Total antioxidant status in sapropel extracts in different sediment depth in lakes in Latvia

Freshwater sapropel is sediment in lakes and has unique structure containing morethan 10% of unevenly distributed organic matter as well as residues of microscopicaquatic organisms with small content of inorganic components of biogenic originand mixture of mineral ingredients. The characteristics of sapropel are determinedby organic, mineral and biological compounds and it has been traditionally usedin skincare and healthcare in external applications. Sapropel extract is a mixture ofchemical elements, hormones, various organic acids and vitamins and is also usedfor therapeutic applications and skincare.In this study the total antioxidant status (TAS) and fulvic acids in sapropelextract from different layers of sapropel sediments from 5 lakes in Latgale, Latvia,were determined and compared with other characteristics of the sapropel like fulvicand humic acids concentration.For each sapropel layer the total antioxidant status was measured. There was nosignificant difference in TAS between different sapropel sediment layers. Medianconcentration of TAS was calculated to for each individual lake. The total antioxidantstatus was from 1.25 ± 0.23 to 0.34 ± 0.15 mmol Trolex/L (M ± SD), it was found thatTAS is considerably higher in organic sapropel extracts (ash content < 30%) (p < 0.02).Currently, the reasons for so large differences in TAS between different lakes arenot fully understood. Antioxidant level in each of the lakes does not correlate withthe concentration of fulvic acids. Lake with the highest fulvic acid concentration40.9 ± 4.7 mg/g has the lowest level of antioxidant status 0.34 ± 0.15 mmol trolex/L.