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Thymus dacicus as a new source of antioxidant and antimicrobial metabolites

Petrović, Silvana, Ušjak, Ljuboš, Milenković, Marina, Arsenijević, Jelena, Drobac, Milica, Drndarević, Aneta, Niketić, Marjan
Journal of functional foods 2017 v.28 pp. 114-121
2,2-diphenyl-1-picrylhydrazyl, Escherichia coli, Klebsiella pneumoniae, Lamiaceae, aerial parts, anti-infective properties, antioxidant activity, antioxidants, essential oils, flowering, food additives, functional foods, gas chromatography-mass spectrometry, gentamicin, geranial, high performance liquid chromatography, hydroxyl radicals, ingredients, metabolites, methanol, methicillin-resistant Staphylococcus aureus, neral, novel foods, oils, polyphenols, rosmarinic acid, synergism, vancomycin
In a search for novel food additives/functional food ingredients, chemical composition, and antioxidant and antimicrobial activities of Thymus dacicus Borbás (Lamiaceae) flowering aerial parts dry methanol extract and essential oil were tested for the first time. HPLC analysis of the extract revealed that among dominant polyphenols, rosmarinic acid was the most abundant (71.33±1.11mg/g). Monoterpenes geranial (34.4%) and neral (23.9%) prevailed in the oil, analyzed by GC and GC–MS. The extract showed pronounced antioxidant activity, with FRAP value of 5.16±0.19mmol Fe2+/g, OH radical SC50 of 18.85μg/mL (determined by 2-deoxyribose assay) and DPPH radical SC50 of 28.04μg/mL. Eight out of ten tested microbial strains were susceptible to the oil in microdilution test. Furthermore, for the combination of the oil and vancomycin/gentamicin, synergism was demonstrated against MRSA, Klebsiella pneumoniae and Escherichia coli in checkerboard test. Obtained results encourage further research of this herb as potentially beneficial ingredient in foodstuffs.