Marina Jušković

Chemical Composition, Antioxidant, and Antimicrobial Activities of Lichen Umbilicaria cylindrica (L.) Delise (Umbilicariaceae)

The phytochemical analysis of methanol and chloroform extracts of Umbilicaria cylindrica was determined by HPLC-UV method. The predominant phenolic compound in both extracts was depsidone, salazinic acid (1). Besides salazinic acid, the tested extracts of U. cylindrica contain norstictic acid (2), methyl-β-orcinol carboxylate (3), ethyl haematommate (4), atranorin (5), and usnic acid (6), in different amounts and relations. The lichen extracts showed comparable and strong antioxidant activity, exhibited higher DPPH and hydroxyl radical scavengings, chelating activity, and inhibitory activity towards lipid peroxidation. The lichen extracts demonstrated important antimicrobial activity against eight strains with MIC values from 15.62 to 62.50 μg/mL. This is the first report of the detail chemical composition and antioxidant activity of the lichen Umbilicaria cylindrica, and the results suggest that this lichen can be used as a new source of the natural antioxidants and the substances with antimicrobial features.

PHENOLIC AND FLAVONOID CONTENT AND ANTIOXIDANT ACTIVITY OF DAPHNE BLAGAYANA GROWING IN SERBIA

ABSTRACT Th e aim of this study was to examine the phenolic and flavonoid contents and antioxidant activities of methanol and chloroform extracts of leaves and twigs of Daphne blagayana. Th e total phenolic content in the chloroform extract of plant twigs (90.26 ± 0.69 mg GA/g) was higher than that of the other extracts (from 76.56±0.89 to 77.45±0.43 mg GA/g). In the case of flavonoids, a greater value was also obtained for the chloroform extract of twigs (35.24±0.55 mg RU/g). Several diff erent methods were used to determine the antioxidant activity of the tested extracts, including total antioxidant capacity, metal chelating activity, hydroxyl radical scavenging activity and inhibitory activity against lipid peroxidation. Our results showed that although secondary metabolites of the plants may contribute significantly to their antioxidant activities, those antioxidant activities were not directly related to the phenolic and flavonoid amounts. Th e results of the present analysis demonstrated, for the first time, that Daphne blagayana leaves and twigs possess high phenolic and flavonoid contents, as well as potential antioxidant activity. Th is study suggests that Daphne blagayana twigs and leaves may potentially be used as an accessible source of natural antioxidants. SAŽETAK Cilj ovog rada je bio da se ispita fenolni i flavodnoidni sadržaj, kao i antioksidativna aktivnost metanolskih i hloroformskih ekstrakta lišća i grančica biljke Daphne blagayana. Ukupan sadržaj fenola u hloroformskom ekstraktu grančica (90.26±0.69 mg GA/g) bio je veći od sadržaja u ostalim ekstraktima (od 76.56±0.89 do 77.45±0.43 mg GA/g). U slučaju flavonoida, maksimalna vrednost je takođe zabeležena kod hloroformskog ekstrakta grančica (35.24±0.55 mg RU/g). Nekoliko različitih metoda su korišćeno za određivanje antioksidantne aktivnosti testiranih ekstrakata uključujući ukupan antioksidantni kapacitet, metal helacionu aktivnost, aktivnost hidroksi radikala i inhibitornu aktivnost prema lipidnoj peroksidaciji. Naši rezultati su pokazali da, iako sekundarni metabolite biljaka mogu značajno doprineti antioksidantnim aktivnostima, ove aktivnosti nisu bile uvek direktno povezane sa količinom fenola i flavonoida u ekstraktima. Rezultati ovih ispitivanja su pokazali, po prvi put, da grančice i lišče biljke Daphne blagayana poseduju visok sadržaj fenola i flavonoida i potencijalno antioksidantno delovanje. Ova studija je pokazala da se lišće i grančice ove biljke mogu potencijalno koristiti kao pristupačan izvor prirodnih antioksidanasa.

PHYTOCHEMICAL AND ANTIMICROBIAL SCREENING OF LEAVES AND STEMS OF BALKAN ENDEMIC SPECIES DAPHNE MALYANA BLEČIĆ

ABSTRACT Daphne malyana Blečić (Thymelaeaceae) is an endemic species of the western part of the Balkan Peninsula. No previous detailed studies exist on D. malyana Blečić. The aim of this study was to provide information on the anatomy of the leaf and stem as well as to perform phytochemical screening and to assay the antimicrobial activity of methanol extracts of the leaves and stems of D. malyana Blečić. The phytochemical analysis showed that coumarins and flavonoids are the major classes of secondary metabolites in both leaves and stems. The antimicrobial activity of the methanol extracts from leaves and stems of D. malyana was also evaluated against six Gram-positive and six Gram-negative bacteria by employing both microdilution and disc diffusion methods. The results from the well-diffusion assay showed significant antimicrobial activity at all tested concentrations of the extracts. The results showed that methanol extracts of leaves and twigs have similar chemical compositions and similar antimicrobial activity. To our knowledge this is the first report on the phytochemistry and antimicrobial activity of this plant species.

Comparative morphoanatomical analysis of the leaves and stems of Daphne (Thymelaeaceae) species

Abstract A study on the morphological variability and ecological differentiation among the species in the genus Daphne was carried out which included seven species from the Balkan Peninsula: Daphne mezereum, D. laureola, D. alpina, D. oleoides, D. malyana, D. cneorum and D. blagayana. In the Balkan Peninsula, the ranges of the species in this genus overlap, which does not occur anywhere else in Europe. Descriptive statistics were measured for 20 quantitative characters of the leves and stems. A comparative analysis of the morpho-anatomical adaptations of these species shows that: D. cneorum, D. malyana and D. oleoides belong to the adaptive type of xerophytes; D. alpina is a xeromesophyte; D. blagayana and D. laureola are mesoxerophytes; and D. mezereum is a mesophyte. Principal component analysis shows the largest contribution to the formation of the variability between the different species is made by characters that are related to leaf shape (leaf length, distance between the largest leaf width and the leaf top, largest width of the leaf, leaf surface area), followed by surface area of abaxial stomata, stem characters (stem cortex thickness and stem diameter) and leaf anatomy characters (thickness of the palisade tissue, thickness mesophyll, number of palisade layers). These features can use to discriminate among the seven studied species, suggesting that leaves and stems of Daphne can represent a source for taxonomically useful characters. Canonical discriminant analysis and the clustering method based on Mahalanobis distances shows that there is significant morphological differentiation among the species studied. The results show that various combinations of morphological and anatomical features contribute to the adaptive capacity of plants to different degrees. The morpho-anatomical features found in all seven species agree with previous infrageneric taxonomic classifications of this genus.