Chitosan as a Functional Carrier for the Local Delivery Anti-Inflammatory Systems Containing Scutellariae baicalensis radix Extract

Abstract

The aim of the study was to establish the influence of chitosan on the preparation of systems containing Scutellariae baicalensis radix extract and to demonstrate the potential of anti-inflammatory action for the treatment of periodontitis. In the first stage, the impact of the variables (extraction mixture composition, temperature, and the number of extraction cycles) on the extracted samples' biological characteristics was analyzed using the Design of Experiments (DoE) approach. The best conditions for baicalin, baicalein, and wogonin extraction from Scutellariae baicalensis radix were 80% methanol in the extraction mixture, 70 °C, and 4 cycles per 60 min. The DoE approach can be used to choose the best chitosan system parameters with equal success. An increase in the deacetylation degree of chitosan used in the system improved the potential for reducing free radicals and inhibiting the hyaluronidase enzyme. Also, increasing the degree of chitosan deacetylation results in increased resistance of the carrier to biodegradation and an extended baicalin release profile, which is also associated with an increase in the viscosity of the chitosan-based system. In total, the system of a freeze-dried extract with chitosan 90/500 in the ratio of 2:1 (system S9) turns out to be the one with the best physicochemical (high percentage of baicalin release and the highest viscosity conditioning the prolonged stay at the site of administration) and biological properties (the highest antioxidant and anti-inflammatory activities), resulting in the highest potential for use in the treatment of oral inflammatory diseases.

Keywords: Scutellariae baicalensis radix; anti-hyaluronidase activity; antioxidant activity; chitosan.

Figure 1

Chromatogram of standards.

Figure 2

Pareto plot of standardized effects for the baicalin content (a) and TPC (b).

Figure 3

Pareto plot of standardized effects for the antioxidant activity using DPPH assay (a) and for anti-hyaluronidase activity (b).

Figure 4

Model utility contour profiles for effect with a positive sign (a) baicalin content and TPC, and negative sign (b) antioxidant and anti-hyaluronidase activities.

Figure 5

FTIR-ATR spectra of baicalin, S. baicalensis radix extract and its systems with chitosan 70/500 (a), chitosan 80/500 (b) and chitosan 90/500 (c). Characteristic bands of S. baicalensis lyophilized extract at 3330 cm⁻¹, 1720 cm⁻¹, and 1660 cm⁻¹ were connected with the stretching vibration of the O–H, –COOH, and C=O groups, where signals at 1600 cm⁻¹ and 1580 cm⁻¹ with the C=C vibration stretching of the aromatic rings in the structure of flavones. The broad bands in the range 1200–900 cm⁻¹ were connected to the various stretching vibrations of C–O bonds of saccharides [21]. Described wavelengths were also those characteristics of baicalin, the main active compound in the extract [35]. When analyzing spectra of chitosan, one can notice characteristic bands at 3360 cm⁻¹ and 3300 cm⁻¹ bands coming from stretching vibrations of O-H and N-H groups, at 2900 cm⁻¹ from C-H vibrations, and at 1650 cm⁻¹ from N-H vibrations. Spectra of chitosans with different degrees of deacetylation do not differ in terms of the position of individual bands. However, quantitative IR analysis may be used to characterize the exact degree of deacetylation [36]. Finally, when analyzing spectra for the systems, it can be observed that the spectra are the sum of the spectra for individual components such as lyophilized extract and chitosan. Thus, it can be concluded that the prepared systems are physical mixtures, and no changes in the chemical structure of the S. baicalensis extract occurred after the system preparation process. Therefore, it is the method of preparing the system that has a decisive impact on the formation of connections between the components, and grinding leads to the formation of only a physical mixture [21], while in the case of other preparation methods, ATR spectra may indicate interactions between the extract and chitosan [22].

Figure 6

Pareto plot of standardized effects for the antioxidant activity using DPPH assay (a) and for anti-hyaluronidase activity (b) for chitosan systems.

Figure 7

Dissolution profiles of baicalin from systems with chitosan 70/500 (a), chitosan 80/500 (b), and chitosan 90/500 (c), and Pareto plot of standardized effects for percentage of dissolved baicalin at 30 min (d).

Figure 8

Component of bioadhesion of systems with chitosan 70/500 (a), chitosan 80/500 (b), and chitosan 90/500 (c), and Pareto plot of standardized effects for the component of bioadhesion (d).

Figure 9

Model utility contour profiles for chitosan systems for effect with a negative sign (a) antioxidant and anti-hyaluronidase activities, and positive sign (b) release of baicalin and component of bioadhesion.