Carbon nanofiber/taurine-catalyzed synthesis of coumarin and 1,2,4,5-tetra-substituted imidazole derivatives under metal-free conditions.

The main subject of this research is the development of a suitable, efficient, and biocompatible carbon nanofiber-based catalytic system for the synthesis of coumarin and 1,2,4,5-tetra-substituted imidazoles. Brønsted acid carbon nanofiber/taurine catalyst was made during three steps: acid treatment, acylation, and then amination. The basic principles and general advantages of the synthesis method are elaborated. The acidity of the prepared nano-catalyst was investigated using the Hammet acidity technique and UV-Vis spectroscopy, and the H0 value for 5 × 10-2 mg/mL of CNF/T in 0.3 mM 4-nitroaniline solution was determined to be 1.47. The structure of the catalyst was successfully characterized using FT-IR, TGA, FESEM, XRD, TEM, EDX, EDS-MAP, BET, and XPS techniques. Here, we report the ability of carbon nanofiber/taurine as a Brønsted acid catalyst for the synthesis of coumarins and 1,2,4,5-tetra-substituted imidazole through a metal-free, cost-effective, and biocompatible multicomponent route. Among the advantages of this protocol are reaction time, excellent efficiency, reusability, and high activity of the catalyst.

Sb(iii)/Gum Arabic composite as a new natural-based environmentally green catalyst for the one-pot pseudo-four-component synthesis of 2H-indazolo[2,1-b] phthalazinetriones.

Sb(iii)-Gum Arabic composite as a unique natural-based and nontoxic catalyst was synthesized and characterized by FT-IR, XRD, TGA, ICP, BET, EDX and mapping. A four-component reaction of phthalic anhydride, hydrazinium hydroxide, aldehyde, and dimedone has been carried out in the presence of Sb(iii)/Gum Arabic composite to synthesise 2H-indazolo[2,1-b] phthalazine triones. The advantages of the present protocol are the appropriate reaction times, eco-friendly nature and high yields.

Synthesis of bis-spiro piperidines using nano γ-alumina supported Sb(v) under ultrasonic irradiation at room temperature conditions.

Group VA metalloid ion Lewis acids, Sb(v) was identified as a highly potent catalyst for the one-pot three-component synthesis of bis-spiro piperidine derivatives. The reaction was performed using amines, formaldehyde, and dimedone under ultrasonic irradiation at room temperature. The strong acidic property of the nano γ-alumina supported antimony(v) chloride plays a key role in accelerating the rate of the reaction and initiates the reaction smoothly. The heterogeneous nanocatalyst was fully characterized by FT-IR spectroscopy, XRD, EDS, TGA, FESEM, TEM, and BET techniques. Also, the structures of the prepared compounds were characterized by 1H NMR and FT-IR spectroscopies.

Fe3O4@nano-almond shell@OSi(CH2)3/DABCO: a novel magnetic nanocatalyst for the synthesis of chromenes.

In this work, we report the synthesis and characterization of Fe3O4@nano-almond shell@OSi(CH2)3/DABCO as a novel magnetic natural-based basic nanocatalyst. The characterization of this catalyst was achieved using different spectroscopy and microscopy techniques, such as Fourier-transform infrared spectroscopy, X-ray diffractometry, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and mapping, vibrating-sample magnetometry, Brunauer-Emmett-Teller measurements, and thermogravimetric analysis. This catalyst was used for the one-pot synthesis of 2-amino-4H-benzo[f]chromenes-3-carbonitrile from the multicomponent reaction of aldehyde and malononitrile with α-naphthol or ß-naphthol under solvent-free conditions at 90 °C. The yields of the obtained chromenes are 80-98%. The attractive features of this process are its easy work-up, mild reaction conditions, reusability of the catalyst, short reaction times and excellent yields.

Fe3O4@nano-almondshell/Si(CH2)3/2-(1-piperazinyl)ethylamine as an effective magnetite almond shell-based nanocatalyst for the synthesis of dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyran derivatives.

The preparation and design of nano-catalysts based on magnetic biopolymers as green and biocompatible nano-catalysts have made many advances. This paper deals with the preparation of magnetite biopolymer-based Brønsted base nano-catalyst from a nano-almond (Prunus dulcis) shell. This magnetite biopolymer-based nano-catalyst was obtained through a simple process based on the core-shelling of nano-almond shell and Fe3O4 NPs and then the immobilization of 3-chloropropyltrimethoxysilane as linker and 2-aminoethylpiperazine as a basic section. Structural and morphological analysis of this magnetite biopolymer-based nano-catalyst were done using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, Thermogravimetric analysis, Vibrating sample magnetization, Energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller, and Transmission electron microscopy techniques. The performance of the synthesized Fe3O4@nano-almondshell/Si(CH2)3/2-(1-piperazinyl)ethylamine as a novel magnetite biopolymer-based nano-catalyst for the synthesis of dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyran was investigated and showed excellent efficiency.

One-pot synthesis of chromenes in the presence of nano-cellulose/Ti(IV)/Fe3O4 as natural-based magnetic nano-catalysts under solvent free conditions.

In this study, the preparation of magnetic catalysts of titanium tetrachloride stabilized on nano-cellulose named cellulose/Ti(IV)/Fe3O4 was investigated. Various methods such as XRD, SEM, FT-IR, BET, EDX, TEM, TGA and VSM were used to characterize the catalysts. Then, the identified catalysts were used for the synthesis of various chromene skeletons via reaction of malononitrile, aldehyde and dimedone, 4-hydroxycoumarine or 2-naphthole at 70 °C under solvent free conditions. The spectroscopic methods used to determine the structure of the products include 13C NMR, 1H NMR and FT-IR.

Nano-SiO2/DBN: an efficacious and reusable catalyst for one-pot synthesis of tetrahydrobenzo[b]pyran derivatives.

BACKGROUND: The nano-sized particles enhance the exposed surface area of the active part of the catalyst, thereby increasing the contact between precursors and catalyst considerably. In this study, nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en was synthesized, characterized and used as a heterogeneous nanocatalyst for the synthesis of tetrahydrobenzo[b]pyran derivatives. Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscopy, Brunauer-Emmett-Teller plot, Energy Dispersive X-ray Spectroscopy and Thermo Gravimetric Analysis were used to discern nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en. RESULTS: Tetrahydrobenzo[b]pyrans were synthesized by using nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en via one-pot three-component condensation of malononitrile, aldehydes and dimedone in H2O/EtOH at 60 °C. The results indicate that tetrahydrobenzo[b]pyrans were synthesized in good to high yields and short reaction times. CONCLUSIONS: The fundamental privileges of this method are short reaction time, plain procedure, recyclability of catalyst and high yields of products.

Rapid four-component synthesis of dihydropyrano[2,3-c]pyrazoles using nano-eggshell/Ti(IV) as a highly compatible natural based catalyst.

Nano-eggshell/Ti(IV) as a novel naturally based catalyst was prepared, characterized and applied for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives. The characterization of nano-eggshell/Ti(IV) was performed using Fourier Transform Infrared spectroscopy, X-ray Diffraction, Field Emission Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, and Thermo Gravimetric Analysis. Dihydropyrano[2,3-c]pyrazoles were synthesized in the presence of nano-eggshell/Ti(IV) via a four component reaction of aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate at room temperature under solvent free conditions. The principal affairs of this procedure are mild condition, short reaction times, easy work-up, high yields, reusability of the catalyst and the absence of toxic organic solvents.

Cancer Treatment by Caryophyllaceae-Type Cyclopeptides.

Cancer is one of the leading diseases, which, in the most cases, ends with death and, thus, continues to be a major concern in human beings worldwide. The conventional anticancer agents used in the clinic often face resistance among many cancer diseases. Moreover, heavy financial costs preclude patients from continuing treatment. Bioactive peptides, active in several diverse areas against man's health problems, such as infection, pain, hypertension, and so on, show the potential to be effective in cancer treatment and may offer promise as better candidates for combating cancer. Cyclopeptides, of natural or synthetic origin, have several advantages over other drug molecules with low toxicity and low immunogenicity, and they are easily amenable to several changes in their sequences. Given their many demanded homologues, they have created new hope of discovering better compounds with desired properties in the field of challenging cancer diseases. Caryophyllaceae-type cyclopeptides show several biological activities, including cancer cytotoxicity. These cyclopeptides have been discovered in several plant families but mainly are from the Caryophyllaceae family. In this review, a summary of biological activities found for these cyclopeptides is given; the focus is on the anticancer findings of these peptides. Among these cyclopeptides, information about Dianthins (including Longicalycinin A), isolated from different species of Caryophyllaceae, as well as their synthetic analogues is detailed. Finally, by comparing their structures and cytotoxic activities, finding the common figures of these kinds of cyclopeptides as well as their possible future place in the clinic for cancer treatment is put forward.

Structure-activity relationship studies of Longicalcynin A analogues, as anticancer cyclopeptides.

Cancer has emerged as the main cause of the highest rate of mortality in the world. Drugs used in cancer, although, show some beneficial effects on cancerous organs, demonstrate side effects on other normal tissues. On the other hand, anticancer peptides, being effective on target tissues, should be safe and less harmful on healthy organs, since peptides have several advantages, i.e., high activity, specificity, affinity, being less immunogenic and not accumulate in the body. In the present work, analogues of Longicalcynin A, a naturally occurring anticancer cyclopeptide, were synthesized and evaluated their cytotoxicity in order to gain information from structure-activity relationships of the such cyclopeptides which may lead to find novel and safer anticancer peptide compound(s) to be used in clinic. Peptides were prepared by the solid-phase peptide synthesis method using trityl-resin. Peptide cyclization was performed in liquid phase. To study anticancer activity of the peptide analogues of Longicalycinin A, several methods including MTT, flow cytometry analysis and Lysosomal membrane integrity assay were employed using two cell lines HepG2 and HT-29. Fibroblast cells were used to control the safety of the synthesized cyclopeptides on normal cells. Two cyclopeptides 11 and 17 with the sequences of cyclo-(Thr-Val-Pro-Phe-Ala) and cyclo-(Phe-Ser-Pro-Phe-Ala), respectively were cytotoxic against the colon as well as hepatic cancer cells with safety profile against fibroblast cells, probably with the mechanism of apoptosis as lysosomal membrane integrity damaged. These cyclopeptides showed to be more favorable compounds better than Longicalycinin A and good candidates to develop cyclopeptides as anticancer agents.

Fe3O4@nano-cellulose/Cu(ii): a bio-based and magnetically recoverable nano-catalyst for the synthesis of 4H-pyrimido[2,1-b]benzothiazole derivatives.

Fe3O4@nano-cellulose/Cu(ii) as a green bio-based magnetic catalyst was prepared through in situ co-precipitation of Fe2+ and Fe3+ ions in an aqueous suspension of nano-cellulose. The mentioned magnetically heterogeneous catalyst was characterized by FT-IR, XRD, VSM, FESEM, TEM, XRF, EDS and TGA. In this research, the synthesis of 4H-pyrimido[2,1-b]benzothiazole derivatives was developed via a three component reaction of aromatic aldehyde, 2-aminobenzothiazole and ethyl acetoacetate using Fe3O4@nano-cellulose/Cu(ii) under solvent-free condition at 80 °C. Some advantages of this protocol are good yields, environmentally benign, easy work-up and moderate reusability of the catalyst. The product structures were confirmed by FT-IR, 1H NMR, and 13C NMR spectra.

Synthesis of Linear and Cyclic Disulfide Heptapeptides of Longicalycinin A and Evaluation of Toxicity on Cancerous Cells HepG2 and HT-29.

In this work, linear and cyclic disulfide heptapeptides of Longicalycinin A have been successfully synthesized by solid phase methodology with Fmoc /t-Bu and solution phase, respectively. 2-Chlorotrityl chloride resin (2-CTC) was used as a solid support. The synthesized linear disulfide analogue of Longicalycinin A was cleaved from the resin as a protected peptide. The final deprotection was performed by treatment with TFA 95% containing scavengers to achieve the deprotected linear disulfide analogue of Longicalycinin A which was characterized by different instrumental methods using LC-MS and FT-IR. Macrocyclization of deprotected linear peptide was done by an oxidating reagent. Linear and cyclic disulfide heptapeptides of Longicalycinin A were evaluated their toxic activity against cell lines of HepG2 and HT-29 using 3- (4, 5-dimethylthiazol-2-yl) -2, -5-diphenyltetrazolium bromide reagent in MTT assay. The synthetic analogues showed a relative good activity against cell lines of HepG2 and HT-29 with IC50 values from 10.33 µg/mL to 12.45 µg/mL, in comparison to the standard drug 5-fluorouracil (5-FU). Safety profiles of the synthesized linear and cyclic disulfide analogues of Longicalycinin A were also examined on skin fibroblast cells. Between the linear and cyclic disulfide heptapeptides of Longicalycinin A, the cyclic peptide showed a considerable toxic activity on the cancerous cell lines along with a low safety result on normal cells. Therefore, the linear disulfide heptapeptide of Longicalycinin A would be encouraging to develop new anticancer agents.

The toxicity study of synthesized inverse carnosine peptide analogues on HepG2 and HT-29 cells.

OBJECTIVE: Cancer has risen as the main cause of diseases with the highest rate of mortality in the world. Drugs used in cancer, usually demonstrate side effects on normal tissues. On the other hand, anticancer small peptides, effective on target tissues, should be safe on healthy organs, as being naturally originated compounds. In addition, they may have good pharmacokinetic properties. carnosine, a natural dipeptide, has shown many biological functions, including anti-oxidant, anti-senescence, anti-inflammatory and anticancer activities. This study, with the aim of introducing new anticancer agents with better properties, is focused on the synthesis and cytotoxic evaluation of some peptide analogues of carnosine. MATERIALS AND METHODS: The cytotoxic activity of the synthesized peptides, prepared by the solid-phase peptide synthesis method, was evaluated against two cell lines of HepG2 and HT-29 using MTT assay, lactate dehydrogenase (LDH) assay and flow cytometry analysis. RESULTS: Linear and cyclic analogues of carnosine peptide showed cytotoxicity, demonstrated by several experiments, against HepG2 and HT-29 cell lines with mean IC50 values ranging from 9.81 to 16.23 µg/ml. Among the peptides, compounds 1c, 3c and 6b (linear analogue of 3c) showed a considerable toxic activity on the cancerous cell lines. CONCLUSION: The cyclic peptide analogues of carnosine with His-ß-Ala-Pro-ß-Ala-His (1c) and ß-Ala-His-Pro-His-ß-Ala (3c) sequences showed cytotoxic activity on cancerous cells of HepG2 and HT-29, better than carnosine, and thus can be good candidates to develop new anticancer agents. The mechanism of cytotoxicity may be through cell apoptosis.

Nano-γ-Al2O3/SbCl5: an efficient catalyst for the synthesis of 2,3-dihydroperimidines.

Nano-γ-Al2O3/SbCl5 as a new Lewis acid nano catalyst was synthesized and characterized by FTIR, XRD, FESEM, TEM, EDS, BET and TGA techniques. Nano-γ-Al2O3/SbCl5 has been employed for synthesis of 2-substituted perimidines via reaction of naphthalene-1,8-diamine with various aldehydes at room temperature under solvent-free conditions. This protocol proffers several benefits including high yields, easy workup, short reaction times and simple reaction conditions.

Efficient one-pot synthesis of new 1-amino substituted pyrrolo[1,2-a]quinoline-4-carboxylate esters via copper-free Sonogashira coupling reactions.

The reactions of several 2-chloroquinoline-3-carboxylate esters with propargyl alcohol and a secondary amine in the presence of palladium catalyst leads to the formation of new alkyl 1-amino substituted pyrrolo[1,2-a]quinoline-4-carboxylate derivatives. This one-pot process, carried out in the absence of any copper salt, provides an efficient method for the synthesis of functionalized pyrrolo[1,2-a]quinolines in good-to-high yields.