Supramolecular Chromatographic Separation of C60 and C70 Fullerenes: Flash Column Chromatography vs. High Pressure Liquid Chromatography

A silica-bound C-butylpyrogallol[4]arene chromatographic stationary phase was prepared and characterised by thermogravimetric analysis, scanning electron microscopy, NMR and mass spectrometry. The chromatographic performance was investigated by using C60 and C70 fullerenes in reverse phase mode via flash column and high-pressure liquid chromatography (HPLC). The resulting new stationary phase was observed to demonstrate size-selective molecular recognition as postulated from our in-silico studies. The silica-bound C-butylpyrogallol[4]arene flash and HPLC stationary phases were able to separate a C60- and C70-fullerene mixture more effectively than an RP-C18 stationary phase. The presence of toluene in the mobile phase plays a significant role in achieving symmetrical peaks in flash column chromatography.

Stigmasterol and Stigmasterone from Methanol Extract of Calophyllum soulattri Burm. F. Stem Bark

Stigmasterol and Stigmasterone from Methanol Extract of Calophyllum soulattri Burm. F. Stem Bark. Calophyllum soulattri Burm. F. has been widely used for herbal medicine. Phytochemical investigation of C. soulattri contains a secondary metabolite of the steroid class. Steroid compounds have various biological activities, such as anti-inflammatory, antioxidant, antiproliferative, antibacterial, antimalarial, and anticancer. Two secondary metabolites steroids have been isolated and identified from the stem bark extract of C. soulattri. Isolation was carried out through the extraction (maceration), fractionation, and purification stages. Maceration is carried out using methanol as a solvent. Fractionation was carried out by vacuum liquid chromatography (VLC), and purification was by flash column chromatography. Identification of combined fractions and determination of pure isolates were used through thin-layer chromatography (TLC). The solvent used in the chromatography methods was a mixture of n-hexane and ethyl acetate. The structure isolates were identified by FTIR, 1H NMR, and 13C NMR and compared with literature data. Secondary metabolites steroids that have been isolated are identical compounds to stigmasterol and stigmasterone.

Synthesis and Physicochemical Properties of [(1R,2S,5R)-2-isopropyl-5-methylcyclohexyloxy]-thiophen-5-yl-substituted Tetrapyrazinoporphyrazine with Magnesium(II) Ion

Tetrapyrazinoporphyrazine with peripheral menthol-thiophenyl substituents was synthesized using Linstead conditions and purified by flash column chromatography. The optimized synthetic and purification procedures allowed us to obtain a new macrocycle with 36% yield. Tetrapyrazinoporphyrazine derivative was characterized by UV–Vis and NMR spectroscopy, as well as MS spectrometry. Complex NMR studies using 1D and 2D NMR techniques allowed the analysis of the bulky menthol-thiophenyl substituted periphery of the new macrocycle. Further, photochemical stability and singlet oxygen quantum yield were determined by indirect method with diphenylisobenzofuran. The new tetrapyrazinoporphyrazine revealed low generation of singlet oxygen with a quantum yield of singlet oxygen formation at 2.3% in dimethylformamide. In turn, the macrocycle under irradiation with visible light presented very high stability with quantum yield for photostability of 9.59 × 10−6 in dimethylformamide, which figures significantly exceed the border for its classification as a stable porphyrinoid (10−4–10−5).

Synthesis and crystal structure of allyl 7-(diethylamino)-2-oxo-2H-chromene-3-carboxylate

The title compound, C17H19NO4, was synthesized by the reaction of 7-(diethylamino)-2-oxo-2H-chromene-3-carboxylic acid with allyl bromide and purified by flash column chromatography on silica gel. Crystals suitable for single-crystal X-ray diffraction were obtained by recrystallization from acetone. The aromatic core of the molecule is not planar with the diethylamino group and with the carboxyl group that are rotated out of the 2-oxo-2H-chromene plane by 6.7 (2)° and 11.4 (2)°. The NC2 unit of the diethylamino group is planar with an angle sum close to 360°. Intermolecular Car—H...Ocarbonyl interactions lead to the formation of chains parallel to the b axis. X-ray powder diffraction analysis proves that the title compound was obtained as a pure phase.

Production and characterization of semi-quinolone antibiotic produced by Streptomyces griseorubens

This work is an attempt to overcome antimicrobial resistance problem which dispersed worldwide inparticular developing countries due to misuse of antibiotics. Actinobacteria were isolated and screenedagainst selected resistant Gram-negative bacteria to detect the powerful antibacterial activity.Identification of the most potent actinobacterial isolate has been carried out using classical and geneticalmethods. Antibacterial compound has been extracted, purified and characterized using accurate and morespecific techniques and instruments. Among forty actinobacterial isolates, only twenty-two isolates couldinhibit the growth of Gram-negative bacteria. The most potent isolate Eg-7 was identified as S.griseorubens, which has a typical 16S rRNA gene. The antibacterial compound was extracted using ethylacetate, and separated by High Performance Liquid Chromatography using methanol and water as amobile phase. Five active peaks were displayed and retained in the range 40 – 45 min, but the last threepeaks were retained at 41.90, 43.43, and 44.54 min, respectively. The crude extract was analyzed byliquid chromatography mass spectrum, where the active peak was displayed at 721.325 m/z. Theantibacterial compound was purified using flash column chromatography and gel filtration columnchromatography. The active fraction was analyzed by Infra-Red spectrum, where a broad absorption at3338 cm-1 was displayed. Molecular formula of an antibacterial compound was determined by massspectrum as C35H26N6O4. Nuclear magnetic resonance analysis was carried out for an antibacterialcompound. These results suggest that a new antibacterial compound that similar quinolone could beproduced by S. griseorubens and exhibited a higher activity against Gram-negative bacteria.

Methyl Radical Initiated Kharasch and Related Reactions

An improved procedure to run halogen atom and related chalcogen group transfer radical additions is reported. The procedure relies on the thermal decomposition of di-<i>tert</i>-butylhyponitrite (DTBHN), a safer alternative to the explosive diacetyl peroxide, to produce highly reactive methyl radicals that can initiate the chain process. This mode of initiation generates byproducts that are either gaseous (N₂) or volatile (acetone and methyl halide) thereby facilitating greatly product purification by either flash column chromatography or distillation. In addition, remarkably simple and mild reaction conditions (refluxing EtOAc during 30 minutes under normal atmosphere) and a low excess of the radical precursor reagent (2.0 equivalents) make this protocol particularly attractive for preparative synthetic applications. This initiation procedure has been demonstrated with a broad scope since it works efficiently to add a range of electrophilic radicals generated from iodides, bromides, selenides and xanthates over a range of unactivated terminal alkenes. A diverse set of radical trap substrates exemplifies a broad functional group tolerance. Finally, di-<i>tert</i>-butyl peroxyoxalate (DTBPO) is also demonstrated as alternative source of <i>tert-</i>butoxyl radicals to initiate these reactions under identical conditions which gives gaseous byproducts (CO₂).

Methyl Radical Initiated Kharasch and Related Reactions

An improved procedure to run halogen atom and related chalcogen group transfer radical additions is reported. The procedure relies on the thermal decomposition of di-<i>tert</i>-butylhyponitrite (DTBHN), a safer alternative to the explosive diacetyl peroxide, to produce highly reactive methyl radicals that can initiate the chain process. This mode of initiation generates byproducts that are either gaseous (N₂) or volatile (acetone and methyl halide) thereby facilitating greatly product purification by either flash column chromatography or distillation. In addition, remarkably simple and mild reaction conditions (refluxing EtOAc during 30 minutes under normal atmosphere) and a low excess of the radical precursor reagent (2.0 equivalents) make this protocol particularly attractive for preparative synthetic applications. This initiation procedure has been demonstrated with a broad scope since it works efficiently to add a range of electrophilic radicals generated from iodides, bromides, selenides and xanthates over a range of unactivated terminal alkenes. A diverse set of radical trap substrates exemplifies a broad functional group tolerance. Finally, di-<i>tert</i>-butyl peroxyoxalate (DTBPO) is also demonstrated as alternative source of <i>tert-</i>butoxyl radicals to initiate these reactions under identical conditions which gives gaseous byproducts (CO₂).

Bioactive Compounds in Moringa oleifera Lam. Leaves Inhibit the Pro-Inflammatory Mediators in Lipopolysaccharide-Induced Human Monocyte-Derived Macrophages

Moringa oleifera (MO) is an important plant for traditional medicine. The present study aimed to identify the MO active phytochemical compounds for their ability against inflamed macrophages. An ethyl acetate extract fraction of MO was fractionation by flash column chromatography. Human macrophages were stimulated by Lipopolysaccharide and then treated with fractions of MO to examine their anti-inflammatory activity and cellular mechanism. The active fractions were analyzed by liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometer (LC-ESI-QTOF-MS). MO treated cells showed a decreased production of pro-inflammatory mediator in response to lipopolysaccharide. This was evident at both mRNA and protein levels. The study revealed that MO suppressed mRNA expression of IL-1, IL-6, TNF-α, PTGS2, NF-κB (P50), and RelA. Furthermore, the extract effectively inhibited the expression of inflammatory mediators, including IL-6, TNF-α, and cyclooxygenase-2. Interestingly, the effect of MO inhibited phosphorylation of IκB-α and the ability to reduce expression of the nuclear factor (NF)-κB p65, suppressing its nuclear translocation. Moreover, LC-ESI-QTOF-MS analysis of the MO active fraction revealed seven compounds, namely 3,4-Methyleneazelaic acid, (2S)-2-phenylmethoxybutane-1,4-diol, (2R)-2-phenylmethoxybutane-1, 4-diol, γ-Diosphenol, 2,2,4,4-Tetramethyl-6-(1-oxobutyl)-1,3,5-cyclohexanetrione, 3-Hydroxy-β-ionone, and Tuberonic acid. Our findings highlight the ability of MO compounds to inhibit inflammation through regulation of the NF-κB pathway.

Monodisperse oligo(δ-valerolactones) and oligo(ε-caprolactones) with docosyl (C22) end-groups

Two different families of monodisperse oligoesters with α-hydroxyl-ω-docosyl (C22) terminal groups [oligo(δ-valerolactone) and oligo(ϵ-caprolactone)] were isolated by flash column chromatography (FCC).