Tatjana Stević

Antioxidant, Cytotoxic, and Antimicrobial Activity of Alnus incana (L.) ssp. incana Moench and A. viridis (Chaix) DC ssp. viridis Extracts

Antioxidant, cytotoxic, and antimicrobial activities of leaves, bark, and cone extracts of Alnus incana (L.) Moench ssp. incana and endemic species A. viridis (Chaix) DC ssp. viridis were evaluated. All extracts were found to be strong 1,1-diphenyl-2-picrylhydrazyl free radical scavengers, exhibiting 50% inhibitory concentration (IC(50)) values of 3.3-18.9 microg/mL, and also showed activity in inhibition of lipid peroxidation with IC(50) values ranging from 38.5 to 157.4 microg/mL. A. incana and A. viridis extracts exhibited significant cytotoxic effects toward HeLa cells, with IC(50) values ranging from 26.02 to 68.5 microg/mL. The most active extract of A. incana bark also contained great amounts of total phenolics (316.2 mg of gallic acid equivalents/g). In our experiment all extracts were virtually nontoxic on brine shrimps. Extracts were screened for activity against 15 microorganisms, and all extracts investigated showed antimicrobial activity. The most active were dry extracts of cones of A. incana and A. viridis with minimum inhibitory concentration values ranging from 0.117 to 0.129 mg/mL.

Chemical Composition and Antimicrobial Activity of the Essential Oils of Micromeria thymifolia (Scop.) Fritsch., M. dalmatica Benth., and Satureja cuneifolia Ten. and Its Secretory Elements

Abstract Light yellowish, pleasant-smelling essential oils were obtained in 0.3%, 1.3%, and 0.8% yields from the aerial parts of S. cuneifolia Ten., M. thymifolia (Scop.) Fritsch., and M. dalmatica Benth, respectively. Thirty-four compounds were identified in the oil of M. dalmatica representing 98.7% of total oil composition, while in the oil of M. thymifolia, 21 were identified representing 78.2% of total oil composition. The major compounds in the oil of M. thymifolia included pulegone (50.4%), piperitenone (10.3%) and piperitenone oxide (4.3%), while the oil of M. dalmatica was rich in pulegone (26.7%), piperitenone (21.8%) and piperitenone oxide (25.4%). Fifty-five compounds were characterized in the oil of S. cuneifolia, representing 92.1% of total oil composition. Linalool (19.9%) and α-pinene (12.3%) were found to be the dominant compounds. Antimicrobial activity was noticed in all examined oils with MIC values ranging from 5.6–54 μg/mL. The most active was the oil of S. cuneifolia, which completely inhibited the growth of mostly all tested microorganisms at the lowest supplied concentration. Glandular trichomes (both peltate and capitate) and nonglandular, uniseriate, simple hairs were distributed on abaxial and adaxial surface of the leaves, calyces and stem in all examined species.

Essential Oil from Blackcurrant Buds as Chemotaxonomy Marker and Antimicrobial Agent

Dormant buds are recognized as valuable side product of the blackcurrant cultivation. Four blackcurrant varieties cultivated in Serbia, i.e., Ben Sarek, Ometa, Ben Lomond, and Ben Nevis, were evaluated for the content, chemical composition, and antimicrobial activity of their bud essential oils. The oil yields of buds harvested during two different growth periods ranged from 1.2–2.0%, and the variety Ometa had the highest yield among the tested varieties. GC‐FID and GC/MS analysis of the oils allowed the identification of eight main components, i.e., α‐pinene (1.6–5.4%), sabinene (1.9–38.4%), δ‐car‐3‐ene (13.0–50.7%), β‐phellandrene (2.9–18.0%), terpinolene (6.6–11.9%), terpinen‐4‐ol (0.9–6.6%), β‐caryophyllene (3.8–10.4%), and α‐humulene (0.2–4.1%). In addition, the similarity degree of the essential‐oil compositions of buds harvested from the upper and lower parts of the shrubs was investigated by hierarchical clustering. All essential oils originating from the same genotype were grouped in the same cluster, indicating the reliability of essential oils as chemotaxonomic markers. For more detailed chemotaxonomic investigations, the three compounds with the greatest variance were chosen, i.e., sabinene, δ‐car‐3‐ene, and β‐phellandrene, which proved to be efficient for the variety distinction. Factor analysis showed that the essential‐oil composition as chemotaxonomic marker in blackcurrants was more reliable for variety Ben Sarek than for variety Ben Nevis. Moreover, it was demonstrated that the essential oils had very strong inhibitory activity against all tested microorganisms. Fungi were more sensitive than bacteria; indeed their growth was completely inhibited at much lower concentrations. In comparison to commercial antibiotics, significantly lower concentrations of the oils were necessary for the complete inhibition of fungal growth.

Chemical Composition and Antimicrobial Activity of Essential Oil of Salvia ringens Sibth. et Sm. var. baldacciana Briq

Abstract Aerial parts of Salvia ringens Sibth. et Sm var.baldacciana Briq.(Lamiceae) collected in Macedonia contained an essential oil in 0.29% yield. The oil was analyzed by GC and GC/MS. The dominant compounds of this oil were 1,8-cineole (33.8%), α—pinene (10.6%) and myrcene (9.8%). It was found that the oil possessed antibacterial activity against all examined bacteria and antifungal activity against C. albicans. The oil showed stronger inhibitory activity against Gram-positive than Gram-negative bacteria.

Chemical Defence in a Millipede: Evaluation and Characterization of Antimicrobial Activity of the Defensive Secretion from Pachyiulus hungaricus (Karsch, 1881) (Diplopoda, Julida, Julidae)

The chemical defence of the millipede Pachyiulus hungaricus is reported in the present paper, in which a chemical characterization is given and antimicrobial activity is determined. In total, independently of sex, 44 compounds were identified. All compounds belong to two groups: quinones and pentyl and hexyl esters of long-chain fatty acids. The relative abundances of quinones and non-quinones were 94.7% vs. 5.3% (males) and 87.3% vs. 12.7% (females), respectively. The two dominant quinones in both sexes were 2-methyl-1,4,-benzoquinone and 2-methoxy-3-methyl-1,4-benzoquinone. Antibacterial and antifungal activity of the defensive secretion was evaluated in vitro against seven bacterial strains and eight fungal species. With the aid of a dilution technique, the antimicrobial potential of the secretion and high sensitivity of all tested strains were confirmed. The lowest minimum concentrations of these compounds (0.20–0.25 mg/mL) were sufficient for inhibition of Aeromonas hydrophila, Listeria monocytogenes and Methicillin resistant Staphylococcus aureus (MRSA). The growth of eight tested fungal species was inhibited by slightly lower concentrations of the secretion, with Fusarium equiseti as the most sensitive fungus and Aspergillus flavus as the most resistant. Values of MIC and MFC in the employed microdilution assay ranged from 0.10 to above 0.35 mg/mL. The given extract contains antimicrobial components potentially useful as therapeutic agents in the pharmaceutical and agricultural industries.

Metabolic changes in Euphorbia palusrtis latex after fungal infection.

The variations of metabolic profile of the latex of wild-growing Euphorbia palustris was carried out using multivariate analysis of 1H NMR spectral data. One population was infected with fungi Fusarium sporotrichioides, Fusarium proliferatum and Alternaria alternata, while the other consisted of healthy plant species. The non-polar metabolites of latex extracts such as benzoyl ingenol-laurate, amyrin decadienoate esters, cis-1,4-polyisoprene, and 24-methylenecycloartanol were identified using 1H and 2D NMR spectra. Principal component analysis of 1H NMR data provided a clear discrimination between the latex of infected and healthy plants. Minimum inhibitory concentration and minimum fungicidal concentration values of the latex extracts of healthy and infected plants were determined. The latex of infected plants was found to contain higher levels of benzoyl ingenol-laurate and 24-methylenecycloartanol, of which concentrations were strongly correlated with the antifungal activities of the latex.