Diheteroarylurea derivatives as adventitious rooting adjuvants in mung bean shoots and M26 apple rootstock

The present research investigates the biological profile of eight symmetrical diheteroarylureas and phenylheteroarylureas, testing their hypothetical cytokinin-like activity and rooting activity. Cytokinin-like activity was assayed by the betacyanin (so-called amaranthin) accumulation test and by the tomato regeneration test. The rooting activity was assessed using the mung bean rooting test, the apple stem slice test and the rooting of apple microcuttings. Three compounds, 1,3-di(pyrazin-2-yl)urea (3a), 1,3-di(benzo[d]oxazol-5-yl)urea (3b) and 1,3-di(benzo[d]oxazol-6-yl)urea (3c), enhanced adventitious root formation in apple stem slice test, but only 3b and 3c were active in the mung bean rooting test. Compound 3b, that showed the best rooting activity, was also able to enhance the adventitious root formation in apple microcuttings. None of the compounds showed cytokinin-like activity.     

N,N′-bis-(2,3-Methylenedioxyphenyl)urea and N,N′-bis-(3,4-methylenedioxyphenyl)urea enhance adventitious rooting in Pinus radiata and affect expression of genes induced during adventitious rooting in the presence of exogenous auxin

We have analyzed the effect of N,N′-bis-(2,3-methylenedioxyphenyl)urea (2,3-MDPU) and N,N′-bis-(3,4-methylenedioxyphenyl)urea (3,4-MDPU), two symmetrically substituted diphenylurea derivatives with no auxin or cytokinin-like activity, on the rooting capacity of Pinus radiata stem cuttings. Results indicate that both diphenylurea derivatives enhance adventitious rooting in the presence of exogenous auxin (indole-3-butyric acid, IBA), even at low auxin concentration, in rooting-competent cuttings, but have no effect on the adventitious rooting of low or null competent-to-root cuttings. Histological analyses show that, in the simultaneous presence of MDPUs and low concentration of exogenous auxin, adventitious root formation is induced in the cell types that retain intrinsic competence to form adventitious roots in response to auxin. The time course of cellular events leading to root formation and the time of root emergence are closely similar to that observed in cuttings treated only with higher auxin concentration. In addition, the mRNA level of a P. radiata SCARECROW-LIKE gene, which is significantly induced in the presence of the optimal concentration (10 μM) of exogenous auxin needed for cuttings to root, is increased in the presence of MDPUs and low concentration of exogenous auxin (1 μM). The expression of a P. radiata SHORT-ROOT gene in rooting-competent cuttings during adventitious rooting is also affected by the presence of MDPUs when combined with auxin. As MDPUs do not affect the expression of either gene in the absence of exogenous auxin, but only in its presence, we suggest that MDPUs could interact, directly or indirectly, with the auxin-signalling pathways in rooting-competent cuttings during adventitious rooting.     

Design and synthesis of novel 3-(benzo[d]oxazol-2-yl)-5-(1-(piperidin-4-yl)-1H-pyrazol-4-yl)pyridin-2-amine derivatives as selective G-protein-coupled receptor kinase-2 and -5 inhibitors

G-protein-coupled receptor kinase (GRK)-2 and -5 are emerging therapeutic targets for the treatment of cardiovascular disease. In our efforts to discover novel small molecules to inhibit GRK-2 and -5, a class of compound based on 3-(benzo[d]oxazol-2-yl)-5-(1-(piperidin-4-yl)-1H-pyrazol-4-yl)pyridin-2-amine was identified as a novel hit by high throughput screening campaign. Structural modification of parent benzoxazole scaffolds by introducing substituents on phenyl displayed potent inhibitory activities toward GRK-2 and -5.     

Development of benzo[d]oxazol-2(3H)-ones derivatives as novel inhibitors of Mycobacterium tuberculosis InhA

A series of twenty seven substituted 2-(2-oxobenzo[d]oxazol-3(2H)-yl)acetamide derivatives were designed based on our earlier reported Mycobacterium tuberculosis (MTB) enoyl-acyl carrier protein reductase (InhA) lead. Compounds were evaluated for MTB InhA inhibition study, in vitro activity against drug-sensitive and -resistant MTB strains, and cytotoxicity against RAW 264.7 cell line. Among the compounds tested, 2-(6-nitro-2-oxobenzo[d]oxazol-3(2H)-yl)-N-(5-nitrothiazol-2-yl)acetamide (30) was found to be the most promising compound with IC₅₀ of 5.12 ± 0.44 μM against MTB InhA, inhibited drug sensitive MTB with MIC 17.11 μM and was non-cytotoxic at 100 μM. The interaction with protein and enhancement of protein stability in complex with compound 30 was further confirmed biophysically by differential scanning fluorimetry.     

Synthesis and anticancer activity of bis-benzo[d][1,3]dioxol-5-yl thiourea derivatives with molecular docking study

New thiourea derivatives incorporating two benzo[d][1,3]dioxol-5-yl moieties have been synthesized through the reaction of two molecules of benzo[d][1,3]dioxol-5-yl isothiocyanate with one molecule of various diamino derivatives. The synthesized compounds were examined for their cytotoxic effects using SRB assay on three cancer cell lines HepG2, HCT116 and MCF-7. Most of compounds showed significant antitumor activity and some compounds showed strong results greater than the reference drug. As example, IC₅₀ values of 1,1′-(1,4-phenylene)bis(3-(benzo[d][1,3]dioxol-5-yl)thiourea) 5 were 2.38 µM for HepG2, 1.54 µM for HCT116 and 4.52 µM for MCF7, while the IC₅₀ values of standard drug doxorubicin were 7.46, 8.29 and 4.56 µM, respectively. Interestingly, these compounds were non cytotoxic toward the tested normal cell line (IC₅₀ value > 150 µM). The anticancer mechanisms were studied via EGFR inhibition assessment, annexin V-FITC apoptosis assessment, cell cycle analysis and study the effect on mitochondrial apoptosis pathway proteins Bax and Bcl-2 as well as molecular docking studies.     

Effect of benzoannulation on tautomeric preferences of 4,6-di(pyridin-2-yl)cyclohexane-1,3-dione

Density functional theory (DFT) calculations at the B3LYP/6-311+G(d,p) level show that 4,6-di(pyridin-2-yl)cyclohexane-1,3-dione is a labile compound. On the other hand, its dienolimine tautomer (4,6-di(pyridin-2-yl)cyclohaxa-1,3-diene-1,3-diol) seems stable enough to be present in vacuum. Alternatively the equilibriated species are (i) dienolimine and enolimine-enaminone ((6Z)-3-hydroxy-6-(pyridin-2(1H)-ylidene)-4-(pyridine-2-yl)cyclohex-3-enone) or (ii) dienolimine, enolimine-enaminone and dienaminone ((4Z,6Z)-4,6-di(pyridin-2(1H)-ylidene)cyclohexane-1,3-dione). Benzoannulation of the pyridine ring at position 5,6 was found to increase the contribution of the tautomers which contain the enaminone moiety. Energies of the transition states between the stable tautomers were also calculated in order to estimate activation energy of the proton transfer. Values of the geometry based harmonic oscillator model of aromaticity (HOMA) index and Laplacian of the electron density in the hydrogen bond critical point (based on quantum theory of atom in molecules) shows that the enaminone moiety in the tautomers studied are stabilized by stronger intramolecular hydrogen bond than this present in the enolimine moiety.     

Synthesis,anticancer and antioxidant activities of some novel N-(benzo[d]oxazol-2-yl)-2-(7- or 5-substituted-2-oxoindolin-3-ylidene) hydrazinecarboxamide derivatives

A series of N-(benzo[d]oxazol-2-yl)-2-(7- or 5-substituted-2-oxoindolin-3-ylidene) hydrazinecarboxamide derivatives were synthesized by treating N-(benzoxazol-2-yl)hydrazinecarboxamide with different isatin derivatives. The newly synthesized compounds were characterized on the basis of spectral analyses. All the synthesized derivatives (Va-l) were screened for anticancer and antioxidant activities. The results showed the anticancer activity of test compounds against HeLa, IMR-32 and MCF-7 cancer cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. All the synthetic compounds produced a dose-dependant inhibition of growth of the cells. The IC₅₀ values of some compounds were comparable with standard anticancer agent, cisplatin. All the title compounds effectively scavenged the free radical, α,α-diphenyl-β-picryl hydrazyl. The test compounds having substitution with different halides (electron withdrawing groups) at C5 position showed more potent anticancer and antioxidant activities than those at C7 position. These results indicate that C5-substituted derivatives may be useful for developing antioxidant agents that play a protective role in many pathological conditions such as cancer, diabetes and so on.     

Design,synthesis, and SAR study of 3-(benzo[d][1,3]dioxol-5-yl)-N-benzylpropanamide as novel potent synergists against fluconazole-resistant Candida albicans

Based on our previous discovery and SAR study on the lead compounds 7d, 5 and berberine which can significantly enhance the susceptibility of fluconazole against fluconazole-resistant Candida albicans, a series of 3-(benzo[d][1,3]dioxol-5-yl)-N-(substituted benzyl)propanamides were designed, synthesized, and evaluated for their in vitro synergistic activity in combination with fluconazole. The series 2a–f were designed by replacing the amide moiety of the lead compound 7d with retro-amide moiety, and compounds 2a and 2b showed more activity than the lead 7d. Furthermore, introducing biphenyl moiety into series 2d–f afforded series 3a–r, most of which exhibited significantly superior activity to the series 2d–f. Especially, compound 3e, at a concentration of 1.0 µg/ml, can enhance the susceptibility of fluconazole against fluconazole-resistant Candida albicans from 128.0 µg/ml to 0.125–0.25 µg/ml. A clear SAR of the compounds is discussed.     

Synthesis,molecular docking and biological evaluation of some newer 2-substituted-4-(benzo[d][1,3]dioxol-5-yl)-6-phenylpyridazin-3(2H)-ones as potential anti-inflammatory and analgesic agents

A new series of 2-substituted-4-(benzo[d][1,3]dioxol-5-yl)-6-phenylpyridazin-3(2H)-one derivatives has been synthesized and studied. The in vivo anti-inflammatory and analgesic activities of the synthesized compounds were evaluated using carrageen rat paw edema model and acetic acid induced writhing model, respectively. Side effect profile of the newly synthesized pyridazinones was assessed by gastric ulcerogenic and anti-platelet activity. The compounds were further evaluated for their inhibitory activity against cyclooxygenase enzyme (COX-1/COX-2) by in vitro colorimetric COX (ovine) inhibitor screening assay method. The p-flourophenylpiperazine substituted analogue 14 exhibited most potent anti-inflammatory and analgesic activities with lower ulcer index and extremely good selectivity towards COX-2 versus COX-1 enzyme with a selectivity index of 10. Molecular docking studies showed appreciable binding of new pyridazinone analogues with the amino acids present at the active site of hCOX-2 enzyme.     

Synthesis, anticancer and antioxidant activities of some novel N-(benzo[d]oxazol-2-yl)-2-(7- or 5-substituted-2-oxoindolin-3-ylidene) hydrazinecarboxamide derivatives

A series of N-(benzo[d]oxazol-2-yl)-2-(7- or 5-substituted-2-oxoindolin-3-ylidene) hydrazinecarboxamide derivatives were synthesized by treating N-(benzoxazol-2-yl)hydrazinecarboxamide with different isatin derivatives. The newly synthesized compounds were characterized on the basis of spectral analyses. All the synthesized derivatives (Va-l) were screened for anticancer and antioxidant activities. The results showed the anticancer activity of test compounds against HeLa, IMR-32 and MCF-7 cancer cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. All the synthetic compounds produced a dose-dependant inhibition of growth of the cells. The IC(50) values of some compounds were comparable with standard anticancer agent, cisplatin. All the title compounds effectively scavenged the free radical, α,α-diphenyl-β-picryl hydrazyl. The test compounds having substitution with different halides (electron withdrawing groups) at C5 position showed more potent anticancer and antioxidant activities than those at C7 position. These results indicate that C5-substituted derivatives may be useful for developing antioxidant agents that play a protective role in many pathological conditions such as cancer, diabetes and so on.     

Synthesis and antifungal activity of benzo[d]oxazole-4,7-diones

Benzo[d]oxazole-4,7-diones were synthesized and tested for in vitro antifungal activity against fungi. Among them tested, many compounds showed good antifungal activity. The results suggest that benzo[d]oxazole-4,7-diones would be potent antifungal agents.     

Conversion of Indole-3-Butyric Acid to Indole-3-Acetic Acid in Shoot Tissue of Hazelnut (<Emphasis Type="Italic">Corylus</Emphasis>) and Elm (<Emphasis Type="Italic">Ulmus</Emphasis>)

Indole-3-butyric acid (IBA) is an endogenous compound that appears to regulate both lateral and adventitious root formation in many plant species and is also the auxin most available commercially for application to promote rooting. IBA is converted to indole-3-acetic acid (IAA) by β-oxidation in the peroxisomes. This process has been observed in a number of plant species and has been shown to be critical for normal root development in response to treatment with IBA. In this study, we investigated this process in hybrid hazelnut (Corylus americana × C. avellana), American elm (Ulmus americana), and Cathedral hybrid elm (U. pumila × U. davidiana var. japonica ‘Cathedral’), in which adventitious rooting is a major bottleneck for vegetative propagation, and the efficacy of IBA treatment is highly variable across different cultivars and at different collection times. Using differentially stable isotope-labeled IBA and IAA tracer and internal standard, respectively, and using gas chromatography coupled with selected reaction monitoring mass spectrometry, IBA-derived IAA was measured in shoot tissue treated with stable isotope-labeled IBA. In elm, higher levels of IBA-to-IAA conversion were generally observed in cultivars which formed adventitious roots most easily in softwood stem cutting trials. IBA-to-IAA conversion was observed in hazelnut genotypes with different rooting abilities and suggested a complex relationship exists between IBA conversion and root organogenesis. In both hazelnut and elm, endogenous free IAA levels were not significantly different across the genotypes examined. High rates of root formation is a key trait for establishment of large-scale production systems. Screening for optimal rates of IBA-to-IAA conversion may facilitate selection against genotypes which respond poorly to exogenous IBA and are thus difficult to propagate using hormone treatment.     

Synthesis and in vitro anti-HIV activity of N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives using MTT method

A series of novel N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives has been synthesized. All the newly synthesized compounds were evaluated for their anti-HIV activity using MTT method. Most of these compounds showed moderate to potent activity against wild-type HIV-1 with an EC₅₀ ranging from >7 EC₅₀ [μg/ml] to <100 EC₅₀ [μg/ml]. Among them, N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide 6v was identified as the most promising compound (EC₅₀ = <7 μg/ml). Among all the compounds, three compounds 6m, 6v and 6u have been exhibits potent anti-HIV activity against MT-4 cells.     

The Weak Cytokinins N,N′-bis-(1-naphthyl)urea and N,N′-bis-(2-naphthyl)urea may Enhance Rooting in Apple and Mung Bean

The present research investigates the possibility that 2 weak urea-type cytokinins, the N,N′-bis-(1-naphthyl)urea and the N,N′-bis-(2-naphthyl)urea, enhance adventitious root formation. The rooting activity was assessed using the stem slice test, the mung bean rooting test and the rooting of apple microcuttings. The two compounds influenced the adventitious rooting process differently as regards the bioassay used. In the stem slice test, in the presence of exogenous auxin, both compounds enhanced the rooted slice percentage. In mung bean shoots, the N,N′-bis-(1-naphthyl)urea enhanced the root formation at the lowest concentration used (0.01 μM) while the N,N′-bis-(2-naphthyl)urea enhanced rooting at higher concentrations. In the rooting test of apple microcuttings the N,N′-bis-(1-naphthyl)urea and the N,N′-bis-(2-naphthyl)urea slightly enhanced only the mean root number per microcutting.     

Synthesis, pharmacological evaluation and docking studies of N-(benzo[d]thiazol-2-yl)-2-(piperazin-1-yl)acetamide analogs as COX-2 inhibitors

The existing NSAIDs having number of toxicities emphasises the need for discovery of new non-toxic anti-inflammatory agents. In this Letter, we present the simple two step chemical synthesis, in vivo pharmacological screening and docking study of few N-(benzo[d]thiazol-2-yl)-2-(piperazin-1-yl)acetamide analogs. Different amino benzothiazoles were chloroacetylated and further reacted with substituted piperazines in presence of a base to get N-(benzo[d]thiazol-2-yl)-2-(piperazin-1-yl)acetamide analogs (A1-C4). These compounds were evaluated for anti-inflammatory activity by carragenan induced paw oedema method. Promising compounds were screened for toxicity by evaluating the ulcerogenic potential. Molecular docking experiments were carried out against COX-2 enzyme using Surflex-Dock GeomX programme of Sybyl software on Dell T-1500 workstation to confirm the mechanism of action of active compounds among the series. In silico study reveal the binding interactions of N-(benzo[d]thiazol-2-yl)-2-(piperazin-1-yl)acetamide analogs with COX-2 protein and is in agreement with the in vivo anti-inflammatory activity.     

α-Glucosidase inhibition activity and in silico study of 2-(benzo[d][1,3]dioxol-5-yl)-4H-chromen-4-one,a synthetic derivative of flavone

A synthetic flavone derivative 2-(benzo[d][1,3]dioxol-5-yl)-4H-chromen-4-one (BDC) was synthesized by the one pot reaction method and assessed for α-glucosidase inhibitory activity. The BDC demonstrated dose dependent inhibition of α-glucosidase activity. A maximum inhibition (99.3 ± 0.26%) of α-glucosidase was observed at 27.6 µM. The maximum α-glucosidase inhibitory activity depicted by BDC 27.6 µM concentration was 22.4 fold over the maximum inhibition observed with acarbose (97.72 ± 0.59% at 669.57 µM), a standard commercial anti-diabetic drug. In contrast to acarbose that depicted competitive type inhibition, kinetic studies of α-glucosidase inhibition by BDC demonstrated non-competitive inhibition with Km of 0.71 mM⁻¹ and a Vmax of 0.028 mmol/min. In silico studies suggest allosteric interaction of BDC with α-glucosidase at a minimum binding energy (ΔG) of −8.64 kcal/mol and Ki of 465.3 nM, whereas, acarbose interacted at the active site of α-glucosidase with ΔG of −9.23 kcal/mol and Ki of 172 nM. Thus BDC significantly inhibited α-glucosidase in comparison to acarbose. Moreover, BDC has been endorsed for drug likeness by evaluating it as per Lipinski rule of five. Thus, BDC can be a lead compound for the management of type-2 diabetes mellitus.     

Synthesis and antimicrobial activity of novel fluorine containing 4-(substituted-2-hydroxybenzoyl)-1H-pyrazoles and pyrazolyl benzo[d]oxazoles

A series of fluorine containing 4-(substituted-2-hydroxybenzoyl) pyrazoles and pyrazolyl benzo[d]oxazoles were synthesized and evaluated for their antibacterial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis and antifungal activity against Candida albicans. The antibacterial activities were expressed as the minimum inhibitory concentration (MIC₅₀) in μg/ml. The compounds 1-(3,4-difluorophenyl)-4-(5-fluoro-2-hydroxybenzoyl)-1H-pyrazole (4b), oxime derivatives such as 1-(3,4-difluorophenyl)-1H-pyrazol-4-yl)(2-hydroxy-4-methylphenyl)methanone oxime (5b) and (5-chloro-2-hydroxyphenyl)(1-(3,4-difluorophenyl)-1H-pyrazol-4-yl)methanone oxime (5e) exhibited promising activities against tested bacterial strains. Except compound 1-(3,4-difluorophenyl)-4-(2-hydroxybenzoyl)-1H-pyrazole (4d), none of the other compounds showed promising antifungal activity.     

Synthesis and optimization of 2-pyridin-3-yl-benzo[d][1,3]oxazin-4-one based inhibitors of human neutrophil elastase

The hit-to-lead optimization of the HNE inhibitor 5-methyl-2-(2-phenoxy-pyridin-3-yl)-benzo[d][1,3]oxazin-4-one is described. A structure–activity relationship study that focused on the 5 and 7 benzoxazinone positions yielded the optimized 5-ethyl-7-methoxy-benzo[d][1,3]oxazin-4-one core structure. 2-[2-(4-Methyl-piperazin-1-yl)-pyridin-3-yl] derivatives of this core were shown to yield HNE inhibitors of similar potency with significantly different stabilities in rat plasma.     

Histological analysis of adventitious rooting in Arabidopsis thaliana (L.) Heynh seedlings

ABSTRACT

Adventititous rooting is essential for the post-embryonic growth of the root apparatus in various species. In Arabidopsis thaliana, adventitious rooting has been reported in some mutants, and auxin seems to be the inducer of the process. The objective of the study was to identify the tissues involved in adventitious rooting in the most commonly used ecotypes for molecular and genetic studies (i.e. Columbia, Wassilewskija and Landsberg erecta) both in the presence and absence of exogenous auxin. Seedlings of the three ecotypes were grown under various conditions. When grown under 16 hours light/day for 11 days, all seedlings showed adventitious roots, both with and without auxin, however, both adventitious and lateral rooting were enhanced by exogenous auxin (2 µM naphthaleneacetic acid). Independently of the presence of auxin and of the ecotype, the hypocotyl pericycle produced adventitious roots directly (i.e., according to the same pattern of lateral root formation by the pericycle cells in the primary root). However, in the presence of auxin, roots of indirect origin also, and mainly, formed and their formation was preceded by the exfoliation of the tissues external to the stele. Exfoliation was caused by cell hypertrophy, separation, and disintegration, which mainly involved the endodermis. At the exfoliation site, the pericycle, with a minor contribution of a few endodermal cells, produced the callus from which indirect roots arose. The finding that adventitious rooting occurs in the absence of auxin (all ecotypes) indicates that this process is part of the normal root apparatus in Arabidopsis, with the hypocotyl pericycle as the target tissue of the process. Exogenous auxin alters adventitious rhizogenesis mainly affecting the endodermis response.     

Comparative effect of IBA, BSAA and 5,6-Cl2-IAA-Me on the rooting of hypocotyl in mung bean

Mung bean hypocotyl cuttings were treated with indole-3-butyric acid (IBA), 3-(benzo[b]selenienyl)acetic acid (BSAA) and 5,6-dichloroindole-3-acetic acid methyl ester (5,6-Cl2-IAA-Me) at different concentrations, respectively. Each chemical produced the maximum number of adventitious roots at a different concentration. Compared with IBA treatment, 5,6-Cl2-IAA-Me and BSAA treatments significantly increased root numbers on hypocotyl cuttings at lower concentration, particularly of 5,6-Cl2-IAA-Me treatment. Combinations of paclobutrazol (PB) with either 5,6-Cl2-IAA-Me or BSAA significantly stimulated the production of more adventitious roots than either chemical alone or combined. Capillary electrophoresis analysis have shown that the levels of IAA, IBA and BSAA in IBA plus PB or BSAA plus PB treatments were higher than those of IBA or BSAA alone. It was suggested that the cause of the synergistic effect of IBA (or BSAA) plus PB treatment might be due to increased endogenous auxin level. The activities of peroxidase and IAA oxidase in the rooting zone coincided with root development, indicating that the activities of these two enzymes were positively correlated to rooting. Peroxidase and IAA oxidase activity in all treatments started 24 h and 12 h after cutting, respectively. It is suggested that the major role of IAA oxidase differed from that of peroxidase in adventitious root formation.