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Miroslav Repčák - One of the best experts on this subject based on the ideXlab platform.
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coumarins of matricaria chamomilla l aglycones and glycosides
Food Chemistry, 2013Co-Authors: Veronika Petruľovaporacka, Miroslav Repčák, Maria Vilkova, Ján ImrichAbstract:Abstract The identity and quantity of coumarin-like compounds in leaves and anthodia of Matricaria chamomilla L. were studied by LC-DAD and NMR. So far, two monosubstituted coumarins, Herniarin and umbelliferone, and two Herniarin precursors were identified therein. In this paper, two other coumarin glycosides and one aglycone were confirmed. Skimmin (umbelliferone-7-O-β- d -glucoside), daphnin (daphnetin-7-O-β- d -glucoside) and daphnetin (7,8-dihydroxycoumarin) were found for the first time in diploid and tetraploid leaves and anthodia of M. chamomilla L. Daphnetin is known as a strong sensitizer, so this compound and its glycosidic derivative can contribute to the allergic potential of chamomile. Commercial chamomile preparations were tested for their presence.
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phenolic glucosides in the course of ligulate flower development in diploid and tetraploid matricaria chamomilla
Food Chemistry, 2009Co-Authors: Miroslav Repčák, Tatiana KrausovaAbstract:Abstract The main secondary metabolites of Matricaria chamomilla ligulate flowers are apigenin-7-O-glucoside derivatives and (Z)- and (E)-2-β- d -glucopyranosyloxy-4-methoxy cinnamic acids (GMCAs), which are the precursors of Herniarin. The quantities of these compounds were determinated in six phases of development of ligulate flowers in diploid and tetraploid cultivar. The content of the apigenin glucoside and its main acylated derivatives in ligulate flowers of diploid plants was found to be significantly higher before the start of flowering in comparison with tetraploid plants. During the flowering and post-flowering phase their content decreased and no difference between diploid and tetraploid plants was observed. The (E)-izomer was the dominant form of 2-β- d -glucopyranosyloxy-4-methoxy cinnamic acid. These secondary stress metabolite precursors were accumulated in higher concentrations in young growing ligulate flowers, but during flowering and post-flowering phases their content decreased. Significantly higher content was found in tetraploid plants in comparison with diploid plants. Aglycones of glycosides were found in low concentrations.
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circadian rhythm of z and e 2 β d glucopyranosyloxy 4 methoxy cinnamic acids and Herniarin in leaves of matricaria chamomilla
Plant Cell Reports, 2009Co-Authors: Miroslav Repčák, Jozef Kovacik, Beňadik Smajda, Adriana EliasovaAbstract:Chamomile (Matricaria chamomilla) in the above-ground organs synthesizes and accumulates (Z)- and (E)-2-β-d-glucopyranosyloxy-4-methoxy cinnamic acids (GMCA), the precursors of phytoanticipin Herniarin (7-methoxycoumarin). The diurnal rhythmicity of the sum of GMCA (maximum before daybreak) and Herniarin (acrophase at 10 h 21 min of circadian time) was observed under artificial lighting conditions LD 12:12. The acrophase is the time point of the maximum of the sinusoidal curve fitted to the experimental data. In continuous light, the circadian rhythms of both compounds were first described with similar acrophases of endogenous rhythms; a significantly different result from that in synchronized conditions. The rhythms’ mesor (the mean value of the sinusoidal curve fitted to the experimental data) under free-running conditions was not influenced. Abiotic stress under synchronized conditions decreased the average content of GMCA to half of the original level and eliminated the rhythmicity. In contrast, the rhythm of Herniarin continued, though its content significantly increased. Nitrogen deficiency resulted in a significant increase in GMCA content, which did not manifest any rhythmicity while the rhythm of Herniarin continued. Circadian control of Herniarin could be considered as a component of the plant’s specialized defence mechanisms.
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salicylic acid induced changes to growth and phenolic metabolism in matricaria chamomilla plants
Plant Cell Reports, 2009Co-Authors: Jozef Kovacik, Jiři Gruz, Martin Backor, Miroslav Strnad, Miroslav RepčákAbstract:The influence of salicylic acid (SA) doses of 50 and 250 μM, for a period of up to 7 days, on selected physiological aspects and the phenolic metabolism of Matricaria chamomilla plants was studied. SA exhibited both growth-promoting (50 μM) and growth-inhibiting (250 μM) properties, the latter being correlated with decrease of chlorophylls, water content and soluble proteins. In terms of phenolic metabolism, it seems that the higher SA dose has a toxic effect, based on the sharp increase in phenylalanine ammonia-lyase (PAL) activity (24 h after application), which is followed by an increase in total soluble phenolics, lignin accumulation and the majority of the 11 detected phenolic acids. Guaiacol-peroxidase activity was elevated throughout the experiment in 250 μM SA-treated plants. In turn, some responses can be explained by mechanisms associated with oxidative stress tolerance; these mitigate acute SA stress (which is indicated by an increase in malondialdehyde content). However, PAL activity decreased with prolonged exposure to SA, indicating its inhibition. Accumulation of coumarin-related compounds (umbelliferone and Herniarin) was not affected by SA treatments, while (Z)- and (E)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acids increased in the 250 μM SA-treated rosettes. Free SA content in the rosettes increased significantly only in the 250 μM SA treatment, with levels tending to decrease towards the end of the experiment and the opposite trend was observed in the roots.
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phenolic compounds composition and physiological attributes of matricaria chamomilla grown in copper excess
Environmental and Experimental Botany, 2008Co-Authors: Jozef Kovacik, Jiři Gruz, Martin Backor, Miroslav Strnad, Jaroslav Tomko, Miroslav RepčákAbstract:Abstract Four-week old plants of chamomile ( Matricaria chamomilla ) cultivated in nutrient solution were exposed to copper (3, 60 and 120 μM) for 10 days. At 120 μM, Cu decreased dry mass production, water, chlorophyll and nitrogen content in both the leaf rosettes and roots. Five phenolic acids were detected in methanol extracts of the leaf rosettes (protocatechuic, p -hydroxybenzoic, vanillic, chlorogenic and salicylic acid) and six additional compounds (gentisic, syringic, caffeic, sinapic and o -/ p -coumaric acid) were released after acid hydrolysis. Most of the 11 phenolic acids detected increased in 60 μM Cu but in the 120 μM treatment their contents were lower or not significantly different from the control. Among coumarin-related compounds, ( Z ) - and ( E )-2-s- d -glucopyranosyloxy-4-methoxycinnamic acids increased in 60 and 120 μM Cu while Herniarin rose in the 3 and 60 μM Cu by the end of the experiment. The amounts of umbelliferone were not affected by any of the doses tested. These facts in relation to antioxidative properties of phenolic metabolites are also discussed. The malondialdehyde content of the leaf rosettes was not affected by exposure of plants to 120 μM Cu in a time-course experiment but in the roots a sharp increase was observed after 24 and 48 h of treatment. At 120 μM, Cu stimulated a 9-fold higher K + loss than the 60 μM treatment while at the lowest concentration it stimulated potassium uptake. Cu accumulation in the roots was 3-, 49- and 71-fold higher than that in the leaf rosettes in the 3, 60, and 120 μM Cu treatments, respectively. Results suggest that 120 μM Cu dose is limiting for chamomile growth under the conditions of present research.
Jozef Kovacik - One of the best experts on this subject based on the ideXlab platform.
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induction of phenolic metabolites and physiological changes in chamomile plants in relation to nitrogen nutrition
Food Chemistry, 2014Co-Authors: Jozef Kovacik, Bořivoj KlejdusAbstract:Abstract Alternative tools, such as the manipulation of mineral nutrition, may affect secondary metabolite production and thus the nutritional value of food/medicinal plants. We studied the impact of nitrogen (N) nutrition (nitrate/ NO 3 - or ammonium/ NH 4 + nitrogen) and subsequent nitrogen deficit on phenolic metabolites and physiology in Matricaria chamomilla plants. NH 4 + -fed plants revealed a strong induction of selected phenolic metabolites but, at the same time, growth, Fv/Fm, tissue water content and soluble protein depletion occurred in comparison with NO 3 - -fed ones. On the other hand, NO 3 - -deficient plants also revealed an increase in phenolic metabolites but growth depression was not observed after the given exposure period. Free amino acids were more accumulated in NH 4 + -fed shoots (strong increase in arginine and proline mainly), while the pattern of roots’ accumulation was independent of N form. Among phenolic acids, NH 4 + strongly elevated mainly the accumulation of chlorogenic acid. Within flavonoids, flavonols decreased while flavones strongly increased in response to N deficiency. Coumarin-related metabolites revealed a similar increase in Herniarin glucosidic precursor in response to N deficiency, while Herniarin was more accumulated in NO 3 - - and umbelliferone in NH 4 + -cultured plants. These data indicate a negative impact of NH 4 + as the only source of N on physiology, but also a higher stimulation of some valuable phenols. Nitrogen-induced changes in comparison with other food/crop plants are discussed.
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accumulation of metals and selected nutritional parameters in the field grown chamomile anthodia
Food Chemistry, 2012Co-Authors: Jozef Kovacik, Jiři Gruz, Bořivoj Klejdus, Frantisek Stork, Josef HedbavnyAbstract:Abstract Accumulation of metals and selected nutritional parameters of chamomile ( Matricaria chamomilla ) anthodia cultured under natural condition on an experimental field in Kosice (Slovak Republic) were studied. Two official cultivars (diploid ‘Novbona’ and tetraploid ‘Lutea’) and two ontogenetic phases of anthodia (‘bud’ and ‘flower’) were compared. K, Ca, Mg, Al, Cu, Cr, Hg and Cd were more accumulated in both bud and flower of diploid plants while accumulation of Fe, Zn, Ni and Pb was ploidy-independent. Bioaccumulation factor was lower than one for toxic metals, indicating that chamomile is an excluder. Tetraploid plants contained lower concentrations of amino acids but higher concentrations of phenolic acids compared to diploid plants. Among phenolic acids, caffeic and vanillic acids were mainly present in the glycosidic form. Reducing sugars (glucose equivalents), total soluble phenols, sum of flavonols, individual flavonols (quercetin and kaempferol), apigenin and Herniarin were more accumulated in anthodia of tetraploid plants. Our data indicate that increase in ploidy level reduces accumulation of toxic metals and amino acids but enhances accumulation of phenolic metabolites. Thus polyploidisation is a good tool to achieve safer chamomile cultivars for pharmaceutical purposes.
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circadian rhythm of z and e 2 β d glucopyranosyloxy 4 methoxy cinnamic acids and Herniarin in leaves of matricaria chamomilla
Plant Cell Reports, 2009Co-Authors: Miroslav Repčák, Jozef Kovacik, Beňadik Smajda, Adriana EliasovaAbstract:Chamomile (Matricaria chamomilla) in the above-ground organs synthesizes and accumulates (Z)- and (E)-2-β-d-glucopyranosyloxy-4-methoxy cinnamic acids (GMCA), the precursors of phytoanticipin Herniarin (7-methoxycoumarin). The diurnal rhythmicity of the sum of GMCA (maximum before daybreak) and Herniarin (acrophase at 10 h 21 min of circadian time) was observed under artificial lighting conditions LD 12:12. The acrophase is the time point of the maximum of the sinusoidal curve fitted to the experimental data. In continuous light, the circadian rhythms of both compounds were first described with similar acrophases of endogenous rhythms; a significantly different result from that in synchronized conditions. The rhythms’ mesor (the mean value of the sinusoidal curve fitted to the experimental data) under free-running conditions was not influenced. Abiotic stress under synchronized conditions decreased the average content of GMCA to half of the original level and eliminated the rhythmicity. In contrast, the rhythm of Herniarin continued, though its content significantly increased. Nitrogen deficiency resulted in a significant increase in GMCA content, which did not manifest any rhythmicity while the rhythm of Herniarin continued. Circadian control of Herniarin could be considered as a component of the plant’s specialized defence mechanisms.
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salicylic acid induced changes to growth and phenolic metabolism in matricaria chamomilla plants
Plant Cell Reports, 2009Co-Authors: Jozef Kovacik, Jiři Gruz, Martin Backor, Miroslav Strnad, Miroslav RepčákAbstract:The influence of salicylic acid (SA) doses of 50 and 250 μM, for a period of up to 7 days, on selected physiological aspects and the phenolic metabolism of Matricaria chamomilla plants was studied. SA exhibited both growth-promoting (50 μM) and growth-inhibiting (250 μM) properties, the latter being correlated with decrease of chlorophylls, water content and soluble proteins. In terms of phenolic metabolism, it seems that the higher SA dose has a toxic effect, based on the sharp increase in phenylalanine ammonia-lyase (PAL) activity (24 h after application), which is followed by an increase in total soluble phenolics, lignin accumulation and the majority of the 11 detected phenolic acids. Guaiacol-peroxidase activity was elevated throughout the experiment in 250 μM SA-treated plants. In turn, some responses can be explained by mechanisms associated with oxidative stress tolerance; these mitigate acute SA stress (which is indicated by an increase in malondialdehyde content). However, PAL activity decreased with prolonged exposure to SA, indicating its inhibition. Accumulation of coumarin-related compounds (umbelliferone and Herniarin) was not affected by SA treatments, while (Z)- and (E)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acids increased in the 250 μM SA-treated rosettes. Free SA content in the rosettes increased significantly only in the 250 μM SA treatment, with levels tending to decrease towards the end of the experiment and the opposite trend was observed in the roots.
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phenolic compounds composition and physiological attributes of matricaria chamomilla grown in copper excess
Environmental and Experimental Botany, 2008Co-Authors: Jozef Kovacik, Jiři Gruz, Martin Backor, Miroslav Strnad, Jaroslav Tomko, Miroslav RepčákAbstract:Abstract Four-week old plants of chamomile ( Matricaria chamomilla ) cultivated in nutrient solution were exposed to copper (3, 60 and 120 μM) for 10 days. At 120 μM, Cu decreased dry mass production, water, chlorophyll and nitrogen content in both the leaf rosettes and roots. Five phenolic acids were detected in methanol extracts of the leaf rosettes (protocatechuic, p -hydroxybenzoic, vanillic, chlorogenic and salicylic acid) and six additional compounds (gentisic, syringic, caffeic, sinapic and o -/ p -coumaric acid) were released after acid hydrolysis. Most of the 11 phenolic acids detected increased in 60 μM Cu but in the 120 μM treatment their contents were lower or not significantly different from the control. Among coumarin-related compounds, ( Z ) - and ( E )-2-s- d -glucopyranosyloxy-4-methoxycinnamic acids increased in 60 and 120 μM Cu while Herniarin rose in the 3 and 60 μM Cu by the end of the experiment. The amounts of umbelliferone were not affected by any of the doses tested. These facts in relation to antioxidative properties of phenolic metabolites are also discussed. The malondialdehyde content of the leaf rosettes was not affected by exposure of plants to 120 μM Cu in a time-course experiment but in the roots a sharp increase was observed after 24 and 48 h of treatment. At 120 μM, Cu stimulated a 9-fold higher K + loss than the 60 μM treatment while at the lowest concentration it stimulated potassium uptake. Cu accumulation in the roots was 3-, 49- and 71-fold higher than that in the leaf rosettes in the 3, 60, and 120 μM Cu treatments, respectively. Results suggest that 120 μM Cu dose is limiting for chamomile growth under the conditions of present research.
Bořivoj Klejdus - One of the best experts on this subject based on the ideXlab platform.
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induction of phenolic metabolites and physiological changes in chamomile plants in relation to nitrogen nutrition
Food Chemistry, 2014Co-Authors: Jozef Kovacik, Bořivoj KlejdusAbstract:Abstract Alternative tools, such as the manipulation of mineral nutrition, may affect secondary metabolite production and thus the nutritional value of food/medicinal plants. We studied the impact of nitrogen (N) nutrition (nitrate/ NO 3 - or ammonium/ NH 4 + nitrogen) and subsequent nitrogen deficit on phenolic metabolites and physiology in Matricaria chamomilla plants. NH 4 + -fed plants revealed a strong induction of selected phenolic metabolites but, at the same time, growth, Fv/Fm, tissue water content and soluble protein depletion occurred in comparison with NO 3 - -fed ones. On the other hand, NO 3 - -deficient plants also revealed an increase in phenolic metabolites but growth depression was not observed after the given exposure period. Free amino acids were more accumulated in NH 4 + -fed shoots (strong increase in arginine and proline mainly), while the pattern of roots’ accumulation was independent of N form. Among phenolic acids, NH 4 + strongly elevated mainly the accumulation of chlorogenic acid. Within flavonoids, flavonols decreased while flavones strongly increased in response to N deficiency. Coumarin-related metabolites revealed a similar increase in Herniarin glucosidic precursor in response to N deficiency, while Herniarin was more accumulated in NO 3 - - and umbelliferone in NH 4 + -cultured plants. These data indicate a negative impact of NH 4 + as the only source of N on physiology, but also a higher stimulation of some valuable phenols. Nitrogen-induced changes in comparison with other food/crop plants are discussed.
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accumulation of metals and selected nutritional parameters in the field grown chamomile anthodia
Food Chemistry, 2012Co-Authors: Jozef Kovacik, Jiři Gruz, Bořivoj Klejdus, Frantisek Stork, Josef HedbavnyAbstract:Abstract Accumulation of metals and selected nutritional parameters of chamomile ( Matricaria chamomilla ) anthodia cultured under natural condition on an experimental field in Kosice (Slovak Republic) were studied. Two official cultivars (diploid ‘Novbona’ and tetraploid ‘Lutea’) and two ontogenetic phases of anthodia (‘bud’ and ‘flower’) were compared. K, Ca, Mg, Al, Cu, Cr, Hg and Cd were more accumulated in both bud and flower of diploid plants while accumulation of Fe, Zn, Ni and Pb was ploidy-independent. Bioaccumulation factor was lower than one for toxic metals, indicating that chamomile is an excluder. Tetraploid plants contained lower concentrations of amino acids but higher concentrations of phenolic acids compared to diploid plants. Among phenolic acids, caffeic and vanillic acids were mainly present in the glycosidic form. Reducing sugars (glucose equivalents), total soluble phenols, sum of flavonols, individual flavonols (quercetin and kaempferol), apigenin and Herniarin were more accumulated in anthodia of tetraploid plants. Our data indicate that increase in ploidy level reduces accumulation of toxic metals and amino acids but enhances accumulation of phenolic metabolites. Thus polyploidisation is a good tool to achieve safer chamomile cultivars for pharmaceutical purposes.
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phenylalanine ammonia lyase activity and phenolic compounds accumulation in nitrogen deficient matricaria chamomilla leaf rosettes
Plant Science, 2007Co-Authors: Jozef Kovacik, Bořivoj Klejdus, Martin Backor, Miroslav RepčákAbstract:Abstract Phenylalanine ammonia-lyase (PAL) activity, accumulation of 11 phenolic acids and 3 coumarin-related compounds (Herniarin and its glucosidic precursors (Z)- and (E)-2-β- d -glucopyranosyloxy-4-methoxycinnamic acids; umbelliferone), biomass production, plant water content and lipid peroxidation status of Matricaria chamomilla L. leaf rosettes subjected to nitrogen (N) deficiency over 12 days were studied. Both biomass and water content of N-deficient rosettes decreased in comparison to controls, while quantities of most benzoic acids (p-hydroxybenzoic, syringic, vanillic), cinnamic acids (caffeic, chlorogenic, o- and p-coumaric, ferulic), Herniarin and (Z)- and (E)-2-β- d -glucopyranosyloxy-4-methoxycinnamic acids increased with prolonged nitrogen deficiency. However, three benzoic derivatives (gallic acid, protocatechuic acid and protocatechuicaldehyde) did not differ significantly from the controls. The content of umbelliferone, a stress metabolite in the leaves of chamomile, was not affected by N deficiency. It thus appears that synthesis of benzoic and cinnamic acids and of coumarins is probably regulated independently. PAL activity was significantly higher in N-deficient leaf rosettes after 4 and 8 days (by 61 and 23%, respectively), but decreased to control level by the end of the experiment. Nevertheless, it can be concluded that this is important biochemical factor contributing to the observed increase of phenolic compounds accumulation by producing nitrogen-free skeletons of t-cinnamate for subsequent pathways of phenylpropanoid metabolism. We also observed that the mechanism of nitrogen deficiency tolerance due to enhanced PAL activity is temporally limited. The non-altered extent of lipid peroxidation expressed as malondialdehyde amounts revealed that membrane integrity was not affected by N deficiency. This phenomenon in correlation to the antioxidative properties of phenolic metabolites is also discussed.
Laurence Lesage-meessen - One of the best experts on this subject based on the ideXlab platform.
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Lavender- and lavandin-distilled straws: an untapped feedstock with great potential for the production of high-added value compounds and fungal enzymes
Biotechnology for Biofuels, 2018Co-Authors: Laurence Lesage-meessen, Marine Bou, Christian Ginies, Didier Chevret, David Navarro, Elodie Drula, Estelle Bonnin, José Del Río, Elise Odinot, Alexandra BisottoAbstract:Background: Lavender (Lavandula angustifolia) and lavandin (a sterile hybrid of L. angustifolia × L. latifolia) essential oils are among those most commonly used in the world for various industrial purposes, including perfumes, pharmaceuticals and cosmetics. The solid residues from aromatic plant distillation such as lavender- and lavandin-distilled straws are generally considered as wastes, and consequently either left in the fields or burnt. However, lavender- and lavandin-distilled straws are a potentially renewable plant biomass as they are cheap, non-food materials that can be used as raw feedstocks for green chemistry industry. The objective of this work was to assess different pathways of valorization of these straws as bio-based platform chemicals and fungal enzymes of interest in biorefinery. Results: Sugar and lignin composition analyses and saccharification potential of the straw fractions revealed that these industrial by-products could be suitable for second-generation bioethanol prospective. The solvent extraction processes, developed specifically for these straws, released terpene derivatives (e.g. τ-cadinol, β-caryophyllene), lactones (e.g. coumarin, Herniarin) and phenolic compounds of industrial interest, including rosmarinic acid which contributed to the high antioxidant activity of the straw extracts. Lavender and lavandin straws were also suitable inducers for the secretion of a wide panel of lignocellulose-acting enzymes (cellulases, hemicellulases and oxido-reductases) from the white-rot model fungus Pycnoporus cinnabarinus. Interestingly, high amounts of laccase and several lytic polysaccharide monooxygenases were identified in the lavender and lavandin straw secretomes using proteomics. Conclusions: The present study demonstrated that the distilled straws of lavender and lavandin are lignocellulosic-rich materials that can be used as raw feedstocks for producing high-added value compounds (antioxidants, aroma) and fungal oxidative enzymes, which represent opportunities to improve the decomposition of recalcitrant lignocellulose into biofuel. Hence, the structure and the physico-chemical properties of these straws clearly open new perspectives for use in biotechnological processes involving especially filamentous fungi. These approaches represent sustainable strategies to foster the development of a local circular bioeconomy.
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Essential oils and distilled straws of lavender and lavandin: a review of current use and potential application in white biotechnology
Applied Microbiology and Biotechnology, 2015Co-Authors: Laurence Lesage-meessen, Jean-claude Sigoillot, Craig B. Faulds, Anne LomascoloAbstract:The Lavandula genus, which includes lavender ( Lavandula angustifolia ) and lavandin ( L. angustifolia × Lavandula latifolia ), is cultivated worldwide for its essential oils, which find applications in perfumes, cosmetics, food processing and, more recently, in aromatherapy products. The chemical composition of lavender and lavandin essential oils, usually produced by steam distillation from the flowering stems, is characterized by the presence of terpenes (e.g. linalool and linalyl acetate) and terpenoids (e.g. 1,8-cineole), which are mainly responsible for their characteristic flavour and their biological and therapeutic properties. Lavender and lavandin distilled straws, the by-products of oil extraction, were traditionally used for soil replenishment or converted to a fuel source. They are mineral- and carbon-rich plant residues and, therefore, a cheap, readily available source of valuable substances of industrial interest, especially aroma and antioxidants (e.g. terpenoids, lactones and phenolic compounds including coumarin, Herniarin, α-bisabolol, rosmarinic and chlorogenic acids). Accordingly, recent studies have emphasized the possible uses of lavender and lavandin straws in fermentative or enzymatic processes involving various microorganisms, especially filamentous fungi, for the production of antimicrobials, antioxidants and other bioproducts with pharmaceutical and cosmetic activities, opening up new challenging perspectives in white biotechnology applications.
Donatella Mares - One of the best experts on this subject based on the ideXlab platform.
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fungal morphogenesis induced by natural and synthetic substances Herniarin induced alterations in the dermatophyte microsporum cookie ajello
Plant Biosystems, 2005Co-Authors: Donatella MaresAbstract:Abstract The effects of either synthetic or natural substances on the normal morphogenetic processes in fungi are reviewed. Original results concerning the changes induced in the dermatophyte Microsporum cookei Ajello by the UVA-activated coumarin, Herniarin, are reported. Alterations in the shape and wall assembly of parietal components are discussed on the basis of the most recent knowledge on the formation and growth of fungal hyphae.