Effects of inhibition of 5-lipoxygenase and 12-lipoxygenase pathways on skeletal muscle fiber regeneration.

We investigated the effect of inhibition of 5-lipoxigenase (LOX) and 12-LOX pathways on the regeneration of skeletal muscle fibers after injury induced by a myotoxin (MTX) phospholipase A2 from snake venom in an in vivo experimental model. Gastrocnemius muscles of mice injected with MTX presented an increase in 5-LOX protein expression, while 12-LOX was found to be a constitutive protein of skeletal muscle. Animals that received oral treatments with 5-LOX inhibitor MK886 or 12-LOX inhibitor baicalein 30 min and 48 h after MTX-induced muscle injury showed a reduction in the inflammatory process characterized by a significant decrease of cell influx and injured fibers in the degenerative phase (6 and 24 h after injury). In the beginning of the regeneration process (3 days), mice that received MK886 showed fewer new basophilic fibers, suggesting fewer proliferative events and myogenic cell fusion. Furthermore, in the progression of tissue regeneration (14-21 days), the mice treated with 5-LOX inhibitor presented a lower quantity of central nucleus fibers and small-caliber fibers, culminating in a muscle that is more resistant to the stimulus of fatigue during muscle regeneration with a predominance of slow fibers. In contrast, animals early treated with the 12-LOX inhibitor presented functional fibers with higher diameters, less resistant to fatigue and predominance of fast heavy-chain myosin fibers as observed in control animals. These effects were accompanied by an earlier expression of myogenic factor MyoD. Our results suggest that both 5-LOX and 12-LOX pathways represent potential therapeutic targets for muscle regeneration. It appears that inhibition of the 5-LOX pathway represses only the degenerative process by reducing tissue inflammation levels. Meanwhile, inhibition of the 12-LOX pathway also favors the anticipation of maturation and earlier recovery of muscle fiber activity function after injury.

Relation between ABCB1 overexpression and COX2 and ALOX5 genes in human erythroleukemia cell lines.

This study aimed to characterize the relationship between the COX2 and ALOX5 genes, as well as their link with the multidrug resistance (MDR) phenotype in sensitive (K562) and MDR (K562-Lucena and FEPS) erythroleukemia cells. For this, the inhibitors of 5-LOX (zileuton) and COX-2 (acetylsalicylic acid-ASA) and cells with the silenced ABCB1 gene were used. The treatment with ASA caused an increase in the gene expression of COX2 and ABCB1 in both MDR cell lines, and a decrease in the expression of ALOX5 in the FEPS cells. Silencing the ABCB1 gene induced a decrease in COX2 expression and an increase in the ALOX5 gene. Treatment with zileuton did not alter the expression of COX2 and ABCB1. Cytometry data showed that there was an increase in ABCB1 protein expression after exposure to ASA. In addition, the increased activity of ABCB1 in the K562-Lucena cell line indicates that ASA may be a substrate for this efflux pump, corroborating the molecular docking that showed that ASA can bind to ABCB1. Regardless of the genetic alteration in COX2 and ABCB1, the direct relationship between these genes and the inverse relationship with ALOX5 remained in the MDR cell lines. We assume that ABCB1 can play a regulatory role in COX2 and ALOX5 during the transformation of the parental cell line K562, explaining the increased gene expression of COX2 and decreased ALOX5 in the MDR cell lines.

Eicosanoids and cancer

Eicosanoids are 20-carbon bioactive lipids derived from the metabolism of polyunsaturated fatty acids, which can modulate various biological processes including cell proliferation, adhesion and migration, angiogenesis, vascular permeability and inflammatory responses. In recent years, studies have shown the importance of eicosanoids in the control of physiological and pathological processes associated with several diseases, including cancer. The polyunsaturated fatty acid predominantly metabolized to generate 2-series eicosanoids is arachidonic acid, which is the major n-6 polyunsaturated fatty acid found in animal fat and in the occidental diet. The three main pathways responsible for metabolizing arachidonic acid and other polyunsaturated fatty acids to generate eicosanoids are the cyclooxygenase, lipoxygenase and P450 epoxygenase pathways. Inflammation plays a decisive role in various stages of tumor development including initiation, promotion, invasion and metastasis. This review will focus on studies that have investigated the role of prostanoids and lipoxygenase-derived eicosanoids in the development and progression of different tumors, highlighting the findings that may provide insights into how these eicosanoids can influence cell proliferation, cell migration and the inflammatory process. A better understanding of the complex role played by eicosanoids in both tumor cells and the tumor microenvironment may provide new markers for diagnostic and prognostic purposes and identify new therapeutic strategies in cancer treatment.

Pedalitin from isodon japonica, an inactivation of soybean lipoxygenase-1 / Pedalitina de isodon japonica, un inactivador de la lipo oxigenasa-1 de poroto de soya

Pedalitin, isolated from the aerial part of Rabdosia japonica (Labiatae), inhibited soybean lipoxygenase-1 (EC 1.13.11.12, Type I) with an IC50 of 152.5 uM. The progress curves for an enzyme reaction, pedalitin inactivate the lipoxygenase-1 in a time dependent, irreversible manner, exhibiting kinetics with a kinact/KI of 59.6 +/- 10 mM-1min-1. In the pseudoperoxidase activity, pedalitin is very slowly oxidized by the soybean lipoxygenase-1 catalyzed decomposition of lipid hydroperoxides.

Pedalitina, aislada de las partes aereas de Rabdosia japonica inhibió a la lipooxigenasa-1 (EC 1.13.11.12 tipo I) con un IC50 de 152.5 uM. La curva de progreso para una acción enzimática, pedalitina inactivó a la lipooxigenasa-1 de una manera dependiente del tiempo, de una manera irreversible, exhibiendo una cinética con una kinact/KI de 59.6 +/- mM-1min-1. En la actividad pseudoperoxidasa, pedalitina es oxidada lentamente por la descomposición de la lípido hidroperóxido de la lipooxigenasa-1 de poroto de soya.

Oxylipins in moss development and defense.

Oxylipins are oxygenated fatty acids that participate in plant development and defense against pathogen infection, insects, and wounding. Initial oxygenation of substrate fatty acids is mainly catalyzed by lipoxygenases (LOXs) and α-dioxygenases but can also take place non-enzymatically by autoxidation or singlet oxygen-dependent reactions. The resulting hydroperoxides are further metabolized by secondary enzymes to produce a large variety of compounds, including the hormone jasmonic acid (JA) and short-chain green leaf volatiles. In flowering plants, which lack arachidonic acid, oxylipins are produced mainly from oxidation of polyunsaturated C18 fatty acids, notably linolenic and linoleic acids. Algae and mosses in addition possess polyunsaturated C20 fatty acids including arachidonic and eicosapentaenoic acids, which can also be oxidized by LOXs and transformed into bioactive compounds. Mosses are phylogenetically placed between unicellular green algae and flowering plants, allowing evolutionary studies of the different oxylipin pathways. During the last years the moss Physcomitrella patens has become an attractive model plant for understanding oxylipin biosynthesis and diversity. In addition to the advantageous evolutionary position, functional studies of the different oxylipin-forming enzymes can be performed in this moss by targeted gene disruption or single point mutations by means of homologous recombination. Biochemical characterization of several oxylipin-producing enzymes and oxylipin profiling in P. patens reveal the presence of a wider range of oxylipins compared to flowering plants, including C18 as well as C20-derived oxylipins. Surprisingly, one of the most active oxylipins in plants, JA, is not synthesized in this moss. In this review, we present an overview of oxylipins produced in mosses and discuss the current knowledge related to the involvement of oxylipin-producing enzymes and their products in moss development and defense.

Efecto in vitro del policosanol (alcoholes de la cera de Saccharum officinarum L) sobre la enzima 5-lipooxigenasa / In vitro effects of policosanol (Saccharum officinarum L wax alcohols) on the 5-lipooxygenase enzyme

INTRODUCTION: policosanol, a mixture of high molecular weight aliphatic alcohols purified from sugarcane with octacosanol as the main component, shows cholesterol-lowering and antiplatelet effects in addition to an inhibitory effect on type I cicloxygenase. OBJECTIVE: to determine whether policosanol may inhibit 5-LOX enzyme activity in vitro. METHODS: effects on 5-LOX enzyme activities were assessed in rat blood polymorphonuclear leukocytes. Vehicle or Policosanol suspensions (0.6 to 6 000 µg/mL) were added to tubes containing the reaction mix and then absorbance changes at 234 nm were measured. RESULTS: added Policosanol inhibited in vitro 5-LOX activity by 30 percent, which was not a significant figure but depended on the concentration(r= 0.992; p< 0.05); it was 1 250 µg/mL. CONCLUSIONS: policosanol did not significantly inhibit 5-LOX enzyme activity in rat PMNL preparations, so that it does not seem to be a dual inhibitor of COX and-LOX enzymes. This result differs from that found for beeswax alcohols and underlines the different effects of the mixtures of long-chain fatty alcohols purified from the sugarcane and the beeswax(AU).

IINTRODUCCIÓN: el policosanol es una mezcla de alcoholes alifáticos aislados y purificados de la caña de azúcar cuyo componente mayoritario es el octacosanol, con efecto sobre la reducción de colesterol y antiagregante plaquetario, además inhibe la ciclooxigenasa (COX) tipo 1. OBJETIVO: determinar el poder de inhibición del policosanol en la actividad de la enzima 5-LOX in vitro. MÉTODOS: el efecto sobre la actividad de la enzima 5-LOX se determinó en leucocitos polimorfonucleares obtenidos de sangre de ratas. Se añadieron vehículo o suspensiones de policosanol (0,6 a 6 000 µg/mL) a tubos que contenían la mezcla de reacción y se medió el cambio de absorbancia a 234 nm. RESULTADOS: la adición de policosanol inhibió in vitro la actividad de la 5-LOX en un 30 por ciento que no fue significativo pero sí dependiente de la concentración (r= 0,992; p< 0,05), inhibición esta que alcanzó 1 250 µg/mL. CONCLUSIÓN: el policosanol no inhibió significativamente la actividad de la enzima 5-LOX en preparación de polimorfonucleares de ratas, por lo que no es un inhibidor dual de las enzimas. Este resultado difiere del encontrado para los alcoholes de la cera de abeja y subraya la diferencia de los efectos hallados entre las mezclas de alcoholes alifáticos de cadenas largas purificados de la caña de azúcar y la cera de abeja(AU)

Dual role of lipoxin A4 in pneumosepsis pathogenesis.

Lipoxin A4 (LXA4) is an endogenous lipid mediator with potent anti-inflammatory actions but its role in infectious processes is not well understood. We investigated the involvement of LXA4 and its receptor FPR2/ALX in the septic inflammatory dysregulation. Pneumosepsis was induced in mice by inoculation of Klebsiella pneumoniae. LXA4 levels and FPR2/ALX expression in the infectious focus as well as the effects of treatment with receptor agonists (LXA4 and BML-111) and antagonists (BOC-2 and WRW(4)) in early (1h) and late (24h) sepsis were studied. Sepsis induced an early increase in LXA4, FPR2/ALX lung expression, local and systemic infection and inflammation, and mortality. Treatment with BOC-2 in early sepsis increased leukocyte migration to the focus, and reduced bacterial load and dissemination. Inhibition of 5- and 15-lipoxygenase in early sepsis also increased leukocyte migration. Early treatment with WRW(4) and BOC-2 improved survival. Treatment with authentic LXA4 or BML-111 in early sepsis decreased cell migration and worsened the infection. In late sepsis, treatment with BOC-2 had no effect, but LXA4 improved the survival rate by reducing the excessive inflammatory response, this effect being abolished by pretreatment with BOC-2. Thus, the anti-inflammatory and pro-resolution mediator LXA4 and its receptor FPR2/ALX levels were increased in the early phase of sepsis, contributing to the septic inflammatory dysregulation. In addition, LXA4 has a dual role in sepsis and that its beneficial or harmful effects are critically dependent on the time. Therefore, a proper interference with LXA4 system may be a new therapeutic avenue to treat sepsis.

Relationships among sensory analysis, isoflavone and hexanal contents of soymilk powder

The objective of this work was to study the sensory attributes and their relationships with isoflavones and hexanal contents of soymilks made in laboratory and commercial samples. The laboratory soymilk samples showed cooked grain and cotton candy aroma and cooked grain, malty and sweetness flavor (a mild flavor). The commercial samples presented stronger roasted soy, rancid, sesame seeds and fishy aroma and roasted soy, sesame seeds and bitterness flavor, and bitter taste (closed nose) and starchy texture. No differences were noted among laboratory soymilks, denoting inactivation of lipoxygenases enzymes in the soymilks process. There were differences between the samples prepared in laboratory and commercial soymilks, which was due to several factors related to processing techniques. The hexanal average content was positively associated with the cooked grain aroma and isoflavones was positively associated with the cooked grain and cotton candy aroma, cooked grain, malty and sweetness flavor and starchy texture.

O trabalho foi conduzido com o objetivo de descrever os atributos sensoriais de bebidas de extratos de soja em pó produzidos a partir de cultivares desprovida de lipoxigenases, convencional e tipo hortaliça e dois extratos comerciais e correlacioná-los com as quantidades de isoflavonas e n-hexanal nos extratos em pó. Os extratos de soja em pó obtidos em laboratório foram caracterizados pelos atributos: aroma de feijão cozido e de algodão doce; sabor de grão cozido, de malte e gosto doce sugerindo, sabor suave. Os extratos comerciais apresentaram forte aroma de soja tostada, de ranço, de sementes de gergelim e de peixe; sabor de soja tostada, gosto amargo e de sementes de gergelim; gosto amargo (com nariz preso) e consistência de amido. Não foram observadas diferenças sensoriais entre os extratos produzidos em laboratório, indicando a ocorrência da inativação das enzimas lipoxigenases durante o processamento dos produtos. Contudo, diferenças marcantes entre os extratos obtidos em laboratório e os comerciais quanto aos atributos sensoriais estudados foram encontradas provavelmente, devido às técnicas desconhecidas de processamento utilizadas pelos fabricantes dos produtos comerciais. O teor médio de n-hexanal presente nos extratos de soja comerciais e produzidos em laboratório apresentou correlação positiva e significativa com o atributo aroma de grão cozido, já a quantidade de isoflavonas com aroma de grão cozido e de algodão doce, sabor de grão cozido, de malte, gosto doce e consistência de amido.