Orathai Sawatdichaikul

Receptor-Based Virtual Screening of EGFR Kinase Inhibitors from the NCI Diversity Database

Epidermal growth factor receptor (EGFR) abnormalities have been associated with several types of human cancer. The crystal structures of its tyrosine kinase domain (EGFR-TK) complexed with small molecule inhibitors revealed the kinase inhibition modes, prompting us to search for novel anti-cancer drugs. A total of 1,990 compounds from the National Cancer Institute (NCI) diversity set with nonredundant structures have been tested to inhibit cancer cell lines with unknown mechanism. Cancer inhibition through EGFR-TK is one of the mechanisms of these compounds. In this work, we performed receptor-based virtual screening against the NCI diversity database. Using two different docking algorithms, AutoDock and Gold, combined with subsequent post-docking analyses, we found eight candidate compounds with high scoring functions that all bind to the ATP-competitive site of the kinase. None of these compounds belongs to the main group of the currently known EGFR-TK inhibitors. Binding mode analyses revealed that the way these compounds complexed with EGFR-TK differs from quinazoline inhibitor binding and the interaction mainly involves hydrophobic interactions. Also, the common kinase-inhibitor (NH---N and CO---HC) hydrogen bonds between the hinge region and the hit compounds are rarely observed. Our results suggest that these molecules could be developed as novel lead compounds in anti-cancer drug design.

In silico screening of epidermal growth factor receptor (EGFR) in the tyrosine kinase domain through a medicinal plant compound database

The unregulated epidermal growth factor receptor tyrosine kinase (ErbB1-TK or EGFR-TK) protein is involved in the proliferation of more than 50% of all cancer types. The reduction of EGFR-TK activity by small or medium-sized molecules has been proven to be an effective treatment for cancer. There is a widespread belief that Chinese medicinal herbs are active against several diseases, including various types of cancer. In this study, 29,960 compounds from the Chemiebase medicinal compound database were virtually screened against the EGFR-TK using AutoDock4.0, GOLD and GLIDE (XP). The results revealed eight potential hits: CAS nos. 104096-45-9, 112649-21-5, 113866-89-0, 142608-98-8, 142608-99-9, 144761-33-1, 155233-17-3 and 80510-05-0. These compounds have been reported to show anticancer activities in the literature. With the help of SiMMap and MOE interaction analysis, the protein–ligand interaction patterns between the functional groups of these compounds and the binding pocket residues were analyzed. Hydrogen bonding and hydrophobic forces are the main components of the interactions of these hits, similar to those observed for the known inhibitors erlotinib, gefitinib and AEE. The physicochemical filter indicates that compounds CAS nos. 104096-45-9 and 144761-33-1 are likely to be potential leads in the drug discovery process.

Computational analyses of curcuminoid analogs against kinase domain of HER2

BackgroundHuman 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, β-diketone, monoketone, pyrazole, and isoxazole.ResultsIn 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.ConclusionsThe 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.

Single base substitution causing the fragrant phenotype and development of a type-specific marker in aromatic coconut (Cocos nucifera).

The fragrance gene, betaine aldehyde dehydrogenase 2 (Badh2), has been well studied in many plant species. The objectives of this study were to clone Badh2 and compare the sequences between aromatic and non-aromatic coconuts. The complete coding region was cloned from cDNA of both aromatic and non-aromatic coconuts. The nucleotide sequences were highly homologous to Badh2 genes of other plants. Badh2 consisted of a 1512-bp open reading frame encoding 503 amino acids. A single nucleotide difference between aromatic and non-aromatic coconuts resulted in the conversion of alanine (non-aromatic) to proline (aromatic) at position 442, which was the substrate binding site of BADH2. The ring side chain of proline could destabilize the structure leading to a non-functional enzyme. Badh2 genomic DNA was cloned from exon 1 to 4, and from exon 5 to 15 from the two coconut types, except for intron 4 that was very long. The intron sequences of the two coconut groups were highly homologous. No differences in Badh2 expression were found among the tissues of aromatic coconut or between aromatic and non-aromatic coconuts. The amino acid sequences of BADH2 from coconut and other plants were compared and the genetic relationship was analyzed using MEGA 7.0. The phylogenetic tree reconstructed by the Bayesian information criterion consisted of two distinct groups of monocots and dicots. Among the monocots, coconut (Cocos nucifera) and oil palm (Elaeis guineensis) were the most closely related species. A marker for coconut differentiation was developed from one-base substitution site and could be successfully used.