The red seaweed Delesseria sanguinea dominantly populates it large artificial reef in the southwestern Baltic Sea. It contains sulfated polysaccharides (SPS), which exhibit a pharmacological profile indicating anti-inflammatory and anti-skin aging potencies. To establish and optimize an extraction procedure for these SPs and to evaluate the influence of several parameters on their quality, 23 algae batches were harvested over the period of four years and extracted by different methods, resulting in 56 SP batches. Extraction with water at 85 degrees C proved to be superior and led to highly reproducible products with average yields of 11.6 +/- 3.9%, reaching 18% in spring. Their quality was independent of generation form and vitality of the algae. The SPs were identified as sulfated branched xylogalactans (degree of sulfation 0.50 +/- 0.08, mean M-r 142000). The coextraction of floridean starch turned out to be the only parameter causing any seasonal variability, However, by using water, this concerns solely the yields of the isolated products. Compared to NaOH extracts, the antielastase activity of H2O extracted SPs was about twice as strong (IC50 0.204 +/- 0.024 mu g/mL) and the batch to batch variability was much lower (CV 11.8 vs 28.6%). In conclusion, SI's from Delesseria sanguinea can be isolated in reproducibly high quality by using a specific extraction procedure. Thus, an important prerequisite for a potential economical utilization is fulfilled.