Danijela Vidic

Total phenolic and flavonoid contents, antioxidant and antimicrobial activities of Alnus glutinosa (L.) Gaertn., Alnus incana (L.) Moench and Alnus viridis (Chaix) DC. extracts

The objective of this study was to determine total phenolic and flavonoid contents, antioxidant and antimicrobial activities of methanolic extracts from the leaves and barks of three Alnus species. The phenolic and flavonoid contents of extracts were determined spectrophotometrically using Folin–Ciocalteau and aluminium chloride methods, respectively. In addition, antioxidant activity of the extracts was determined using 1,1-diphenyl-2-picrylhydrazyl radical scavenging method. The antimicrobial activity was performed by disc diffusion assay against six reference bacterial strains including Gram-negative and Gram-positive bacteria and two fungal strains. Extract of Alnus viridis bark contained the highest amounts of total phenolics (780 mg CAT/g), while extract of A. viridis leaves had the highest amount of flavonoids (30.01 mg RUT/g). All extracts showed antioxidant activity higher than thymol, which was used as a positive probe. The largest diameters of inhibition zone (25 mm) were recorded with Bacillus subtilis 168 M and Staphylococcus aureus ATCC 6538.

Influence of the Continental Climatic Conditions on the Essential‐Oil Composition of Salvia brachyodonVandas Transferred from Adriatic Coast

Essential‐oil profile of Salvia brachyodon Vandas, an endemic Dinaric species transferred from Adriatic Coast to the continental climatic conditions, was determined. Hydrodistilled oils obtained from the plant material collected in three‐year field trial were subjected to the detailed GC/MS analysis. Hundred and fifty volatile compounds were identified in four samples. Comparison of the chemical composition of the isolated essential oils showed that population collected one year after transfer preserved sesquiterpene character of its oil (74.3%), while all subsequent samples gave the oils of monoterpene type with 1,8‐cineole as the principal constituent (22.2–42.3%). The high degree of variation in the qualitative and quantitative composition of the volatile constituents revealed the strong influence of environmental conditions on the nature of plant chemical composition that has an important role in a plant adaptation.

Essential oil composition and antioxidant activity of four Asteraceae species from Bosnia

Abstract Hydrodistilled volatile oils from Achillea millefolium L., Arnica montana L., Artemisia absinthium L., and Artemisia annua L. were analyzed by GC/MS. One hundred sixty-seven compounds were identified in all samples, ranging from 74.3% to 96.4% of the total oil. A high percentage of oxygenated monoterpenes is the main characteristic of A. millefolium and A. absinthium oils with camphor (19.2%) and isoascaridol (21.9%) as the major constituents, respectively. In contrast, the main component of A. annua oil was oxygenated sesquiterpene selina-3,11-dien-6-α-ol (9.6%), while the chemical composition of A. montana oil was characterized by a high content of fatty acids with n-hexadecanoic acid (16.1%) as the main constituent. Antioxidant activity was tested using four different methods, DPPH, ABTS, Reducing power, and Phosphomolybdenum assay. The highest antioxidant activity had essential oil of A. montana using DPPH and Phosphomolibdenum assay, A. millefolium in ABTS method, while A. absinthium oil showed the best ability to reduce Fe ions.

Chemical composition of the essential oil of Stachys menthifolia Vis.

Stachys menthifolia Vis. (Lamiaceae) is an endemic species from the Balkan Peninsula spread throughout Albania, Greece, Montenegro, and Croatia. This article presents the first investigation of the essential oil composition of this species from Croatia. Aerial parts of the plant were collected from three different natural habitats in the region of Biokovo Mountain. The studied populations showed similarity in qualitative, but not in quantitative, composition of their essential oils. Hydrodistilled volatile oil obtained from the plant material of S. menthifolia was subjected to gas chromatographic analysis coupled to mass spectrometry. More than 100 compounds were identified in the three samples, representing 86.8–90.8% of the total oil. The terpene profile of S. menthifolia is characterized by a high content of oxygenated sesquiterpenes (48.4–58.9%) and diterpene hydrocarbons (3.5–25.2%), with 8-α-acetoxyelemol (6.9–21.3%), abietatriene (3.5–21.1%), and 4′-methoxyacetophenone (4.5–17.0%) as the main constituents.

Comparison of Essential Oil Prof iles of Satureja montana L. and Endemic Satureja visianii Šilic

Abstract Satureja is a genus of the well-known medicinal plants of Lamiaceae family that comprises numerous species growing wild in the Mediterranean area. The essential oils of Satureja visianii Šilic and Satureja montana L., growing together at the same habitat under similar environmental conditions, were subjected to detailed gas chromatography-mass spectrometry analysis in order to compare their chemical composition. S. visianii Šilic is a stenoendemic species with narrow geographical distribution limited to only one locality, Pelješac Peninsula in Croatia. More than one hundred twenty compounds were identified in both plant oils representing 90.4 % - 99.5 % of the total oil. The most abundant components in S. visianii essential oil were viridiflorol (17.9 %), borneol (12.6 %) and camphor (6.5 %), while S. montana oil was rich in phenolic compounds carvacrol (59.1 %) and thymol (20.1 %).

Volatile constituents, phenolic compounds, and antioxidant activity of Calamintha glandulosa (Req.) Bentham.

BACKGROUND Calamintha glandulosa (Req.) Bentham is an aromatic perennial plant belonging to the family Lamiaceae, mostly found on rocky pastures, dry meadows, and abandoned places of the Mediterranean area. Plants belonging to this genus are known as highly aromatic and to possess significant antimicrobial and antifungal properties. The aim of this study was to provide clear picture of the volatiles of this plant species, and, for the first time, to present C. glandulosa from Croatia in terms of its antioxidant activity. RESULTS The essential oil and headspace obtained from odorous parts of C. glandulosa were subjected to capillary gas chromatography-mass spectrometry analysis. More than 50 volatile compounds were identified in six samples obtained using different extraction techniques. The most abundant components in all the samples examined were oxygenated monoterpenes, with piperitone (19.9-59.5%) and piperitenone (7.1-42.6%) as the main representatives. The total phenolic content of extracts obtained by successive Soxhlet extraction was measured, and the scavenging potency of the samples, indicated as IC50 values, were examined using four different spectrophotometric and spectrofluorimetric methods. In all cases the essential oil showed the lowest antioxidant activity, while the aqueous extract showed the highest. This can be explained by the levels of the phenolic compounds in the samples examined. CONCLUSIONS A clear picture of aroma profile of C. glandulosa is presented, and the results obtained differ from those published previously. The high antioxidant potential of C. glandulosa from Croatia was established for the first time. Results from the present study suggest further analysis on this plant species in order to define its medicinal properties.

Antioxidant and antiproliferative activities of Helleborus odorus Waldst. & Kit, H. multifidus Vis. and H. hercegovinus Martinis

This study was undertaken in order to evaluate possible antioxidative and antiproliferative activities of three Helleborus taxa. The dry leaves and roots of three Helleborus taxa were extracted with ethanol and water. A phytochemical evaluation of the selected extracts was performed using spectrophotometric methods and a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay was used for measuring the antioxidative activity of extracts. The antiproliferative activity of the three Helleborus taxa was studied using Burkitts lymphoma B cells (BJAB) cell lines. The phytochemical evaluation showed that the leaves contain high levels of total phenolic and flavonoid content. Results from the DPPH assay indicated that the activity of the ethanol and water extracts of the leaves was higher than that of positive control (thymol). Extracts from the roots of H. odorus also displayed higher antioxidant activity than the positive probe, while H. mulifidus and H. hercegovinus root extracts were less effective. A statistically significant correlation between total phenolic content and antioxidative properties indicates that these compounds contribute to the antioxidant activity. The highest percentage of cell growth inhibition was observed when testing the water root extracts of H. multifidus (50.14%) and H. hercegovinus (49.04%). In contrast, the water leaf extract of H. hercegovinus exhibited the lowest inhibition of cell growth (8.59%), although it showed strong antioxidant activity.

Acetylcholinesterase Inhibition and Antioxidant Activity of N-trans-Caffeoyldopamine and N-trans-Feruloyldopamine

Phenolic acids and their derivatives found in nature are well-known for their potential biological activity. In this study, two amides derived from trans-caffeic/ferulic acid and dopamine were synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR), mass spectrometry, proton and carbon-13 nuclear magnetic resonance spectroscopy. The compounds were tested for the inhibition of acetylcholinesterase (AChE) from Electrophorus electricus and for antioxidant activity by scavenging 2,2-diphenyl-1-pycrylhydrazyl free radical (DPPH•) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS•+), reducing ferric ions, and ferrous ions chelation. N-trans-Feruloyldopamine displayed the highest inhibitory effect on AChE with half-maximal inhibitory concentration (IC50) values of 8.52 μM. In addition, an in silico study was done to determine the most favorable AChE cluster with the synthesized compounds. Further, these clusters were investigated for binding positions at the lowest free binding energy. Both synthesized hydroxycinnamates were found to be better antioxidants than the parent acids in in vitro tests applied. N-trans-Caffeoyldopamine showed the best antioxidant activity in the three tested methods—against non-biological stable free radicals IC50 5.95 μM for DPPH•, 0.24 μM for the ABTS•+ method, and for reducing power (ascorbic acid equivalent (AAE) 822.45 μmol/mmol)—while for chelation activity against Fe2+ ions N-trans-feruloyldopamine had slightly better antioxidant activity (IC50 3.17 mM).

Effects of Different Methods of Isolation on Volatile Composition of Artemisia annua L.

In order to determine influence of extraction method on volatile oil composition of Artemisia annua L., steam distillation, hydrodistillation, organic solvent extraction, and headspace sampling have been applied. The relative abundance of volatile compounds from the odorous aerial parts of A. annua, obtained by different extraction techniques, was analyzed by GC-MS. Exactly fifty constituents were identified. The leaf and flower essential oil yield ranged from 0.9 to 2.3% (v/w). Oxygenated monoterpenes were predominant in all samples ranged from 42.6% for steam-distilled fraction of petroleum ether extract to 70.6% for headspace of plant material. Essential oils isolated by steam distillation and hydrodistillation indicate that A. annua belongs to artemisia ketone chemotype with its relative content of 30.2% and 28.3%, respectively. The principal constituent in headspace sample of plant material was also artemisia ketone (46.4%), while headspace of petroleum ether extract had camphene (25.6%) as the major compound. The results prove the combined approaches to be powerful for the analysis of complex herbal samples.

HPLC-ED Analysis of Phenolic Compounds in Three Bosnian Crataegus Species

The aim of this work was the qualitative and quantitative determination of selected phenolic compounds in three Crataegus species grown in Bosnia. Crataegus plants are consumed for medicinal purposes and as foodstuff in the form of canned fruit, jam, jelly, tea, and wine. Two samples of plant material, dry leaves with flowers, and berries of three Crataegus species—Crataegus rhipidophylla Gand., Crataegus x subsphaericea Gand., and Crataegus x macrocarpa Hegetschw.—were analyzed. Twelve ethanolic extracts were isolated from the selected plant material using Soxhlet and ultrasound extraction, respectively. Soxhlet extraction proved to be more effective than ultrasound extraction. A simple and sensitive method, high-performance liquid chromatography with electrochemical detection, HPLC-ED, was used for the simultaneous determination of phenolic acids and flavonoids in Crataegus species. The content of gallic acid in the extracts ranged from 0.001 to 0.082 mg/g dry weight (DW), chlorogenic acid from 0.19 to 8.70 mg/g DW, and rutin from 0.03 to 13.49 mg/g DW. Two flavonoids, vitexin and hyperoside, commonly found in chemotaxonomic investigations of Crataegus species, were not detected in the examined extracts. In general, leaves with flowers samples are richer in gallic acid and rutin, whereas the berries samples are richer in chlorogenic acid. Distinct similarities were found in the relative distribution of gallic acid among the three species. Extracts of C. x macrocarpa had the highest content of all detected compounds, while significant differences were found in rutin content, depending on the plant organ. To the best of our knowledge, this is the first study reporting content of phenolic compounds in Crataegus rhipidophylla Gand., Crataegus x subsphaericea, and Crataegus x macrocarpa from Bosnia.