Table 2.

In vivo models evaluating oregano extracts and essential oil

Model	Experimental conditions	Significant findings	Citation
P. acnes-induced mouse ear edema	• 8-week old ICR mice • Groups (5 mice each): ○ Ethanolic OE (2 mg/10 μL) in 5% DMSO ○ Vehicle control (5% DMSO) • Propionibacterium acnes (6 × 10⁷ CFU/10 μL PBS) was inoculated in right ear by intradermal injection and PBS (10 μL) was injected in right ear • Ethanolic OE or vehicle (5% DMSO) was injected in both ears directly after P. acnes • 24 hours after P. acnes injection, mouse ear swelling was measured and mice were euthanized	• P. acnes injection increased ear thickness by 2.5-fold and ear weight by 2.3-fold • OEO reduced P. acnes-induced ear thickness by 32% and ear weight by 37%	⁴¹
Streptozotocin-induced type 1 diabetes mice	• 8–12 week old C57BL/6 mice • Groups (≥7 mice each): ○ Streptozotocin (40 mg/kg/day) + OE (2 mg/day) ○ Streptozotocin only • Streptozotocin (40 mg/kg/d) was administered through intraperitoneal (IP) injection at multiple low doses (MLDS) for 5 consecutive days • Ethyl acetate OE administered by IP at 2 mg doses for 10 consecutive days, starting on same day as Streptozotocin dosing	• Streptozotocin administration alone resulted in 80% development of hyperglycemia in mice, and ethyl acetate OE administration reduced hyperglycemic development to 15% of mice • Ethyl acetate OE reduced the number of F4/80* macrophages and concentrations of IL-1β and IL-6, while also increasing concentrations of TNF and IL-10 • Th1 and Th17 cell counts decreased with ethyl acetate administration, along with concentrations of associated cytokines IFN-γ and IL-17	⁴
TNBS-induced colitis mice	• 7-week old Balb/c mice • Groups (16 mice each): ○ Group A: TNBS + 0.4% thyme oil + 0.2% oregano oil ○ Group B: TNBS + 0.2% thyme oil + 0.1% oregano oil ○ Group C: TNBS + 0.1% thyme oil + 0.05% oregano oil ○ Group D: TNBS only ○ Group E: Sham • Colitis induced by intrarectal administration of 120 mg/kg TNBS in 50% ethanol • Thyme and oregano oil combinations were administered for 7 consecutive days	• Mice in Group B recovered body weight significantly compared to TNBS-only mice • Mice in Group B had a significantly lower colonic damage score compared to TNBS-only mice • The mRNA and protein levels of IL-1β and IL-6 cytokines was significantly reduced in Group B mice	⁴²