Cyclic dipeptides produced by marine sponge-associated bacteria as quorum sensing signals.

Four bacterial strains belonging to the genera Vibrio, Pseudoalteromonas and Photobacterium were isolated from the marine sponges Dysidea avara and Geodia cynodium. A Bacillus strain was isolated from Ircinia variabilis. A screening of molecules involved in quorum sensing (QS) was carried out by TLC-overlay and a new "plate T-streak" test. To analyze quorum quenching (QQ), a plate T-streak was performed with Chromobacterium violaceum. Strains of Vibrio isolated from both marine sponges and a strain of Photobacterium isolated from G. cynodium, activated QS bioreporters. A strain of Pseudoalteromonas isolated from D. avara showed QQ activity. Finally, it is reported that cyclic dipeptides isolated from strains of Vibrio sp. and Bacillus sp. (isolated from D. avara and I. variabilis, respectively) were involved in the QS mechanism. The simultaneous presence of bacteria that showed contrasting responses in bioassays for QS signal molecule synthesis in marine sponges could add an interesting dimension to the signalling interactions which may be happening in sponges

Further in vitro biological activity evaluation of amino-, thio- and ester-derivatives of avarol

The acetylcholinesterase inhibitory and/or antitumour activities of amino-, thio-and ester-derivatives of avarol selected were evaluated for the first time at in vitro conditions. Avarol-3',4'-dithioglycol (1) and avarol-4'-(3) mercaptopropionic acid (3) were shown to be the best inhibitors of the enzyme tested (0.50 mu g and IC50 0.05mM and 0.50 mg and IC50 0.12 mM, respectively), while 4'-tryptamine-avarone (9) and avarol-3'-(3) mercaptopropionic acid (2) exhibited the highest cytotoxicity against the human breast T-47D cancer cell line (IC50 0.66 mu g/mL and 1.25 mu g/mL, respectively). According to experimental data obtained, the sesquiterpenoid hydroquinone structure of bioactive avarol derivatives may inspire development of new pharmacologically useful substances to be used in the treatment of Alzheimer's disease and/or human breast tumour

A New Lichen Depsidone from L Obaria Pulmonaria

The continuation of our phytochemical survey of Lobaria pulmonaria (L.) Hoffm. (Lobariaceae), has led to the isolation and identification of a new lichen depsidone (1) characterised by the normal analytical and spectroscopic techniques. Unlike previously isolated depsidone (2) from the same species, the compound 1 has not showed activity in the acetylcholinesterase inhibition test on Thin-layer chromatography plate

Stictic acid inhibits cell growth of human colon adenocarcinoma HT-29 cells

The growth inhibition of stictic acid, a secondary metabolite isolated from the lichen Lobaria pulmonaria (L.) Hoffm. (Lobariaceae), was evaluated in vitro on three human cell lines for the first time. The cell lines HT-29 and MCF-7 were utilized for measuring the activity of stictic acid against cancer cells, while the cell line MRC-5 was selected for estimation of its effect on normal cells. The results suggest a moderate anticancer activity (IC50 value for the cell line HT-29 was 29.29 mu g/ml) and a low growth inhibition on nonmalignant cells (IC50 value for the cell line MRC-5 was 2478.40 mu g/ml) of stictic acid. This natural product can be considered as a promising lead compound for the design of novel human colon adenocarcinoma drugs. (C) 2013 Production and hosting by Elsevier B.V

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

This study aimed to determine antiradical (DPPH center dot and (OH)-O-center dot) 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)-O-center dot (3.21 mu g/mL), among the rest due to the presence of gallic, p-coumaric and caffeic acids. At the concentration of 100 mu g/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

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 thioavarol derivatives (14-25), were evaluated. Structure-activity relationships among these thio derivatives were determined

Acetylcholinesterase inhibition activity of acetylated depsidones from Lobaria pulmonaria

As part of our ongoing project of new acetylcholinesterase inhibitors from lower marine and terrestrial species, a phytochemical investigation was conducted on a foliose lichen, Lobaria pulmonaria (L.) Hoffm. (Lobariaceae), from Bosnia and Herzegovina. The study led to the isolation of a mixture of acetylated depsidones which showed a moderate activity (0.5 mu g) in the acetylcholinesterase inhibition test on Thin-layer chromatography plate. Our results indicate for the first time the significance of depsidones, highly specific metabolites from lichen species, in searching for these inhibitors which still represent the best drugs currently available for the management of Alzheimer's disease

A novel β-orcinol depsidone of lichen lobaria pulmonaria

In continuation of our phytochemical survey of Lobaria pulmonaria has led to the identification of deoxystictic acid in this foliose lichen species for the first time. The isolated β-orcinol depsidone showed moderate anti-hydroxyl radical activity using fluorescence spectroscopy at in vitro conditions. Phytochemistry Aromatic secondary metabolite Anti-hydroxyl radical activity. This work was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Research grant No. 172053). The assistance of Mr. V. Mirra (CNR-ICB, Pozzuoli-Naples, Italy) is gratefully acknowledged

Acetylcholinesterase Inhibition Activity of a Mixture of Methylated Depsidones from the Lichen Lobaria pulmonaria

A phytochemical investigation conducted on a folise lichen, Lobaria pulmonaria (L.) Hoffm. (Lobariaceae), from Bosnia and Herzegovina led to a mixture of methylated depsidones which showed acetylcholinesterase inhibition activity (2 mu g) in the acetylcholinesterase inhibition test on thin-layer chromatography plate. Present results indicate for the first time the potential of methylated depsidones in searching for these inhibitors, which still represent the best drugs currently available for the management of Alzheimer's disease

Composition of the lipophilic extract from the sponge Suberites domuncula

The composition of the lipophylic extract from the sponge Suberites domuncula was investigated. Lipids and their fatty acids, as well as volatile compounds and sterols were identified. Stanols are the main class of steroids in the investigated sponge. A high concentration of unsaturated long chain fatty acids (C26C28) was identified. The presence of branched and odd fatty acids indicates associated bacteria in the sponge