Sakshi Balwani

Inhibitory effect of β-diketones and their metal complexes on TNF-α induced expression of ICAM-1 on human endothelial cells

Recent reports show that the natural beta-diketone curcumin displays important biological properties regarding the intercellular adhesion molecule-1 (ICAM-1), which plays a critical role in the immune responses and inflammation. In this study the ICAM-1 inhibitory activity of beta-diketone compounds, which are curcumin models lacking aromatic peripheral hydroxyl and methoxy groups, along with some metal derivatives is investigated. Beta-diketones are systematically more active than metal complexes and the best obtained inhibition is 75% for both groups. The best inhibitors are 4-benzoyl-3-methyl-1-phenyl-pyrazol-5-one (HQ(Ph)) among the ligands, and sodium benzoylacetonato among metal derivatives. These results appear in line with the reported antitumor activity of related species. Since 4-acyl-5-pyrazolones posses four tautomeric forms, those corresponding to HQ(Ph) were investigated using density functional theory. Docking of all HQ(Ph) tautomers on ICAM-1 protein was performed suggesting one keto-enol form favored to act in biological environment.

Ethyl gallate isolated from Pistacia integerrima Linn. inhibits cell adhesion molecules by blocking AP-1 transcription factor

ETHNOPHARMACOLOGICAL RELEVANCE Galls from Pistacia integerrima Linn. (kakadshringhi) have been used as therapeutic agent for various inflammatory diseases in Indian system of traditional medicine. However, the active constituents underlying the medicinal properties of the Pistacia integerrima Linn. have not been thoroughly investigated yet. AIM OF THE STUDY Deregulated expression of cell adhesion molecules (CAMs) on vascular endothelium aggravates the inflammatory condition in various chronic diseases. In this work, we aimed to identify the active constituent from leaf gall of Pistacia integerrima Linn. using CAMs expression assay in activity guided purification, followed by determining the molecular mechanism of action. MATERIAL AND METHODS Cell based ELISA for LPS induced CAMs expression in human vein endothelial cells (HUVECs) was used for the activity guided isolation form Pistacia galls followed by structural determination of active constituent using IR, MS and NMR spectroscopy. Mechanism of action of the active constituent was investigated by western blot, RT-PCR and EMSA experiments. RESULTS In our study, ethyl gallate (EG) was identified as the active constituent of Pistacia integerrima Linn. for mediating its anti-inflammatory activity. It significantly attenuated LPS induced ICAM-1 and VCAM-1 at the protein and mRNA levels. At a functional level, it inhibited the adhesion of neutrophils to LPS activated endothelium. To identify its mechanism of action, we demonstrated that EG inhibited LPS induced cell adhesion molecules expression by blocking AP-1 transcription factor without affecting nuclear transcription factor-κB (NF-κB). CONCLUSION Our results suggest that EG could be useful as a lead molecule for developing therapeutic agent for various inflammatory diseases.

Design, synthesis and anti-inflammatory evaluation of PEGylated 4-methyl and 4,8-dimethylcoumarins

Aberrant interaction between the leukocyte and the endothelial cell (EC) resulting from the deregulated expression of cell adhesion molecules (CAMs) on the endothelium results in uncontrolled inflammation leading to various inflammatory disorders. The existing drugs used to modulate the cytokine-induced expression of cell molecules have severe side effects. Therefore, there is an unmet therapeutic need to develop potent and safe drugs to treat inflammatory disorders. In the present study, novel PEGylated and non-PEGylated 4-methyl and 4,8-dimethylcoumarin derivatives were designed, synthesized and, evaluated for ICAM-1 inhibitory activity. The PEGylated coumarins were synthesized in two different ways. In the first approach, diesters of 4-methyl and 4,8-dimethylcoumarin were co-polymerized, separately with poly(ethylene glycol) using Candida antarctica lipase under solventless conditions. In the other approach, 4-methyl and 4,8-dimethylcoumarins were suitably converted to their bromo analogues and were tethered to already synthesized PEGylated polymers. Synthesized derivatives were evaluated for anti-inflammatory activities with respect to their ability to inhibit the TNF-alpha induced ICAM-1 (intercellular cell adhesion molecule-1) on human endothelial cells. It was found that PEGylated 4-methyl and 4,8-dimethylcoumarin derivatives were more effective than their non-PEGylated analogues to inhibit ICAM-1 expression. The present study opens new vista for PEGylated non-steroidal anti-inflammatory compounds and their further investigations.

Ethyl gallate attenuates acute lung injury through Nrf2 signaling.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is the clinical syndrome of persistent lung inflammation caused by various direct and indirect stimuli. Despite advances in the understanding of disease pathogenesis, few therapeutic have emerged for ALI/ARDS. Thus, in the present study we evaluated the therapeutic potential of ethyl gallate (EG), a plant flavanoid in the context of ALI using in vivo (BALB/c) and in vitro models (human monocytes). Our in vivo data supports the view that EG alleviates inflammatory condition in ALI as significant reduction in BALF neutrophils, ROS, proinflammatory cytokines and albumin levels were observed with the single i.p of EG post LPS exposure. Also, histochemical analysis of mice lung tissue demonstrated that EG restored LPS stimulated cellular influx inside the lung airspaces. Unraveling the mechanism of action, our RT-PCR and western blot analysis suggest that enhanced expression of HO-1 underlies the protective effect of EG on ROS level in mice lung tissue. Induction of HO-1 in turn appears to be mediated by Nrf2 nuclear translocation and consequent activation and ablation of Nrf2 activity through siRNA notably abrogated the EG induced protective effect in LPS induced human monocytes. Furthermore, our results indicate that EG generated moderate amounts of H2O2 could induce Nrf2 translocation in the in vitro systems. However, given the insignificant amount of H2O2 recorded in the injected material in the in vivo system, additional mechanism for EG action could not be excluded. Nevertheless our results highlight the protective role of EG in ALI and provide the novel insight into its usefulness as a therapeutic tool for the treatment of ALI.

Regulation of NF-κB Activation through a Novel PI-3K-Independent and PKA/Akt-Dependent Pathway in Human Umbilical Vein Endothelial Cells

The transcription factor NF-κB regulates numerous inflammatory diseases, and proteins involved in the NF-κB-activating signaling pathway are important therapeutic targets. In human umbilical vein endothelial cells (HUVECs), TNF-α-induced IκBα degradation and p65/RelA phosphorylation regulate NF-κB activation. These are mediated by IKKs (IκB kinases) viz. IKKα, β and γ which receive activating signals from upstream kinases such as Akt. Akt is known to be positively regulated by PI-3K (phosphoinositide-3-kinase) and differentially regulated via Protein kinase A (PKA) in various cell types. However, the involvement of PKA/Akt cross talk in regulating NF-κB in HUVECs has not been explored yet. Here, we examined the involvement of PKA/Akt cross-talk in HUVECs using a novel compound, 2-methyl-pyran-4-one-3-O-β-D-2′,3′,4′,6′-tetra-O-acetyl glucopyranoside (MPTAG). We observed that MPTAG does not directly inhibit IKK-β but prevents TNF-α-induced activation of IKK-β by blocking its association with Akt and thereby inhibits NF-κB activation. Interestingly, our results also revealed that inhibitory effect of MPTAG on Akt and NF-κB activation was unaffected by wortmannin, and was completely abolished by H-89 treatment in these cells. Thus, MPTAG-mediated inhibition of TNF-α-induced Akt activation was independent of PI-3K and dependent on PKA. Most importantly, MPTAG restores the otherwise repressed activity of PKA and inhibits the TNF-α-induced Akt phosphorylation at both Thr308 and Ser473 residues. Thus, we demonstrate for the first time the involvement of PKA/Akt cross talk in NF-κB activation in HUVECs. Also, MPTAG could be useful as a lead molecule for developing potent therapeutic molecules for diseases where NF-κB activation plays a key role.

2-Methyl-pyran-4-one-3-O-β-D-glucopyranoside isolated from leaves of Punica granatum inhibits the TNFα-induced cell adhesion molecules expression by blocking nuclear transcription factor-κB (NF-κB)

Here, we report bioactivity-guided isolation, purification and characterization of a novel compound, 2-methyl-pyran-4-one-3-O-β-d-glucopyranoside (MPG) from the leaves of Punica granatum. The structure of MPG was established on the basis of its detailed spectral analyses. We demonstrated that MPG not only inhibited the expression of cell adhesion molecules but also significantly blocked its functional consequence, that is, the adhesion of neutrophils on human endothelial cells monolayer. To elucidate the molecular mechanism of action of MPG, we showed that MPG decreased the transcript levels of ICAM-1, VCAM-1 and E-selectin genes. Using electrophoretic mobility shift assay (EMSA) and western blot analyses, we demonstrated that MPG significantly blocked both the TNFα-induced translocation and activation of nuclear transcription factor-κB (NF-κB). Thus, MPG could be useful as a novel lead molecule for developing future anti-inflammatory agents.

Design, synthesis and biological activity evaluation of regioisomeric spiro-(indoline-isoxazolidines) in the inhibition of TNF-α-induced ICAM-1 expression on human endothelial cells

Different regioisomeric spiro-(indoline-isoxazolidines) have been synthesized by the microwave mediated cycloaddition reaction between ethyl(5-fluoro-3-indolylidene)-acetate/ethyl(3-indolylidene)-acetate and the substituted α,N-diphenylnitrones. These compounds were screened for their anti-inflammatory activities through inhibition of TNF-α-induced ICAM-1 expression on human endothelial cells. Spiro-(indoline-isoxazolidine) 9p was found to be the most potent compound in inhibiting the ICAM-1 expression. Furthermore, compound 9p significantly inhibited the adhesion of neutrophils to the endothelium in a concentration-dependent manner and also blocked the translocation of NF-κBp65 subunit from the cytoplasm to the nucleus. We believe that compound 9p could be useful in developing better anti-inflammatory molecules for various inflammatory diseases where NF-κB plays a key role.