Slobodan Sukdolak

Antimicrobial Activities of Essential Oil and Methanol Extract of Teucrium montanum

This study was designed to examine the chemical composition of essential oil and the in vitro antimicrobial activities of essential oil and methanol extract of Teucrium montanum. The inhibitory effects of essential oil and methanol extracts of T. montanum were tested against 13 bacterial and three fungal species by using disc-diffusion method. GC/MS analyses revealed that essential oil contains mainly δ-cadinene (17.19%), β-selinene (8.16%) α-calacorene (4.97%), 1,6-dimethyl-4-(1-methylethyl)-naphthalene (4.91%), caryophyllene (4.35%), copaene (4.23%), torreyol (3.91%), 4-terpineol (3.90%), cadina-1,4-diene (3.39%), β-sesquiphellandrene (3.34%), τ-cadinol (3.12%) and γ-curcumene (3.18%). The essential oil has antibacterial as well as antifungal effect.

Evaluation of Antimicrobial Activity of the Lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa , and Umbilicaria cylindrica

The antimicrobial properties of acetone, methanol, and aqueous extracts of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica were studied comparatively in vitro. Antimicrobial activities of the extracts of different lichens were estimated by the disk diffusion test for Gram-positive bacteria, Gram-negative bacteria, and fungal organisms, as well as by determining the MIC (minimal inhibitory concentration). The obtained results showed that the acetone and methanol extracts of Lasallia pustulata, Parmelia sulcata, and Umbilicaria crustulosa manifest antibacterial activity against the majority of species of bacteria tested, in addition to selective antifungal activity. The MIC of lichen extracts was lowest (0.78 mg/ml) for the acetone extract of Lasallia pustulata against Bacillus mycoides. Aqueous extracts of all of the tested lichens were inactive. Extracts of the lichen Umbilicaria cylindrica manifested the weakest activity, inhibiting only three of the tested organisms.

An efficient synthesis and antioxidant properties of novel imino and amino derivatives of 4-hydroxy coumarins.

Series of imino and amino derivatives of 4-hydroxy coumarins were synthesized via conventional and microwave promoted procedure and evaluated for antioxidant potential through different in vitro models such as (DPPH) free radical scavenging activity, linoleic acid emulsion model system, reducing power assay and phosphomolybdenum method. All prepared compounds possess good antioxidant activity and among them p-nitro-phenyl derivative 6c with IC50 at 25.9 μM possesses radical scavenging activity which is comparable to standard BHT, while the best reducing power was observed in a case of benzyl amino compound 8c (RP50 255.6 μM). Also, observed data indicated that compounds may serve as inhibitors of lipid peroxidation process.

Synthesis and Molecular Descriptor Characterization of Novel 4-Hydroxy-chromene-2-one Derivatives as Antimicrobial Agents

Several novel 4-hydroxy-chromene-2-one derivatives 2b-16b were easily prepared through condensation reactions with microwave heating and characterized by elemental analysis, IR, 1H-NMR and mass spectrometry. Geometry optimization of these compounds was executed by PM3, PM5 and Minimize Energy methods to describe them via molecular descriptors. The antimicrobial activity of the synthesized compounds was evaluated against different microbial strains using two different methods: the diffusion method and the micro-dilution method. All data indicated that the products possess antimicrobial activity which depends on the nature of substituent attached to the benzopyran moiety. In general, after 24 h the MIC values of most tested coumarins was 0.13 mg/mL, but compounds 1 and 6b displayed the strongest antimicrobial activity on the tested cultures of bacteria after 48 h. Compound 13b has the strongest growth inhibitory potential on fungus C. albicans, tested by diffusion method, with an inhibition zone of 30-37 mm at a concentration of 150 µg/mL. The conclusion of this experiment is that the synthesized compounds have varied and different influence on different classes of bacteria and the fungus C. albicans.

Design of Novel 4-Hydroxy-chromene-2-one Derivatives as Antimicrobial Agents

This paper presents the design of novel 4-hydroxy-chromene-2 one derivatives, based on previously obtained minimal inhibitory concentration values (MICs), against twenty four microorganism cultures, Gram positive and negative bacteria and fungi. Two of our compounds, 3b (MIC range 130–500 μg/mL) and 9c (31.25–62.5 μg/mL), presented high potential antimicrobial activity. The compound 9c had equal activity to the standard ketoconazole (31.25 μg/mL) against M. mucedo. Enlarged resistance of S. aureus, E. coli and C. albicans on the effect of potential drugs and known toxicity of coumarin antibiotics, motivated us to establish SAR and QSAR models of activity against these cultures and correlate biological activity, molecular descriptors and partial charges of functional groups to explain activity and use for the design of new compounds. The QSAR study presents essential relation of antimicrobial activity and dominant substituents, 4-hydroxy, 3-acetyl and thiazole functional groups, also confirmed through molecular docking. The result was ten new designed compounds with much improved predicted inhibition constants and average biological activity.

Chemical composition, cytotoxic and antioxidative activities of ethanolic extracts of propolis on HCT-116 cell line.

BACKGROUND Propolis is a complex resinous sticky substance that honeybees collect from buds and exudates of various plants. Owing to its versatile biological and pharmacological activities, propolis is widely used in medicines, cosmetics and foods. The aim of this study was to evaluate the cytotoxic and antioxidative effects of various ethanolic extracts of propolis (EEPs) on human colon cancer cell line HCT-116 and compare them with their composition determined by HPLC-DAD. RESULTS The most abundant flavonoids in all samples were chrysin, pinocembrin and galangin (12.697-40.811 µg mg⁻¹), while the main phenolic acids were caffeic acid, ferulic acid and isoferulic acid. Dose- and time-dependent inhibition of growth of HCT-116 cells was observed for all propolis samples, with IC₅₀ values ranging from 26.33 to 143.09 µg mL⁻¹. Differences in cytotoxic activity of propolis samples were associated with differences in their composition. All EEP samples reduced both superoxide anion radical and nitrite levels and also had strong DPPH-scavenging activity. CONCLUSION All tested propolis samples had pronounced cytotoxic and antioxidative activities.

Synthesis and antimicrobial evaluation of some novel 2-aminothiazole derivatives of 4-hydroxy-chromene-2-one.

Syntheses of 2‐aminothiazole derivatives of 4‐hydroxy‐chromene‐2‐one 2c–10c are reported in this paper. These compounds 2c–10c were prepared from 3‐(2‐bromoacetyl)‐4‐hydroxy‐chromene‐2‐one 1 and corresponding thiourea derivatives 2b–10b using Hantzsch reaction. The structures of all compounds were confirmed by IR and 1H‐NMR spectroscopy and elemental analyses. The molecules 2c–10c were evaluated for in vitro antimicrobial activity against ten bacteria and twelve fungi. All tested compounds exhibited antibacterial and antifungal activity.

Antimicrobial activity of extracts of the lichens Cladonia furcata, Parmelia caperata, Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla

Antimicrobial features of acetone, methanol and aqueous extracts of lichens of Cladonia furcata, Parmelia caperata, Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla were investigated by two different methods at the same time. Testing of antimicrobial activities of extracts from five species of lichens was performed by disc diffusion test in relation to Gram-positive and Gram-negative bacteria and fungal organisms, and through determination of minimal inhibitory concentration (MIC) by Broth Tube Dilution method. The obtained results indicated that acetone and methanol extracts of all investigated lichens in different concentrations manifested selective antibacterial and antifungal activity. That activity was more evident in relation to Gram-positive, than Gram-negative bacteria and fungal organisms. Acetone and methanol extracts of lichens Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla inhibited the growth of all tested microorganisms, most of all of lichens Cladonia furcata and Parmelia caperata. Although, the methanol extracts were generally the most active against the test organisms, the lowest MIC value was measured for acetone extract of species Cladonia furcata 0.39 mg/mL in relation to bacterium Bacillus subtilis. Aqueous extracts of investigated lichens were inactive against all tested organisms.

Synthesis, characterization and cytotoxicity of a new palladium(II) complex with a coumarine-derived ligand

The new coumarine derivative, 3-(1-(2-hydroxyethylamino)ethylidene)chroman-2,4--dione, and corresponding palladium(II) complex have been synthesized and characterized by microanalysis, infrared, (1)H and (13)C NMR spectroscopy. The proposed structure of the complex was confirmed on the basis of the X-ray structural study. The palladium(II) complex decreased viability of L929 mouse fibrosarcoma, U251 human glioma and B16 mouse melanoma cell lines in a dose dependent manner, while its ligand exhibited no significant cytotoxicity. The cytotoxic effect of the complex was comparable to that of cisplatin, and mediated by apoptosis associated with oxidative stress, mitochondrial depolarization and caspase activation. Therefore, our results indicate that newly synthesized palladium(II) complex might be a potential candidate for anticancer therapy.

Antimicrobial activity of the essential oil obtained from roots and chemical composition of the volatile constituents from the roots, stems, and leaves of Ballota nigra from Serbia.

The chemical composition of essential oils obtained from the roots, stems, and leaves of Ballota nigra, growing in Serbia, was investigated by gas chromatography/mass spectrometry analyses. Kovats indices, mass spectra, and standard compounds were used to identify a total of 115 individual compounds. The plant produces two types of essential oils. Oils derived from stems and leaves were sesquiterpene rich (78.17% and 88.40%, respectively), containing principally beta-caryophyllene, germacrene D, and alpha-humulene, present in appreciable amounts. In contrast, oil derived from the root was dominated by p-vinylguiacol (9.24%), borneol (7.51%), myrtenol (7.13%), trans-pinocarveol (5.22%), pinocarvone (4.37%), 2-methyl-3-phenylpropanal (4.32%), and p-cymen-8-ol (4.30%). Essential oil obtained from the roots was evaluated for the antimicrobial activity against seven bacterial species and one fungi.