R(+)-alpha lipoic acid (RALA) is one of the cofactors for mitochondrial enzymes and, therefore, plays a central role in energy metabolism. RALA is unstable when exposed to low pH or heat, and therefore, it is difficult to use enantiopure RALA as a pharma- and nutra-ceutical. In this study, we have aimed to stabilize RALA through complex formation with cyclodextrins (CDs). α-CD, β-CD and γ-CD were used for the formation of these RALA-CD complexes. We confirmed the complex formation using differential scanning calorimetry and showed by using HPLC analysis that complexed RALA is more stable than free RALA when subjected to humidity and high temperature or acidic pH conditions. Scanning electron microscopy studies showed that the particle size and shape differed depending on the cyclodextrin used for complexation. Further, the complexes of CD and RALA showed a different particle size distribution pattern compared with that of CD itself or that of the physical mixture of RALA and CD.

To determine the bioavailability of tocotrienol complex with gamma-cyclodextrin, the effects of tocotrienol/gamma-cyclodextrin complex on tocotrienol concentration in rat plasma and tissues were studied. Rats were administered by oral gavage an emulsion containing tocotrienol, tocotrienol with gamma-cyclodextrin, or tocotrienol/gamma-cyclodextrin complex. At 3 h after administration, the plasma gamma-tocotrienol concentration of the rats administered tocotrienol/gamma-cyclodextrin complex was higher than that of the rats administered tocotrienol and gamma-cyclodextrin. In order to determine the effect of complexation on tocotrienol absorption, rats were injected with Triton WR1339, which prevents the catabolism of triacylglycerol-rich lipoprotein by lipoprotein lipase, and then administered by oral gavage an emulsion containing tocotrienol, tocotrienol with gamma-cyclodextrin, or tocotrienol/gamma-cyclodextrin complex. The plasma gamma-tocotrienol concentration of the Triton-treated rats administered tocotrienol/gamma-cyclodextrin complex was higher than that of the other Triton-treated rats. These results suggest that complexation of tocotrienol with gamma-cyclodextrin elevates plasma and tissue tocotrienol concentrations by enhancing intestinal absorption.

R-α-lipoic acid (R-LA) is a cofactor of mitochondrial enzymes and a very strong antioxidant. R-LA is available as a functional food ingredient but is unstable against heat or acid. Stabilized R-LA was prepared through complexation with γ-cyclodextrin (CD), yielding R-LA/CD. R-LA/CD was orally administered to six healthy volunteers and showed higher plasma levels with an area under the plasma concentration-time curve that was 2.5 times higher than that after oral administration of non-complexed R-LA, although the time to reach the maximum plasma concentration and half-life did not differ. Furthermore, the plasma glucose level after a single oral administration of R-LA/CD or R-LA was not affected and no side effects were observed. These results indicate that R-LA/CD could be easily absorbed in the intestine. In conclusion, γ-CD complexation is a promising technology for delivering functional but unstable ingredients like R-LA.

The internal and external morphology of spray‐dried powders were investigated as a function of the operating conditions of the spray dryer by using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The blend of gum arabic (GA) and maltodextrin (MD) solution, which is normally used in the encapsulated food industry, was prepared at 30% solid content of the mass ratio of GA and MD of 1 to 3. In order to make the powder particles visible by CLSM, fluorescein sodium was used to label the solid materials. The solutions were fed through an Ohkawara L‐8 type spray dryer at different inlet air temperatures and atomizing speeds. An increase in the vacuole as well as the particle size was observed when the inlet air temperature was increased. Smaller vacuoles and lower yields of vacuoles were observed when using low atomization speeds. The density of powders decreased with an increase of the inlet air temperature as well as with an increase of the atomizing speed. Furthermore, the surface morphology presented smooth and shriveled particles for all powders, but deeper surface grooving for low inlet air temperatures. More grooves were observed by using a low atomizing speed. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.

We previously reported the bioavailability enhancement of lipophilic Coenzyme Q10 (CoQ10) by complexing with γ-Cyclodextrin (γCD) in spite of poorly-soluble characteristics in water. We recently found the most plausible explanation mechanism which is due to the significant increase of water solubility of CoQ10 with the aid of sodium taurocholate (Na TCA) as a major component of bile acid in small intestine. By adding Na TCA into a water suspension of CoQ10-γCD complex, water soluble Na TCA-γCD complex is formed by the substitution of guest molecule from CoQ10 to Na TCA since Na TCA has higher association constant with γCD than CoQ10. Generally CoQ10 molecule agglutinates in water to form visible particles. But the dissociated CoQ10 from γCD cavity could be significantly solubilized in water captured in the midst of Na TCA micelle. This method could be applied for the other nutra-ceuticals like Curcumin and R-α-Lipoic acid. In the wake of the breakthrough projects using various nutra-ceutical-γCD complexes and Na TCA, we could also establish this new nanotech formulation system in personal care field by the combination of cosme-ceutical-γCD complexes with a cosmetic ingredient, dipotassium glycyrrhizate (GZK 2 ) which has high association constant as well as Na TCA.