Free docosahexaenoic acid promotes ferroptotic cell death via lipoxygenase dependent and independent pathways in cancer cells.

PURPOSE: Ferroptosis is a form of regulated cell death that has the potential to be targeted as a cancer therapeutic strategy. But cancer cells have a wide range of sensitivities to ferroptosis, which limits its therapeutic potential. Accumulation of lipid peroxides determines the occurrence of ferroptosis. However, the type of lipid involved in peroxidation and the mechanism of lipid peroxide accumulation are less studied. METHODS: The effects of fatty acids (10 µM) with different carbon chain length and unsaturation on ferroptosis were evaluated by MTT and LDH release assay in cell lines derived from prostate cancer (PC3, 22RV1, DU145 and LNCaP), colorectal cancer (HT-29), cervical cancer (HeLa) and liver cancer (HepG2). Inhibitors of apoptosis, necroptosis, autophagy and ferroptosis were used to determine the type of cell death. Then the regulation of reactive oxygen species (ROS) and lipid peroxidation by docosahexaenoic acid (DHA) was measured by HPLC-MS and flow cytometry. The avtive form of DHA was determined by siRNA mediated gene silencing. The role of lipoxygenases was checked by inhibitors and gene silencing. Finally, the effect of DHA on ferroptosis-mediated tumor killing was verified in xenografts. RESULTS: The sensitivity of ferroptosis was positively correlated with the unsaturation of exogenously added fatty acid. DHA (22:6 n-3) sensitized cancer cells to ferroptosis-inducing reagents (FINs) at the highest level in vitro and in vivo. In this process, DHA increased ROS accumulation, lipid peroxidation and protein oxidation independent of its membrane receptor, GPR120. Inhibition of long chain fatty acid-CoA ligases and lysophosphatidylcholine acyltransferases didn't affect the role of DHA. DHA-involved ferroptosis can be induced in both arachidonate lipoxygenase 5 (ALOX5) negative and positive cells. Down regulation of ALOX5 inhibited ferroptosis, while overexpression of ALOX5 promoted ferroptosis. CONCLUSION: DHA can effectively promote ferroptosis-mediated tumor killing by increasing intracellular lipid peroxidation. Both ALOX5 dependent and independent pathways are involved in DHA-FIN induced ferroptosis. And during this process, free DHA plays an important role.

Omega-3 polyunsaturated fatty acids protect against inflammation through production of LOX and CYP450 lipid mediators: relevance for major depression and for human hippocampal neurogenesis.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can exert antidepressant, anti-inflammatory and neuroprotective properties, but the exact molecular mechanism underlying their effects is still not fully understood. We conducted both in vitro and clinical investigations to test which EPA or DHA metabolites are involved in these anti-inflammatory, neuroprotective and antidepressant effects. In vitro, we used the human hippocampal progenitor cell line HPC0A07/03C, and pre-treated cells with either EPA or DHA, followed by interleukin 1beta (IL1ß), IL6 and interferon-alpha (IFN-α). Both EPA and DHA prevented the reduction in neurogenesis and the increase in apoptosis induced by these cytokines; moreover, these effects were mediated by the lipoxygenase (LOX) and cytochrome P450 (CYP450) EPA/DHA metabolites, 5-hydroxyeicosapentaenoic acid (HEPE), 4-hydroxydocosahexaenoic acid (HDHA), 18-HEPE, 20-HDHA, 17(18)-epoxyeicosatetraenoic acid (EpETE) and 19(20)-epoxydocosapentaenoic acid (EpDPA), detected here for the first time in human hippocampal neurones using mass spectrometry lipidomics of the supernatant. In fact, like EPA/DHA, co-treatment with these metabolites prevented cytokines-induced reduction in neurogenesis and apoptosis. Moreover, co-treatment with 17(18)-EpETE and 19(20)-EpDPA and the soluble epoxide hydroxylase (sEH) inhibitor, TPPU (which prevents their conversion into dihydroxyeicosatetraenoic acid (DiHETE)/ dihydroxydocosapentaenoic acid (DiHDPA) metabolites) further enhanced their neurogenic and anti-apoptotic effects. Interestingly, these findings were replicated in a sample of n = 22 patients with a DSM-IV Major Depressive Disorder, randomly assigned to treatment with either EPA (3.0 g/day) or DHA (1.4 g/day) for 12 weeks, with exactly the same LOX and CYP450 lipid metabolites increased in the plasma of these patients following treatment with their precursor, EPA or DHA, and some evidence that higher levels of these metabolites were correlated with less severe depressive symptoms. Overall, our study provides the first evidence for the relevance of LOX- and CYP450-derived EPA/DHA bioactive lipid metabolites as neuroprotective molecular targets for human hippocampal neurogenesis and depression, and highlights the importance of sEH inhibitors as potential therapeutic strategy for patients suffering from depressive symptoms.

Defense-related Proteins from Chelidonium majus L. as Important Components of its Latex.

The aim of this review is to cover most recent research on plant pathogenesis- and defenserelated proteins from latex-bearing medicinal plant Chelidonium majus (Papaveraceae) in the context of its importance for latex activity, function, pharmacological activities, and antiviral medicinal use. These results are compared with other latex-bearing plant species and recent research on proteins and chemical compounds contained in their latex. This is the first review, which clearly summarizes pathogenesisrelated (PR) protein families in latex-bearing plants pointing into their possible functions. The possible antiviral function of the latex by naming the abundant proteins present therein is also emphasized. Finally latex-borne defense system is hypothesized to constitute a novel type of preformed immediate defense response against viral, but also non-viral pathogens, and herbivores.

Effects of recombinant lipoxygenase on the rheological properties of dough and the quality of noodles.

BACKGROUND: The effects of purified recombinant lipoxygenase (ana-rLOX) on the rheological properties of dough and the quality of noodles made from wheat flour with low protein content (Yanmai 15) were studied. RESULTS: The addition of ana-rLOX increased dough stability time, decreased the degree of softening within 12 min, enhanced the resistance to extension, and increased the extensibility with 135 min of resting time. The mechanical spectra of the dough showed an increase in both storage modulus (G') and loss modulus (G″) with increasing ana-rLOX levels. The L(*) values of the noodle sheets increased by 2.34 compared with the control after storing for 1 h at room temperature. The textural parameters of noodles improved after ana-rLOX addition, including hardness, gumminess, chewiness and springiness. The wheat flour treated with the ana-rLOX had a higher cooking yield and lower cooking loss for the resulting noodles. The scanning electron microscopy results revealed that gluten was formed in the noodle samples that were treated with ana-rLOX. CONCLUSION: In this study, ana-rLOX was applied to noodles during the noodle-making process, and both dough rheological characteristics and noodle quality were improved. © 2015 Society of Chemical Industry.

Apontamentos acerca da Cadeia do Ser e o lugar dos negros na filosofia natural na Europa setecentista / Notes on the Chain of Being and the place of blacks in eighteenth-century European natural philosophy

Por meio da análise de obras acadêmicas produzidas por filósofos naturais no século XVIII, pretendemos discutir algumas ideias recorrentes acerca da Grande Cadeia do Ser. Para tal, analisamos as relações entre filosofia e teologia natural no período. Reavaliamos ainda alguns elementos da Cadeia do Ser, investigando autores que discorreram sobre o tema em seus escritos. Por fim, elencamos um ponto específico das discussões setecentistas sobre a scala naturae, qual seja, as diversas e nem sempre convergentes ideias de que, a partir de características específicas, haveria diferenças entre os homens, bem como seu consequente lugar na Cadeia do Ser.

This examination of academic works produced by eighteenth-century natural philosophers discusses some recurring ideas about the Chain of Being. To this end, the article analyzes the relations between natural philosophy and theology during the period. It also re-evaluates some elements of the Chain of Being through an exploration of authors who addressed the topic in their writings. Lastly, it identifies a specific element within eighteenth-century discussions of scala naturae, to wit, the various and not always convergent ideas about whether there are differences between humans based on specific characteristics and, consequently, about the places they occupy in the chain of being.

Antioxidant/Prooxidant and antibacterial/probacterial effects of a grape seed extract in complex with lipoxygenase.

In an attempt to determine the antioxidant/prooxidant, antibacterial/probacterial action of flavan-3-ols and procyanidins from grape seeds, pure catechin (CS), and an aqueous grape seed extract (PE), were applied in the absence and presence of pure lipoxygenase (LS) or in extract (LE) to leucocyte culture, Escherichia coli B 41 and Brevibacterium linens, and observed whether there was any effect on lipid peroxidation, cytotoxicity, or growth rate. Short time periods of coincubation of cells with the polyphenols, followed by the exposure to LS and LE, revealed a high level of lipid peroxidation and a prooxidative effect. Longer coincubation and addition of LS and LE resulted in the reversal of the prooxidant action either to antioxidant activity for CS + LS and PE + LS or to the control level for CS + LE and PE + LE. Lipid peroxidation was significantly reduced when cells were exposed to polyphenols over a longer period. Longer exposure of E. coli to CS or PE followed by addition of LS for 3 h resulted in bactericidal activity. Significant stimulatory effect on microbial growth was observed for PE + LS and PE + LE treatments in B. linens, illustrating the potential probacterial activity in B. linens cultures. Lipoxygenase-polyphenols complex formation was found to be responsible for the observed effects.

Absence of an effect of vitamin E on protein and lipid radical formation during lipoperoxidation of LDL by lipoxygenase.

Low-density lipoprotein (LDL) oxidation is the primary event in atherosclerosis, and LDL lipoperoxidation leads to modifications in apolipoprotein B-100 (apo B-100) and lipids. Intermediate species of lipoperoxidation are known to be able to generate amino acid-centered radicals. Thus, we hypothesized that lipoperoxidation intermediates induce protein-derived free radical formation during LDL oxidation. Using DMPO and immuno-spin trapping, we detected the formation of protein free radicals on LDL incubated with Cu(2+) or the soybean lipoxidase (LPOx)/phospholipase A2 (PLA2). With low concentrations of DMPO (1mM), Cu(2+) dose-dependently induced oxidation of LDL and easily detected apo B-100 radicals. Protein radical formation in LDL incubated with Cu(2+) showed maximum yields after 30 min. In contrast, the yields of apo B-100 radicals formed by LPOx/PLA2 followed a typical enzyme-catalyzed kinetics that was unaffected by DMPO concentrations of up to 50mM. Furthermore, when we analyzed the effect of antioxidants on protein radical formation during LDL oxidation, we found that ascorbate, urate, and Trolox dose-dependently reduced apo B-100 free radical formation in LDL exposed to Cu(2+). In contrast, Trolox was the only antioxidant that even partially protected LDL from LPOx/PLA2. We also examined the kinetics of lipid radical formation and protein radical formation induced by Cu(2+) or LPOx/PLA2 for LDL supplemented with α-tocopherol. In contrast to the potent antioxidant effect of α-tocopherol on the delay of LDL oxidation induced by Cu(2+), when we used the oxidizing system LPOx/PLA2, no significant protection was detected. The lack of protection of α-tocopherol on the apo B-100 and lipid free radical formation by LPOx may explain the failure of vitamin E as a cardiovascular protective agent for humans.

[Study on activation of benzo(a)pyrene and DNA damage mediated by lipoxygenase in human bronchial epithelial cells].

OBJECTIVE: The oxidation of benzo (a) pyrene mediated by 5-lipoxygenase (5-LOX) were investigated in HBE cells in order to provide further proof that lipoxygenase is the alternative pathway for the oxidation of xenobiotics. METHODS: Enzymic experiment: Soybean lipoxygenase (SLO), substrate (benzo[a] pyrene) and other component react in the enzymic system and the reaction product are detected by spectrophotometry. At the same time, in vitro detect of benzo (a) pyrene-DNA adducts with a UV spectrophotometer and HPLC. Cellular experiment: After HBE cells exposure to different poison (B[a]P 4, 8, 16, 32, 64, 128µmol/L, AA-861, naproxen or α- naphthoflavone 0.1, 1, 10 µmol/L) for 24 hours, the effect of benzo (a) -pyrene on cell survival rate were assessed by reductions of tetrazolium dye (MTT) and flow cytometry in cultured HBE cells, and the protein expressions of 5-lipoxygenase in the cells are tested by western-blot, and the DNA damages by the single cell gel electrophoresis. And then, the effect of the specific inhibitor of 5-lipoxygenase (AA-861) on 5-lipoxygenase protein expression and DNA damage in the cells are detected. RESULTS: SLO can catalyze the co-oxidation of benzo (a) pyrene to generate benzo (a) pyrene-7,8-epoxide in the presence of hydrogen peroxide. GTP can inhibit the reaction , the IC50 value is 0.46 mg/L, the model equation is Probit (P) = 0.8985+2.6824 Log (dose). SLO can catalyze the co-oxidation of benzo (a) pyrene to generate a new product, but fail to form DNA adducts in vitro. HBE cell viability decreased with the benzo (a) pyrene concentration increased , but AA-861 and naproxen can inhibit it. Flow cytometry and single cell gel electrophoresis experiments show, Benzo (a) pyrene can induce 5-lipoxygenase protein expression, but AA-861 cannot in HBE. Benzo (a) pyrene causes toxic action and DNA damage in HBE, which can significantly inhibit by AA-861, the difference is statistically significant (P < 0.05). CONCLUSIONS: The co-oxidate of benzo (a) pyrene by 5-LOX turns into electrophiles that covalently bind to DNA and induce DNA damage, which can be significantly inhibited by AA-861.

AmbLOXe--an epidermal lipoxygenase of the Mexican axolotl in the context of amphibian regeneration and its impact on human wound closure in vitro.

OBJECTIVE: The Mexican axolotl (Ambystoma mexicanum) is a well-characterized example for intrinsic regeneration. As lipoxygenase signaling is of crucial importance to scarless mammalian wound healing, we postulated that lipoxygenases might be expressed during amphibian regeneration and they might also influence human cells under appropriate conditions. In this study we identified an amphibian lipoxygenase and evaluated its impact on human cells in an in vitro wound model. METHODS: cDNA encoding for amphibian epidermal lipoxygenase (AmbLOXe) was polymerase chain reaction amplified and sequenced followed by phylogenic classification based on T-coffee alignment. Distribution of AmbLOXe was examined in various Ambystoma tissues, using polymerase chain reaction and in situ hybridization. Lipoxgenase influence was investigated using an outgrowth model of amphibian epidermal cells. Human osteosarcoma, as well as keratinocyte cell lines expressing AmbLOXe, were tested concerning in vitro wound closure in a monolayer scratch model. RESULTS: We isolated AmbLOXe from Ambystoma limb bud blastema identified as a homologue of human epidermal lipoxygenase. Amphibian epidermal lipoxygenase is expressed in Axolotl limb blastema and in epidermal cells which show decreased cell migration and proliferation rates when treated with LOX inhibitors. Furthermore, human osteosarcoma and keratinocyte cells showed increased rates of cell migration if transfected with AmbLOXe. CONCLUSION: In this study, AmbLOXe, a new effector of amphibian regeneration is described. In consideration of the presented data, AmbLOXe is important for amphibian epidermal cell proliferation and migration. As AmbLOXe expressing human osteosarcoma and keratinocyte cell lines showed increased rates of in vitro wound closure, an influence of amphibian mediators on human cells could be described for the first time.

Effects of maté tea intake on ex vivo LDL peroxidation induced by three different pathways.

Yerba maté (Ilex paraguariensis) is a native South America plant widely consumed as different beverages. Yerba maté leaves contains high concentrations of polyphenols that are responsible for its high in vitro and in vivo antioxidant activity. The in vivo antioxidant properties vis a vis LDL particles has not yet been studied for maté tea, the roasted yerba maté product. The aim of this study was to evaluate the antioxidant activity of maté tea ingestion ex vivo on human LDL. Fasting peripheral venous blood samples of healthy women were taken in three different times: before drinking the tea, one hour later and after one week (7 days) of daily consumption of maté tea. The isolated LDL was oxidized by three different pathways [copper (CuSO4), lipoxygenase and peroxynitrite (SIN-1)]. Conjugated dienes and structural modifications on LDL were evaluated. Ingestion of maté tea increased LDL resistance towards ex vivo copper oxidation, but did not alter the peroxidation pattern when SIN-1 or lipoxygenase were used as oxidants.

Dual inhibition of cyclooxygenase and lipoxygenase enzymes by human cerebrospinal fluid.

Thromboxane A2 (TXA2) formed in damaged brain tissue and after thromboembolism and subarachnoid haemorrhage is responsible for cerebral vasospasm. In the present study, we examined the effect of human cerebrospinal fluid (CSF) on the production of thromboxane-A2 (TXA2) and 12-hydroxy-eicosatetraenoic acid (12-HETE) by human blood platelets. CSF was drawn by lumbar puncture from normal healthy volunteers (n = 17) and samples judged to be normal after routine examination in the clinical laboratories and were used fresh. We found that CSF inhibited the production of TXA2 and 12-HETE by blood platelets incubated with C14 labelled arachidonic acid (AA) in a concentration-related manner. Further biochemical analysis using proteolytic enzymes, gel filtration and membrane partition chromatography showed that the inhibitory activity was peptidic in nature and associated with a peptide of low molecular weight (1,400 Da). This study is the first to demonstrate that human CSF contains a dual inhibitor of cyclooxygenase (COX) and lipoxygenase enzymes in CSF.

Biochemistry and pharmacology of endovanilloids.

Endovanilloids are defined as endogenous ligands and activators of transient receptor potential (TRP) vanilloid type 1 (TRPV1) channels. The first endovanilloid to be identified was anandamide (AEA), previously discovered as an endogenous agonist of cannabinoid receptors. In fact, there are several similarities, in terms of opposing actions on the same intracellular signals, role in the same pathological conditions, and shared ligands and tissue distribution, between TRPV1 and cannabinoid CB(1) receptors. After AEA and some of its congeners (the unsaturated long chain N-acylethanolamines), at least 2 other families of endogenous lipids have been suggested to act as endovanilloids: (i) unsaturated long chain N-acyldopamines and (ii) some lipoxygenase (LOX) metabolites of arachidonic acid (AA). Here we discuss the mechanisms for the regulation of the levels of the proposed endovanilloids, as well as their TRPV1-mediated pharmacological actions in vitro and in vivo. Furthermore, we outline the possible pathological conditions in which endovanilloids, acting at sometimes aberrantly expressed TRPV1 receptors, might play a role.

Effect of soybean lipoxygenase on volatile generation and inhibition of Aspergillus flavus mycelial growth.

Volatiles generated from lipoxygenase (LOX) normal and LOX deficient soybean (Glycine max) varieties with and without added lipase inhibited Aspergillus flavus mycelial growth and aflatoxin production. Soybean volatiles were analyzed using a solid phase microextraction (SPME) method combined with gas chromatography-mass spectrometry (GC-MS). Twenty-one compounds, including 11 aldehydes, three alcohols, four ketones, one furan, one alkane, and one alkene were detected in the LOX normal soybean line. However, only nine volatile compounds were observed in the LOX deficient soybean variety. The antifungal aldehydes hexanal and (E)-2-hexenal were observed in both LOX normal and LOX deficient lines and were detected at significantly higher amounts in soybean homogenate with added lipase. These aldehydes may be formed through alternate pathways, other than the LOX pathway, and may account for the inhibition of A. flavus growth observed. Other volatiles detected, particularly the ketones and alcohols, may contribute to the antifungal activity observed in both LOX normal and LOX deficient soybean lines. These results suggest that other factors, other than LOX activity, may better explain why soybeans are generally not as severely affected by A. flavus and aflatoxin contamination as other oilseed crops.

TRPV1 receptor: a target for the treatment of pain, cough, airway disease and urinary incontinence.

The TRPV1 channel is mainly expressed in sensory nerves. Activation of the channel induces neuropeptide release from central and peripheral sensory nerve terminals, resulting in the sensation of pain, neurogenic inflammation, smooth muscle contraction and cough. The TRPV1 channel can be activated by vanilloids such as capsaicin, as well as endogenous stimulators including H(+), heat, lipoxygenase products and anandamide. TRPV1 channel function is upregulated by several endogenous mediators present in inflammatory conditions, which decreases the threshold for activation of the channel. Under these conditions, TRPV1 can be activated by physiological body temperature, slight acidification or lower concentration of TRPV1 agonists. There is evidence that TRPV1 plays a role in the development of pathophysiological changes and symptoms in several diseases. In this review, we discuss TRPV1 channel activation and regulation in normal and diseased conditions, the role of TRPV1 in pain, cough, asthma and urinary incontinence, and the potential use of TRPV1 antagonists as a novel therapy for these diseases.

Eicosanoid metabolism in squamous cell carcinoma cell lines derived from primary and metastatic head and neck cancer and its modulation by celecoxib.

Eicosanoid metabolism through cyclooxygenases (COXs) and lipoxygenases (LOXs) generates various lipids that play a role in squamous cell carcinogenesis. We used pairs of head and neck squamous cell carcinoma (HNSCC) cell lines derived from primary and metastatic tumors of the same patient to analyze eicosanoid metabolites by ESI-LC/MS/MS and COX/LOX expression by western immunoblotting. The effects of celecoxib on eicosanoid synthesis and HNSCC cell growth were examined. Prostaglandin E2 (PGE2) was the major metabolite in three of six cell lines. COX-2 was detected in three cell lines, which produced PGE2 (two from metastases). We found low expression of COX-1 at similar intensities for each pair of cell lines. 5-LOX was detected in all cells. Some expressed 12-LOX, 15-LOX-1, and 15-LOX-2, but there was no correlation between enzyme expression and endogenous product content. Exogenous arachidonic acid did not change the profile of eicosanoid biosynthesis. Low doses of celecoxib inhibited formation of PGE2 in UMSCC-14A cells by 84% as early as 6 hours. In contrast, 5-HETE, 12-HETE, and 15-HETE levels were increased by approximately 40-, 5- and 3-fold, respectively, with a decline to baseline levels within 24 hours. High dose celecoxib increased the 12-HETE level 2.3-fold after 3 days of incubation. Celecoxib inhibited growth of all HNSCC cell lines in a concentration-dependent manner regardless of their COX expression (IC50 values after 3 days; 33 to 62 microM). Our findings provide new informations about individual eicosanoids produced by HNSCC cells and their differential regulation by the selective COX-2 inhibitor celecoxib.

[Stimulatory response to the oxidation of benzidine and other xenobiotics mediated by lipoxygenase in the presence of phenothiazines].

OBJECTIVE: To test the possibility that certain efficient substrates for lipoxygenase (LOX) produce shuttle oxidants that stimulate the generation of reactive oxygen species from other chemicals. METHODS: Metabolic interactions were conducted in vitro between chlorpromazine (BZ) or other phenothiazines and benzidine or other xenobiotics mediated by soybean lipoxygenase (SLO) or purified human term placental lipoxygenase (HTPLO) in the presence of hydrogen peroxide, and the rates of xenobiotics oxidation were measured by spectroscopic analysis. RESULTS: Chlorpromazine cation radical (CPZ(*+)) generated by lipoxygenase triggered a rapid oxidation of benzidine to benzidine diimine cation. Under the experimental conditions used, the metabolic interaction resulted in a 42-fold greater stimulation than BZ alone in the rate of BZ oxidation. The magnitude of stimulation of benzidine oxidation exhibited a dependence on the pH of the reaction medium, amount of the enzyme, and concentration of chlorpromazine, BZ, and hydrogen peroxide. A number of other phenothiazines were also found to stimulate BZ oxidation, albeit to a lesser degree. Chlorpromazine cation radical stimulated the oxidation of all six other xenobiotics tested. The highest stimulation (94-fold) was noted in the oxidation of tetramethyl phenylenediamine to Wursters blue radical, while the lowest stimulatory response (2-fold) was observed in guaiacol. Preliminary data showed that purified HTPLO also displayed a similar stimulatory response to benzidine oxidation in the presence of chlorpromazine. CONCLUSION: Both soybean lipoxygenase and purified human term placental lipoxygenase can mediate stimulatory response to the oxidation of benzidine and other xenobiotics in the presence of phenothiazines.

In vitro proliferation of fibrosarcoma cells depends on intact functions of lipoxygenases and cytochrome P-450-monooxygenase.

Proliferation of mouse fibrosarcoma cells G:5:113 was studied in vitro after affecting particular pathways of arachidonic acid metabolism by selected inhibitors. After 48 hours of cultivation with nonspecific lipoxygenase inhibitors, nordihydroguaiaretic acid (NDGA) and esculetin; a specific 12-lipoxygenase inhibitor, baicalein; and inhibitor of five-lipoxygenase activating protein, MK-886, markedly suppressed the number of cells and induced significant changes in cell cycle distribution in a dose-dependent manner. While proadifen, an inhibitor of cytochrome P-450-monooxygenase, applied in low concentrations, increased the cell number, at higher concentrations, it inhibited cell proliferation and significantly changed the cell cycle. Cyclooxygenase inhibitors, ibuprofen, flurbiprofen, and diclofenac suppressed cell numbers only moderately without any changes in the cell cycle. The occurrence of apoptosis was not significant for any of the selected drugs in comparison with untreated control cells. Moreover, not even one of the drugs caused the specific cleavage of poly (ADP-ribose) polymerase to the 89-kDa fragment, however, a decrease in total amount of this protein was observed after treatment with NDGA and esculetin. We conclude that the proliferation ability of fibrosarcoma cells G:5:113 in vitro depends on intact functions of 5-lipoxygenase, 12-lipoxygenase, and cytochrome P-450-monooxygenases, and that the effects of inhibitors do not include regulation of apoptosis.

Bleaching of browned water yam (Dioscorea alata) with African oil bean seed lipoxygenase (Part 2).

Purified African oil bean seed lipoxygenase was used to bleach water yam tubers that were browned by exposing their cut surfaces to air. The enzyme solution destroyed the polyphenols extracted from the browned water yams and the polyphenols at the browned yam tubers which resulted in the bleaching of the browned yam tubers to their original white colour. The destruction of the polyphenol extract and the bleaching of the browned yam tubers were found to be dependent on the enzyme concentration of the enzyme.

The hypolipidemic natural product Commiphora mukul and its component guggulsterone inhibit oxidative modification of LDL.

There is accumulating evidence that LDL oxidation is essential for atherogenesis, and that antioxidants that prevent this oxidation may either slow down or prevent atherogenesis. In the present study, we found that Commiphora mukul and its cholesterol-lowering component, guggulsterone, effectively inhibited LDL oxidation mediated by either catalytic copper ions, free radicals generated with the azo compound 2,2'-azobis-(2-amidinopropane)dihydrochloride (AAPH), soybean lipoxygenase enzymatically, or mouse peritoneal macrophages. This inhibition was assessed by the decrease in the following parameters describing LDL oxidation: conjugated dienes, relative electrophoretic mobility (REM), thiobarbituric acid reactive substances, lipid hydroperoxides, oxidation-specific immune epitopes as detected with a monoclonal antibody against oxidized LDL, and the accumulation of LDL derived cholesterol esters in mouse peritoneal macrophages. We concluded that C. mukul and its lipid-lowering component, guggulsterone, significantly inhibit LDL oxidation. The combination of antioxidant and lipid-lowering properties of C. mukul and guggulsterone makes them especially beneficial against atherogenesis.