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S. Fialová, D. Tekeľová and D. Grančai

The content of phenolic compounds in underground and aerial parts of different Mentha species

Mentha L., the genus belonging to family Lamiaceae, subfamily Nepetoidae, has high commercial importance in the pharmacy as well as in food industry. Mints are available in all five continents and are important sources of each traditional medicine in the prevention and therapy of plenty of diseases. The most active compounds are essential oil and polyphenols. In the past the secondary metabolites in aerial parts were examined, but there is no evidence about the determination of secondary metabolites in underground parts of mints. Therefore the object of this work was to determine the content of phenolic compounds (total hydroxycinnamic derivatives (THD) and flavonoids) of methanol extracts of rhizomes of different Mentha L. and their comparison with leaves extracts. The contents of secondary metabolites were determined using spectrophotometric methods of Slovak Pharmacopoeia. We have detected similar quantities of THD in leaves (0.79 - 2.48 %) and rhizomes (0.96 - 2.18 %), but underground parts were poor in content of flavonoids (< 0.1 %). The free radical scavenging activity using DPPH free radical was investigated as well. A bit stronger antioxidant activity was shown in leaves extracts considering flavonoids content.

Open access

D. Tekeľová, J. Tóth, Sz. Czigle and A. Koutsoulas

Abstract

Salvia officinalis L. (sage) is an important essential oil containing Mediterranean medicinal plant that is commonly cultivated for pharmaceutical uses. In addition to essential oil, other compounds participate on the biological effects of sage, mainly diterpenes, triterpenes and phenolic compounds of the hydroxycinnamic and flavonoid types. Sage essential oil content is known to differ in plant parts, and to be influenced by plant phenophase, climatic and edaphic conditions. This work deals with the study of total hydroxycinnamic derivatives (THD), and specifically rosmarinic acid (RA), content variation in different aerial parts of sage linked to different harvest times. Dry sage leaves (Salviae officinalis folium) THD content was quantified using a pharmacopoeial method, and varied between 3.06 % and 3.52 % in different harvest times, with maxima in youngest plant shoot leaves and newly-grown shoots in September. Sage stems showed similar THD content variations when linked to harvest times, however with lower percentage, 1.33 - 3.04 %. Rosmarinic acid variability showed the same trends, its content ranged between 0.76 % and 1.65 % in leaves, and between 0.19 % and 0.83 % in stems, respectively. Highest percentages of both THD and RA were found in top leaves, lowest in leaves from the middle of the stem. When linked to plant phenophase, the content of THD and RA decreased at flowering time.

Open access

S. Fialová, D. Tekeľová, E. Švajdlenka, P. Potúček, K. Jakubová and D. Grančai

Abstract

Mentha × piperita (L.) Huds. of the family Lamiaceae is a very important species for commercial exploitation due to the high content of essential oil. Besides the essential oils, there are also other significant secondary metabolites in peppermint, especially flavonoids and hydroxycinnamic derivatives. In this study, we evaluate the variability of essential oil constituents and of phenolic compounds in the leaves of M. × piperita during the development of inflorescence. Similar studies, dealing with the variation of the essential oils and its composition, have been performed in the past, but no attention was paid to the variation of other secondary metabolites. We examined M. × piperita cv. ‘Perpeta’, the domestic cultivar. The plants were cultivated in the climatic conditions of south-west Slovakia. The contents of secondary metabolites were investigated in the week periods, from the beginning of inflorescence formation to the end of flowering. The yield and the quality of essential oil have been carried out by distillation and gas chromatography mass spectrometry (GC-MS). The phenolic substances were analysed using spectrophotometric methods according to European Pharmacopoeia. The highest contents of phenolic substances have been found in leaves of plants during the flowering phenophase, the same stage when essential oil of mint also achieves the highest quality.

Open access

S. Fialová, L. Halušová, D. Tekeľová and D. Grančai

Abstract

The identification of species in the genus Mentha is especially difficult because of the ease of hybridization, favoured by gynodioecy, which is further complicated by polymorphism, cultivation, polyploidy and vegetative propagation. This all explains the genicpopulation and microevolutionary background for variability of mints. In this work we studied the usage of micromorphological and phytochemical parameters in identification and characterization of selected Mentha species. On abaxial surface of leaves of 20 Mentha populations we determined the size and the number of peltate glandular trichomes. The essential oil was analysed by GC MS. We identified and characterized populations of M. × piperita, M. spicata, M. spicata subsp. condensata, M. spicata var. crispa, M. spicata var. citrata, M. × gentilis, M. aquatic, M. arvensis amd M. longifolia. The size and the number of peltate glandular trichomes contribute to characterisation of some Mentha species (especially in M. longifolia and M. × piperita).

Open access

S. Fialová, D. Tekeľová, K. Rendeková, J. Klinčok, M. Kolárik, K. Kurucová and D. Grančai

Abstract

Mints rank among the most important Lamiaceae plants. In addition to essential oil, they contain many valuable phenolic compounds, including flavonoids and phenolic acids that participate in mints’ pharmacological properties. In this work, we examined the contents of phenolic compounds variation in the course of 4 years of vegetation. We compared the contents of total hydroxycinnamic derivatives expressed as rosmarinic acid (λ = 505 nm), total polyphenols and tannins expressed as rosmarinic acid (λ = 760 nm), and flavonoids expressed as luteolin-7-O-glucoside (λ = 392 nm) and quercetin (λ = 420 nm) in 1-, 2-, 3-, and 4-year-old plants’ dry leaves, respectively. Spectrophotometric methods of the European Pharmacopoeia were employed. Our results show high levels of active phenolic compounds, particularly in 3- and 4-year-old plants.