Anti-inflammatory effect of water-soluble complex of 1'-acetoxychavicol acetate with highly branched ß-1,3-glucan on contact dermatitis.

The anti-inflammatory effect on contact dermatitis of the water solubilized 1'-Acetoxychavicol Acetate (ACA) by complexation with ß-1,3-glucan isolated form Aureobasidium pullulans black yeast is reported. It is well-known that ACA possesses a function to inhibit the activation of NF-κB by which genes encoding proinflammatory cytokines, chemokines, and growth factors are regulated. However, because ACA is quite insoluble in water, its usefulness has been extremely limited. On the other hand, a triple-helical polysaccharide ß-1,3-glucan can include hydrophobic compounds into intrastrand hydrophobic cavity and solubilize poorly water-soluble compounds. In this study, solubilization of ACA by complexation with highly branched ß-1,3-glucan was achieved. The effect of anti-inflammatory response of water-soluble ACA complex with ß-1,3-glucan was confirmed in vitro and in vivo.

Biological activity of water-soluble inclusion complexes of 1'-acetoxychavicol acetate with cyclodextrins.

1'-Acetoxychavicol acetate (ACA), isolated from the rhizomes and the seeds of the Zingiberaceae plant, has a variety of biological activities such as antitumor, antiallergic and repellent effects. However, ACA seems to have some disadvantages which may limit for future possible clinical applications, for example, its poor water solubility. Furthermore, ACA is not stable in aqueous solutions and undergoes hydrolysis and/or isomerization. To improve the solubility and stability of ACA in water, we prepared the inclusion complexes with various ß-cyclodextrins (ß-CDs).In aqueous solution, the association constants of ACA with various CDs were estimated at 662±95 (ß-CD), 336±70 (methyl-ß-CD, Meß-CD), and 322±44M(-1) (hydroxypropyl-ß-CD, HPß-CD), respectively, by a spectrofluorometric displacement method based on competition between a guest and a fluorescent probe for CDs. It was revealed that almost all ACAs existed as a free molecule in the CD-containing aqueous solution. However, in the case of preparing the inclusion complexes of CDs with ACA by a solid phase 'high-speed vibration milling' technique, the average inclusion rates of the obtained water-soluble complexes were calculated as 88±13% (ß-CD), 70±1% (Meß-CD), and 63±2% (HPß-CD), respectively, by (1)H NMR analysis. To characterize the structures of the CD·ACA complexes, 2,3,6-trimethyl-ß-CD (TMeß-CD)·ACA complex was prepared as a model compound (inclusion rate: 40%). As a result of 2D ROESY experiments, it was considered that the aromatic ring of ACA is located in the narrow side of the hydrophobic cavity of the TMeß-CD and both 1'- and 4-acetoxy groups of ACA positioned in the vicinity of the secondary and primary methoxy groups of TMeß-CD, respectively. Furthermore, we examined the apoptogenic activity of CD·ACA complexes to evaluate whether or not the bioactivities of ACA were affected by their inclusion. Although the cytotoxicity of all CD·ACA complexes in human epithelial carcinoma HeLa cells and murine adenocarcinoma colon26 cells were diminished as compared with the ACA alone, only HPß-CD·ACA maintained high levels of activity. In addition, HPß-CD·ACA, and Meß-CD·ACA showed suppressive effect for the transcription factor NF-κB activation on LPS-activated murine macrophage RAW264.7 cells and the former was more active complex. Furthermore, HPß-CD·ACA inhibited the in vivo tumor growth of tumor-bearing mice, although the activity was slightly weak compared with that of free ACA. These results indicate that HPß-CD is the best host molecule for ACA to form a water-soluble complex with the similar biological activity of free ACA.