Essential oil of Lavandula mairei var. antiatlantica as a natural agent against microbial growth and insect-driven biodeterioration

This study aims to assess the antioxidant, antibacterial, antifungal, and behavioral effects of the essential oil of L. mairei var. antiatlantica. The antioxidant potential was measured using DPPH, β-carotene-linoleic acid, ABTS, FRAP, and TAC assays. As for the antimicrobial effect, the antibacterial effect was assessed against Staphylococcus aureus (ATCC6538), Escherichia coli (ATCC25922), Klebsiella pneumoniae (LMG20218), and Salmonella enterica (LMG7233), while the antifungal effect was monitored against Aspergillus flavus. The repellent and antifeedant effects were evaluated against Tribolium castaneum, Tribolium confusum, and Tenebrio molitor. As for the in silico study, molecular docking was performed using the two major compounds of the EO, carvacrol and carvacrol methyl ether against bacterial (DNA gyrase MurA) and fungal targets (Lanosterol 14-alpha demethylase and UDP-GlcNAc pyrophosphorylase). Regarding the antioxidant effect, the IC50 values were 3.32, 1.43, and 1.44 mg/mL in the DPPH, β-carotene-linoleic acid, and ABTS assays, respectively, while the EC50 values in the FRAP and TAC assays were 2.16 and 2.17 mg/mL, respectively. Regarding the antimicrobial effect, L. mairei var. antiatlantica EO exhibited strong inhibition against all bacterial strains, with the lowest MIC (0.078 mg/mL) recorded for S. enterica. Additionally, strong mycelial growth inhibition was observed against A. flavus, with IC50 values of 19.52 and 27.36 μL/mL after 72 and 96 h, respectively. In terms of repellent efficiency, the highest percentages of repellency (PR) were observed for T. molitor, with 98% and 90% recorded after 4 and 24 h, respectively. As for the antifeedant effect, 95% and 98% were the highest feeding deterrence index (FDI) percentages recorded in the case of T. molitor exposed to 0.48 and 0.96μL/pellet, respectively. The molecular docking results revealed that the highest affinity was recorded between carvacrol methyl ether and the two fungal targets Lanosterol 14-alpha demethylase (−7.3 kcal/mol) and UDP-GlcNAc pyrophosphorylase (−7.3 kcal/mol) against −7.2 and −7.0 kcal/mol in the case of carvacrol. These multifaceted effects highlight the potential of this EO as a natural, green alternative for biodeterioration control.