Effect of allyl-isothiocyanate on survival and antimicrobial peptide expression following oral bacterial infections in Drosophila melanogaster.

Since infections with antibiotic-resistant bacteria cause increasing problems worldwide, the identification of alternative therapies is of great importance. Plant-derived bioactives, including allyl-isothiocyanate (AITC), have received attention for their antimicrobial properties. The present study therefore investigates the impact of AITC on survival and antimicrobial peptide (AMP) levels in Drosophila melanogaster challenged with the fly pathogenic bacteria Pectobacterium carotovorum subsp. carotovorum and Leuconostoc pseudomesenteroides. AITC, a sulfur-containing compound derived from glucosinolates, exhibits antimicrobial properties and has been suggested to modulate AMP expression. By using D. melanogaster, we demonstrate that AITC treatment resulted in a concentration-dependent decrease of survival rates among female flies, particularly in the presence of the Gram-negative bacterium Pectobacterium carotovorum subsp. carotovorum, whereas AITC did not affect survival in male flies. Despite the ability of isothiocyanates to induce AMP expression in cell culture, we did not detect significant changes in AMP mRNA levels in infected flies exposed to AITC. Our findings suggest sex-specific differences in response to AITC treatment and bacterial infections, underlining the complexity of host-pathogen interactions and potential limitations of AITC as a preventive or therapeutic compound at least in D. melanogaster models of bacterial infections.

Identification of a Grain Beetle Macrolide Pheromone and Its Synthesis by Ring-Closing Metathesis Using a Terminal Alkyne.

A major C18-macrolide was found during analysis of the frass of the storage beetle Oryzaephilus surinamensis to be (9Z,12Z,15R)-octadeca-9,12-dien-15-olide (10, cucujolide XI). The synthesis used ring-closing alkyne metathesis as a key step. The highly active 2,4,6-trimethylbenzylidyne molybdenum complex [MesCMo{OC(CF3)2Me}3] (12) allowed the use of a terminal alkyne and afforded the product in excellent yield. Bioassays proved the activity of the R-enantiomer 10 in the aggregation of the beetle. Cucujolide XI is the first macrolide pheromone oxidized at the ω-4 position.