Preparation, characterization, and antioxidative activity of Bletilla striata polysaccharide/chitosan microspheres for oligomeric proanthocyanidins

ABSTRACT

Novel oligomeric proanthocyanidins/Bletilla striata polysaccharide/chitosan (OPC/BSP/CTS) microspheres were obtained by spray-drying method. The morphology, size, physicochemical characterization, and in vitro release behavior of the formulation were evaluated. The results of scanning electron microscopy showed OPC-loaded microspheres with considerably wrinkled surfaces and drug-free microspheres with smooth surfaces. Particle-size analysis showed that the diameters of the OPC/BSP/CTS microspheres were 1–5 µm, with uniform distribution (polydispersity below 0.465). Fourier transform infrared indicated the occurrence of a chemical reaction between BSP and CTS. The OPC formed intermolecular hydrogen bonds with BSP/CTS carriers or transmuted amorphous structure. Differential scanning calorimetry displayed the absence of interaction; OPC was only physically encapsulated in the polymer matrix and OPC changed the crystallinity. All the microspheres showed desirable biodegradation rates; the high CTS content retarded their degradation and extended administration times. OPC/BSP/CTS microspheres showed pronounced antioxidant activity than pure OPC. These microspheres can be used as a potential platform to efficiently deliver unstable drugs as a sustained-release oral drug delivery system.

KEYWORDS:

• Bletilla striata polysaccharide
• chitosan
• microspheres
• oligomeric proanthocyanidins
• spray-drying
• sustained-release

Additional information

Funding

The authors are grateful for the generous financial support from National Key Technology R&D Program of the Ministry of Science and Technology (No. 2013GA740103); National Natural Science Foundation of China (No. 81573717); Shandong Provincial Natural Science Foundation, China (ZR2012CM025) for grant support; and Department of Science and Technology of Weifang City (2014WS045).