A solid preparation of phytochemicals: improvement of the solubility and bioavailability of astragaloside IV based on β-cyclodextrin microencapsulation

Astragaloside IV/β-cyclodextrin inclusion complex (AsIV/β-CD IC) was successfully prepared by low-temperature sedimentation technology. Under the preparation conditions inclusion temperature 60 °C, inclusion time 3 h, core–wall material molar ratio 1:1, and inclusion rate 750 rpm, the optimal encapsulation efficiency reached 81.63%. It was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and thermogravimetric (TGA). Physicochemical characterization of the AsIV/β-CD IC indicated that the complexation of AsIV/β-CD was successful, and the thermal stability of AsIV was improved clearly. Through granulation technology, astragalus saponin granules (ASG) with uniform size from AsIV/β-CD IC were obtained. ASG possessed significant water solubility and storage stability beside fine taste. In addition, ASG demonstrated beneficial bioactivity in antioxidant and antibacterial functions. Antioxidative stress detection showed that ASG could inhibit the increase of malondialdehyde (MDA) content and the decrease of superoxide dismutase (SOD) content in cells caused by lipopolysaccharides (LPS). In addition, in vitro antibacterial experiments of ASG showed that ASG has obvious antibacterial activity against 6 strains, especially the minimum inhibitory concentration (MIC) value of Escherichia coli and Bacillus subtilis reached 12.5 mg/mL.

Graphical abstract