Combination of various compounds and essential oils for pharmaceutical formulations withdraw attention. In this present study, it was aimed to evaluate the in vitro potential synergistic antibacterial effect of Lavandula latifolia (spike lavender) essential oil with camphor by using the checkerboard method against the human pathogens; Staphylococcus aureus and Listeria monocytogenes. Pharmacopoeia quality L. latifolia essential oil and racemic camphor were analyzed and verified by GC-FID and GC/MS, simultaneously. In vitro antibacterial activity of essential oil and camphor (MIC range: 0.16–20 mg/mL) and standard antimicrobial clarithromycin (MIC range: 0.125–16 μg/mL) were carried out by broth microdilution against S. aureus and L. monocytogenes standard strains, respectively. Resulting antibacterial effects were evaluated for their fractional inhibitory concentrations (FICs) as antagonistic, additive and synergistic effects. The analytical results showed that the major component of essential oil was linalool (45.2%) and 1,8-cineole (25.6%). Antibacterial effects of essential oil were determined as MIC 1.25–5 mg/mL. As a result of the experiments, L. latifolia essential oil–camphor combinations were identified as “synergistic (FIC ≤ 0.5), and additive (0.5 < FIC ≤ 1)” in the respective combinations, suggesting further evaluation for formulations for potential antimicrobial applications in food and pharmaceuticals.

No abstract

Three iridoid glycosides, 5-allosyloxy-aucubine (1), melittoside (2), ajugol (3), five phenylethanoid glycosides, verbascoside (4), martynoside (5), leucoseptoside A (6), lamalboside ( 7), decaffeoylverbascoside (8), four flavonoids, xanthomicrol (9), isoscutellarein 7-O-[6'''-O-acetyl-b-allopyranosyl-(1!2)]-b-glucopyranoside (10), 4'-O-methylisoscutellarein 7-O-[6'''-O-acetyl-b-allopyranosyl-(1!2)]b-glucopyranoside (11), 3'-hydroxy-4'-O-methylisoscutellarein 7-O-[6'''-O-acetyl-b-allopyranosyl-(1!2)]-b-glucopyranoside (12), and two lignan glycosides dehydrodiconiferylalcohol 4-O-b-D-glucopyranose (13) and pinoresinol 4'-O-b-glucopyranoside (14) were isolated from the aerial parts of Sideritis germanicopolitana. Their structures were determined on the basis of detailed NMR and HRESIMS analyses. To our knowledge, all compounds are being reported for the first time from S. germanicopolitana, while the isolated lignans (13 and 14) are new for the genus Sideritis. In vitro evaluation of AChE, BChE and LOX inhibitory effects of all the tested compounds (1-14) resulted in low to moderate activities.