RESUMEN
Essential oils are known to exhibit diverse antimicrobial properties, showing their value as a natural resource. Our work aimed to investigate the primary mode of action of Cuban Lippia graveolens (Kunth) essential oil (EO) against Salmonella enterica subsp. enterica serovar Typhimurium (S. enterica ser. Typhimurium). We assessed cell integrity through various assays, including time-kill bacteriolysis, loss of cell material with absorption at 260 and 280 nm, total protein leakage, and transmission electron microscopy (TEM). The impact of L. graveolens EO on membrane depolarization was monitored and levels of intracellular and extracellular ATP were measured by fluorescence intensity. The minimum inhibitory and bactericidal concentrations (MIC and MBC) of L. graveolens EO were 0.4 and 0.8 mg/mL, respectively. This EO exhibited notable bactericidal effects on treated cells within 15 min without lysis or leakage of cellular material. TEM showed distinct alterations in cellular ultrastructure, including membrane shrinkage and cytoplasmic content redistribution. We also observed disruption of the membrane potential along with reduced intracellular and extracellular ATP concentrations. These findings show that L. graveolens EO induces the death of S. enterica ser. Typhimurium, important information that can be used to combat this foodborne disease-causing agent.
RESUMEN
Blattella germanica (Linneaus, 1767) es una especie de cucaracha considerada plaga de la salud pública por estar asociada a gran número de microorganismos causantes de enfermedades al hombre. Para su control se utilizan diferentes tipos de formulaciones a base de insecticidas sintéticos a los cuales en su gran mayoría es resistente. En este contexto existe un interés creciente por los insecticidas botánicos. En el siguiente trabajo se evaluaron los aceites de Citrus aurantium (L.,1753), Ocimum basilicum (L.,1753), Piper aduncum subsp ossanum (C.DC. Saralegui) y Eucalyptus globulus (Labill, 1800) mediante aplicación tópica de un microlitro en el primer esternito abdominal de los individuos. Los cuatro aceites mostraron actividad insecticida sobre adultos de B. germanica con CL50 que oscilaron entre 58 µg/µL para O. basilicum y 250 µg/µL para P. aduncum(AU)´
Blattella germanica (Linneaus, 1767) is a cockroach species considered a public health pest, since it is associated with a great number of disease-causing microorganisms in humans. For its control, different types of synthetic-based insecticidal formulations are used, to which it is mostly resistant. In this context, there is a growing interest in botanical insecticides. In this research, oils from Citrus aurantium (L., 1753), Ocimum basilicum (L., 1753), Piper aduncum subsp. ossanum (C.DC. Saralegui), and Eucalyptus globulus (Labill, 1800) were evaluated by topical application of 1 µL to the first abdominal sternum of the individuals. The four essential oils evaluated showed insecticidal activity against adult B. germanica with LC50 ranging from 58µg/µL for O. basilicum to 250µg/µL for P. aduncum(AU)´
