Abstract
Natural products represent a vital source of chemical entities for the development of anti-infective agents. Insects face constant threats from pathogens and have evolved diverse mechanisms of the infection response. Among various insect species, the chemical protection provided by Galleria mellonella eggs against microorganisms remains poorly understood. This study aimed to investigate whether G. mellonella produces chemical compounds that could serve as anti-infective agents against clinically important bacteria. Additionally, the study examined the effects of larval exposure to bacterial antigens from multidrug-resistant Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosaon the chemical composition, morphology, and anti-infective properties of the eggs. Larvae were challenged with antigens derived from multidrug-resistant Gram-positive and Gram-negative bacteria. Eggs from intragroup mating were collected and analyzed by using histological and physicochemical techniques, including field-emission gun scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Antibacterial and antibiofilm activities of the egg extracts were assessed using broth microdilution and crystal violet assays, respectively. The volatile compound profile of the extracts was characterized by gas chromatography-mass spectrometry. This pioneering study demonstrates the broad-spectrum antibacterial activity of G. mellonella eggs against clinically relevant bacteria. Notably, the antibacterial efficacy of the mucous layer extract was significantly enhanced when larvae were exposed to Gram-positive bacterial antigens. Dotriacontane and tetracontane were identified as the predominant volatile compounds. These findings highlight G. mellonella eggs as a promising source of bioactive compounds and underscore the potential of long-chain hydrocarbons in the development of novel antibacterial agents.