4-methoxyphenyl Amino Research Articles

Synthesis, Characterization and Thermal Properties of Oxo Methacrylate-Containing Polymer/Clay Nanocomposites

In this study, synthesis and characterization of polymer/clay based nanocomposites was performed using 2-(4-methoxyphenyl amino)-2-oxoethyl methacrylate (MPAEMA) and organoclay. The amount of organoclay in nanocomposites synthesized by in situ polymerization method was determined as 3% and 5%. FTIR, XRD, and SEM were used as characterization techniques. It was determined from XRD and SEM results that the morphology of nanocomposites exfoliated. Then, the thermal properties of nanocomposites were investigated using the TGA/DTA/DTG simultaneous system. In thermal analysis, it was seen that the thermal stability increased when the clay amount increased. It is thought that this newly synthesized synthetic polymer/clay nanocomposites with natural clay content will serve different areas due to its environmentally friendly-biodegradable properties.

ERK mediated upregulation of death receptor 5 overcomes the lack of p53 functionality in the diaminothiazole DAT1 induced apoptosis in colon cancer models: efficiency of DAT1 in Ras-Raf mutated cells.

Backgroundp53 is a tumour suppressor protein that plays a key role in many steps of apoptosis, and malfunctioning of this transcription factor leads to tumorigenesis. Prognosis of many tumours also depends upon the p53 status. Most of the clinically used anticancer compounds activate p53 dependent pathway of apoptosis and hence require p53 for their mechanism of action. Further, Ras/Raf/MEK/ERK axis is an important signaling pathway activated in many cancers. Dependence of diaminothiazoles, compounds that have gained importance recently due to their anticancer and anti angiogenic activities, were tested in cancer models with varying p53 or Ras/Raf mutational status.MethodsIn this study we have used p53 mutated and knock out colon cancer cells and xenograft tumours to study the role of p53 in apoptosis mediated by diaminothiazoles. Colon cancer cell lines with varying mutational status for Ras or Raf were also used. We have also examined the toxicity and in vivo efficacy of a lead diaminothiazole 4-Amino-5-benzoyl-2-(4-methoxy phenylamino)thiazole (DAT1) in colon cancer xenografts.ResultsWe have found that DAT1 is active in both in vitro and in vivo models with nonfunctional p53. Earlier studies have shown that extrinsic pathway plays major role in DAT1 mediated apoptosis. In this study, we have found that DAT1 is causing p53 independent upregulation of the death receptor 5 by activating the Ras/Raf/MEK/ERK signaling pathway both in wild type and p53 suppressed colon cancer cells. These findings are also confirmed by the in vivo results. Further, DAT1 is more efficient to induce apoptosis in colon cancer cells with mutated Ras or Raf.ConclusionsMinimal toxicity in both acute and subacute studies along with the in vitro and in vivo efficacy of DAT1 in cancers with both wild type and nonfunctional p53 place it as a highly beneficial candidate for cancer chemotherapy. Besides, efficiency in cancer cells with mutations in the Ras oncoprotein or its downstream kinase Raf raise interest in diaminothiazole class of compounds for further follow-up.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-016-0505-7) contains supplementary material, which is available to authorized users.

Diaminothiazoles evade multidrug resistance in cancer cells and xenograft tumour models and develop transient specific resistance: understanding the basis of broad-spectrum versus specific resistance.

Acquired drug resistance poses a challenge in cancer therapy. Drug efflux is the most common mechanism of resistance displayed by hydrophobic drugs beyond a certain size. However, target specific changes and imbalance between the pro- and anti-apoptotic proteins are also found quite often in many tumours. A number of small antimitotic agents show high potential for multidrug resistant tumours, mainly because they are able to evade the efflux pumps. However, these compounds are also likely to suffer from resistance upon prolonged treatment. Thus, it is important to find out agents that are sensitive to resistant tumours and to know the resistance mechanisms against small molecules so that proper combinations can be planned. In this report, we have studied the efficiency of diaminothiazoles, a novel class of tubulin targeting potential anticancer compounds of small size, in multidrug resistant cancer. Studies in model cell lines raised against taxol and the lead diaminothiazole, DAT1 [4-amino-5-benzoyl-2-(4-methoxy phenyl amino) thiazole], and the xenograft tumours derived from them, show that diaminothiazoles are highly promising against multidrug resistant cancers. They were able to overcome the expression of efflux protein MDR1 and certain tubulin isotypes, could sensitize improper apoptotic machinery and ablated checkpoint proteins Bub1 and Mad2. Further, we have found that the resistance against microtubule binding compounds with higher size is broad-spectrum and emerges due to multiple factors including overexpression of transmembrane pumps. However, resistance against small molecules is transient, specific and is contributed by target specific changes and variations in apoptotic factors.

Reversible Action of Diaminothiazoles in Cancer Cells Is Implicated by the Induction of a Fast Conformational Change of Tubulin and Suppression of Microtubule Dynamics

Diaminothiazoles are novel cytotoxic compounds that have shown efficacy toward different cancer cell lines. They show potent antimitotic and antiangiogenic activity upon binding to the colchicine-binding site of tubulin. However, the mechanism of action of diaminothiazoles at the molecular level is not known. Here, we show a reversible binding to tubulin with a fast conformational change that allows the lead diaminothiazole DAT1 [4-amino-5-benzoyl-2-(4-methoxy phenyl amino)thiazole] to cause a reversible mitotic block. DAT1 also suppresses microtubule dynamic instability at much lower concentration than its IC(50) value in cancer cells. Both growth and shortening events were reduced by DAT1 in a concentration-dependent way. Colchicine, the long-studied tubulin-binding drug, has previously failed in the treatment of cancer due to its toxicity, even though it generates a strong apoptotic response. The toxicity is attributable to its slow removal from the cell due to irreversible tubulin binding caused by a slow conformational change. DAT1 binds to tubulin at an optimal pH lower than colchicine. Tubulin conformational studies showed that the binding environments of DAT1 and colchicine are different. Molecular dynamic simulations showed a difference in the number of H-bonding interactions that accounts for the different pH optima. This study gives an insight of the action of compounds targeting tubulin's colchicine-binding site, as many such compounds have entered into clinical trials recently.

Upregulation of DR5 receptor by the diaminothiazole DAT1 [4-amino-5-benzoyl-2-(4-methoxy phenyl amino) thiazole] triggers an independent extrinsic pathway of apoptosis in colon cancer cells with compromised pro and antiapoptotic proteins

Mitochondria mediated signalling is the more common way of apoptosis induction exhibited by many chemotherapeutic agents in cancer cells. Death receptor mediated signalling for apoptosis in many cells also requires further amplification from the mitochondrial pathway activation through tBid. Thus the potential of most chemotherapeutic agents in tumours with intrinsic apoptosis resistance due to changes in molecules involved in the mitochondrial pathway is limited. Diaminothiazoles were shown earlier to bind to tubulin thereby exhibiting cytotoxicity towards different cancer cells. We observed that the lead diaminothiazole, DAT1 [4-amino-5-benzoyl-2-(4-methoxy phenyl amino) thiazole] could induce apoptosis in the colon cancer cell line HCT116 by both pathways. However, in contrast to many other chemotherapeutic agents, DAT1 triggered apoptosis where the intrinsic pathway was blocked by changing the pro and antiapoptotic proteins. An independent extrinsic pathway activation triggered by the upregulation of DR5 receptor accounted for that. The induction of DR5 occurred in the transcriptional level and the essential role of DR5 was confirmed by the fact that siRNA downregulation of DR5 significantly reduced DAT1 induced apoptosis. HCT116 cells were earlier shown to have a type II response for apoptosis induction where extrinsic pathway was connected to the intrinsic pathway via the mediator protein tBid. Our finding thus indicates that the signalling events in the manifestation of apoptosis depend not only on the cancer cell type, but also on the inducer. Our results also place diaminothiazoles in a promising position in the treatment of tumours with compromised apoptotic factors.

Antioxidant activity of an aminothiazole compound: Possible mechanisms

Oceans are among the richest natural sources of many bioactive compounds. Several of these compounds have shown pharmacological activities for many diseases. Dendrodoine (5-[(3- N-dimethylamino)-1,2,4-thiadiazolyl]-3-indanyl methanone) is an alkaloid extracted from the marine tunicate Dendrodoa grossularia. Aminothiazoles have a wide range of biological activities including anti-tumor and antioxidant properties. The aim of our study was to examine the antioxidant ability of an aminothiazole derivative, dendrodoine analogue (DA) [(4-amino-5-benzoyl-2-(4-methoxy phenylamino) thiazole] which has been chemically synthesized and is similar to dendrodoine. In all the biochemical assays used in our study, corresponding to different levels of protection, DA showed concentration dependent antioxidant ability. DA (3.07 μM) showed an ability to inhibit 2,2′-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical formation to the extent of 0.17 μM of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). The ferric complex reducing ability of 3.07 μM DA was equivalent to 110 μM Trolox. 3.07 μM DA gave 84% protection against deoxyribose degradation, a measure of hydroxyl radical scavenging. DA also has an ability to scavenge NO radical, 3.07 μM DA effecting 20% scavenging. Concentration dependent inhibition of lipid peroxidation and protein oxidation induced by 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) and ascorbate-Fe 2+ was observed with low concentrations of DA (1.5–3.07 μM). Mechanistic studies using pulse radiolysis revealed that DA scavenges peroxyl radicals with a bimolecular rate constant of 3 × 10 8 M −1 s −1. Moreover, the initially formed nitrogen-centered radical gets transformed into sulfur-centered radical before furnishing any final product. Our results indicated that DA can be a free radical scavenger and potential antioxidant for future application.

Role of an Aminothiazole Derivative on Ethanol-Induced Toxicity

ABSTRACTThe protective effect of dendrodoine analog (DA) [4-amino-5-benzoyl-2-(4-methoxy phenylamino) thiazole] at three doses (5, 10, and 15 mg/kg body weight) was investigated on ethanol-induced hyperlipidemia. Hepatotoxicity was induced by administering 7.9 g ethanol/kg body weight for 45 days by intragastric intubation. Our results showed increased activity of aspartate transaminase (AST), alkaline phosphatase (ALP), and gamma glutamyl transferase (GGT) and increased levels of cholesterol, triglycerides, and phospholipids in the plasma of alcohol-given group when compared with normal control group. The levels of tissue (liver and kidney) cholesterol and triglycerides were increased significantly in alcohol control rats when compared with normal control rats. The levels of phospholipids decreased significantly in the liver and kidney of alcohol control rats when compared with normal control rats. The activity of phospholipase A and phospholipase C increased significantly in the liver of alcohol control rats when compared with normal control rats. Intragastric administration of DA at 10 mg/kg body weight effectively lowered the activity of hepatic marker enzymes (GGT, AST, and ALP), phospholipase A, and phospholipase C, and decreased the levels of plasma and tissue lipids. The level of tissue phospholipids increased significantly when DA was administered at a dose of 10 mg/kg body weight along with alcohol when compared with alcohol control group. Thus, we propose that DA exerts a hepatoprotective effect by modulating liver marker enzymes and lipid levels at a dosage of 10 mg/kg body weight.