Mentha longifolia_phenolic_composition

Mentha longifolia (L.) L. (ML) is characterised by polychemism in terms of volatiles and polyphenols. Despite this, ML has not yet been utilized in the industry. This study examined the specific polyphenol composition and its correlations with in vitro antioxidant properties of five accessions of different origins. The study included two habitats and three consecutive years.
The concentration of rosmarinic acid (RA) (4011-55145 mg/kg dry weight, DW), eriocitrin (0-45306 mg/kg), luteolin-7-O-rutinoside (161-30848 mg/kg), cynaroside (0-9076 mg/kg) and hesperidin (144-7138 mg/kg) showed significant, site – and year – independent differences among the accessions. The accumulation of eriocitrin demonstrated significant elevations, especially in the 2nd-year-old plantations (2-fold to 45-fold in comparison to 1st year). RA concentration presented phenophase-dependent changes, which were, however, different in the populations. Accumulation of hesperidin, on the other side, showed significant changes between habitats. Distinction of polyphenol chemotaxa in the species is proposed as a conclusion: one luteolin-7-O-glycosides-flavanone-RA-rich type, one luteolin-7-O-rutinoside/RA type, and two RA-based types, poorer in flavonoids, distinguishable by the presence or absence of eriocitrin and the flavone contents. RA and eriocitrin concentrations demonstrated the strongest correlation with the antioxidant activities of the extracts. Chemotypes rich in rosmarinic acid or flavonoids may serve as valuable raw materials for the food industry and in phytotherapy.