Screening of Critical Variables of Andrographis paniculata Extract Loaded onto Chitosan Microparticles

Andrographis paniculata (AP) is a medicinal plant commonly found in Malaysia. However, the main challenges hindering its clinical values is its low bioavailability and solubility in aqueous environment which can be improved by incorporating it into a nanocarrier system. Therefore, this study was conducted to screen the critical variables involved in the development of AP extract-loaded chitosan microparticles. Nine formulations (coded as F1 to F9) at varying chitosan-to-tripolyphosphate (TPP) mass ratio (2:1, 4:1, and 6:1) and reaction time (30, 60, and 90 minutes) were tested utilizing the onefactor-at-a-time (OFAT) technique and characterized by means of their particle size, polydispersity index (PDI), and encapsulation efficiency (EE). The best formulation was further characterized for its zeta potential (ζ-potential), morphology, and stability. F2 was discovered as the best formulation in the first screening with a particle size of 0.595 ± 0.014 μm, PDI of 0.284 ± 0.011, and EE of 81.18 ± 5.53%. Further testing on the formulation revealed a ζ-potential of 6.4 ±1.51 mV with a spherical and smooth-surface microparticles in dispersion. The microparticles were also stable at 4 °C with minimal change in size after 14 days. In conclusion, these results show that entrapment of AP extract into chitosan-TPP microparticles were achievable at good characteristics and stability and could be further studied as a form for delivering therapeutic activities of AP at targeted site.