Phytochemical Analysis and Evaluation of Antioxidant, Antimicrobial, and Antidiabetic Activities of Micromeria Myrtifolia

Abstract

Natural compounds have been extensively investigated for new drug discoveries. Micromeria genus is known to be rich in essential oils and bioactive constituents possessing significant biological activities. The current work aims to explore the phytochemical composition of M. myrtifolia liquid extracts and to evaluate their antioxidant, antimicrobial, and antidiabetic activity in vitro. The LC-MS/MS detected various phenolic compounds, especially in the aqueous extract. The aqueous extract of M. myrtifolia positively inhibited α-amylase activity with an IC₅₀ value of 174.44 ± 0.68 mg/mL, and showed the highest antioxidant activity as it scavenged the DPPH radicals from 23.25% to 63.72% with increasing concentration from ~ 0.04 to 0.15 mg/mL. On the other hand, ethyl acetate extract illustrated the lowest antioxidant activity as the % radical scavenging activity of 77% was achieved at the concentration of 7.5 mg/mL. Tested extracts were more effective against Gram-positive bacteria in a dose-dependent manner with logarithmic CFU reduction. Micromeria myrtifolia methanol extract exhibited potential antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis with an MICs value of 3.15 μg/μL and 25 μg/μL, respectively. In comparison, ethyl acetate and hexane extracts had antibacterial activity against Streptomyces epidermidis at MICs of 3.125 μg/μL and 12.5 μg/μL, respectively. Gram-negative bacteria were more challenging to eradicate; however, ethyl acetate, methanol and dichloromethane extracts were successful in reducing the number of Escherichia coli CFUs in a dose-dependent manner at MIC of 25 μg/μL for both ethyl acetate and methanol extracts and at MIC of 50 μg/μL for dichloromethane extract. While Pseudomonas aeruginosa only responded to hexane extract at MIC of 50 μg/μL. The antioxidant, antibacterial, and antidiabetic effects of M. myrtifolia extracts bear significant clinical and therapeutic implications. Furthermore, the potent antioxidant properties make M. myrtifolia extract promising candidates for developing nutraceuticals or pharmaceuticals, particularly for conditions associated with oxidative stress.