Identification of active components in the extracts of Hypericum Perforatum L. and Oliveria Decumbens Vent. and evaluation of their antioxidant and antimicrobial effects on some microorganisms

Essential oils and extracts of medicinal plants have been highly regarded as natural food additives and preservatives due to the presence of bioactive compounds and functional activities, including antioxidant and antimicrobial properties. In this research, Hypericum perforatum and Oliveria decumbens were extracted by the maceration method and ultrasonic waves. Total phenolic compounds, and antioxidant as well as antimicrobial activities were assessed by GC-MS. Minimum inhibitory and minimum bactericidal concentrations against Escherichia coli, Staphylococcus aureus, and Aspergillus niger were evaluated. The results showed that 19 main compounds, the most important of which are Thymol (24.40%), Carvacrol (23.00%), and Myristicin (9.78%), comprise 90.22% of O. decumbens extract. In the extract of H. perforatum, 20 compounds constitute 94.16% of the extract, among which Hypericin (25.92%) and Hyperforin (16.69%) are the most important effective compounds. The content of phenolic compounds of Hypericum perforatum and O. decumbens extracts were 24.0 and 9.5 mg/g of dry weight, respectively. H. perforatum extract shows higher antioxidant activity compared to O. decumbens extract (IC50 of H. perforatum and O. decumbens extracts are 0.173 and 0.470 g/ml, respectively). The extract of H. perforatum inhibited the activity of S. aureus and E. coli, however, did not significantly inhibit the activity of A. niger.