Freshwater Sapropel: Biologically Active Components and Methods of Extraction

Previously, sapropel has been commonly used in agriculture, cosmetology and medicine in its raw form and there has been no generally accepted method or standard for realizing sapropel extract. However, for sapropel usage in medicine, balneology and pharmacy, it is essential to develop quality criteria for raw sapropel and its extracts. This review aims at discussing and summing up different techniques for extracting bioactive compounds from sapropel as well as the possibilities of creating quality criteria. This paper covers existing analytical techniques and methodologies; currently, there are few extraction methods using several extractants for obtaining bioactive components from raw sapropel. Different freshwater sapropel types have been described and characterized. Bioactive components in sapropel have been identified and explained. Humic acids and fulvic acids have been identified as the main substances and their extraction methods have been listed. Solid-liquid, ultrasound assisted and supercritical fluid extraction methods have been pointed out as the most suitable. Additionally, analysis and storage conditions of the extracts have been discussed. There have been found to be no commonly accepted standard methods for sapropel extraction, or for the analysis and characterization of the sapropel extracts. For pharmacological applications, a common approach for the extraction process of active substances from sapropel and the analysis procedures of the extracts need to be established. This review will help equip other researchers with the latest information on this topic.