Acetoxymethyl Derivative Research Articles

Fluorescent Probe as Dual-Organelle Localizer Through Differential Proton Gradients Between Lipid Droplets and Mitochondria.

Dual-organelle molecular localizers represent powerful new tools allowing the exploration of interorganelle physical contacts and subcellular chemical communication. Here, we describe new dynamic molecular probes to localize mitochondria and lipid droplets taking advantage of the differential proton gradients present in these organelles as well as the activity of mitochondrial esterase. We unveil their potential utility when organelle retention mechanisms and proton gradients are synchronized, an insight that has not been documented previously. Our discoveries indicate that dual-organelle probes serve as a valuable multiplexing assay during starvation-induced autophagy. The pioneering molecular mechanism they employ opens doors to avoid using labile esters such as acetoxymethyl derivatives which are not optimal in imaging microscopy assays.

Phosphonomethylated acetoxymethyl derivatives of acetylfurans and alkyl furoates with the remote location of substituents: synthesis and further transformations

Methods of synthesis of phosphonomethylated acetoxymethyl derivatives of acetylfurans and alkyl furoates with the remote location of functional groups were developed. Investigation of methanolysis of these compounds in presence of sodium methylate showed that complete transesterification of acetates is achived when the equimolar amount of base is used. It takes place due to high acidity of furan alcohols. If acetoxymethyl group is located in the position 3 of the furan ring, and diethoxyphosphorylmethyl one - in the position 2, cleavage of P-C bond takes place. If phosphonomethyl group is located in the position 3, and acetoxymethyl one occupies position 2 or 4, transesterification of ester groups of phosphonate takes place, but P-C bond is not touched. The ester group of carbonic acid is transesterified in any case. The alcohols formed are oxidized according to Kollins to give the corresponding aldehydes. 2-Furylbenzo[ d ]thiazole having ester and diethoxyphosphorylmethyl groups in the furan ring was synthesized by reacting methyl 2-(diethoxyphosphorylmethyl)-5-formylfuran-3-carboxylate with 2-aminothiophenol.

Phosphonomethylated Acetoxymethyl Derivatives of Acetylfurans and Alkyl Furoates with the Remote Location of Substituents: Synthesis and Further Transformations

Phosphonomethylated Acetoxymethyl Derivatives of Acetylfurans and Alkyl Furoates with the Remote Location of Substituents: Synthesis and Further Transformations

Phosphonomethylated Acetoxymethyl Derivatives of Acetylfurans and Alkyl Furoates with Neighboring Location of Substituents: Synthesis and Following Transformations

Phosphonomethylated Acetoxymethyl Derivatives of Acetylfurans and Alkyl Furoates with Neighboring Location of Substituents: Synthesis and Following Transformations

Rational Design of a Near-infrared Fluorescence Probe for Ca2+ Based on Phosphorus-substituted Rhodamines Utilizing Photoinduced Electron Transfer.

Fluorescence imaging in the near-infrared (NIR) region (650-900 nm) is useful for bioimaging because background autofluorescence is low and tissue penetration is high in this range. In addition, NIR fluorescence is useful as a complementary color window to green and red for multicolor imaging. Here, we compared the photoinduced electron transfer (PeT)-mediated fluorescence quenching of silicon- and phosphorus-substituted rhodamines (SiRs and PRs) in order to guide the development of improved far-red to NIR fluorescent dyes. The results of density functional theory calculations and photophysical evaluation of a series of newly synthesized PRs confirmed that the fluorescence of PRs was more susceptible than that of SiRs to quenching via PeT. Based on this, we designed and synthesized a NIR fluorescence probe for Ca2+ , CaPR-1, and its membrane-permeable acetoxymethyl derivative, CaPR-1 AM, which is distributed to the cytosol, in marked contrast to our previously reported Ca2+ far-red to NIR fluorescence probe based on the SiR scaffold, CaSiR-1 AM, which is mainly localized in lysosomes as well as cytosol in living cells. CaPR-1 showed longer-wavelength absorption and emission (up to 712 nm) than CaSiR-1. The new probe was able to image Ca2+ at dendrites and spines in brain slices, and should be a useful tool in neuroscience research.

Synthesis and transformation of 6-aminomethyl derivatives of 7-hydroxy-2'-fluoroisoflavones

Mannich aminomethylation of 8-methyl-7-hydroxy-2'-fluoroisoflavones applying bis-(N,N-dimethylamino)methane afforded C-6 substituted N,N-dimethylaminomethyl derivatives. Subsequent acetylation of these compounds in acetic anhydride in the presence of potassium acetate provided access to the corresponding acetoxymethyl derivatives that were converted to hydroxymethyl- and alkoxymethyl-substituted 7-hydroxyisoflavonoids. Addition of 3-(N,N-dimethylamino)-5,5-dimethyl-2-cyclohexen-1-one or 1,3-dimethyl-5-aminopyrazole with thermally generated ortho-quinone methides led to hetero-Diels–Alder or Michael adducts.

Sulfur-assisted ring contraction of polyfluoroalkylthiopyran derivatives as a route to functionalized fluorine-containing thiophenes

A synthetic route to functionalized α-(polyfluoroalkyl)thiophenes based on the reactions of ring contraction of polyfluoroalkyl substituted thiopyran derivatives has been explored. Potent 6-membered precursors for the preparation of thiophenes were obtained by the addition of bromine to the double bonds of 2-chloro-2-(trifluoromethyl)-3,6-dihydro-2H-tetrahydrothiopyran and 6-(polyfluoroalkyl)-2H-thiopyrans. The reactions of the resulted 4,5-dibromo-2-chloro-2-(trifluoromethyl)tetrahydrothiopyrans and trans-3,4-dibromo-6-(polyfluoroalkyl)-3,4-dihydro-2H-thiopyrans with sodium acetate in acetic acid produced 2-(acetoxymethyl)-5-(polyfluoroalkyl)thiophenes. Base-catalyzed methanolysis of the acetoxymethyl derivatives allowed preparing the corresponding 2-(hydroxymethyl)-5-(polyfluoroalkyl)thiophenes. The mechanism, which includes formation and nucleophilic cleavage of thiiranium cations, has been suggested for the transformation of dibromothiopyran derivatives to substituted thiophenes.

Analysis of the HNO and NO donating properties of alicyclic amine diazeniumdiolates

Nitroxyl (HNO) donors have been shown to elicit a variety of pharmacological responses, ranging from tumoricidal effects to treatment of heart failure. Isopropylamine-based diazeniumdiolates have been shown to produce HNO on decomposition under physiological conditions. Herein, we report the synthesis and HNO release profiles of primary alicyclic amine-based diazeniumdiolates. These compounds extend the range of known diazeniumdiolate-based HNO donors. Acetoxymethyl ester-protected diazeniumdiolates were also synthesized to improve purification and cellular uptake. The acetoxymethyl derivative of cyclopentylamine diazeniumdiolate not only showed higher cytotoxicity toward cancer cells as compared to the parent anion but was also effective in combination with tamoxifen for targeting estrogen receptor α-negative breast cancer cells.

Enhancement of Apoptotic and Autophagic Induction by a Novel Synthetic C-1 Analogue of 7-deoxypancratistatin in Human Breast Adenocarcinoma and Neuroblastoma Cells with Tamoxifen

Breast cancer is one of the most common cancers amongst women in North America. Many current anti-cancer treatments, including ionizing radiation, induce apoptosis via DNA damage. Unfortunately, such treatments are non-selective to cancer cells and produce similar toxicity in normal cells. We have reported selective induction of apoptosis in cancer cells by the natural compound pancratistatin (PST). Recently, a novel PST analogue, a C-1 acetoxymethyl derivative of 7-deoxypancratistatin (JCTH-4), was produced by de novo synthesis and it exhibits comparable selective apoptosis inducing activity in several cancer cell lines. Recently, autophagy has been implicated in malignancies as both pro-survival and pro-death mechanisms in response to chemotherapy. Tamoxifen (TAM) has invariably demonstrated induction of pro-survival autophagy in numerous cancers. In this study, the efficacy of JCTH-4 alone and in combination with TAM to induce cell death in human breast cancer (MCF7) and neuroblastoma (SH-SY5Y) cells was evaluated. TAM alone induced autophagy, but insignificant cell death whereas JCTH-4 alone caused significant induction of apoptosis with some induction of autophagy. Interestingly, the combinatory treatment yielded a drastic increase in apoptotic and autophagic induction. We monitored time-dependent morphological changes in MCF7 cells undergoing TAM-induced autophagy, JCTH-4-induced apoptosis and autophagy, and accelerated cell death with combinatorial treatment using time-lapse microscopy. We have demonstrated these compounds to induce apoptosis/autophagy by mitochondrial targeting in these cancer cells. Importantly, these treatments did not affect the survival of noncancerous human fibroblasts. Thus, these results indicate that JCTH-4 in combination with TAM could be used as a safe and very potent anti-cancer therapy against breast cancer and neuroblastoma cells.

A novel synthetic C-1 analogue of 7-deoxypancratistatin induces apoptosis in p53 positive and negative human colorectal cancer cells by targeting the mitochondria: enhancement of activity by tamoxifen

The natural compound pancratistatin (PST), isolated from the Hymenocallis littoralis plant, specifically induces apoptosis in many cancer cell lines. Unlike many other chemotherapeutics, PST is not genotoxic and has minimal adverse effects on non-cancerous cells. However, its availability for preclinical and clinical work is limited due to its low availability in its natural source and difficulties in its chemical synthesis. Several synthetic analogues of 7-deoxypancratistatin with different modifications at C-1 were synthesized and screened for apoptosis inducing activity in human colorectal cancer (CRC) cells. We found that a C-1 acetoxymethyl derivative of 7-deoxypancratistatin, JC-TH-acetate-4 (JCTH-4), was effective in inducing apoptosis in both p53 positive (HCT 116) and p53 negative (HT-29) human CRC cell lines, demonstrating similar efficacy to that of natural PST. JCTH-4 was able to decrease mitochondrial membrane potential (MMP), increase levels of reactive oxygen species in isolated mitochondria, cause release of the apoptogenic factor cytochrome c (Cyto c) from isolated mitochondria, and induce autophagy in HCT 116 and HT-29 cells. Interestingly, when JCTH-4 was administered with tamoxifen (TAM), there was an enhanced effect in apoptosis induction, reactive oxygen species (ROS) production and Cyto c release by isolated mitochondria, and autophagic induction by CRC cells. Minimal toxicity was exhibited by a normal human fetal fibroblast (NFF) and a normal colon fibroblast (CCD-18Co) cell line. Hence, JCTH-4 is a novel compound capable of selectively inducing apoptosis and autophagy in CRC cells alone and in combination with TAM and may serve as a safer and more effective alternative to current cancer therapies.

Chemoenzymatic synthesis of Amaryllidaceae constituents and biological evaluation of their C-1 analogues. The next generation synthesis of 7-deoxypancratistatin and trans-dihydrolycoricidine.

An efficient synthesis of C-1 derivatives of 7-deoxypancratistatin is reported. The key steps include the following: selective opening of an epoxide with aluminum acetylide in the presence of an aziridine; solid-state silica-gel-catalyzed opening of an aziridine; and oxidative cleavage of a phenanthrene core and its recyclization to phenanthridone to provide the key C-1 aldehyde 22. The conversion of this aldehyde to C-1 acetoxymethyl and C-1 hydroxymethyl derivatives is described along with the evaluation of their biological activity against several cancer cell lines and in an apoptosis study. The C-1 acetoxymethyl derivative has shown promising activity comparable to that of the natural product. In addition, a total synthesis of trans-dihydrolycoricidine and a formal total synthesis of 7-deoxypancratistatin are reported from aldehyde 22. Detailed experimental and spectral data are provided for all new compounds.

Antitumor activity of N-heterocyclic carboxaldehyde thiosemicarbazone derivatives.

Antitumor activity of N-heterocyclic carboxaldehyde thiosemicarbazone derivatives was examined in ascites sarcoma-180 system. Among isoquinoline-1-carboxaldehyde thiosemicarbazone derivatives, the parent compound, IQ-1, was the most active and less toxic. On the other hand, among the pyridine-2-carboxaldehyde thiosemicarbazone derivatives tested, 5-acetoxymethyl and 5-isonicotinoyl derivatives were active, and their therapeutic indices were 190 and 54, respectively. In other tumor systems, acetoxymethyl derivative was markedly active against Ehrlich ascites carcinoma, leukemia L-1210, and leukemia C-1498, while moderately effective against Nakahara-Fukuoka sarcoma, but it was not active against adenocarcinoma-755. Isonicotinoyl derivative was markedly active against Ehrlich ascites carcinoma, leukemia L-1210, and leukemia C-1498, while moderately active against adenocarcinoma-755, and slightly active against Nakahara-Fukuoka sarcoma.

Design of a Practical Fluorescent Probe for Superoxide Based on Protection–Deprotection Chemistry of Fluoresceins with Benzenesulfonyl Protecting Groups

A strategy for designing probes based on protection-deprotection chemistry involving fluoresceins and their benzenesulfonyl (BES) derivatives has led to the development of a much more practical superoxide (O(2) (-.)) probe than the previously reported bis(2,4-dinitro-BES) tetrafluorofluorescein (6 a). Examination of various BES derivatives, developed from the starting point of the prototype probe 6 a, yielded 4,5-dimethoxy-2-nitro-BES tetrafluorofluorescein (BESSo; 7 j) as the optimal reagent. A microtiter plate assay with BESSo showed a tenfold improved detection limit for O(2) (-.) compared with such an assay based on 6 a. BESSo showed markedly better specificity for O(2) (-.) than for GSH or other reactive oxygen species, and this specificity was significantly higher than that of Fe(2+) and some reducing enzymes. These features have resulted in the development of an assay based on BESSo that is capable of providing more unambiguous results for O(2) (-.) release from neutrophils, with or without stimulation by phorbol myristate acetate, as compared with an assay based on 6 a. Intracellular generation of O(2) (-.) in human Jurkat T cells stimulated by butyric acid has been measured by using flow cytometry and fluorescence microscopy utilizing the acetoxymethyl derivative of BESSo.

Elegant Synthesis of Novel Pyrroles and Dipyrrylmethane of Biosynthetic Importance.

Ethyl 4-ethoxycarbonylmethyl-3,5-dimethylpyrrole-2-carboxylate (1) has been synthesized by extension and modification of Knorr pyrrole synthesis. Its acetoxymethyl derivative (2) has also been synthesized. Diethyl 3,3'-bis(ethoxycarbonylmethyl)-4,4'-dimethyl-2,2'-dipyrrylmethane-5,5'-dicarboxylate has been synthesized by self-condensation of 2.

Elegant synthesis of novel pyrroles and dipyrrylmethane of biosynthetic importance

Ethyl 4-ethoxycarbonylmethyl-3,5-dimethylpyrrole-2-carboxylate (1) has been synthesized by extension and modification of Knorr pyrrole synthesis. Its acetoxymethyl derivative (2) has also been synthesized. Diethyl 3,3'-bis(ethoxycarbonylmethyl)-4,4'-dimethyl-2,2'-dipyrrylmethane-5,5'-dicarboxylate has been synthesized by self-condensation of 2.

Platelet collagen receptor integrin alpha2beta1 activation involves differential participation of ADP-receptor subtypes P2Y1 and P2Y12 but not intracellular calcium change.

In agonist-induced platelet activation, the collagen platelet receptor integrin alpha2beta1 is activated to high-affinity states through ADP involvement [Jung, S.M. & Moroi, M. (2000) J. Biol. Chem. 275, 8016-8026]. Here we determined the ADP-receptor subtypes involved and their relative contributions to alpha2beta1 activation (assessed by soluble-collagen binding) using the P2Y12 antagonist AR-C69931MX and P2Y1 antagonists adenosine 3',5'-diphosphate (Ado(3,5)PP) and adenosine 3'-phosphate 5'-phosphosulfate (AdoPPS). All three inhibited alpha2beta1 activation induced by low or high ADP, low thrombin, or low collagen-related peptide (CRP) concentrations; however, AR-C69931MX was markedly more inhibitory than the P2Y1 antagonists, suggesting the greater contribution of P2Y12. Inhibition patterns by various combinations of AR-C69931MX, AdoPPS, and wortmannin suggested that P2Y1 and P2Y12 mediate alpha2beta1 activation through different pathways, with possible involvement of phosphoinositide 3-kinase in both. Low concentrations of the acetoxy-methyl derivative of 1,2-bis(o-aminophenoxy) ethane-N,N,N',N'-tetra-acetic acid (calcium chelator) markedly decreased alpha2beta1 activation by low thrombin or CRP, but did not affect that by low or high ADP. Measurements of intracellular Ca2+ level (fluorimetric method) and alpha2beta1 activation (soluble-collagen binding) in the same platelet preparation indicated that alpha2beta1 activation via ADP receptors was independent of intracellular Ca2+ release. Our data indicate that integrin alpha2beta1 activation by ADP occurs through an inside-out signaling mechanism involving differential contributions by P2Y1 and P2Y12 wherein each contributes to some portion of the activation, with the stronger contribution of P2Y12. Furthermore, intracellular Ca2+ increase is not directly related to integrin alpha2beta1 activation, meaning that it is separate from the calcium mobilization pathways that these two ADP receptors are involved in.

Synthesis and Characterization of Derivatives of a Hydroxymethyl Ruthenium Complex

Reaction of cis-Ru(bpy)2(CO)CH2OH+PF6- (1, bpy = 2,2‘-bipyridine) with acetic anhydride yields the corresponding acetoxymethyl derivative 2. However, reaction of 1 with a large excess of acetic acid in acetonitrile yields compound 3, containing an acetamidomethyl ligand instead of the acetoxymethyl group. Compounds 2 and 3 have been characterized by X-ray crystallography; in the crystalline state, 3 exists as a binuclear compound held together by hydrogen bonds to a single water molecule through the acetyl carbonyl groups.

Distinct subpopulations in HaCaT cells as revealed by the characteristics of intracellular calcium release induced by phosphoinositide-coupled agonists.

Intracellular calcium release induced by transient applications of phosphoinositide agonists was measured using adherent single HaCaT keratinocytes loaded with the acetoxymethyl derivative of fura-2. Application of ATP, bradykinin and formyl-Met-Leu-Phe (fMLP) resulted in a transient increase in intracellular calcium concentration ([Ca2+]i) with an average half-width of 40+/-21 s and a decay time constant of 15+/-10 s (mean +/- SD, n = 108), irrespective of the agonist applied. The cells could be classified into two groups: in 53% of the cells repeated stimulation brought about a progressively smaller change in [Ca2+]i (type 1 cells), whereas in the remaining cells the amplitude of the calcium transients was essentially unchanged (type 2 cells). Furthermore, calcium transients in type 1 cells had broader half-widths and slower decays. No difference was found between the agonists in respect of the characteristics of the evoked calcium transient within each subpopulation. However, bradykinin and fMLP desensitized some cells. These results indicate that the activation of the inositol trisphospate transduction pathway by different agonists induces a characteristic elevation of [Ca2+]i within a given cell. Our results demonstrate that cultured HaCaT keratinocytes are heterogeneous in respect of the calcium transients evoked by the activators of this second messenger system.

Anodic decarboxylative oxidation of carboxymethyluracil and -thymine isomers

The anodic oxidative decarboxylation of isomers of uracil and thymine acetic acids was studied. Electrolysis in methanolic or ethanolic solutions yielded respective alkoxymethyl derivatives via carbocationic intermediates. In acetic acid/sodium acetate medium, these were trapped by acetate, resulting in corresponding acetoxymethyl derivatives. Electrolysis in fully deuterated methanol or deuterated acetic acid, allow to obtain respective trideuterated compounds.

Porphyrins with exocyclic rings. Part 5. Synthesis of a naphtho[1,2-b]porphyrin.

Condensation of 2-acetyl-1-tetralone with diethyl aminomalonate in refluxing acetic acid gave a dihydronaphtho-pyrrole 9a in excellent yield. Transesterification with benzyl alcohol gave the corresponding benzyl ester 9b and subsequent regioselective oxidation with lead tetraacetate afforded the acetoxymethyl derivative 13. Pyrrole 13 condensed with the α-unsubstituted pyrrole 14 to give the asymmetrical dipyrrylmethane 15 and hydrogenolysis over 10% palladium-charcoal yielded the related dicarboxylic acid 16. Acid catalyzed condensation of 16 with dipyrrylmethane dialdehyde 18 gave the dihydronaphthoporphyrin 17 in 44% yield. Alternatively, 17 condensed with two equivalents of pyrrole aldehyde 19 in the presence of HBr to give the a,c-biladiene 20 and cyclization with CuCl 2 in DMF, followed by demetallation with 10% H 2SO 4 in TFA, afforded 17 in 37% yield. Dehydrogenation of 17 with DDQ in refluxing toluene gave 8, the first example of a naphthoporphyrin, in 76% yield. Porphyrin 8 exhibited an unusual electronic spectrum and this may have value in the characterization of sedimentary porphyrins.