GIPC-phospholipase D in plants

Previously, we detected an unknown sphingophospholipid in cabbage leaves and identified it as phytoceramide-1-phosphate (PC1P). We also found an enzyme activity that produces PC1P by glycosylinositol phosphoceramide (GIPC)-specific hydrolysis in cabbage leaves. To characterize the GIPC-specific phospholipase D (GIPC-PLD) activity, we investigated distributions of GIPC-PLD activity in 25 tissues of 10 plants. In most plants, the GIPC-PLD activity was the highest in roots. Young leaves of cabbage and Welsh onion had higher activities than corresponding aged outer leaves. The GIPC-PLD activities in leaves, stems and roots of mung bean were higher in the sprouting stage than in more mature stages. We also examined distribution of substrate GIPC and product PC1P, and found that GIPC was ubiquitously distributed at 50-280 nmol/g (wet wt) in tissues of plants, whereas PC1P was detectable (3-60 nmol/g wet wt.) only in tissues showing considerable GIPC-PLD activity. These results suggest a possibility that GIPC-PLD activity is involved in plant growth

Lysophosphatidic acid in medicinal herbs enhances prostaglandin E2 and protects against indomethacin-induced gastric cell damage in vivo and in vitro

Lysophosphatidic acid (LPA) is a bioactive phospholipid that induces diverse biological responses. Recently, we found that LPA ameliorates NSAIDs-induced gastric ulcer in mice. Here, we quantified LPA in 21 medicinal herbs used for treatment of gastrointestinal (GI) disorders. We found that half of them contained LPA at relatively high levels (40–240 μg/g) compared to soybean seed powder (4.6 μg/g), which we previously identified as an LPA-rich food. The LPA in peony (Paeonia lactiflora) root powder is highly concentrated in the lipid fraction that ameliorates indomethacin-induced gastric ulcer in mice. Synthetic 18:1 LPA, peony root LPA and peony root lipid enhanced prostaglandin E2 production in a gastric cancer cell line, MKN74 cells that express LPA2 abundantly. These materials also prevented indomethacin-induced cell death and stimulated the proliferation of MKN74 cells. We found that LPA was present in stomach fluids at 2.4 μM, which is an effective LPA concentration for inducing a cellular response in vitro. These results indicated that LPA is one of the active components of medicinal herbs for the treatment of GI disorder and that orally administered LPA-rich herbs may augment the protective actions of endogenous LPA on gastric mucosa

Reduced kidney levels of lysophosphatidic acids in rats after chronic administration of aristolochic acid: Its possible protective role in renal fibrosis

Aristolochic acid (AA) is considered to be a causative agent for progressive interstitial renal fibrosis, leading to AA nephropathy. Lysophosphatidic acid (LPA) is a mediator in the onset of renal fibrosis. In this study, we analyzed the molecular species of LPA and its precursor lysophospholipids in kidney tissue from rats exposed to AA. Daily intraperitoneal injections of AA for 35 days to rats gave rise to fibrosis in kidney, decreased the kidney levels of LPA, lysophosphatidylserine and lysophosphatidylinositol. In rat renal cell lines (NRK52E and NRK49F), AA-induced cytotoxicity was potentiated by Ki16425, LPA1,3 receptor antagonist. The level of mRNA encording α-smooth muscle actin was significantly increased by AA-treatment only in NRK52E cells, while the mRNA level of collagen III was decreased in both NRK52E and NRK49F cells. These results suggest that endogenous LPA in rat kidney prevents AA-induced renal fibrosis

Measurement of Lipid Hydroperoxides by the Ferric-Xylenol Orange Method (1) Characteristics of the Ferric-Xylenol Orange/Membrane Phosphatidylcholine Complex

The ferric-xylenol orange (FOX) method for measurement of hydroperoxides is based on a technique that employs reduction of peroxides in an acidic condition by Fe2+ and formation of the colored ferric-xylenol orange (XO/Fe3) product with a peak at 560 nm. The 560 nm absorbance peak of XO/Fe3+ shifts to a 610 nm peak with high absorption intensity in the presence of phosphatidylcholine. This is useful for quantification of peroxides such as phospholipid hydroperoxides. Based on this finding, we recently reported a modified FOX method. We now show by measurements of absorbance, broadening of the electron paramagnetic resonance spectrum, changes in the vesicle size and their zeta potentials, the effects of detergents, and manipulation of the membrane lipid composition that the XO/Fe3 -phosphatidylcholine complex forms only in the presence of intact phosphatidylcholine membranes. The phosphate group on the phospholipid plays a role in this interaction which may involve an electron transfer from the phosphate to the Fe3+. A positively charged quaternary amine on the phosphatidylcholine is also necessary to give a peak absorbance at 610 nm. Our observations are consistent with binding of one X0/Fe3+ COmplex to about 3 molecules of the egg yolk phosphatidylcholine carrying a zero net charge.6 page(s