Sapropel-enriched sodium carboxymethyl cellulose gel systems: formulation approaches, stability and bioactive potential

Abstract

Sapropel, a sediment rich in organic matter and bioactive compounds, has significant potential for pharmaceutical and cosmetic applications. This study aimed to develop a stable, water-soluble hydrogel containing sapropel extract as a delivery platform for these bioactive compounds. Sodium carboxymethylcellulose (Na-CMC) was used as a gelling agent in eight formulations, with or without sapropel extract, and buffer solutions (NaCl, MgSO₄, MgCl₂). The gels were evaluated for organoleptic properties, pH, viscosity, stability, and thermal resistance over a 2-year period under different storage conditions.

All sapropel extract containing formulations exhibited a smooth, homogeneous and light-yellow appearance with good stability and spread ability. The pH levels ranged from 4.7 to 7.4, within the acceptable range for skin application, although formulations with MgCl₂ showed greater pH fluctuations. Viscosity analyses revealed that sapropel extract decreased viscosity, particularly under fluctuating temperatures. MgSO₄-buffered formulations exhibited the most stable viscosity over time. However, some formulations demonstrated decreased stability and viscosity after prolonged exposure to elevated temperatures and UV light. Centrifugal and thermal tests confirmed the physical stability of the gels, with no phase separation observed.

Overall, the study confirms the feasibility of incorporating sapropel extract into stable, water-soluble hydrogels, making them suitable for potential therapeutic and cosmetic uses.