Particles size and antioxidant activities of the Centella asiatica particles produced at different time of milling

Summary form only given. Nowadays the demand on producing fine powders or particles is high due to the importance of these particles in material and nanotechnology field. So many milling techniques were developed in order to fulfill this demand. Centella Asiatica contains asiaticoside as bioactive constituent that has the ability for skin healing. Unfortunately the normal powders are hard to be absorbed by the body effectively. In order to improve the value of use, nano Centella Asiatica powder was prepared. The influences of time grinding were carried out at 0.5, 2, 4, 6, 8 hours and 10 hours. The effects of ball milling at different times were characterized using particles size analysis and FTIR Spectroscopy. The fineness of ground product were evaluated by recording the z-Average (nm), undersize distribution and polydispersity index (Pdl). As a result the smallest size particles by mean is 233 nm while FTIR spectra shows there is no changing in the major component in the Centella Asiatica powders on grinding time. As we can see from figure 2(c) the shorter grinding time will produce larger mean particles size compared to the longer grinding time. This can be understood from the interaction of particles and the grinding ball. Interaction between frictional and impact forces due to the collision of ball and inner wall of jar which move at the difference speeds which will unleash a high dynamic of energies. FESEM image (fig. 3) of spray dried nanoparticles show cake-like structure before remilling. The cake-like structure formed due to the fusion of individual particles during freeze drying. The stress generated during freeze drying leads to the destabilization of colloidal suspension of centella asiatica. There is a phase separation into ice and cryo-concentrated solution during freezing. In this case cryoconcentrated consists of components in the suspension as nanoparticles, stabilizer and others. From FT-IR spectra in figure 3 (a), there is not much difference i- appearance for both compounds. There is no pattern in decreasing particles size will enhance the percentage of transmission as has been studied by Yang et al. (1986). This can be explained by the agglomeration and fusion of some individual particles with one another. Thus the presences of agglomerated and flocculated particles lead to the failure to exhibit the correlation between particles size and intensities of absorption in IR spectra. Furthermore increasing of milling time, there is no structural changes in powders thus strongly suggests the marker compound is still present at the various times of grinding.