Boris Pejin

Synthesis and Biological Activities of Thio-avarol Derivatives

Eleven new thio-avarol derivatives (3-13) were synthesized. Their antimicrobial, brine shrimp lethality, and free-radical scavenging activities and acetylcholinesterase inhibition, together with 12 already reported semisynthetic thio-avarol derivatives (14-25), were evaluated. Structure-activity relationships among these thio derivatives were determined.

Satureja horvatii essential oil: In vitro antimicrobial and antiradical properties and in situ control of Listeria monocytogenes in pork meat

The dominant compounds in Satureja horvatii oil were p-cymene (33.14%), thymol (26.11%) and thymol methyl ether (15.08%). The minimum inhibitory concentration (MIC) varied from 0.03 to 0.57 mg/mL for bacteria, and from 0.56 to 2.23 mg/mL for yeast strains, while minimum bactericidal/yeast-cidal concentration (MBC/MYC) varied from 0.07 to 1.15 mg/mL and 1.11 to 5.57 mg/mL for bacteria and yeasts, respectively. The antiradical potential of the essential oil was evaluated using hydroxyl radical (•OH) generated in Fenton reaction. The meat preserving potential of essential oil from Satureja horvatii was investigated against L. monocytogenes. Essential oil successfully inhibited development of L. monocytogenes in pork meat. Sensorial evaluation on flavor and color of meat was performed. The color and flavor of meat treated with essential oil improved after 4 days of storage. S. horvatii essential oil can act as a potent inhibitor of food spoiling microorganisms, in meat products and also can be a useful source of natural antioxidants.

New and Highly Potent Antitumor Natural Products from Marine-Derived Fungi: Covering the Period from 2003 to 2012

This review covers the 2003-2012 literature data published for antitumor natural products from marine-derived fungi. The focus is on new and highly potent cytotoxic compounds, together with details related to the relevant fungal species. It describes 22 promising bioactives, originating mainly from symbiotic fungi. The chemical structures of all highlighted organic molecules are briefly discussed.

In vitro anti-quorum sensing activity of phytol

Anti-quorum sensing activity of the diterpene phytol was evaluated in vitro for the first time. This compound (at three sub-MIC concentrations – 0.5, 0.25 and 0.125 MIC, respectively) reduced the formation of Pseudomonas aeruginosa PAO1 biofilm in the range of 74.00–84.33% exhibiting higher activity than the both positive controls used, streptomycin and ampicillin. Phytol (0.5 MIC) also effectively reduced P. aeruginosa twitching and flagella motility. Indeed, the bacteria treated were incapable of producing a twitching zone and had almost round, smooth and regular colony edges. Finally, the tested compound (0.5 MIC) exhibited good P. aeruginosa pyocyanin inhibitory activity (51.94%) practically to the same extent as streptomycin (52.09%). According to the experimental data obtained, this phytol property may inspire design of medical foods targeting P. aeruginosa quorum sensing activity.

Further in vitro evaluation of antiradical and antimicrobial activities of phytol

The antiradical activity of phytol was evaluated by electron paramagnetic resonance towards hydroxyl radical (√OH), superoxide anion radical (), methoxy radical (√CH2OH), carbon-dioxide anion radical (), as well as towards nitric-oxide radical (√NO) and 2,2-diphenyl-1-picrylhydrazyl (√DPPH) radical. It reduced the production of all tested radicals showing more promising activity against , √CH2OH and √DPPH radicals (56%, 50% and 48%, respectively) in comparison with √NO, and √OH radicals (38%, 23% and 15%, respectively). The antimicrobial activity of phytol was evaluated by the microdilution method against eight bacterial and eight fungal strains. To varying degrees, it was proven to be active against all tested bacteria and fungi (MIC 0.003–0.038 mg/mL and MBC 0.013–0.052 mg/mL, MIC 0.008–0.016 mg/mL and MFC 0.090–0.520 mg/mL, respectively). According to the obtained results, medical foods containing phytol may support development of new therapies for heart disease.

An insight into the cytotoxic activity of phytol at in vitro conditions

The cytotoxicity of the diterpene alcohol, phytol, was evaluated by using the MTT assay in vitro against seven tumour cells and one normal cell of human origin. The compound tested induced concentration-dependent cytotoxic response in all cell lines, demonstrating to be most and least effective against the breast adenocarcinoma MCF-7 and the prostate adenocarcinoma PC-3 cells, respectively (IC50 8.79 ± 0.41 μM and 77.85 ± 1.93 μM). The IC50 values towards the other five tumours (HeLa, HT-29, A-549, Hs294T and MDA-MB-231) ranged from 15.51 to 69.67 μM. However, mild toxicity was detected against the foetal lung fibroblast MRC-5 cells at the concentrations used (IC50 124.84 ± 1.59 μM). According to the experimental data obtained, this cost-effective natural product widely present in the biosphere may inspire the development of new drug-like substances with improved cytotoxic activity on breast cancer.

Fatty acids of Rhodobryum ontariense (Bryaceae)

The chemical composition of Rhodobryum ontariense (Kindb.) Kindb. has not been previously investigated. Fatty acids of this moss were analysed qualitatively and quantitatively with an aim to identify its corresponding pattern. A total of eight fatty acids were identified including two acetylenic ones: 9,12,15-octadecatrien-6-ynoic acid (42.26%), α-linolenic acid (20.32%), palmitic acid (14.31%), 9,12-octadecadienoic-6-ynoic acid (13.31%), linoleic acid (5.25%), oleic acid (2.47%), stearic acid (1.14%) and γ-linolenic acid (0.92%). To our knowledge, this is the first record of acetylenic fatty acids in the genus Rhodobryum. In general, acetylenic fatty acids vary considerably among different moss groups and have been used as a chemotaxonomic character in bryophyte classifications. Other species of Rhodobryum from Asia have been traditionally used in ethno medicine by indigenous cultures. Two fatty acids of those reported here, 9,12,15-octadecatrien-6-ynoic and α-linolenic acid, have known cardio protective activity, which supports respective claims of traditional herbal use of these mosses.

Anti-quorum sensing activity of selected sponge extracts: a case study of Pseudomonas aeruginosa

The anti-quorum sensing activities towards the bacterium Pseudomonas aeruginosa PA01 (pyocyanin production, biofilm formation and twitching and flagella motility) of two crude extracts (methanol and acetone) of the freshwater sponge Ochridaspongia rotunda (Arndt, 1937) were evaluated in vitro for the first time. Both extracts demonstrated P. aeruginosa pyocyanin inhibitory activity, reducing its production for 49.90% and 42.44%, respectively. In addition, they both showed higher anti-biofilm activity (48.29% and 53.99%, respectively) than ampicillin (30.84%). Finally, O. rotunda extracts effectively reduced twitching and flagella motility of P. aeruginosa. Taken all together, these results suggest that endemic sponge species from the oldest lake in Europe may offer novel bioactive natural products with promising medicinal potential towards P. aeruginosa infections.

Preliminary Data on Essential Oil Composition of the Moss Rhodobryum ontariense (Kindb.) Kindb.

ABSTRACT The essential oil composition of the moss Rhodobryum ontariense obtained by hydrodistillation was preliminary analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Thirteen compounds (86.41% of the total oil) were identified. The main chemical constituents were phytol (31.95%) and 1-octen-3-ol (15.44%). Such an abundance of phytol has not yet been reported in other mosses. Four chemicals (cis-decahydronaphthalene, allo-hedycaryol, jasmone and 2,5,5,8a-tetramethyl1,4,4a,5,6,7,8,8a-octahydronaphthalene-1-carboxylic acid, methyl ester) are first records, not only for the genus Rhodobryum and mosses in general, but also for the group of bryophytes as a whole.

The lignicolous fungus Trametes versicolor (L.) Lloyd (1920): a promising natural source of antiradical and AChE inhibitory agents

Abstract This study aimed to determine antiradical (DPPH• and •OH) and acetylcholinesterase (AChE) inhibitory activities along with chemical composition of autochtonous fungal species Trametes versicolor (Serbia). A total of 38 phenolic compounds with notable presence of phenolic acids were identified using HPLC/MS-MS. Its water extract exhibited the highest antiradical activity against •OH (3.21 μg/mL), among the rest due to the presence of gallic, p-coumaric and caffeic acids. At the concentration of 100 μg/mL, the same extract displayed a profound AChE inhibitory activity (60.53%) in liquid, compared to donepezil (89.05%), a drug in clinical practice used as positive control. The flavonoids baicalein and quercetin may be responsible compounds for the AChE inhibitory activity observed. These findings have demonstrated considerable potential of T. versicolor water extract as a natural source of antioxidant(s) and/or AChE inhibitor(s) to be eventually used as drug-like compounds or food supplements in the treatment of Alzheimer’s disease.