• Journal of Integrative Natural Science
• /
• v.7 no.3
• /
• pp.159-165
• /
• 2014

Pyrazole, hydroxyimino, aldehyde and isoxazole derivatives exhibit a broad spectrum of biological activities such as antimicrobial, anti-inflammatory and antitumor activities. With growing application on their synthesis and bioactivity, chemists and biologists in recent years have considerable attention on the research of these derivatives. In the view of potential importance of these derivatives, we have crystallized few of the derivatives and its report has been published. The present study focuses on docking studies of these derivatives against Phospholipases $A_2$ enzyme. This enzymes has implicated as potential targets for anti-inflammatory drug design. co-crystal structure (PDB ID: 1POE) of $PLA_2$ deposited in Protein Data Bank has been retrieved for docking analysis. Docking studies using Schrodinger's GLIDE reveals that these derivatives shows better binding energy and score in the defined active site. These results may provide a guiding role to design a lead molecule which may reduce inflamation.

• Food Science and Industry
• /
• v.51 no.2
• /
• pp.100-113
• /
• 2018

To obtain an edible grade oil from crude oil extracted from oil-bearing materials, it is generally necessary to carry out a refining process composed with degumming, deacidification, bleaching, and deodorization, to remove undesirable matters which affect the quality and shelf life of oils. The main purpose of degumming is to remove gum material mainly consisted with phospholipids. Phospholipases convert nonhydratable phospholipids into their hydratable forms which can be removed by centrifugation. In comparison with conventional water and acid degumming processes, enzymatic degumming can result the lower phosphatide content in oil than conventional processes. The enzymatic degumming can be conducted with the reduced amount of acid, and contributes to generate less amount of wastewater, decrease of operating cost, and increase oil recovery yield. The phospholipases used in enzymatic degumming process are phospholipase A1, A2, B, and C.

• Parasites, Hosts and Diseases
• /
• v.49 no.1
• /
• pp.1-8
• /
• 2011

The pathogenesis and pathophysiology of Acanthamoeba infections remain incompletely understood. Phospholipases are known to cleave phospholipids, suggesting their possible involvement in the host cell plasma membrane disruption leading to host cell penetration and lysis. The aims of the present study were to determine phospholipase activities in Acanthamoeba and to determine their roles in the pathogenesis of Acanthamoeba. Using an encephalitis isolate (T1 genotype), a keratitis isolate (T4 genotype), and an environmental isolate (T7 genotype), we demonstrated that Acanthamoeba exhibited phospholipase $A_2$ (PLA$_2$). and phospholipase D (PLD) activities in a spectrophotometry-based assay. Interestingly, the encephalitis isolates of Acanthamoeba exhibited higher phospholipase activities as compared with the keratitis isolates, but the environmental isolates exhibited the highest phospholipase activities. Moreover, Acanthamoeba isolates exhibited higher PLD activities compared with the PLA$_2$. Acanthamoeba exhibited optimal phospholipase activities at $37^{\circ}C$ and at neutral pH indicating their physiological relevance. The functional role of phospholipases was determined by in vitro assays using human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier. We observed that a PLD-specific inhibitor, i.e., compound 48/80, partially inhibited Acanthamoeba encephalitis isolate cytotoxicity of the host cells, while PLA$_2$-specific inhibitor, i.e., cytidine 5'-diphosphocholine, had no effect on parasite-mediated HBMEC cytotoxicity. Overall, the T7 exhibited higher phospholipase activities as compared to the T4. In contract, the T7 exhibited minimal binding to, or cytotoxicity of, HBMEC.

• The Korean Journal of Physiology and Pharmacology
• /
• v.5 no.4
• /
• pp.287-297
• /
• 2001

Contraction of smooth muscle is initiated by an increase in cytosolic $Ca^{2+}$ leading to activation of $Ca^{2+}$/ calmodulin-dependnet myosin light chain (MLC) kinase and phosphorylation of MLC. The types of contraction and signaling mechanisms mediating contraction differ depending on the region. The involvement of these different mechanisms varies depending on the source of $Ca^{2+}$ and the kinetic of $Ca^{2+}$ mobilization. $Ca^{2+}$ mobilizing agonists stimulate different phospholipases $(PLC-{\beta},\;PLD\;and\;PLA_2)$ to generate one or more $Ca^{2+}$ mobilizing messengers $(IP_3\;and\;AA),$ and diacylglycerol (DAG), an activator of protein kinase C (PKC). The relative contributions of $PLC-{\beta},\;PLA_2$ and PLD to generate second messengers vary greatly between cells and types of contraction. In smooth muscle cell derived form the circular muscle layer of the intestine, preferential hydrolysis of $PIP_2$ and generation of $IP_3$ and $IP_3-dependent\;Ca^{2+}$ release initiate the contraction. In smooth muscle cells derived from longitudinal muscle layer of the intestine, preferential hydrolysis of PC by PLA2, generation of AA and AA-mediated $Ca^{2+}$ influx, cADP ribose formation and $Ca^{2+}-induced\;Ca^{2+}$ release initiate the contraction. Sustained contraction, however, in both cell types is mediated by $Ca^{2+}-independent$ mechanism involving activation of $PKC-{\varepsilon}$ by DAG derived form PLD. A functional linkage between $G_{13},$ RhoA, ROCK, $PKC-{\varepsilon},$ CPI-17 and MLC phosphorylation in sustained contraction has been implicated. Contraction of normal esophageal circular muscle (ESO) in response to acetylcholine (ACh) is linked to $M_2$ muscarinic receptors activating at least three intracellular phospholipases, i.e. phosphatidylcholine-specific phospholipase C (PC-PLC), phospholipase D (PLD) and the high molecular weight (85 kDa) cytosolic phospholipase $A_2\;(cPLA_2)$ to induce phosphatidylcholine (PC) metabolism, production of diacylglycerol (DAG) and arachidonic acid (AA), resulting in activation of a protein kinase C (PKC)-dependent pathway. In contrast, lower esophageal sphincter (LES) contraction induced by maximally effective doses of ACh is mediated by muscarinic $M_3$ receptors, linked to pertussis toxin-insensitive GTP-binding proteins of the $G_{q/11}$ type. They activate phospholipase C, which hydrolyzes phosphatidylinositol bisphosphate $(PIP_2),$ producing inositol 1, 4, 5-trisphosphate $(IP_3)$ and DAG. $IP_3$ causes release of intracellular $Ca^{2+}$ and formation of a $Ca^{2+}$-calmodulin complex, resulting in activation of myosin light chain kinase and contraction through a calmodulin-dependent pathway.

• Tuberculosis and Respiratory Diseases
• /
• v.69 no.4
• /
• pp.256-264
• /
• 2010

Background: According to the notion of the immunoregulatory functions of moxifloxacin (MFX), the effect of MFX on the neutrophilic respiratory burst in conjunction with the expression of cytosolic phospholipase $A_2$ ($cPLA_2$) was investigated. Methods: The effects and possible mechanisms of MFX on neutrophilic respiratory burst in oleic acid (OA)-induced acutely injured rats lung and OA-stimulated, isolated murine neutrophils were probed, associated with the expression of cytosolic phospholipase $A_2$ in vivo and in vitro. Results: In the OA-induced acutely-injured lungs, neutrophils were accumulated, which was attenuated by MFX. The parameters denoting a neutrophilic respiratory burst, such as nitro blue tetrazolium reaction, cytochrome-c reduction, neutrophil aggregation, $H_2O_2$ production in neutrophils revealed increased neutrophilic respiratory burst by OA, and MFX decreased all of these parameters. In addition, the enhanced expression of $cPLA_2$ in the lung and isolated murine neutrophils by OA were decreased by MFX. Conclusion: MFX suppresses the OA-induced neutrophilic respiratory burst by the suppression of $cPLA_2$ in neutrophils.

• Journal of Applied Biological Chemistry
• /
• v.64 no.3
• /
• pp.317-322
• /
• 2021

Among the different cardiovascular disorders (CVDs), the activation of platelets is a necessary step. Based on this knowledge, therapeutic treatments for CVDs that target the disruption of platelet activation are proving to be worthwhile. One such substance, a bioactive 6,7-dihydroxy derived from coumarin, is 6,7-Dihydroxy-2H-1-benzopyran-2-one (esculetin). This compound has demonstrated several pharmacological effects on CVDS as well as various other disorders including diabetes, obesity, and renal failure. In various reports, esculetin and its effect has been explored in experimental mouse models, human platelet activation, esculetin-inhibited collagen, and washed human platelets exhibiting aggregation via arachidonic acid. Yet, esculetin affected aggregation with agonists like U46619 or thrombin in no way. This study investigated esculetin and how it affected human platelet aggregation activated through U46619. Ultimately, we confirmed that esculetin had an effect on the aggregation of human platelets when induced from U46619 and clarified the mechanism. Esculetin interacts with the downregulation of both phosphoinositide 3-kinase/Akt and mitogen-activated protein kinases, important phosphoproteins that are involved in activating platelets and their signaling process. The effects of esculetin reduced TXA₂ production, phospholipase A₂ activation, and platelet secretion of intracellular granules (ATP/serotonin), ultimately causing inhibition of overall platelet aggregation. These results clearly define the effect of esculetin in inhibiting platelet activity and thrombus formation in humans.

• Tuberculosis and Respiratory Diseases
• /
• v.68 no.6
• /
• pp.334-344
• /
• 2010

Background: Based on the known immunoregulatory functions of moxifloxacin on phagocytes, the therapeutic effect of moxifloxacin on oleic acid (OA)-induced acute lung injury (ALI) was investigated. Methods: Moxifloxacin (10 mg/kg) was given to male Sprague-Dawley rats that had been given oleic acid (OA, $30{\mu}L$) intravenously. Five hours after OA injection, parameters demonstrating ALI were assessed to measure the effects of moxifloxacin on acute lung injury. Results: The pathological findings of OA-induced ALI's was diminished by moxifloxacin. Through ultrastructural and $CeCl_3$ EM histochemistry, moxifloxacin was confirmed to be effective in decreasing oxidative stress in the lung as well. Indices of ALI, such as lung weight/body weight ratio, protein content in bronchoalveolar lavage fluid, and lung myeloperoxidase were decreased by moxifloxacin. In diaminobenzidine immunohistochemistry, fluorescent immunohistochemistry, and Western blotting of the lung, moxifloxacin had decreased the enhanced expression of secretory phospholipase $A_2$ ($sPLA_2$) by OA. Conclusion: We concluded that moxifloxacin was effective in lessening acute inflammatory pulmonary edema caused by OA, by inhibiting the neutrophilic respiratory burst, which was initiated by the activation of $sPLA_2$.

• BMB Reports
• /
• v.47 no.7
• /
• pp.361-368
• /
• 2014

Lipid components in biological membranes are essential for maintaining cellular function. Phosphoinositides, the phosphorylated derivatives of phosphatidylinositol (PI), regulate many critical cell processes involving membrane signaling, trafficking, and reorganization. Multiple metabolic pathways including phosphoinositide kinases and phosphatases and phospholipases tightly control spatio-temporal concentration of membrane phosphoinositides. Metabolizing enzymes responsible for PI 4,5-bisphosphate (PI(4,5)P2) production or degradation play a regulatory role in Toll-like receptor (TLR) signaling and trafficking. These enzymes include PI 4-phosphate 5-kinase, phosphatase and tensin homolog, PI 3-kinase, and phospholipase C. PI(4,5)P2 mediates the interaction with target cytosolic proteins to induce their membrane translocation, regulate vesicular trafficking, and serve as a precursor for other signaling lipids. TLR activation is important for the innate immune response and is implicated in diverse pathophysiological disorders. TLR signaling is controlled by specific interactions with distinct signaling and sorting adaptors. Importantly, TLR signaling machinery is differentially formed depending on a specific membrane compartment during signaling cascades. Although detailed mechanisms remain to be fully clarified, phosphoinositide metabolism is promising for a better understanding of such spatio-temporal regulation of TLR signaling and trafficking.

• Reproductive and Developmental Biology
• /
• v.28 no.2
• /
• pp.89-94
• /
• 2004

This study was conducted to determine expression of acyl-CoA synthetase 4(ACS4), which is involved in converts arachidonic acid to postaglandins, in the mouse uterus during pregnancy. In arachidonic acid metabolism, acyl-CoA synthetase plays a key role in the esterification of free arachidonic acid into membrane phospholipids. Following its release by the action of calcium dependent phospholipases, free arachidonic acid is believed to be rapidly converted to arachidonoyl-CoA and reesterified into phospholipids in order to prevent excessive synthesis of prostaglandins. Here we demonstrate that ACS4 gene are differentially regulated in the peri-implatation mouse uterus. During the preimplantation period(days 0.5∼3.5), the ACS4 gene was expressed in the uterus until day 3.5 after which the expression was downregulated. The expression of cPLA2, COX1, and COX2 gene was similar to that of ACS4 gene in the preimplantation periods. However expression levels of COX1 gene show much variation on the various days of pregnancy examined. These data, suggest that ACS4 expression in preimplantation period is involved in initial attachment reaction with cPLA2, COX1, and COX2 gene.

• The Korean Journal of Physiology and Pharmacology
• /
• v.14 no.6
• /
• pp.427-433
• /
• 2010

This study was conducted to investigate the effects of extremely low frequency electromagnetic fields (EMF) on signal pathway in plasma membrane of cultured cells (RAW 264.7 cells and RBL 2H3 cells), by measuring the activity of phospholipase $A_2$ ($PLA_2$), phospholipase C (PLC) and phospholipase D (PLD). The cells were exposed to the EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. The basal and $0.5\;{\mu}M$ melittin-induced arachidonic acid release was not affected by EMF in both cells. In cell-free $PLA_2$ assay, we failed to observe tbe change of $cPLA_2$ and $sPLA_2$ activity. Also both PLC and PLD activities did not show any change in the two cell lines exposed to EMF. This study suggests that the exposure condition of EMF (60 Hz, 0.1 or 1 mT) which is 2.4 fold higher than the limit of occupational exposure does not induce phospholipases-associated signal pathway in RAW 264.7 cells and RBL 2H3 cells.