Extraction and antioxidant activity of freshwater sapropel poly-acids

The aim the study was extraction of humic and fulvic poly-acids from sapropel sediment and determination of its antioxidant activity for development of topical applications improving lymph and blood circulation in joints. Sapropel sediment from different layers and different locations were analyzed. Mineral, organic and chemical compounds represented the properties of sapropel extract as well as antioxidant properties. Antioxidant activity was measured with spectrometric methods, that are based on ability to scavenge free DPPH and ABTS radicals, also total phenolic content and total antioxidant status was provided. Sapropel extracts also were tested in in vitro to evaluate optimal concentration for further use in topical medicinal applications. Balb/c 3T3 mouse dermal fibroblast and HaCaT keratinocyte growth was monitored using Cell IQ. All studied samples had antioxidant effect that varied between different lakes but was similar for different layers in the same lake. It was found that antioxidant levels are higher in sapropel samples with higher humic acid concentration. There is strong correlation (R2 = 0.90) between antioxidant levels and humic acid concentration in sapropel extract. Preliminary results indicate that Sapropel extract in high concentrations (70 μg/ml, 140 μg/ml) may promote cell growth shortly (up to 6h); low concentration seems to have no harmful effect on cell growth. Due to strong correlation between antioxidant levels and humic acid concentration in sapropel extract as well its promotion on cell growth in in vitro tests, it can be used as topical application. The ratio of humic and fulvic acids together with other characteristics of the sapropel like - pH, organic matter content and ash content can be used to characterise the sapropel from particular lake and can be used as tool for the identification of the source of sapropel in pharmaceutical and cosmetics product production. The research was co-financed by project No.1.1.1.1/16/A/165.