed the presence of a male-specific compound. GC-electroantennographic detector experiments indicated that the antennae of females are highly sensitive to this male-specific compound. GC-mass spectrometry and GC-FTIR analyses suggested a methyl branched hydrocarbon structure for this compound. After synthesis of three different proposed structures, the natural product was indentified as 5,9,17-trimethylhenicosane, which was strongly attractive to females in Y-tube olfactometer bioassays. Analysis of dissected body parts of adults revealed that the pheromone is produced in the lateral accessory glands of the metathoracic scent gland of males only.