Tropical plant extracts as potential antihyperglycemic agents

Preliminary investigations on 14 plant extracts (obtained by ethanolic and aqueous extraction) identified those having high antioxidant and a significant total phenolic content. Antihyperglycemic, α-amylase and α-glucosidase inhibition activities were also observed. A correlation between the antihyperglycemic activity, total phenolic content and antioxidant (DPPH scavenging) activity was established. To further substantiate these findings, the possibility of tannins binding non-specifically to enzymes and thus contributing to the antihyperglycemic activity was also investigated. Our study clearly indicated that the antihyperglycemic activity observed in the plant extracts was indeed not due to non-specific tannin absorption.     

Synthesis of fused 1,2,4-triazines as potential antimicrobial and antitumor agents

5-Benzylidene-3-(p-chlorophenyl)-2-aminothiocarbonyl-1,2,4-triazine (2) was prepared via condensation of oxazolinone (1) with thiosemicarbazide. Fused 1,2,4-triazine derivatives (3, 4 and 9) were synthesized from the reaction of compound 2 with ω-bromomethyl aryl ketones, ethyl chloroacetate, and acetic anhydride. Treatment of 4 with acetic anhydride and aromatic aldehydes yielded the corresponding acetyl, diacetyl derivatives (6 and 7) and 7-benzylidene-5-(p-chlorophenyl)-4-thioxo-3-arylidene-1,2,4-triazino [2,1-a]-1,2,4-triazine-1,8-diones (8). The electron impact mass spectra of both the above series of compounds have also been recorded and their fragmentation pattern is discussed. All synthesized fused 1,2,4-triazine derivatives were primary in vitro screened for their antimicrobial and antitumor activity.

     

Isolation of sesquiterpenoids from sponge Dysidea avara and chemical modification of avarol as potential antitumor agents

The marine sponge Dysidea avara contained avarol (1) and avarone (2). Avarol on acylation yielded 2',5'-O-dibenzoylavarol (3); 2,5'-O-(4-chlorobenzoyl)avarol (4); 2,5'-O-dicinnamoylavarol (5); 2,5'-O-(4-bromobenzoyl)avarol(6); 2',5'-O-dioctanoylavarol (7); 2',5'-O-(4-fluorobenzoyl)avarol (8) and diacetylavarol (9). The structural elucidation of all the compounds 1-9 have been done by spectral analysis. The cytotoxicity of these compounds were also determined and evaluated. Compounds 6 and 9 showed selective cytotoxicity against Hepa (human hepatoma) and KB cell lines respectively.     

Synthesis and biological evaluation of new pyrrolopyrazinone compounds as potential antitumor agents

A series of pyrrolo[1,2-a]pyrazinone compounds(5a-9f) were synthesized,and their cytotoxic activity against SKOV-3,A549.HeLa cells in vitro were evaluated by the MTT method.Some of the compounds showed potential antitumor activity against three tumor cell lines.Among them,compounds 9c and 9d showed the most potent cytotoxic activity.The preliminary mechanism of action was discussed.     

Synthesis and biological evaluation of novel acenaphthene derivatives as potential antitumor agents

Twelve novel acenaphthene derivatives have been synthesized. The structures of all compounds were confirmed by 1H-NMR, MS and elemental analysis. Their antitumor activities were evaluated in six human solid tumor cell lines, namely non-small cell lung cancer (H460), human colon adenocarcinoma (SW480), human breast cancer cell (MDA-MB-468 and SKRB-3), human melanoma cell (A375) and human pancreatic cancer (BxPC-3). Among them, compound 3c shows the best antitumor activity against SKRB-3 cell line, as high as the positive control adriamycin.     

Synthesis and biological evaluation of some novel thiadiazole-benzofuran hybrids as potential antitumor agents

Two series of novel 1,3,4-thiadiazole-benzofuran and 1,3,4-thiadiazole-furochromene derivatives were synthesized through heterocyclization of alkyl 2-(1-(6-hydroxy-4,7-dimethoxybenzofuran-5-yl)ethylidene)hydrazine-1-carbodithioate 3a–f and 2-(1-(5-methoxy-8-methyl-2,6-dioxo-2,6-dihydropyrano[3,2-g]chromen-3-yl)ethylidene)hydrazinecarbothioamide 9a,b with various hydrazonoyl halides, respectively. The structure of the newly synthesized products was elucidated through elemental analysis, spectral data and alternative routes whenever possible. Ten new compounds were evaluated for their anticancer activity against the human breast carcinoma (MCF-7) cell lines in comparison with reference doxorubicin using MTT assay. The results showed that some new compounds have promising anticancer activity.     

Noncovalent complexes of water-soluble polymers and organoplatinum compounds as potential time-release antitumor agents

The complexation of appropriate organoplatinum compounds by water-soluble polymers has the potential to provide a time-release formulation which might afford a substantial reduction in the severity of side effects associated with use of organoplatinum antitumor agents. Both poly-(N-vinylpyrrolidone)(PVP) and poly(N-vinyl-5-methyl-2-oxazolidone)(PVOM) form stable, biologically active, molecular complexes with organoplatinum compounds containing polar aromatic ligands. Platinum compounds suitable for complexation by these polymers include cis-dichloro(4-substituted o-phenylenediamine)platinum(II), 4-substitutedcatecholato(1,2-diaminocyclohexane)platinum(II), and 4-substitutedphthallato(1,2-diaminocyclohexane)-platinum(II) compounds.     

Synthesis and characterization of rhenium complexes of 1,2,3-trihydroxybenzene as potential antitumor agents

Oxorhenium(V) complexes composed of β-emitting ¹⁸⁶Re and ¹⁸⁸Re isotopes are of current interest in radiopharmaceutical medicine. Rhenium complexes of 1,2,3-trihydroxybenzene were prepared by reactions of a Re(V) precursor (tetrabutylammonium tetrachlorooxorhenate) with twofold molar excess of the ligand in acetonitrile. The structural formulae of the complexes and their consequent reaction products, as well as those of the final reaction products bis(1,2,3-trihydroxybenzene)-dioxorhenium(VII) and 1,2,3-trihydroxybenzene-chloro-dioxorhenium(VII), synthesized in two different reactions differing in the amount of triethylamine added to the reaction mixture, were estimated by means of physicochemical and spectroscopic methods. ESI-MS spectra in negative mode were also obtained. The reactions during the course of complex formation and consequent decomposition were primarily followed by ESI-MS, and time-dependent ESI-MS signals were recorded and compared to those obtained by UV/Vis absorption spectroscopy.     

Total synthesis and absolute configuration of otteliones A and B, novel and potent antitumor agents from a freshwater plant

[reaction: see text] The first enantioselective total synthesis of otteliones A and B, biologically important and structurally novel natural products, has been successfully achieved. This total synthesis fully confirms the absolute configuration of these natural products.     

Synthesis of 3'-beta-carbamoylmethylcytidine (CAMC) and its derivatives as potential antitumor agents

3'-beta-Carbamoylmethylcytidine (CAMC) and its derivatives were synthesized using an intramolecular Reformatsky-type reaction promoted by SmI2 as the key step. In vitro tumor cell growth inhibitory activity was evaluated and CAMC was found to exhibit potent cytotoxicity against various human tumor cell lines. From a structure-activity relationship study it was postulated that the cytotoxic mechanism of action of CAMC did not require phosphorylation at the 5'-hydroxyl group. This study provides a novel strategy for the development of a new type of antitumor nucleoside.     

Design,synthesis and biological evaluation of new rhodacyanine analogues as potential antitumor agents

In an attempt to develop potent antitumor agents,new rhodacyanine analogues containing the pyridinium ring（5a-5h）,the isoquinolinium ring（6a-6c） and the quinolinium ring（7a-7e） linked to the rhodanine ring via N-N covalent bond were designed, synthesized and evaluated for antitumor activity against human lung cancer cell line（H460） by MTT assay in vitro.Most of the tested compounds showed enhanced antitumor activity with IC₅₀ values ranging from 0.006 to 9.2 u,mol/L as compared to the lead compound MKT-077.Among them,the most promising compound 7d(IC₅₀ = 0.006μmol/L) was 216.7 times more active than MKT-077(IC₅₀ = 1.3μmol/L).The preliminary structure-activity relationship of the target compounds was discussed.     

Synthesis and biological evaluation of novel N-methyl-picolinamide-4-thiol derivatives as potential antitumor agents

A novel series of N-methylpicolinamide-4-thiol derivatives were synthesized and evaluated on human cancer cell lines. Among them, compound 6p displayed potent and broad-spectrum anti-proliferative activities in vitro on some human cancer cell lines, even better than sorafenib. The advanced kinase inhibitory assays showed that compound 6p could selectively inhibit Aurora-B kinase. The biological results were rationalized by the molecular docking study, which indicated the stable interactions of 6p with the Aurora-B kinase.     

Synthesis,characterization and DNA-binding properties of Ru(II) complexes coordinated by ofloxacin as potential antitumor agents

Three Ru complexes coordinated by oxfloxacin, [Ru(L)₂(OFX)]Cl·2H₂O (L = bpy, 1; dmbpy, 2; phen, 3; and OFX = ofloxacin), were synthesized and characterized. These complexes can inhibit the growth of cervical cancer HeLa cells efficiently. Furthermore, these three complexes exhibited excellent binding affinities with DNA, as confirmed by spectroscopy methods and viscosity experiments. Therefore, the synthesized Ru(II) complexes have excellent DNA-binding abilities with potential applications in cancer chemotherapy.     

G-rich sequence-specific recognition and scission of human genome by PNA/DNA hybrid G-quadruplex formation

Hole in one: A single peptide nucleic acid (PNA) effectively targets the G-rich region in double-stranded DNA through formation of a PNA/DNA hybrid G-quadruplex. Only one target site in the whole human genome was selectively cleaved by the hybrid G-quadruplex. Such site-selective scission of DNA is central to gene manipulation for molecular biology, biotechnology, and therapy.     

Formation and recognition of G-quadruplex in promoter of c-myb oncogene by electrospray ionization mass spectrometry

In this study, electrospray ionization mass spectrometry (ESI-MS) is used to study the formation of G-quadruplex by d(GGAGGAGGAGGA) which locates at the promoter region of c-myb gene. In addition, a natural small molecule, dehydrocorydaline from a Chinese herb, is found to have the highest binding affinity with the G-quadruplex in nine natural small molecules studied, and the binding selectivity of this natural molecule toward the c-myb G-quadruplex with respect to corresponding duplex DNA is significantly higher than that of the broad-spectrum G-quadruplex-ligand TMPyP4. The result from ESI-MS indicates that the gas-phase kinetic stability of the G-quadruplex can be enhanced by binding of dehydrocorydaline. To further investigate the binding properties of dehydrocorydaline to the G-quadruplex, Autodock3 is used to calculate the docked sites and docked energies of small molecules binding to the G-quadruplex and the result shows that the docked energy of dehydrocorydaline is the biggest in the nine small molecules used, consistent with the result from ESI-MS.     

Development and thermodynamic evaluation of novel lipid raft stationary phase chromatography for screening potential antitumor agents

Novel lipid raft stationary phase chromatography (LRSC), with lipid rafts that contain abundant tropomyosin‐related tyrosine kinase A receptors immobilized on the stationary phase, was developed for a high‐throughput screening of potentially active antitumor agents. Lestaurtinib was used as a model compound to determine the operational parameters of the LRSC. Of all the factors considered, the particle size of column packing, the column temperature and the flow rate were of immense importance in determining the performance of the established LRSC system. In order to profoundly comprehend the binding interaction between the model drug and the receptors on the column, thermodynamic studies were employed. The results revealed that the interaction was spontaneous and exothermic, a typical enthalpy‐driven process. Additionally, the primary forces were hydrogen bonding and van der Waals forces. In evaluating the applicability of the method, active extracts from Albizziae Cortex were screened out using the LRSC system under the optimized conditions. The bioactive components were successfully confirmed by the MTT assay. In conclusion, it could be said that the LRSC is a good model for screening potential antitumor agents because of its viability, rapid response and scalable features. Copyright © 2014 John Wiley & Sons, Ltd.     

Biosynthesis, total syntheses, and antitumor activity of tanshinones and their analogs as potential therapeutic agents

Tanshinones are a series of abietane diterpenes, isolated exclusively from Salvia miltiorrhiza and related species. More than 40 tanshinones and their analogs have been isolated since the 1930s. Their biosynthetic pathway correlates with the MEP/DOXP pathway, and many key enzymes, such as mCPS, are responsible for establishing their molecular scaffolds and stereospeci?city. Because of their unique structural characteristics and promising biological activities, total syntheses of various tanshinones have attracted the interest of many synthetic chemists, including R. H. Thomson, H. Kakisawa, R. L. Danheiser, Y. Inouye and J. K. Snyder. Tanshinones and their analogs exhibit interesting and broad antitumor activity in various cell and animal models. Most recently, the tanshinone analog neo-tanshinlactone has shown potent and selective activity against breast cancer. This review will discuss the biosynthesis, total syntheses, and antitumor activities of tanshinones,especially neo-tanshinlactone and its analogs.     

Characterization of extracts from Papaver rhoeas and potential valorization of these extracts in dyeing applications

The aim of our work is to study the dyeing properties of extracts from natural sources such as Papaver rhoeas by modifying the conditions of the dyeing process, choosing other substrates that could be pretreated by innovative and environmentally friendly processes. The results obtained show a fairly high fixation of the extracts on the natural and artificial fibers. The use of mordants allowed the dye to be better fixed on the dyed fibers and to give several shades to the fabric. The rate of essential oil contained in Papaver rhoeas was considered important by the Clevenger process. Screening of extractive revealed the presence of polyphenols, saponins, sterols, alkaloids and flavonoids. In this study, the extractive from Papaver rhoeas was investigated as textile dyestuff.     

The preparation and evaluation of 1-substituted 1,2,3,4-tetrahydro- and 3,4-dihydro-beta-carboline derivatives as potential antitumor agents

A series of 1-substituted 1,2,3,4-tetrahydro- and 3,4-dihydro-beta-carboline derivatives have been synthesized and evaluated for antitumor activity against murine P-388 and human tumor cell lines, KB-16, A-549 and HT-29. All of the compounds prepared, except for 19, showed significant cytotoxicity. Among them, compound 29 exhibited the most potent activity against all tested tumor cell lines. There was an apparent lack of correlation regarding cytotoxicity between 1,2,3,4-tetrahydro- and 3,4-dihydro-beta-carbolines. This study is the first to discover compound 29 as a potential lead for the development of future anticancer agents. The mode of inhibition for compound 29 was proposed.