Objective: The purpose of this study was to evaluate the essential oil composition as well as antibacterial activities of essential oil and leaves extracts of Lantana camara against five bacterial strains. Methods: Essential oil was obtained by hydro-distillation from the leaves and analyzed by GC and GC-MS. The antibacterial activities of essential oil and the leaves extracts were tested by using disk diffusion method against five bacterial strains. Results: Thirty seven compounds were identified representing 98.11% of the total oil, of which trans-caryophyllene (13.95%), bicyclogermacrene (9.77%), α-curcumene (8.57%), sabinene (8.28%), (E)-citral (6.90%), 1,8 cineole (5.06%), α-pinene (4.03%), γ-terpinene (3.83%) and germacrene D (3.13%) were detected as major components. In respect to the antibacterial activities, essential oil showed the high degree of sensitivity against Micrococcus luteus, Escherichia coli, Staphylococcus aureus and Bacillus cereus except Pseudomonas aeruginosa while extracts of leaves obtained through petroleum ether, benzene, methanol and water exhibited good to moderate antimicrobial activity against all tested bacterial strains. Conclusions: The present study suggested that M. luteus showed best zone of inhibition for the essential oil as well as aqueous extract among all the tested bacterial strains. The most active extract can be subjected to isolation of the therapeutic antimicrobials to carry out further pharmacological evaluation.

Pregnane X receptor (PXR) is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes [e.g., cytochrome P450 3A4 (CYP3A4)] and transporters. Although the regulation of PXR target genes is well-characterized, less is known about the regulation of PXR protein level. By screening an RNAi library, we identified the F-box-only protein 44 (FBXO44) as a novel E3 ligase for PXR. PXR abundance increases upon knockdown of FBXO44, and, inversely, decreases upon overexpression of FBXO44. Further analysis revealed that FBXO44 interacts with PXR, leading to its ubiquitination and proteasomal degradation, and we determined that the F-box associated domain of FBXO44 and the ligand binding domain of PXR are required for the functional interaction. In summary, FBXO44 regulates PXR protein abundance, which has downstream consequences for CYP3A4 levels and drug-drug interactions. The results of this study provide new insight into the molecular mechanisms that regulate PXR protein level and activity and suggest the importance of considering how modulating E3 ubiquitin ligase activities will affect PXR-mediated drug metabolism.