Development of microparticles containing callus extract of Thunbergia Laurifolia for wound dressing material

Abstract

The purpose of this study was to develop the delivery system of Thunbergia laurifolia Linn. (Rang Chuet) callus extract (TC) as an encapsulated microparticles and its wound dressing material. The encapsulated TC microparticles (TC-MPs) were prepared by spray drying (SD) and freeze drying (FD) processes using polysaccharide gel from durian fruit-hulls (DG) and sodium alginate (AG) as an encapsulation polymer. Selected stable TC-MPs were incorporated into freeze dried DG patch for wound dressing delivery system. Rosmarinic acid (RA) was used as chemical maker and as a model for encapsulation study of the plant callus extract. In preliminary study of the encapsulated RA microparticles, it was found that SD process created spherical shape microparticles where as FD process created irregular flat shape particles after sieving to obtain small particles. DG polymer caused shrinking on the particles obtained from SD process and produced particles larger than those of AG for both processes. Surface morphology shows that DG created more roughness than AG and the mixture of polymers lead to producing smoother surface. Solid state characterization shows that RA turned into amorphous and was incorporated into the polymer as the disappearance of its melting peak alter SD and FD processes. Entrapment efficiency (%EE) of crosslinked SD microparticles was drastically lower than those of noncrosslinked, and microparticles created by SD showed lower entrapment than those from FD process. DG exhibits slower release than AG since the structure of DG has more branch chains which might have slower gelling time and longer release period of the trapped substance. Standard RA shows its stability decreased 26.44% after 3 months. Stable formulations including of SN-1AG, FC-1DG, FC-2AG, FC-2DG and FC-2DGAG1:1 were chosen for TC encapsulation. T. laurifolia callus were grown in MS media with 1 mg/L of NAA and 2 mg/L of BA and analyzer using HPLC and founder that 1 mg of callus extract contains 22.05 mcg of RA and %yield of callus extract was 0.72%. Selected TC-MPs were prepared. The morphology, solid state properties, entrapment efficiency results were similar to those of encapsulated RA microparticles, but TC-FC-1DG shows the fastest release at initial phase and TC-FC-2DGAG1:1 released the fastest rate in later phase. In case of stability, TC-FC-2DGAS1:1 shows the best improved stability of rosmarinic acid in all conditions. These encapsulated microparticles were incorporated into the freeze dried patch. The TC-MPs-loaded patches display slower release than the patch loaded TC (PTC) and the stability results were improved compare to PTC in all conditions. These results support the ability of TC delivery system from DG freeze dried patch used for wound dressing material and suitable to be developed further in biomedical applications.