Pavle Mašković

Antioxidant activity of selected plant species; potential new sources of natural antioxidants

The aim of this study was to examine six plants from Serbia for their potential antioxidant activity. Therefore, six antioxidant activity assays were carried out, including: total antioxidant capacity, DPPH free-radical scavenging, the inhibitory activity toward lipid peroxidation, Fe(3+)- reducing power, Fe(2+)- chelating ability and hydroxyl radical scavenging activity. Total phenolic and flavonoid contents were also determined for each alcoholic extract. Cotinus coggygria extract contained the highest amount of total phenols (413mg GAE /g dry extract), while the highest proportion of flavonoids was found in the Echium vulgare methanol extract (105 mg RU/g). Cotinus coggygria and Halacsya sendtneri alcoholic extracts showed the highest total antioxidant capacity (313 and 231 mg AA/g dry extract), as well as DPPH free-radical scavenging (IC(50)=9 and 99 μg/ml), inhibitory activity toward lipid peroxidation (IC(50)=3 and 17 μg/ml) and reducing power. Whereas, the greatest hydroxyl radical scavenging activity, as well as ferrous ion chelating ability showed Echium vulgare, Echium rubrum and Halacsya sendtneri.

Free radical scavenging activity, total phenolic and flavonoid contents of mulberry (Morus spp. L., Moraceae) extracts

Mulberry (Morus spp. L., Moraceae) fruits, leaves, bark and branch have been used in traditional medicine as diuretic, hypoglycemic and hypotensive. The mechanism of their effects is correlated with the content of active components. Objective of this work was to evaluate and compare antioxidant properties of different extracts of two Morus species growing in Serbia: Morus alba L. (white mulberry) and Morus nigra L. (black mulberry). Potential antioxidant activity, content of antioxidant compounds (phenolics and flavonoids) and radical scavenging capacity, tested by DPPH method, were evaluated. The phenolic and flavonoid composition of different Morus extracts was determined by the HPLC method. The extracts prepared from fruits, leaves and roots of M. alba and M. nigra exhibited different characteristics. The highest extraction yield was achieved by M. alba leaves extraction (23.40%). M. nigra roots extract shown the highest total phenolics (186.30 mg CAE/g), while highest total flavonoids content (67.37 mg RE/g) was determined for M. nigra leaves extracts. In addition, black mulberry leaves extracts with the highest antioxidant activity had the highest phenolic acids contents. The dominant phenolic components in the samples were rutin and chlorogenic acid. All investigated mulberry dry extracts shown high content of phenolic compounds and significant antioxidant activity. This work contributes to knowledge of the antioxidant properties of Morus species. The obtained results may be useful in the evaluation of new dietary supplements and food products.

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 Compounds and Biological Activity of Kitaibelia vitifolia

This study was aimed at evaluating the antioxidant activity and efficacy of the ethanolic extract of the endemic plant species Kitaibelia vitifolia in inhibiting the growth of selected fungi and bacteria. Antimicrobial activity was tested using the broth dilution procedure for determination of minimum inhibitory concentration (MIC). MICs were determined for eight selected indicator strains. The highest susceptibility to K. vitifolia ethanolic extract among the bacteria tested was exhibited by Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 25923, and Klebsiella pneumoniae ATCC 13883 (MIC=15.62 μg/mL), followed by Escherichia coli ATCC 25922 and Proteus mirabilis ATCC 14153 (MIC=31.25 μg/mL), and Proteus vulgaris ATCC 13315 (MIC=62.50 μg/mL). Of the fungi, Candida albicans ATCC 10231 (MIC=15.62 μg/mL) showed the highest susceptibility, and Aspergillus niger ATCC 16404 (MIC=31.25 μg/mL) had the lowest. Results showed that K. vitifolia extract possesses antioxidant activity, with total antioxidant capacity of 75.45±0.68 μg of ascorbic acid/g and 50% inhibition concentration values of 47.45±0.55 μg/mL for 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, 35.35±0.68 μg/mL for inhibitory activity against lipid peroxidation, 95.25±0.52 μg/mL for hydroxyl radical scavenging activity, and 31.50±0.35 μg/mL for metal chelating activity. Total phenolics, flavonoids, condensed tannins, and gallotannins were 85.25±0.69 mg of gallic acid (GA)/g, 45.32±0.55 mg of rutin/g, 54.25±0.75 mg of GA/g, and 41.74±0.55 mg of GA/g, respectively. The phenolic composition of K. vitifolia extract was determined by high-performance liquid chromatography. Rosmarinic acid was found to be the dominant phenolic compound of the extract.

Comparative analysis of antioxidant, antimicrobiological and cytotoxic activities of native and fermented chamomile ligulate flower extracts

AbstractMain conclusionThe work investigated differences in apigenin content, as well as in other compounds, and examined the chemical profiles, antioxidant, antimicrobial and cytotoxic effects of extracts obtained from native and fermented chamomile ligulate flowers. Chamomile (Chamomilla recutita L.) has a long history of being used as a medicinal plant due to many health benefits, including antiinflammatory, anticancer, antispasmodic, radical-scavenging effects and others. Apigenin is recognized as one of the most bioactive phenolic compounds in chamomile. In comparison to its bound forms, which include mostly apigenin-7-O-β-glucoside and various acylated forms, the aglycone is attributed with much higher bioactivity. Due to this fact, in this work ligulate florets of chamomile anthodium were subjected to a fermentation process using native chamomile enzymes to hydrolyze bound forms of apigenin to free aglycone. The contents of apigenin and apigenin-7-O-β-glucoside were determined in both fermented and nonfermented samples by UHPLC-MS–MS analysis to define the efficiency of conversion. After defining their chemical profiles, the extracts of fermented and nonfermented chamomile samples were also compared with respect to their antioxidant, antimicrobial and cytotoxic effects. The antioxidant effects of the obtained extracts were defined by electron spin resonance analysis for hydroxyl and superoxide radicals. The antimicrobial activity was defined for eight microbial strains, whereas cytotoxic activity was evaluated using two human cell lines (human cervix carcinoma and human rhabdomyosarcoma) and murine fibroblasts.

Biochemical and pharmacological evaluation of 4-hydroxychromen-2-ones bearing polar C-3 substituents as anticoagulants.

The objective of this study was to investigate in vitro and in vivo anticoagulant activity of sixteen 4-hydroxycoumarin derivatives bearing polar C-3 scaffolds. The activity was evaluated by measuring prothrombin time. Enhanced anticoagulant activity in vitro was observed for all tested compounds. Upon successive administration of 0.5 mg/kg of body weight to adult Wistar rats, over a period of five days, four derivatives (2b, 4c, 5c and 9c) presented anticoagulant activity in vivo. The most active compound was 2b, with PT = 30.0 s. Low or non-toxic effects in vivo were determined based on the catalytic activity of liver enzymes and the concentration of bilirubin, iron and proteins. Metabolic pathways of the most active compounds in vivo were determined after GC/MS analysis of collected rat urine samples. The excretion occurs by glucuronidation of 7-hydroxy forms of tested derivatives. In vivo results were described using PLS-based CoMFA and CoMSIA 3D-QSAR studies, which showed CoMFA-SE (q(2) = 0.738) and CoMSIA-SEA (q(2) = 0.763) to be the statistically most relevant models. Furthermore, molecular docking and DFT mechanistic studies performed on the rat VKORC1 homology model revealed interactions between the 4-OH coumarin group in the form of phenolic anion and the Cys135 catalytic site in the transition state.

Chemical composition and antioxidant activity of lichen Toninia candida

In the present investigation, methanol, chloroform and petrol ether extracts from the lichen Toninia candida (Weber) Th. Fr, Catillariaceae, were assayed for their antioxidant activity. The phenolic composition of the extracts was determined by HPLC-UV analysis. The predominant phenolic compound in all the extracts was depsidone, norstictic acid. All the tested extracts of T. candida contain, besides norstictic acid, atranorin, stictic, protocetraric and usnic acid, but 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. This is the first report of chemical composition and antioxidant antimicrobial activity of the lichen Toninia candida.

Biological activities of phenolic compounds and ethanolic extract of Halacsya sendtneri (Boiss) Dőrfler

The objective of this study was to evaluate the efficacy of the ethanolic extract of endemic plant Halacsya sendtneri in inhibiting the growing of the test fungi and bacteria as well as to determine its genotoxic potential and toxicity using the Allium anaphase-telophase assay. Minimum inhibitory concentrations (MIC) were determined for 15 indicator strains of pathogens, representing both bacteria and fungi. The highest susceptibility to the ethanolic extract of H.sendtneri was exhibited by Pseudomonas glycinea (FSB4), (MIC=0.09 mg/ml) among the bacteria, and by Phialophora fastigiata (FSB81), (MIC=1.95 mg/ml) among the fungi. The composition of H. sendtneri extracts was also determined using HPLC analysis. Rosmarinic acid was found to be the dominant phenolic compound. The Allium anaphase-telophase genotoxicity assay revealed that the ethanolic extract of H. sendtneri at concentrations of 31.5 mg/l and below does not produce toxic or genotoxic effects. This is the first report of chemical constituents, genotoxic and antimicrobial activities of the endemic species, H. sendtneri.

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.

Biological activity and chemical profile of Lavatera thuringiaca L. extracts obtained by different extraction approaches

BACKGROUND Lavatera thuringiaca L. is herbaceous perennial plant from Malvaceae family, which is known for its biological activity and richness in polyphenolic compounds. Despite this, the information regarding the biological activity and chemical profile is still insufficient. PURPOSE Aim of this study was to investigate biological potential and chemical profile of Lavatera thuringiaca L., as well as influence of applied extraction technique on them. STUDY DESIGN AND METHODS Two conventional and four non-conventional extraction techniques were applied in order to obtain extracts rich in bioactive compound. Extracts were further tested for total phenolics, flavonoids, condensed tannins, gallotannins and anthocyanins contents using spectrophotometric assays. Polyphenolic profile was established using HPLC-DAD analysis. Biological activity was investigated regarding antioxidant, cytotoxic and antibacterial activities. Four antioxidant assays were applied as well as three different cell lines for cytotoxic and fifteen bacterial strain for antibacterial activity. RESULTS AND CONCLUSION Results showed that subcritical water extraction (SCW) dominated over the other extraction techniques, where SCW extract exhibited the highest biological activity. Study indicates that plant Lavatera thuringiaca L. may be used as a potential source of biologically compounds.