Phytochemical profiling and microencapsulation of three lavender essential oils: Synergistic antibacterial potential with antibiotics

Abstract

Encapsulating essential oils (EOs) enhances their efficacy as natural antimicrobial agents by mitigating the limitations of their pure form. This study aimed to investigate the encapsulation of EOs derived from three Lavandula species of the Lamiaceae family (L. tenuisecta Coss. Ex Ball, L. mairei Humbert Var. and L. maroccana Murb) and to assess their antibacterial synergy with two conventional antibiotics. The EOs were microencapsulated with maltodextrin 19 using the spray-drying technique. Their antibacterial efficacy and synergistic effects with antibiotics were assessed through microdilution, checkerboard, and time-kill assays. The EOs from the three studied Lavandula species were primarily composed of carvacrol, ranging from 68.69 % to 70.01 %. Encapsulation yields for L. mairei, L. tenuisecta, and L. maroccana were 70.84 %, 66.00 %, and 64.23 %, respectively, with efficiency rates of 87.16 %, 90.47 %, and 89.47 %. The microcapsules of the EOs displayed smooth, spherical external structures free from cracks and visible pores. These encapsulated oils demonstrated notable inhibitory effects against prominent drug-resistant pathogens Staphylococcus aureus and Escherichia coli, with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) ranging from 0.50 mg/mL to 1.66 mg/mL. According to the fractional inhibitory concentration index (FICI) and time-kill results, the encapsulated EOs synergistically enhanced the efficacy of ampicillin and ciprofloxacin, reducing their MICs by 2- to 8-fold and 8- to 32-fold, respectively. These results support using encapsulated EOs from Moroccan lavender species, highlighting their potential as primary or complementary antibacterial agents.