The rhizomes of Origanum vulgare exhibit antioxidant and antimicrobial activity comparable to the leaves

Our study aimed to examine the antibacterial and antioxidant activity of Origanum vulgare underground parts (OVr) besides the leaves (OVl) that are used conventionally. Antioxidant activity was determined using the DPPH model as IC₅₀ of OVl 6.32 µg/mL and OVr 8.50 µg/mL. In ABTS assay, the IC₅₀ of OVl was 11.86 µg/mL and OVr 7.55 µg/mL. The determination of intracellular oxidative stress by DCFH-DA assay resulted in a reduction of ROS production in NIH/3t3 cells treated with H₂O₂ by OVl, IC₅₀=3.95 µg/mL, and OVr, IC₅₀=3.23 µg/mL.

The antioxidant activity of rosmarinic acid (positive control) was slightly stronger in all assays (1.83 µg/mL, 3.27 µg/mL and 1.57 μg/mL, respectively). The antimicrobial activity of OVl and OVr was tested by broth microdilution assay. MICs and MBCs of OVr are 2.5 mg/mL for MSSA and MRSA. MIC and MBC of OVl against P. mirabilis is also 2.5 mg/mL, whereas MIC and MBC of OVr is 5 mg/mL. Both extracts also inhibited the growth of E. faecalis (MIC OVl=10 mg/mL, MIC OVr=2.5 mg/mL), but they did not act as bactericidals. P. aeruginosa, E. coli, K. pneumoniae and C. albicans were found to be resistant against both. LC-MS-DAD analysis revealed rosmarinic acid and oreganol A as major compounds. In conclusion, O. vulgare rhizomes showed significant antioxidant and antimicrobial action and might be intended as an alternative to the leaves.

Funding This work was supported by grants APVV-19-0056 and VEGA 1/0284/20.

Publication History

Article published online:
16 November 2023