IntroductionWild mint or horsemint (Mentha longifolia (L.) L., syn. Mentha sylvestris L.) is a perennial herb belonging to the genus Mentha of the family Lamiaceae. The genus Mentha includes about 20 species with many subspecies and varieties including many medicinal and culinary herbs. These taxa can hybridize easily and thus their differentiation is relatively difficult. In recent years, morphological, cytological, and chemotaxonomic studies made the classification of Mentha plants more clear. The genus is indigenous in Eurasia, Africa, and Australia. The species Mentha longifolia (ML) is common in Eurasia, the Atlas Mountains, Egypt, the Arabian Peninsula, and South Africa.In Linnaeus' herbarium in 1753 he determined three varieties of Mentha spicata: M. spicata var. viridis, var. longifolia, and var. rotundifolia. In Flora Monspeliensis he listed Mentha longifolia, but in the second edition of Species Plantarum in 1763 he mentioned var. longifolia within Mentha sylvestris. Today the name Mentha longifolia (L.) L. is accepted. ML has many subspecies and varieties, similarly to other mint plants. The subspecies longifolia is best known. Other subspecies, subsp. noeana, subsp. grisella, and subsp. typhioides, are known from Eurasia.Further subspecies are indigenous in South Africa: subsp. capensis, subsp. wissii, and subsp. polyadena. Other subspecies of ML varieties are also described from Central Europe. In 1893, M. sylvestris Linnaeus var. globifera Waisbecker & Borbás was determined from a sample that originated in Kőszeg (Güns), West Hungary; the specimen was deposited in the Gray Herbarium (GH) under No. GH00415377. A further variety, var. lavanduliodora, is grown in the botanical garden of Bratislava (Fialová and Tekel' ová, 2008). In the Herbarium of Eszterházy Károly University (EGR) there are more different specimens of M. longifolia. The most valuable specimen was collected by M Vrabély in 1863 in the Mátra Mountains (Sass-Gyarmati and Vojtkó, 2010).Generally, ML contains four main types of bioactive ingredients. These are flavonoids, phenolic acids (predominantly caffeic acid derivatives), essential oil based on a couple of monoterpene ketones (Hajlaoui et al., 2002;Iqbal et al., 2013;Llórens-Molina et al., 2015), and eucalyptol (Murad et al., 2016), as well as various triterpenes including phytosterols.The most frequent caffeic acid-originated component of the plant is rosmarinic acid (Mimica-Dukić et al.,