Potential Biological Activities of Clausena Essential Oils for the Treatment of Diabetes.

Diabetes mellitus constitutes one of the most important public health problems. It is defined as a metabolic disorder characterized by a chronic hyperglycemic condition. The inhibition of α-glucosidase and inflammation effects is still considered a strategy for the treatment of diabetes. The aim of this study was to search for new and effective natural functional foods agents for the complementary treatment of diabetes and other related complications. The essential oils from the leaves of three Clausena plants collected in Thailand: C. harmandiana, C. guillauminii and C. excavata were obtained by hydrodistillation. The chemical compositions, antioxidant, anti-α-glucosidase and anti-inflammatory activities of these essential oils were evaluated. The C. excavata and C. harmandiana essential oils contained seselin and terpinen-4-ol, respectively, as the major components and showed strong inhibition of DPPH free radical, α-glucosidase, lipoxygenase and nitric oxide activities with the IC50 values ranging from 0.031±0.005 to 0.702±0.003 mg/mL. From these results, it may be concluded that seselin and terpinen-4-ol are important for high antioxidant, anti-α-glucosidase, and anti-inflammatory activities. Therefore, these Clausena essential oils may be useful in industrial applications for the treatment of diabetes and other related complications.

In-vitro Studies of Anti-EGFR Tyrosine Kinase Activity of Thai nutraceutical Plants.

Functional foods have emerged as a new approach to improve human health in term of nutraceutical to prevent people from illness rather than cure patients through medical treatment. In Asian society, particularly in Thailand, the utilizations of functional ingredients have been integrated in every parts of ordinary life. In this study, the tyrosine kinase activity of epidermal growth factor receptor (EGFR) inhibiting properties of 23 Thai's herbs-ethanol extracts have been examined. The crude extracts of only four species that inhibit the activity of EGFR-tyrosine kinase, Azadirachta indica (neem, Sa-dao), Brucea javanica (L.) Merr. (Rajadad), Hibiscus sabdariffa L. (Roselle, Krachiap daeng), and Saccharum chinensis Roxb. (Red sugar cane). Moreover, only ethanol extractions from A. indica and B. javanica were also showed antitumor effect to non-small cell lung cancer, A549 cells.

Computational analyses of curcuminoid analogs against kinase domain of HER2.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2) has an important role in cancer aggressiveness and poor prognosis. HER2 has been used as a drug target for cancers. In particular, to effectively treat HER2-positive cancer, small molecule inhibitors were developed to target HER2 kinase. Knowing that curcumin has been used as food to inhibit cancer activity, this study evaluated the efficacy of natural curcumins and curcumin analogs as HER2 inhibitors using in vitro and in silico studies. The curcumin analogs considered in this study composed of 4 groups classified by their core structure, ß-diketone, monoketone, pyrazole, and isoxazole. RESULTS: In the present study, both computational and experimental studies were performed. The specificity of curcumin analogs selected from the docked results was examined against human breast cancer cell lines. The screened curcumin compounds were then subjected to molecular dynamics simulation study. By modifying curcumin analogs, we found that protein-ligand affinity increases. The benzene ring with a hydroxyl group could enhance affinity by forming hydrophobic interactions and the hydrogen bond with the hydrophobic pocket. Hydroxyl, carbonyl or methoxy group also formed hydrogen bonds with residues in the adenine pocket and sugar pocket of HER2-TK. These modifications could suggest the new drug design for potentially effective HER2-TK inhibitors. Two outstanding compounds, bisdemethylcurcumin (AS-KTC006) and 3,5-bis((E)-3,4-dimethoxystyryl)isoxazole (AS-KTC021 ),were well oriented in the binding pocket almost in the simulation time, 30 ns. This evidence confirmed the results of cell-based assays and the docking studies. They possessed more distinguished interactions than known HER2-TK inhibitors, considering them as a promising drug in the near future. CONCLUSIONS: The series of curcumin compounds were screened using a computational molecular docking and followed by human breast cancer cell lines assay. Both AS-KTC006 and AS-KTC021 could inhibit breast cancer cell lines though inhibiting of HER2-TK. The intermolecular interactions were confirmed by molecular dynamics simulation studies. This information would explore more understanding of curcuminoid structures and HER2-TK.

Inhibitory mechanism of pure curcumin on Wilms' tumor 1 (WT1) gene expression through the PKCα signaling pathway in leukemic K562 cells.

The aim of this study was to investigate the inhibitory mechanism of pure curcumin on WT1 expression in leukemic K562 cells. Pure curcumin suppressed WT1 expression, independent of effects on protein degradation or WT1 mRNA stability. Chromatin immunoprecipitation and reporter gene assays indicate that pure curcumin treatment attenuates WT1 auto-regulation. Interestingly, PKCα inhibition mimicks the repressive effects of pure curcumin in K562 cells. Conversely, myristoylated PKCα over-expression increased WT1 expression and reversed the inhibitory effect of pure curcumin. Our study indicates that pure curcumin attenuates WT1 auto-regulatory function through inhibition of PKCα signaling in K562 cells.