Polyphenolic fingerprint of methanolic extracts of Mentha sp. cultivated in Slovakia

Mentha L. species (Lamiaceae) represent a large source of natural antioxidants, mainly of phenolic origin [1]. HPLC-DAD and LC/MS/MS were used for a qualitative examination of polar flavonoids and phenolcarboxylic acids in methanolic extracts of leaves of different Mentha sp. Flavonoid-O-glycosides eriocitrine (1), luteolin-7-O-glucuronide (2), luteolin-7-O-rutinoside (3), luteolin-7-O-glucoside (4), naringenin-7-O-rutinoside (5), apigenin-7-O-rutinoside (6), hesperetin-7-O-rutinoside (7), diosmin (8) were identified as major flavonoid constituents. Beside the caffeic acid derivatives lithospermic acid (9) and rosmarinic acid (10), salvianolic acid B (11) was detected which has not been described for Mentha sp. previously. This work additionally presents the flavonoid spectrum of M.×villosa Huds. (cv. 'Snežná') for the first time. The polyphenolic fingerprints of Mentha leaves indicate the metabolic plasticity of the investigated species and beside the essential oil also flavonoids and phenolcarboxylic acids could serve as additional markers for their differentiation.

Mentha L.	1	2	3	4	5	6	7	8	9	10	11
M.×piperita cv.'Perpeta'	+++	+	++	tr	tr	+	++	++	+	++	+
M. spicata	tr	-	+	tr	tr	tr	+	+	+	+++	tr
M. spicata var. crispa	+	tr	+	tr	tr	+	++	+	++	+++	++
M.×villosa	+++	+	+++	+	+	+	++	++	tr	+++	tr
M.×villosa cv. 'Snežná'	+++	+	+++	+	+	+	++	++	+	+++	tr
M. longifolia	+++	tr	++	+	+	++	tr	tr	+	+++	tr
M. longifolia var. lavanduliodora	+	tr	++	+	tr	+	+++	+++	+	+++	tr
+++, ++, + (level of presence), – (absence), tr (trace)

Acknowledgements: VEGA grant SR 1/4289/07

Reference: [1] Fialova, S. et al. (2008) Acta Facult. Pharm. Univ. Comenianae 55: p 96–102.