Lithothamnion muelleri treatment ameliorates inflammatory and hypernociceptive responses in antigen-induced arthritis in mice.

Rheumatoid Arthritis (RA) is a chronic disease characterized by persistent inflammation and pain. Alternative therapies to reduce these symptoms are needed. Marine algae are valuable sources of diverse bioactive compounds. Lithothamnion muelleri (Hapalidiaceae) is a marine algae with anti-inflammatory, antitumor, and immunomodulatory properties. Here, we investigated the potential anti-inflammatory and analgesic activities of L. muelleri in a murine model of antigen-induced arthritis (AIA) in mice. Our results demonstrate that treatment with L. muelleri prevented inflammation and hypernociception in arthritic mice. Mechanistically, the crude extract and the polysaccharide-rich fractions of L. muelleri may act impairing the production of the chemokines CXCL1 and CXCL2, and consequently inhibit neutrophil influx to the knee joint by dampening the adhesion step of leukocyte recruitment in the knee microvessels. Altogether our results suggest that treatment with L.muelleri has a potential therapeutic application in arthritis treatment.

Chemical characterization and antiherpes activity of sulfated polysaccharides from Lithothamnion muelleri.

We report herein the chemical characterization and antiherpes activity of polysaccharides from the red alga Lithothamnion muelleri (Hapalidiaceae). The polysaccharide-rich fractions B1 and B2 were obtained by extraction with Na2CO3 and were purified by size exclusion chromatography to afford Fra-B1 and Fra-B2. The polysaccharides were characterized by FT-IR and chemical analysis (total contents of carbohydrates, proteins, sulfate and uronic acid), whereas their average molecular weights were estimated by high performance gel permeation chromatography. The monosaccharide analysis detected galactose, glucose, xylose, mannose, rhamnose and arabinose in the four polysaccharide samples. Antiherpetic in vitro assays showed that B1 and B2 inhibited Herpes Simplex Virus types 1 and 2 (HSV-1 and HSV-2) when added simultaneously to viral infection affording selectivity indices (SI=CC50/EC50) higher than 20. Investigation of the mechanism of action indicated that B1 and B2 act on the initial steps of HSV replication, mainly inhibiting viral adsorption but also viral penetration into the cells.

Antiadhesive activity of polysaccharide-rich fractions from Lithothamnion muelleri.

Red seaweeds are known sources of polysaccharides, some of which possess antiadhesive properties by inhibition of P-selectin-mediated leukocyte rolling. We here report the chemical composition and the antiadhesive activity of polysaccharide-rich fractions from the red alga Lithothamnion muelleri (Hapalidiaceae). The crude fractions enriched in polysaccharides B1 and B2 were obtained, respectively, by sequential extraction with 1% and 2% (w/v) Na2CO3 solution, at 60 degrees C. Fractionation of B1 and B2 by gel permeation chromatography afforded three polysaccharide-rich fractions each, whose compositions were characterized by chemical analysis (total contents of carbohydrates, proteins, sulfate, and uronic acid); their molecular weights were estimated by high-performance gel permeation chromatography (HPGPC). The antiadhesive activity of B1-derived fractions was assayed by visualizing lipopolysaccharides-induced leukocyte rolling under intravital miscroscopy. The intravenous injection of fractions B1a and B1b in mice, at the dose of 10 mg/kg body weight, reduced leukocyte rolling by approximately 90%; fucoidan (10 mg/kg body weight) employed as positive control induced a similar response. Therefore, the sulfated polysaccharides of L. muelleri deserve further evaluation as potential templates for the development of new anti-inflammatory agents.