Semi-Continuous Fermentation of Onion Vinegar and Its Functional Properties.

For the fermentation of vinegar using onion, acetic acid bacteria and yeast strains with high fermentation ability were screened. Among them, Saccharomyces cerevisiae 1026 was selected as a starter for ethanol production and Acetobacter orientalis MAK88 was selected as a vinegar producer. When the two-stage fermentation of onion vinegar was performed at 28 °C, the titratable acidity reached 4.80% at 24 h of fermentation. When semi-continuous fermentation proceeded to charge-discharge consisting of three cycles, the acetic acid content reached 4.35% at 48 h of fermentation. At this stage, the fermentation efficiency, acetic acid productivity, and specific product formation rate were 76.71%, 17.73 g/(L·d), and 20.58 g/(g·h), respectively. The process in this study significantly reduced the fermentation time and simplified the vinegar production process. The content of total flavonoids and total polyphenols in onion vinegar were 104.36 and 455.41 µg/mL, respectively. The antioxidant activities of onion vinegar in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid (ABTS⁺) radical scavenging activity, and reducing power were 75.33%, 98.88%, and 1.28, respectively. The nitrite scavenging abilities of onion vinegar were 95.38 at pH 1.2. The onion vinegar produced in this study showed higher organoleptic acceptability than commercial onion vinegar.

Topical anti-inflammatory effect of tirucallol, a triterpene isolated from Euphorbia lactea latex.

Latex from Euphorbia lactea (Euphorbiaceae), a native Dominican medicinal plant, is claimed to be useful in the treatment of inflammation. Topical application of tirucallol, a tetracyclic triterpene isolated from Euphorbia lacteal latex, suppressed ear edema in the mouse model in a dose-dependent manner, as well as affecting the influx of polymorphonuclear cells in response to topical application of 12-O-tetradecanoylphorbol-acetate (TPA) in the mouse ear. In addition, the effect of tirucallol, on some macrophage functions was analyzed in vitro. Non-toxic concentrations of tirucallol potently inhibited nitrite production in lipopolysaccharide-stimulated macrophages. Western blot analysis showed that nitric oxide reduction was a consequence of the inhibition of inducible nitric oxide synthetase expression although tirucallol slightly affected to prostaglandin E(2) (PGE(2)) generation. The results of the study revealed that tirucallol (0.3%), present in Euphorbia lactea latex, exerts a topical anti-inflammatory effect in vivo, via a mechanism of action related to the neutrophil migration. On the other hand, it can be deduced that the mechanism of the anti-inflammatory activity of this triterpene is related to the control of the production of NO and its effect on the expression of iNOS.

Interaction of dicaffeoylquinic derivatives with peroxynitrite and other reactive nitrogen species.

Plant phenolic antioxidants, among them catechins and hydroxycinnamoyl conjugates, constitute a well defined class of inhibitors of reactive nitrogen species (RNS). To gain deeper insight in this field, we examined the effects of 3,5-di-O-caffeoylquinic acid (DCA), its methyl ester (DCE) and epigallocatechin gallate (EGCG) in nitrative and oxidative processes. These compounds were found to be strong inhibitors of the nitration of tyrosine residues induced by ONOO- in bovine seroalbumin, with their IC50 values (10-40 microM) notably decreasing in the presence of bicarbonate. When studied on the intracellular protein tyrosine nitration induced by ONOO- in cultured murine fibroblasts as well as that induced by phorbol ester (PMA) in nitrite-supplemented human neutrophils, all three phenolics were also effective (100% and over 75% inhibition for fibroblasts and neutrophils, respectively, at 25 microM). This ability seems to be due to a direct interaction with ONOO- or with the species generated by leukocytes. The possible interference with the production of NO was also studied: both DCA and EGCG inhibited nitrite production in LPS-stimulated macrophages by 24% and 40%, respectively, and the expression of nitric oxide synthase-2 (NOS-2), as well. DCA and EGCG reduced by 52% and 59%, respectively, the NF-kappaB transcriptional activity. In contrast, DCE did not show any effect. The assayed phenolics exert varying degrees of protection against the chemical modifications induced by RNS depending not only on the hydroxyl pattern, but also on the presence of bicarbonate.

Anti-allergic activity of 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide.

Glycyrrhizin (18beta-glycyrrhetinic acid-3-O-beta-D-glucuronopyranosyl-(1 --> 2)-beta-D-glucuronide, GL) was transformed to 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide (GAMG) by Streptococcus LJ-22. The antiallergic activities of GL and GAMG was measured using a RBL cell assay system and contact hypersensitivity model mice. GAMG exhibited anti-allergic activity with IC50 values of 0.28 mM. GAMG, which is sweeter than GL, and 18beta-glycyrrhetinic acid, which is a GAMG metabolite by human intestinal bacteria, also inhibited the passive cutaneous anaphylaxis and skin contact inflammation. In conclusion, GAMG may be useful as a new sweet food additive and an anti-allergic agent.

Reactive nitrogen species scavenging, rather than nitric oxide inhibition, protects from articular cartilage damage in rat zymosan-induced arthritis.

1. The contribution of nitric oxide (NO) and peroxynitrite (PN) to inflammation in a zymosan-induced (1 mg, intra-articular, i.art.) rat model of arthritis was assessed by histopathology and by measuring the glycosaminoglycan (GAG) content of the articular cartilage. 2. Progression of the chronic synovitis in zymosan-induced arthritis (ZYA) was associated with increased nitrite and nitrotyrosine (3-NT) levels in the joint exudates that paralleled a progressive loss of the GAG content. An increase in 3-NT was also observed after i.art. PN. 3. The nonselective nitric oxide synthase (NOS) inhibitor l-N(G)-nitroarginine methyl ester (25-75 mg x kg(-1)day(-1)) or the selective inducible NOS inhibitor aminoguanidine (50-100 mg x kg(-1)day(-1)) given 1 h before (prophylactic) or 3 days after (therapeutic) injection of the zymosan ameliorated the synovitis, but worsened the GAG loss, as measured at the end of the experiment (day 7). 4. The PN scavenger uric acid (100-250 mg x kg(-1) i.p. four times daily) given prophylactically until the end of the experiment (day 14), in a dose compatible with its PN scavenging activity, significantly decreased both the synovitis and the GAG loss. 5. In conclusion, PN formation is associated with cartilage damage in addition to proinflammatory activity in ZYA. NOS inhibitors and a PN scavenger were able to reduce the cellular infiltration, while displaying opposite effects on cartilage homeostasis either by enhancing or ameliorating the damage, respectively.

Effect of ornithine on the ileal histology, nitric oxide production and lipid peroxidation in LPS-induced endotoxemia.

Effect of ornithine which is known to inhibit L-arginine uptake via cationic amino acid transport system has been tested, and compared to aminoguanidine, an iNOS inhibitor in lypopolysaccharide (LPS)-induced endotoxemia in rats. Serum nitrite/nitrate and malondialdehyde (MDA) level have been measured, and ileal histology has also been examined. Endotoxin increased serum nitrite/nitrate and MDA levels from 15.7+/- 2.4 micromol/ml and 2.1 +/-0.2 nmol/ml to 23.1 +/- 1.0 micromol/ml and 5.2+/- 0.3 nmol/ml (both P<0.05), respectively. In addition, LPS caused ileal degeneration. L-ornithine (500 mg/kg) did not improve septic manifestations, i.e., serum nitrite/nitrate and MDA levels did not differ from those in endotoxemia. Neither does it have an improving action on ileal histology. However, higher dose of L-ornithine (2,500 mg/kg) lowered the increased level of nitrite/nitrate and MDA by LPS. Moreover, it restored ileal histology from grade 3 (median) to 0 (median) (P<0.05). On the other hand, aminoguanidine (100 mg/kg) normalized serum nitrite/nitrate and MDA levels but not ileal histology in endotoxemic rats. In conclusion, high dose of L-ornithine could improve endotoxemic parameters in LPS-treated rats.

Gypenosides derived from Gynostemma pentaphyllum suppress NO synthesis in murine macrophages by inhibiting iNOS enzymatic activity and attenuating NF-kappaB-mediated iNOS protein expression.

Gypenosides isolated from Gynostemma pentaphyllum are widely used in traditional Chinese medicine, with beneficial effects reported in numerous diseases, including inflammation and atherosclerosis, although the mechanism underlying these therapeutic effects is unknown. Because increased nitric oxide (NO) plays a role in these pathological conditions, we investigated whether the pharmacological activity of gypenosides is due to suppression of NO synthesis. The markedly increased production of nitrite by stimulation of RAW 264.7 murine macrophages with 1 microg/mL lipopolysaccharide (LPS) for 20 h (unstimulated: 0.3+/-0.3 microM vs. LPS: 32.5+/-1.2 microM) was dose-dependently inhibited by gypenosides (0.1-100 microg/mL). When cells were pretreated with gypenosides (for 1h) prior to LPS stimulation, subsequent NO production was significantly attenuated (IC(50) of 3.1+/-0.4 microg/mL) (P<0.05). Gypenosides (25 microg/mL) produced the same maximum inhibition of LPS-induced NO production as aminoguanidine, a standard inhibitor of NOS enzymes. Suppression of NO production occurred both by direct inhibition of the activity and expression of iNOS. Inhibition of iNOS protein expression appears to be at the transcriptional level, since gypenosides decreased LPS-induced NF-kappaB activity in a dose-dependent manner (P<0.05), with significant inhibition achieved following pretreatment with 10 microg/mL gypenoside. Taken together, these results suggest that gypenosides derived from G. pentaphyllum suppress NO synthesis in murine macrophages by inhibiting iNOS enzymatic activity and attenuating NF-kappaB-mediated iNOS protein expression, thereby implicating a mechanism by which gypenosides may exert their therapeutic effects.

Effects of some inhibitors on the nitrosation of drugs in human gastric juice.

The nitrosation of several drugs under simulated stomach conditions was only weakly inhibited by the beverages studied. With easily and rapidly nitrosatable drugs, such as aminophenazone or piperazine, administered orally, the use of an inhibitor of nitrosation is to be recommended. Of all the substances investigated, ascorbic acid should be regarded as the best inhibitor because of its pronounced activity at the pH values occurring in the stomach and its lack of toxic effects. We would like to propose that the drugs under consideration should be made up to contain a sufficient amount of ascorbic acid.