HMBC Techniques Research Articles

Multifaceted insights into Cu(II) complexes with bis(benzimidazole) ligands: Structural investigation, theoretical studies, cytotoxicity evaluation, and antioxidant summarizing

In this study, the synthesized two new ligands, namely bis(1H-benzo[d]imidazole-1-yl) methane [L1] and 1,2-bis(1H-benzo[d]imidazole-1-yl) ethane [L2], from benzimidazole. They chose 1,2-dibromomethane and 1,2-dibromoethane as they are widely used in environmental catalysis and as ligands in conjugated configurations. The researchers were able to synthesize the Cu(II) complexes, [Cu(L1)2]Cl2 or [1] and [Cu(L2)2]Cl2 or [2], at room temperature. They used several analytical techniques, including elemental analysis, magnetic moment measurement, UV–visible spectroscopy, FT-IR spectroscopy, FT-Raman spectroscopy, NMR spectroscopy (including 1H, 13C, DEPT-135, HSQC, and HMBC techniques), ESI-MS analysis, thermogravimetric analysis, and ESR spectroscopy, to characterize the synthesized compounds. They found that the ESR spectra of complexes [1] and [2] suggest that both metal complexes have square planar coordination spheres. In the DFT study of the geometrical optimization of both complexes, the central plane consists of the Cu metal atom connected to four nitrogen atoms. The Cu–N bond lengths are measured at 2.194 Å for [1] and 2.176 Å for [2] whereas the FMO theory's slight reduction in the HOMO-LUMO gap for [2] suggests that it is more reactive and less stable compared to [1]. In addition, the researchers tested the effect of these compounds on human cervical cancer cell lines (HeLa) which showed significant cytotoxic effects under laboratory conditions. Complex [2] had a significant inhibitory impact on the growth of cancer cells. The researchers also assessed the antioxidant effects of the ligands and metal complexes using DPPH, OH, and NO assays and found that [2] had the most potent inhibitory effect on the radicals, with IC50 values of 36.11 μM (DPPH), 28.18 μM (OH), and 26.20 μM (NO).

Acetonyl C^N^N platinum(II) complexes of arylbipyridines.

This paper presents the first example of the formation of acetonyl tridentate CˆNˆN complexes of arylbipyridines in the reaction of chloroplatinum complexes with acetone in the presence of alkali. The chemical structure of obtained substances was established by means of 1H,13C NMR, COSY, HSQC, and HMBC techniques. The attribution of all proton and carbon signals in NMR spectra was performed using 1D and 2D NMR experiments for the synthesized acetonyl cycloplatinated complexes. A comparative analysis of the values of the C-Pt spin-spin coupling constants of the same order was carried out, which showed a significant difference in bond lengths and valence angles inthe cyclic fragments of the arylbipyridine ligand.

Synthesis and Antioxidant Evaluation of O-Methylated Emodacidamides: Starting from Parietin, a Secondary Metabolite of Lichen Xanthoria parietina.

Polyhydroxy-anthraquinones bearing amino acids are found rather seldom in nature. Emodacidamides, isolated from a marine-derived fungus, Penicillium sp. SCSIO sof101 by Luo et al. (2017) are the first natural example of amino acid conjugated anthraquinone. In this study, O-methylated emodacidamides and emodinic acid-anilides were synthesized starting from parietin, extracted from the lichen Xanthoria parietina (L.) Th. Fr. The structural elucidations of prepared compounds were confirmed by 1D and 2D NMR analyses including HSQC and HMBC techniques. In addition, all newly synthesized compounds were evaluated for the antioxidant activities with free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging. The synthesized compounds showed low to moderate antioxidant and DPPH scavenging activities. The antioxidant activities were supported within quantum chemical calculations using the DFT-B3LYP/6-311++G(d,p) level of theory. It is observed that the antioxidant activity of emodacidamides mostly depends on the phenolic groups on anthraquinone ring. The phenolic groups on other substituents help to improve antioxidant activity and also the position of hydroxy group is a decisive factor for antioxidant ability.

Diarylation of thiazolopyrimidines by laccase and their in vitro evaluation as antitumor agents

A mild and efficient method was developed for the synthesis of new derivatives of thiazolo[3,2-a] pyrimidin-3(2H)-ones from available starting materials based on the oxidation of catechols to ortho-quinone by Myceliophthora thermophila laccase (Novozym 51,003) and 1,4-addition of active methylene carbon to these in situ generated intermediates in moderate to good yields (35–93%). The structure of the products was confirmed through 1H NMR, 13C NMR, HMBC, HSQC, DEPT-135, and mass spectroscopy techniques. These novel compounds were evaluated as active antitumor agents against human colorectal adenocarcinoma and liver adenocarcinoma cell lines. All compounds displayed potent inhibition activities against the HT-29 cell line with IC50 values of 9.8–35.9 µM, superior to the positive control doxorubicin, and most showed potent anticancer activities against the HepG2 cell line.

Isolation and structural characterization of two novel oxidative degradation products of losartan potassium active pharmaceutical ingredient using advanced analytical techniques.

Losartan potassium (losartan) is the most frequently utilized antihypertensive medication in the world. However, partial oxidation of losartan produces toxic by-products that could be harmful to living organisms. Therefore, it is necessary to degrade the losartan and identify the potential toxic oxidative degradation products to minimize their formation during manufacturing, formulation, storage, and packing conditions. Oxidative degradation experiments of losartan were performed according to ICH guidelines. The degradation products were detected using ultra-high-performance liquid chromatography-mass spectrometry analysis, isolated by using preparative HPLC, and identified by using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopic techniques. The degradation products (DP-1, DP-2, and DP-3) were identified as (((2'-(2H-tetrazol-5-yl)-[1,1'-biphenyl]-4-yl)methyl)amino)-2-oxoethylpentanoate, 5-(4'-((2 butyl-4-chloro-5-(hydroxymethyl)-1H-imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-yl)-1H tetrazol-1-ol, and 5-(4'-((2-butyl-4-chloro-5-(hydroxymethyl)-1H-imidazol-1 yl)methyl)-[1,1'-biphenyl]-2-yl)-2H-tetrazol-2-ol, respectively. Forced degradation of losartan potassium API under oxidative condition indicates the formation of two major novel oxidative degradation products (DP-2 and DP-3) and one minor known degradation product (DP-1).Preparative HPLC used for the isolation of the resultant DPs and their structures were successfully established using UHPLC-MS, 1H NMR, 13C NMR, HSQC, HMBC, and HRMS spectroscopic techniques.

Azo-hydrazone molecular switches: Synthesis and NMR conformational investigation.

A series of five intramolecularly hydrogen-bonded arylhydrazone (aryl = phenol, p-nitrophenol, anisole, quinoline) derived molecular switches have been synthesized and characterized by NMR and HRMS techniques. It was found that the compounds exist as different isomers in solution. An investigation of both conformational and/or configurational changes of the azo-hydrazone compounds was carried out by 1D 1 H- and 13 C- spectra, 2D NOESY, COSY, HSQC, and HMBC techniques. It was found that these stimuli-responsive molecular switches exist mainly in the E form by intramolecularly hydrogen bonded between NH and the pyridine nitrogen at equilibrium. Deprotonation of the neutral E form yields the E' deprotonated isomer. Prediction of 13 C-NMR chemical shifts was achieved by DFT quantum mechanical calculations. Anions have traditionally been difficult to calculate correctly, so calculations of the anion using different functionals, basis sets, and solvent effects are also included. Deuterium isotope effects on the 13 C-NMR chemical shifts were employed in the assignments and furthermore utilized as indicators of intramolecular hydrogen bonding. Studies in various organic solvents including CDCl3 , CD3 CN, and DMSO-d6 were also performed aiming to monitor dynamic changes over several days. The effect of the hydrogen bonded solvents leads to Z forms.

Isolation, characterisation, antifungal activity and validated UPLC/MS/MS method for quantification of novel compound from Artemisia tournefortiana Reichb

Investigation into the chemical diversity of Artemisia tournefortiana resulted in isolation of one novel compound named tournefortin A and two known artemetin and tournefortin B bioactive compounds. Tournefortin B is first time obtained from natural source. The structure of all the isolated compounds were elucidated by detailed 1D and 2D NMR including HSQC, HMBC, 1H-1HOSY and NOESY spectroscopic techniques. Minimum inhibitory concentration (MIC) of all the tested compounds against tested fungal strains lies between 0.4 and 6.4 µg/mL and lowest MIC of 0.4 µg/mL of compound tournefortin A was found against Alternaria alternate. All the isolated compounds were quantified through UPLC/MS/MS and the developed method will serve as a first fingerprint method for the rapid determination of these phytomolecules in various plant extracts. Tournefortin B was found to be present in higher concentration. The higher antifungal effect of the isolated compounds suggests that this plant could act as potential source of antimicrobial agents.

Synthesis, spectral, stereochemical, biological, molecular docking and DFT studies of 3-alkyl/3,5-dialkyl-2r,6c-di(naphthyl)piperidin-4-one picrates derivatives

A new series of 3-alkyl/3,5-dialkyl-2r,6c-di(naphthyl)piperidin-4-one picrates (1-6) were synthesized their chemical structures were confirmed by elemental analysis, FT-IR, 1H and 13C NMR and mass spectral techniques and for compound 4 was characterized by HOMOCOSY, HSQC, HMBC, NOESY, and DEPT NMR spectral techniques. From the NMR spectral data, the observed chemical shifts and coupling constants suggested that compounds (1-6) adopt a normal chair conformation with equatorial orientation of all the naphthyl groups at C-2 and C-6 and alkyl group at C-3 and C-5 and from the 1H chemical shifts H-5a and H-3a have a higher magnitude than H-5e. This is due to 1,3 diaxial interaction between axial NH proton and axial protons at C-3 and C-5. The synthesized compounds were screened for their bacterial activity against Escherichia coli, Staphylococcus aureus, Bacillus.subtilis, Vibreo cholerae and Pseudomonas aeruginosa and fungal activity against Candida albicans, Aspergillus niger, Aspergillus flavus and Trichophyton rubrum. All the compounds showed good antibacterial and antifungal activities. The optimized molecular structure of the synthesized compounds (1-6) were studied by using DFT/B3LYP/6-311++G(d,p) basis set. The calculated electrical dipole moment (µ) and first hyperpolarizability (βo) values shows that all the molecules might have nonlinear optical (NLO) behavior. The HOMO-LUMO transition implies that intra-molecular charge transfer takes place within the molecule. Molecular electrostatic potential (MEP) surface is used to understand the reactive sites of a molecule. To establish information about the molecular interactions between protein and this novel compound theoretically, docking studies were carried out in detail.

New iridoids from the roots of Valeriana jatamansi Jones

Two new iridoids namely valerialloside A and valerianoside A (1 and 2) along with five known compounds (3–7) were isolated from the roots of Valeriana jatamansi Jones. The structure of new compounds were determined using 1D and 2D NMR including 1H- 1H COSY, HSQC, HMBC and NOESY spectroscopic techniques.

Structural and In Silico Characterization of Small Molecules Isolated from Eichhornia crassipes.

Eichhornia crassipes has been reported to have various medicinal properties including anticancer activities. The plant was collected from the Shire river in Malawi, and two cytotoxic compounds, benzene-1,4-diol and nonanedioic acid, were isolated and characterized for the first time in the leaves and roots of the plant. 1H NMR, COSY, HSQC, HMBC, 13-C, and LCMS spectroscopic experimental techniques were used to identify the compounds in their pure forms. In silico experiments showed that both compounds do not have AMES toxicity and do not inhibit cytochrome P450 enzymes, but nonanedioic acid acts as a CYP2D6 substrate. This work showed that Eichhornia crassipes can be considered to have a role as a source of potential hits and leads to drug development that can be rationally optimized for drugs.

Endophytic association of bioactive and halotolerant Humicola fuscoatra with halophytic plants, and its capability of producing anthraquinone and anthranol derivatives.

Halophytic plants growing in harsh desert environments are rich reservoirs of unique endophytic microorganisms. Here, healthy fresh plants of the families Tamaricaceae and Amarantaceae at three saline locations in Iran were investigated for their bioactive endophytic fungi. Among a vast number of isolates, eight isolates were identified as Humicola fuscoatra (Sordariomycetes, Pezizomycotina, Ascomycota) by microscopy and representative DNA sequences of the 5.8S rDNA (ITS) and partial β-tubulin (TUB2). Those isolates were halotolerant, and highly bioactive, so that their intra- and extra-cellular metabolites possessed in vitro antifungal, antibacterial and antiproliferative activities, against a number of fungal and bacterial plant pathogens including the fungi Arthrobotrys conoides, Pyrenophora graminea, Pyricularia grisea and the bacteria Agrobacterium tumefaciens, Pseudomonas syringae and Xanthomonas oryzae. Chemical analyses of metabolites from the endophytes using HNMR, CNMR, NOESY, COSY, HMBC, HSQC, DEPT, TOCSY and EI MASS techniques identified 3,8-dihydroxy-1-methyl-9,10-anthracenedione (aloesaponarin II; an anthraquinone derivative), 1,8,9-anthracenetriol structure (chrysarobin; an anthranol derivative) and 2,4-di-tert-butylthiophenol in fungal extracts. To the best of our knowledge, this is the first report of endophytic association of halotolerant H. fuscoatra isolates with Tamaricaceae and Amarantaceae, and their bioactivity against plant pathogens. Also, the capability of chrysarobin and aloesaponarin II production is new to the fungal kingdom. These findings may find application in agriculture, pharmacology, and biotechnology.

Preparation of Methacrylate-based Polymers Modified with Chiral Resorcinarenes and Their Evaluation as Sorbents in Norepinephrine Microextraction.

Aminomethylation reactions between chiral amino compounds (S)-(-)-1-phenylethylamine and l-proline with tetranonylresorcinarene and tetra-(4-hydroxyphenyl)resorcinarene in presence of formaldehyde were studied. The reaction between l-proline and resorcinarenes generated regioselectively chiral tetra-Mannich bases, due to the molecular incorporation of the fragment of the chiral amino acid. On the other hand, tetranonylresorcinarene and (S)-(-)-1-phenylethylamine formed regio- and diasteroselectively chiral tetrabenzoxazines, both by chiral auxiliary functionalization and by the transformation of the molecular structure that confers inherent chirality. The products obtained were characterized using IR, 1H-NMR, 13C-NMR, COSY, HMQC, and HMBC techniques. The reaction of (S)-(-)-1-phenylethylamine with tetra-(4-hydroxyphenyl)resorcinarene did not proceed under the experimental conditions. Once the chiral aminomethylated tetra-(4-hydroxyphenyl)resorcinarene was obtained, the chemical modification of poly(GMA–co–EDMA) was studied, and the results showed an efficient incorporation of the aminomethylated compound. For the physical modification, chiral aminomethylated tetranonylresorcinarenes were employed, finding that the incorporation of modified resorcinarenes occurs, but with less efficiency than that observed using chemical modification. The modified polymers were characterized via FT-IR, scanning electron microscopy imaging, and elemental analysis. Finally, polymers modified with chiral resorcinarenes were used as sorbents in norepinephrine microextraction; for practical purposes, artificial urine was prepared and used. To perform the microextraction, the decision was made to use the modern rotating-disk sorptive extraction technique (RDSE), because of its analytical attributes as a green, or eco-friendly, technique. According to the results, the method preliminarily validated for the determination of norepinephrine in artificial urine shows that the modified polymer with chiral derivative of tetra-(4-hydroxyphenyl)resorcinarene worked effectively as a new sorbent phase for the quantitative microextraction of norepinephrine, exhibiting high stability and homogeneity of composition and structure within the working range.

Synthesis and Characterisation of Indium(III) Bis-Thiosemicarbazone Complexes: 18F Incorporation for PET Imaging

Several structurally related indium chlorido complexes of bis-thiosemicarbazones were prepared, starting from the appropriately substituted bis-thiosemicarbazones, using sodium methoxide in methanol. Detailed NMR studies were conducted to assign the structure including COSY, HSQC, and HMBC techniques. The structures of all indium complexes were solved using single crystal X-ray diffraction. The chlorido ligand was present at the apex of the square pyramidal coordination sphere in all indium complexes. In some complexes, an intermolecular hydrogen bond was present between the chlorine atom and an NH group. Three different indium chlorido complexes were converted into the corresponding fluorido-derivative by a simple halide exchange method using K18F. These novel complexes, containing the positron emitting isotope 18F, may have potential applications in positron emission tomography (PET).

Biological Control of Potato Common Scab With Rare Isatropolone C Compound Produced by Plant Growth Promoting Streptomyces A1RT.

Potato is prone to many drastic diseases like potato common scab (CS). As no highly effective methods exist for managing CS, this study explored the possibility of using biological control. Ten bacterial strains were isolated from CS-infected potato tubers from four different locations of Punjab, Pakistan, and identified based on biochemical and molecular analysis. Analysis of 16s rDNA sequences amplified by PCR revealed the isolated bacterial strains to be Streptomyces scabies, S. turgidiscabies and S. stelliscabiei. Pathogenic islands were also confirmed among the isolates after identification of txtAB, nec1, and tomA genes with PCR amplification. One strain isolated from soil was antagonistic to the pathogenic Streptomyces spp., and determined to be Streptomyces A1RT on the basis of 16s rRNA sequencing. A methanolic extract of Streptomyces A1RT contained Isatropolone C, which was purified and structurally determined by 1H- and 13C-NMR, 1H/1H-COSY, HMQC, and HMBC techniques. Streptomyces A1RT also produced the plant growth hormone indole-3-acetic acid (IAA) with a titer of 26 μg ml-1 as confirmed by spectrophotometry and HPLC. In a greenhouse assay, disease severity index was established from 0 to 500. Average disease severity indexes were recorded as 63, 130.5, and 78 for Streptomyces scabies, S. turgidiscabies and S. stelliscabiei, respectively. When Streptomyces A1RT was applied in soil that contained one of these pathogenic isolates, the average disease severity indexes were significantly (P < 0.05) reduced to 11.1, 5.6 and 8.4, respectively. A significant increase in tuber weight and shoot development was also observed with the tubers treated with Streptomyces A1RT. The use of the plant growth-promoting Streptomyces A1RT against potato CS thus provides an alternative strategy to control the disease without affecting environmental, plants, animals and human health.

Insight on the structural aspect of ENR-50/TiO2 hybrid in KOH/C3H8O medium revealed by NMR spectroscopy

The ring-opening reactions (ROR) of epoxide groups in epoxidized natural rubber/titania (ENR-50/TiO2) hybrid in potassium hydroxide/isopropanol medium were examined using NMR spectroscopy and supported by the FTIR technique. The thermal behaviour of the hybrid was also studied using TG/DTG and DSC analyses. The 1H NMR results suggested that 16.82% of ROR occurred in the hybrid, while the 13C NMR results exhibited five new peaks at δ 19.5, 71.0, 73.7, 91.7 and 94.4 ppm in the hybrid. 2D NMR, such as HMQC, HMBC and COSY techniques, further scrutinized these assignments. The FTIR spectrum exhibited Ti-O-C characteristics via the peak at 1028 cm−1. The TG/DTG results showed four steps of thermal degradation at 44–148, 219–309, 331–489 and 629–810 °C due to the existence of Ti moieties along with a polymer chain mixture (intact and ring-opened epoxide groups) of ENR-50, which in turn led to an increase in the Tg value of the hybrid to 27 °C compared to that of purified ENR-50 at −17.72 °C.

Synthesis and structure of alkyl 2-arylsulfanyl-3-nitroacrylates

Alkyl 2-arylsulfanyl-3-nitroacrylates were synthesized by the conjugate Michael addition of thiophenols to alkyl 3-bromo-3-nitroacrylates followed by elimination of HBr on treatment with Et3N. When treated with 4-chlorothiophenol in the presence of Et3N, alkyl 2-[(4-chlorophenyl) sulfanyl]-3-nitroacrylates can be transformed into alkyl 2,3-bis[(4-chlorophenyl)sulfanyl]- acrylates. The structures of the synthesized compounds were characterized by IR, UV, 1H and 13C{1H} NMR spectroscopy using 1H–13C HMQC, 1H–13C, and 1H–15N HMBC techniques. Methyl 2-[(4-methylphenyl)sulfanyl]-3-nitroacrylate exists as the Z-isomer, as confirmed by X-ray diffraction.

Design, synthesis, biological assessment and molecular docking studies of new 2-aminoimidazole-quinoxaline hybrids as potential anticancer agents

In a search for novel antiproliferative agents, a series of quinoxaline derivatives containing 2-aminoimidazole (8a–8x) were designed and synthesized. The structures of synthesized compounds were confirmed by IR, 1H NMR, 13C NMR, Mass Spectroscopy and analyzed using HSQC, COSY, ROESY, HMBC techniques. The anticancer activity of all derivatives were evaluated for colon cancer and breast cancer cell lines by the MTT assay and acridine orange/ethidium bromide double staining method. The anti-cancer effect in human colon cancer (HCT-116) and breast cancer (MCF-7) cell lines exhibited that compounds 8a, 8s, 8t, 8w, 8x appeared as potent antiproliferative agents and especially inhibited the human colon cancer cell proliferation with percentage of inhibition by over 50%. The most active compound was (E)-4-phenyl-1-((quinoxalin-2-ylmethylene)amino)-1H-imidazol-2-amine (8a) with the highest inhibition for MCF-7 (83.3%) and HCT-116 (70%) cell lines after 48 and 24h, respectively. Molecular docking studies of these derivatives within c-kit active site as a validated target might be suggested them as appropriate candidates for further efforts toward more potent anticancer compounds.

Phosphorus-nitrogen compounds. part 38. Syntheses, characterizations, cytotoxic, antituberculosis and antimicrobial activities and DNA interactions of spirocyclotetraphosphazenes with bis-ferrocenyl pendant arms

The reactions of N4P4Cl8 (1), with two equimolar amounts of N-(1-ferrocenylmethyl)-N-methyl-propylenediamine gave the monoferrocenyl-spiro (as a byproduct), bisferrocenyl-2-trans-6-dispiro (2) and bisferrocenyl-2-cis-6-dispiro (3) cyclotetraphosphazenes. The 2-trans-6-dispiro (2) was reacted with excess monoamines to produce the tetraamino products (2a-2d). The one equimolar amount of the diamines and dialkoxides with 2 afforded the mono-diamino (2e and 2f) and mono-dialkoxy (2g and 2h) cyclotetraphosphazenes. Whereas, excess diamines and dialkoxides with 2 produced the bis-diamino (2i and 2j) and bis-dialkoxy (2k and 2l) bisferrocenyl-2-trans-6-dispirocyclotetraphosphazenes. The structures of the compounds were verified by elemental analyses, ESI-MS, FTIR, HSQC, HMBC, 1H, 13C, and 31P NMR techniques. The molecular structures of 2 and 2b were established by X-ray crystallography. Compounds 2e and 2f have two stereogenic P-atoms. Additionally, the structures of 2i-2l containing tetraspiro rings in the skeletons look similar a propeller. The Fc groups of the cyclotetraphosphazenes were found to be redox active with two-reversible electron oxidations. The antimicrobial activity of the compounds was examined against some bacteria and yeast strains. The interactions of the compounds with DNA revealed that the compounds caused conformational changes even strand break on supercoiled DNA helix. Furthermore, the compounds (except 2, 2a and 2d) inhibited DNA restriction indicating compounds binding to A/A and G/G nucleotides of the DNA. The evaluations of the cytotoxic activity against L929 fibroblast and DLD-1 colon cancer cell lines were carried out. Some of the compounds were evaluated for antituberculosis activity against reference strain Mycobacterium tuberculosis H37Rv, and 2i and 2l displayed antituberculosis activity against H37Rv.

Selective O-Alkylation of the Crown Conformer of Tetra(4-hydroxyphenyl)calix[4]resorcinarene to the Corresponding Tetraalkyl Ether.

Reactions of glycidyl methacrylate with the crown and chair conformers of tetra(4-hydroxyphenyl)calix[4]resorcinarene were studied. The reactions were done over epoxide groups present in the ester, which can easily undergo an opening reaction with hydroxyl groups in the macrocyclic system. Initially, epoxidation reactions were carried out with pure conformers, and it was observed that the reaction between tetra(4-hydroxyphenyl)calix[4]resorcinarene fixed in the chair conformation does not occur, while for the molecule fixed in the crown conformation only one tetraalkylated derivative was obtained. The obtained product was characterized using IR, 1H-NMR, 13C-NMR, COSY, HMQC and HMBC techniques. An exhaustive NMR study showed that the reaction is selective at the hydroxyl groups in the lower rim, without affecting the hydroxyl groups in the upper rim. In addition, the RP–HPLC analysis of the epoxidation reaction mixture, using both crown and chair conformers, showed that only the crown conformer reacted under tested conditions. Finally, a comparative study of the reactivity of tetranonylcalix[4]resorcinarene with glycidyl methacrylate showed that the reaction does not take place. Instead, the formation of the tetranonylcalix[4]resorcinarene tetrasodium salt was observed, which confirms that the hydroxyl groups in the upper rim are unreactive under these conditions.

Inhibition of proinflammatory mediators by coumaroyl lupendioic acid, a new lupane-type triterpene from Careya arborea, on inflammation-induced animal model

Ethnopharmacological relevanceCareya arborea Roxb. (Lecythidaceae) is a large tree found throughout India in deciduous forests and grasslands. C. arborea is traditionally used in tumors, inflammation, anthelmintic, bronchitis, epileptic fits, astringents, antidote to snake-venom, skin disease, diarrhea, dysentery with bloody stools, dyspepsia, ulcer, tooth ache, and ear pain. Aim of the studyIn our previous work, the methanolic extract of Careya arborea stem bark showed significant anti-inflammatory activity. As a continuity of that work, this study aimed at the isolation and evaluation of the anti-inflammatory effect of coumaroyl lupendioic acid, a new lupane-type triterpene from Careya arborea stem bark. Further, to give an insight into the underlying mechanism of action of the compound on the modulation of proinflammatory mediators. Materials and methodsMethanolic extract of Careya arborea stem bark was suspended in water, and sequentially fractionated with n-hexane and ethyl acetate. Further ethyl acetate fraction was subjected to medium pressure liquid chromatography (MPLC) to isolate the active molecules. The isolated compounds were characterized by the various spectral techniques namely UV, IR, 1H NMR, 13C NMR, DEPT, 1H–1H COSY, HMBC and Mass spectral techniques. In vitro COX-1 and COX-2 enzyme inhibition assays using human whole blood was performed to investigate the inhibitory effect of the isolated compounds. The resulted potent COX-2 inhibitor of the isolated constituents compound 5, designated as coumaroyl lupendioic acid (CLA), was investigated in carrageenan induced inflammation and its effect was also compared with betulinic acid (BA) at the doses of 10 and 20mgkg−1, p.o. using indomethacin and celecoxib (10 and 20mgkg−1, p.o., respectively) as reference drugs. The effect of CLA on the production of NO, MPO, PGE2, TNF-α, IL-1β and IL-6 were assessed. In addition, the histopathology and immunohistochemistry (NF-ҡB, COX-2 and TNF-α protein expression) in paw tissues were also carried out. ResultsThe chromatographic fractionation of the methanolic extract resulted in isolation of six new derivatives of lupane type triterpenes for the first time from the stem bark of C. arborea; 3β-hydroxy-lup-5,20 (29),21-trien-28-oic acid (Compound 1), 1, 3, 13, 16-tetrahydroxy-lup-9(11), 20(29)-diene-28-oic acid (Compound 2), 1, 7-di hydroxy betulinic acid (Compound 3), 3β-O-dihydrocinnamyl betulinic acid (Compound 4), 3β-O-trans-coumaryl-lup-6, 9(11), 20(29)-triene-27, 28-dioic acid (Compound 5), 16β-hydroxy-2, 3-seco-lup-5, 20(29)-dien-2, 3, 28-trioic acid (Compound 6). Among the all isolated compounds 3β-O-trans-coumaryl-lup-6, 9(11), 20(29)-triene-27, 28-olioic acid designated as coumaroyl lupendioic acid (CLA) showed higher COX-2 selectivity which is comparable to reference drug (celecoxib). CLA significantly reduced carrageenan induced inflammation whereas CLA revealed greater effect as compared to BA at the similar corresponding doses. Moreover, CLA significantly inhibited pro-inflammatory mediators elevated by carrageenan. CLA also preserved the tissue architecture as evidenced by the histopathology. Furthermore, immunohistochemical studies revealed that CLA significantly down regulated NF-ҡB, COX-2 and TNF-α protein expression. ConclusionThe study gives an insight into the molecular mechanisms of coumaroyl lupendioic acid and suggests that the down-regulations of proinflammatory mediators provide credence to the ethno botanical use of the plant in the management of inflammation.