Nguyen Dang Hung

Antioxidant and lipoxygenase inhibitory activity of oligostilbenes from the leaf and stem of Vitis amurensis.

ETHNOPHARMACOLOGICAL RELEVANCE The root and stem of Vitis amurensis (Vitaceae) have popularly used as traditional medicine for treatment of cancer and various pains in Korea and Japan. Recent studies, its root and stem possess anti-inflammatory, anti-tumor activities, and protective effects against beta-amyloid-induced oxidative stress. AIM OF THE STUDY This study deals with the isolation, structural identification of the potent bioactive compounds from the leaf and stem, and their antioxidant capacity, as well as anti-inflammatory effect via lipoxygenase inhibitory assay. MATERIALS AND METHODS All isolated compounds yielded after using column chromatography were identified base on the physico-chemical properties and 1D, 2D NMR spectra. The scavenge ability against DPPH and ABTS(+) radicals, and to inhibit lipid peroxidation, as well as lipoxygenase type I inhibitory activity of all isolates were performed using in vitro assays. RESULTS Eleven resveratrol derivatives (1-11), including a new oligostilbene cis-amurensin B (9), whose structures were determined on the basis of extensively spectral analyses, were isolated from the leaf and stem of Vitis amurensis. The isolates (1-11) were examined for their antioxidant activities by evaluating scavenge ability against DPPH and ABTS(+) radicals, and to inhibit lipid peroxidation. Stilbenes 1 and 4, and oligostilbenes 5-10 displayed moderate anti-lipid peroxidation activities, but all the isolates exhibited strong ABTS(+) radical scavenging activity in the dose-dependent manner. In addition, the isolates showed stronger inhibitory capacity against soybean lipoxygenase type I than that of baicalein, a positive control. Of the isolates, r-2-viniferin (8) exhibited the strongest scavenging activity against ABTS(+) radical with TEAC value of 5.57, and the most potential inhibitory effect on soybean lipoxygenase with the IC(50) value of 6.39 microM. CONCLUSION This is the first report on the potential antioxidant and LOX-1 inhibitory effects of oligostilbenes isolated from the leaf and stem of Vitis amurensis. In addition, chemical compositions isolated from the leaf and stem are almost similar to those isolated from the root of Vitis amurensis. Therefore, the results may explain, in part, the uses of the leaf and stem, as well as the root of Vitis amurensis in the Korean traditional medicine.

Oxidative inactivation of lactonase activity of purified human paraoxonase 1 (PON1).

Paraoxonase1 (PON1), one of HDL-associated antioxidant proteins, is known to lose its activity in vivo systems under oxidative stress. Here, we examined the effect of various oxidants on lactonase activity of PON1, and tried to protect the lactonase activity from oxidative inactivation. Among the oxidative systems tested, the ascorbate/Cu(2+) system was the most potent in inactivating the lactonase activity of purified PON1; in contrast to a limited role of Fe(2+), Cu(2+) (0.05-1.0 microM) remarkably enhanced the inactivation of PON1 in the presence of ascorbate (0.02-0.1 mM). Moreover, Cu(2+) alone inhibited the lactonase activity at concentrations as low as 1 microM. The ascorbate/Cu(2+)-mediated inactivation of PON1 lactonase activity was prevented by catalase, but not general hydroxyl radical scavengers, suggesting the implication of Cu(2+)-bound hydroxyl radicals in the oxidative inactivation. Compared to arylesterase activity, lactonase activity appears to be more sensitive to Cu(2+)-catalyzed oxidation. Separately, ascorbate/Cu(2+)-mediated inactivation of lactonase activity was prevented by oleic acid as well as phoshatidylcholine. Taken together, our data demonstrate that Cu(2+)-catalyzed oxidation may be a primary factor to cause the decrease of PON1 lactonase activity under oxidative stress and that lactonase activity of PON1 is most susceptible to ascorbate/Cu(2+) among PON1 activities. In addition, we have showed that radical-induced inactivation of lactonase activity is prevented by some lipids.

Mechanisms for anti-inflammatory effects of 1-[15(S)-hydroxyeicosapentaenoyl] lysophosphatidylcholine, administered intraperitoneally, in zymosan A-induced peritonitis

BACKGROUND AND PURPOSE Lysophosphatidylcholines (lysoPCs) with polyunsaturated acyl chains are known to exert anti‐inflammatory actions. 15‐Lipoxygeanation is crucial for anti‐inflammatory action of polyunsaturated acylated lysoPCs. Here, the anti‐inflammatory actions of 1‐(15‐hydroxyeicosapentaenoyl)‐lysoPC (15‐HEPE‐lysoPC) and its derivatives were examined in a mechanistic analysis.

Anti-inflammatory action of arachidonoyl lysophosphatidylcholine or 15-hydroperoxy derivative in zymosan A-induced peritonitis

Arachidonic acid, released from PLA(2) hydrolysis of phosphatidylcholine, is converted to pro-inflammatory or anti-inflammatory mediators. Although lysophosphatidylcholine (lysoPC), another product, is known to be pro-inflammatory, the role of polyunsaturated lysoPCs is not clear. Here, we examined the role of arachidonoyl-lysoPC and its lipoxygenation product in inflammation. First, when the effect of arachidonoyl-lysoPC, administrated i.v., on zymosan A-induced plasma leakage in mice was examined, arachidonoyl-lysoPC was found to prevent zymosan A-induced plasma leakage remarkably. As the interval time between lysoPC administration and zymosan A challenge was extended, the suppression of plasma leakage was augmented, suggesting that a metabolism of arachidonoyl-lysoPC may be implicated in anti-inflammatory action. Additionally, 4-methyl-2-(4-methylpiperazinyl)pyrimido[4,5-b] benzothiazine, an inhibitor of 15-lipoxygenase, was found to diminish the suppressive action of arachidonyl-lysoPC, indicating that 15-HPETE-lysoPC may be a metabolite responsible for anti-inflammatory action of arachidonoyl-lysoPC. In support of this, 15-HPETE-lysoPC (ED(50), 32 microg/kg) exhibited a greater anti-inflammatory action than arachidonoyl-lysoPC. Further, mechanistic analysis indicates that anti-inflammatory action of 15-HPETE-lysoPC was related largely to the formation of lipoxin, and to less extent to the inhibition of LTC biosynthesis, but not to PGE formation. Further, i.p. administration of arachidonoyl-lysoPC or 15-HPETE-lysoPC also exhibited a dose-dependent effect, although less efficient than i.v. injection. Additionally, the time-dependent suppression was more remarkable for 15-HPETE-lysoPC than arachidonoyl-lysoPC, suggestive of different mechanisms for anti-inflammatory action in peritoneum. Taken together, it is proposed that arachidonoyl-lysoPC and its oxidation product may belong to endogenous lipids displaying anti-inflammatory effects in vivo.