Determination of phenolic compositions and antioxidant activities of mentha spicata l. subspecies by LC-MS/MS method

In gerenal terms antioxidant compounds are important in contributing to the protection of living organizms for the cell integrity and thus widely used in foods to avoid spoilage and detoriation. For the lifespan and quality of living organizms maintaining the cell integrity is also vital. Maintaining the integrity of cell membranes is largely possible with the intact cell lipid layers. It is known that this integrity may be achieved by antioxidant substances. For this purpose generally synthetic antioxidants are used more frequently. However, the in the light of increasing scientific evidence on the potential harmful effects of synthetic chemicals versus natural substances continue to be the subject of increasing antioxidant research. In this present work, Mentha spicata L. ssp. spicata and Mentha spicata ssp. tomentosa (Briq.) Harley two subspecies of Mentha spicata L growing in Turkey, were investigated and analyzed in most detail for their phenolic composition, respectively. High Pressure Liquid Chromatography- Mass Spectroscopy/ Mass Spectroscopy (HPLC-MS/MS) was used in the detection and elucidation of 80 compounds. 18 of the phenolics were identified in Mentha species and 25 of them were identified in the Mentha spicata genus for the first time. New phenolic compounds for the Mentha sp. are namely: salvianolic acid F, sagerinic acid, icariside B5 glucopyranoside, apigenin acetylglucoside, luteolin acetylglucoside, salvianolic acid C, salvianolic acid A, feruloylquinic acid, poncirin, methyl lithospermate, dimethyl litospermate, methyl danshensu, 4-caffeoylquinic acid, 3-caffeoylquinic acid, 3-coumaroylquinic acid, 4-coumaroylquinic acid, caffeoyl glucose, and dimethyl rosmarinate, respectively. Other phenolic compounds reported in Mentha species but not in Mentha spicata are namely; salvianolic acid E, 12-hydroxyjasmonate sulphate, protocatechuic acid hexoside, methyl rosmarinate, genkwanin, vicenin-2 and the danshensu dimer, respectively. Antioxidant activity of the extracts were determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH?) radical scavenging activity, ß-carotene-linoleic acid co-oxidation assay and linoleic acid peroxidation assay. ABTS? radical scavenging activity was calculated as trolox equivalent (TEAC). Post column derivatization with ABTS?radical was also done for evaluation of all phenolics within the extracts. Active coumpounds were determined using LC-MS/MS. In addition, the reduction power and chemical composition of extracts were analysed by spectrophotometric (total phenol, total flavonoids, total flavonols) and chromatographic (HPLC, GC/MS, GC/FID, LC-MS/MS) techniques. ,Keywords: Lamiaceae, Mentha spicata; Mentha spicata ssp. spicata; Mentha spicata ssp. tomentosa; HPLC-MS, Phenolic Compounds; Antioxidant activity