Cyclodextrins Propolis Extract Encapsulation: Physicochemical Characterization, Toxicity Effect, and Application on Animal Sperm Cold Preservation

Propolis is composed of several bioactive compounds, which give it many beneficial biological effects. The use of cyclodextrins (CDs) is necessary when aiming to enhance the stability, absorption, and solubility of these substances in physiological media. The purpose of the present work is to study solubility diagrams of propolis extract of Melbou region (PEM) in the presence of CDs: alpha-CD, beta-CD, and PM-beta CD, then to formulate an optimized preparation of the inclusion complex using a D-optimal experimental design with three factors (ratio, ethanol solvent, and temperature). The optimal formulation is characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The cytotoxic and protective effects of the optimal formulation are evaluated in vitro against human red blood cells (RBCs) and beef sperm. The results show that PM-beta CD is more efficient, this is confirmed with an optimal formulation that obtained using 40 mL of solvent, a temperature of 40 degrees C with 1:1 stoichiometry. The cytotoxicity tests revealed that PEM and its inclusion complex are non-toxic to RBCs and can maintain sperm conservation. It is concluded that PM-beta CD is more suitable to improve the solubility and stability of PEM constituents, and their non-toxic effect has been approved.