Anti-respiratory syncytial virus and anti-herpes simplex virus activity of chemically engineered sulfated fucans from Cystoseira indica.

Seaweed polysaccharides, particularly sulfated ones, exhibited potent antiviral activity against a wide variety of enveloped viruses, such as herpes simplex virus and respiratory viruses. Different mechanisms of action were suggested, which may range from preventing infection to intracellular antiviral activity, at different stages of the viral cycle. Herein, we generated two chemically engineered sulfated fucans (C303 and C304) from Cystoseira indica by an amalgamated extraction-sulfation procedure using chlorosulfonic acid-pyridine/N,N-dimethylformamide and sulfur trioxide-pyridine/N,N-dimethylformamide reagents, respectively. These compounds exhibited activity against HSV-1 and RSV with 50 % inhibitory concentration values in the range of 0.75-2.5 µg/mL and low cytotoxicity at concentrations up to 500 µg/mL. The antiviral activities of chemically sulfated fucans (C303 and C304) were higher than the water (C301) and CaCl2 extracted (C302) polysaccharides. Compound C303 had a (1,3)-linked fucan backbone and was branched. Sulfates were present at positions C-2, C-4, and C-2,4 of Fucp, and C-6 of Galp residues of this polymer. Compound C304 had a comparable structure but with more sulfates at C-4 of Fucp residue. Both C303 and C304 were potent antiviral candidates, acting in a dose-dependent manner on the adsorption and other intracellular stages of HSV-1 and RSV replication, in vitro.

Production and characterization of rhamnolipids by Pseudomonas aeruginosa isolated in the Amazon region, and potential antiviral, antitumor, and antimicrobial activity.

Biosurfactants encompass structurally and chemically diverse molecules with surface active properties, and a broad industrial deployment, including pharmaceuticals. The interest is growing mainly for the low toxicity, biodegradability, and production from renewable sources. In this work, the optimized biosurfactant production by Pseudomonas aeruginosa BM02, isolated from the soil of a mining area in the Brazilian Amazon region was assessed, in addition to its antiviral, antitumor, and antimicrobial activities. The optimal conditions for biosurfactant production were determined using a factorial design, which showed the best yield (2.28 mg/mL) at 25 °C, pH 5, and 1% glycerol. The biosurfactant obtained was characterized as a mixture of rhamnolipids with virucidal properties against Herpes Simplex Virus, Coronavirus, and Respiratory Syncytial Virus, in addition to antimicrobial properties against Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecium), at 50 µg/mL. The antitumor activity of BS (12.5 µg/mL) was also demonstrated, with potential selectivity in reducing the proliferation of breast tumor cells, after 1 min of exposure. These results demonstrate the importance of studying the interconnection between cultivation conditions and properties of industrially important compounds, such as rhamnolipid-type biosurfactant from P. aeruginosa BM02, a promising and sustainable alternative in the development of new antiviral, antitumor, and antimicrobial prototypes.