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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

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.

Open access

M. Kameníková, S. Fialová, A. Ťažký and I. Čičová

Abstract

The content of phenolic compounds (total phenolic compounds, tannins, flavonoids and anthocyanidins) of three species of thyme (Thymus pulegioides, Thymus pannonicus, Thymus praecox) of different origin (Bohemian-Moravian highlands, Křivoklat and Považsky Inovec) was determined using spectrophotometric methods of European Pharmacopoeia 8th edition. Furthermore, the determination of the content of essential oil and analysis of its constituents was realised. The amount of total phenolics was determined by a spectrophotometric method using the Folin-Ciocalteu reagent. Their content ranged from 3.87 to 8.86%. The content of tannins was established on a preliminary determination of the total phenolics, followed by adsorption of tannins on hide powder. The amount of tannins in our samples varied from 1.96 to 5.65%. The content of total flavonoids was determined by a spectrophotometric method using aluminium chloride. Quantitative analysis of flavonoids has shown that content in our samples ranged from 0.59 to 1.52% expressed as luteolin-7-O-glucoside (λ = 392 nm) and from 0.41 to 1.12% expressed as rutin (λ = 420 nm). Anthocyanins represent a small amount of total polyphenol content in Thymus species. In our samples, the content of anthocyanins expressed as cyanidin-3-O-glucoside varied from 0.02 to 0.1%. The determination of essential oil was realised by method of European Pharmacopoeia 8th edition. Its contents in our samples ranged from 0.2 to 0.75%. Gas chromatography-mass spectrometry was used for essential oil analysis. According to the presence of main monoterpene in Thymus essential oil, we can distinguish three chemotypes: thymol, carvacrol and linalool. Due to variations of chemical constituents of thyme essential oil, it was possible to observe a relationship between occurrence of certain chemotype and origin of sample. Differences in content of flavonoids have not shown a significant relationship to locality of origin.

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.