Abstract
Aqueous extracts and organic solvent extracts of isolated marine cyanobacteria strains were tested for antimicrobial activity against a fungus, Gram-positive and Gram-negative bacteria and for cytotoxic activity against primary rat hepatocytes and HL-60 cells. Antimicrobial activity was based on the agar diffusion assay. Cytotoxic activity was measured by apoptotic cell death scored by cell surface evaluation and nuclear morphology. A high percentage of apoptotic cells were observed for HL-60 cells when treated with cyanobacterial organic extracts. Slight apoptotic effects were observed in primary rat hepatocytes when exposed to aqueous cyanobacterial extracts. Nine cyanobacteria strains were found to have antibiotic activity against two Gram-positive bacteria, Clavibacter michiganensis subsp. insidiosum and Cellulomonas uda. No inhibitory effects were found against the fungus Candida albicans and Gram-negative bacteria. Marine Synechocystis and Synechococcus extracts induce apoptosis in eukaryotic cells and cause inhibition of Gram-positive bacteria. The different activity in different extracts suggests different compounds with different polarities.
Highlights
The potential contribution of marine organisms to the discovery of new bioactive molecules is increasingly challenging [1,2]
In this work we describe biological activities of marine cyanobacteria strains belonging to the genera Synechocystis and Synechococcus isolated from the temperate Atlantic coast of Portugal
Fourteen marine cyanobacteria strains belonging to the genera Synechocystis and Synechococcus (Table 1), isolated from Portuguese rocky shores along the Northwestern, Central and South coastline were unialgal nonaxenic cultivated on a large scale for biological activity screening
Summary
The potential contribution of marine organisms to the discovery of new bioactive molecules is increasingly challenging [1,2]. Natural products have been isolated from a wide variety of taxa and tested for various biological activities. Among these taxa, cyanobacteria are regarded as good candidates for drug discovery, with applications in agriculture [3], industry [4] and especially, in pharmaceuticals [5]. The role of bioactive molecules in the producer organism itself is poorly understood but, considering the wide spectrum of biological adaptations and tolerance to environmental stress revealed by cyanobacteria, some of these compounds can be produced in an attempt to confer advantages for their survival. Research on biological active compounds produced by cyanobacteria has been focused especially on freshwater species. We screened marine cyanobacteria aqueous extracts and extracts obtained with organic solvents for antifungal and antibacterial activity. Cytotoxic activity was investigated using primary rat hepatocytes and human HL-60 cells
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