Selective inhibition of arachidonate 5‐lipoxygenase by novel acetohydroxamic acids: biochemical assessment in vitro and ex vivo

Abstract

1 The chemically novel acetohydroxamic acids, BW A4C, BW A137C and BW A797C, are potent inhibitors of the synthesis of leukotriene B4 (LTB4) from arachidonic acid by human leucocyte homogenates: the concentrations required for 50% inhibition (ICjo) were 0.1 ym, 0.8 pm and 0.5 JM respectively. Inhibition was less at higher concentrations of arachidonic acid.2 These compounds also inhibited the synthesis of ["4C]-5-HETE from ["4C]-arachidonic acid and the calcium-dependent synthesis of LTB4 from 5-HPETE. This, therefore, suggests that they inhibit 5-lipoxygenase and LTA4 synthase. 3 Concentrations of acetohydroxamic acids required to inhibit metabolism of arachidonic acid by cyclo-oxygenase, 12-lipoxygenase and 15-lipoxygenase were 10 to 100 times higher than those required to inhibit 5-lipoxygenase. 4 The compounds were potent inhibitors of LTB4 synthesis induced by the ionophore, A23187, in human intact leucocytes. This inhibition was reversed by washing the cells. They were also potent, selective inhibitors of LTB4 synthesis induced by A23187 in whole rat blood: binding to rat plasma proteins did not greatly reduce the effectiveness of the compounds. 5 The effects of the acetohydroxamic acids, administered either intravenously or orally to rats, on the synthesis of LTB4, and thromboxane B2 (TXB2) in A23187-stimulated blood ex vivo was studied. The three compounds caused dose-dependent inhibition of the synthesis of LTB4 but not

Mechanism of muscle protein degradation in cancer cachexia

“…Inhibition could, however, be achieved by the addition of the cycloxoygenase inhibitor indomethacin (0.2 mM). There was a decrease by both the polyunsaturated fatty acid EPA (0.5 mM) and the lipoxygenase inhibitor BWA4C (Tateson et al, 1988) at high concentrations (1.77 mM) although the values were still significantly elevated compared to the control. Protein degradation in isolated gastrocnemius muscle could not be induced by the purified lipid mobilising factor produced by the MAC16 tumour .…”

Reactive oxygen species and lipoxygenases regulate the oncogenicity of NPM-ALK-positive anaplastic large cell lymphomas

“…Moreover, nuclear translocation was observed in NPM-ALK( þ ) NIH-3T3 cells, confirming the regulation of 5-LOX activity by the oncogene (Figure 4b). To further clarify the involvement of 5-LOX in the inhibition of NPM-ALK observed on NDGA treatment, we took an advantage of the 5-LOXspecific inhibitor, BW A4C (Tateson et al, 1988). As observed with NDGA, incubation of ALCL cells with BW A4C also inhibited proliferation and ALK activity (Figures 4c and d), apart from inducing apoptosis (Figure 3b), strongly suggesting that 5-LOX plays an Lysates were analysed by western blotting using anti-phosphoAkt(S473), anti-AKT anti-phosphosignal transducer and activator of transcription factor 3 (STAT3)(Y705), anti-STAT3, anti-phospho-p38, anti-p38 and anti-extracellular signal-regulated kinase (ERK1/2) from Cell Signaling Technologies.…”

In Vitro effect of D‐004, a lipid extract of the ground fruits of the cuban royal palm (Roystonea regia), on rat microsomal lipid peroxidation

“…After centrifugation, the band of mononuclear cells formed at the interface was removed with a Pasteur pipette and washed with 50 mM phosphate buffer/1 mM EDTA, pH 7 by successive centrifugations at 400 × g for 10 min. The cytosolic fraction was obtained as described (Tateson et al, 1988). In brief, the cells were sonicated, centrifuged at 2000 × g and 0°C for 10 min and the supernatant centrifuged…”