Soyong Jang

Synthesis of novel trans-stilbene derivatives and evaluation of their potent antioxidant and neuroprotective effects

A convenient synthesis and the biological properties of new amides, esters and other derivatives of trans-stilbene are described. The key synthetic strategies involve the Wittig-Horner reaction of a phosphonium salt 9 and an aldehyde 10 to generate (E)- or (Z)-olefins and a coupling reaction of an acid 12 and various amines 13a-n to give trans-stilbene derivatives 15a-n in high yields. A amide derivative 15g showed three times more in vitro free radical-scavenging activity than resveratrol, while another 15d exhibited strong inhibitory activity against lipopolysaccharide (LPS)(a)-induced NO generation. Allylamide analogue 15a showed the most potent neuroprotective activity in glutamate-induced primary cortical neuron cells.

Elevation of Sphinganine 1-Phosphate as a Predictive Biomarker for Fumonisin Exposure and Toxicity in Mice

Fumonisins are specific inhibitors of ceramide synthase in sphingolipid metabolism. An alteration in sphingolipid metabolism as a result of fumonisin B1 (FB1) exposure is related to cell death, and sphinganine/sphingosine ratio has been used as an indicator of fumonisin exposure in animals. The objective of this study was to investigate a new biochemical marker for the prediction of fumonisin-induced toxicity. When mice were treated with FB1 (10 mg/kg ip/d) for 5 d, the serum levels of sphingoid bases and their 1-phosphate were markedly elevated. The accumulation of sphingosine 1-phosphate (So-1-P) and sphinganine 1-phosphate (Sa-1-P) in serum following FB1 treatment was more apparent than elevated levels of sphingosine (So) and sphinganine (Sa). Sa-1-P/So-1-P ratio in serum was more elevated than Sa/So ratio following fumonisin B1 treatment, indicating that phosphorylation of sphingoid bases may be a sensitive biomarker for fumonisin exposure. In addition, the tissue levels of Sa and Sa-1-P were also significantly elevated in kidneys, liver, heart, lung and brain. FB1-induced toxicity was confirmed microscopically in both liver and kidneys. Liver lesions consisted of centrilobular hypertrophy and cytoplasmic vacuolization. In addition, hepatic binucleated cells were increased and acidophilic body was observed in FB1-treated mice. Kidney lesions were consistent with tubular nephrosis, and tubules were dilated and contained cell debris in FB1-exposed mice. These results suggested that the elevation of Sa-1-P as well as Sa in serum would be a specific biomarker for predicting FB1 exposure, and elevated tissue levels of Sa-1-P may be related to fumonisin toxicity in animals.

Efficient Synthesis and Neuroprotective Effect of Substituted 1,3-Diphenyl-2-propen-1-ones

An efficient synthesis involving a key aldol reaction and biological properties of 1,3-diphenyl-2-propen-1-ones 8- 20 is described. The in vitro activity for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging of 10 and 11 was 2 times higher than that for resveratrol. Compounds 9 and 11 were the strongest in suppression of in vitro nitric oxide (NO) generation and antiexcitotoxicity. Molecular modeling proposes an electron-donating group at the para position of acetophenones that leads to a dramatic increase in the suppression of NO production.

Anti-Inflammatory and Neuroprotective Effects of Constituents Isolated from Rhodiola rosea

To determine the biological activity of Rhodiola rosea, the protein expression of iNOS and proinflammatory cytokines was measured after the activation of murine microglial BV2 cells by LPS under the exposure of constituents of Rhodiola rosea: crude extract, rosin, rosarin, and salidroside (each 1–50 μg/mL). The LPS-induced expression of iNOS and cytokines in BV2 cells was suppressed by the constituents of Rhodiola rosea in a concentration-dependent manner. Also the expression of the proinflammatory factors iNOS, IL-1β, and TNF-α in the kidney and prefrontal cortex of brain in mice was suppressed by the oral administration of Rhodiola rosea crude extract (500 mg/kg). To determine the neuroprotective effect of constituents of Rhodiola rosea, neuronal cells were activated by L-glutamate, and neurotoxicity was analyzed. The L-glutamate-induced neurotoxicity was suppressed by the treatment with rosin but not by rosarin. The level of phosphorylated MAPK, pJNK, and pp38 was increased by L-glutamate treatment but decreased by the treatment with rosin and salidroside. These results indicate that Rhodiola rosea may have therapeutic potential for the treatment of inflammation and neurodegenerative disease.

Attenuation of morphine tolerance and withdrawal syndrome by coadministration of nalbuphine.

Morphine has been used widely on the treatment of many types of chronic pain. However the development of tolerance to and dependence on morphine by repeat application is a major problem in pain therapy. The purpose of the present study was to investigate whether combined administration of nalbuphine with morphine affects the development of tolerance to and dependence on morphine. We hypothesize that the use of nalbuphine, κ-agonist may prove to be useful adjunct therapy to prevent morphine-induced undesirable effects in the management of some forms of chronic pain. Morphine (10 mg/kg) was injected to rats intraperitoneally for 5 day. The variable dose of nalbuphine (0.1, 1.0 and 5.0 mg/kg) was administered (i.p.) in combination with morphine injection. The development of morphine tolerance was assessed by measuring the antinociceptive effect with the Randall-Selitto apparatus. The development of dependence on morphine was determined by the scoring the precipitated withdrawal signs for 30 min after injection of naloxone (10 mg/kg, i.p.). Nalbuphine did not attenuate antinociceptive effect of morphine in rats. Interestingly, combined administration of morphine with nalbuphine (10∶1) significantly attenuated the development of dependence on morphine. The elevation of [3H]MK-801 binding in frontal cortex, dentate gyrus, and cerebellum after chronic morphine infusion was suppressed by the coadministration of nalbuphine. In addition, the elevation of NR1 expression by morphine was decreased by the coadministration of nalbuphine in rat cortex. These results suggest that the coadministration of nalbuphine with morphine in chronic pain treatment can be one of therapies to reduce the development of tolerance to and dependence on morphine.

Changes of [3H]MK-801, [3H]muscimol and [3H]flunitrazepam binding in rat brain by the prolonged ventricular infusion of transformed ginsenosides.

Ameliorating effects of ginseng were observed on neuronal cell death associated with ischemia or glutamate toxicity. Ginseng saponins are transformed by intestinal microflora and the transformants would be absorbed from intestine. In the present study, we have investigated the effects of transformed ginsenoside Rg3, Rh2 and compound K on the modulation of NMDA receptor and GABAA receptor binding in rat brain. The NMDA receptor binding was analyzed by quantitative autoradiography using [3H]MK-801 binding, and GABAA receptor bindings were analyzed by using [3H]muscimol and [3H]flunitrazepam binding in rat brain slices. Ginsenoside Rg3, Rh2 and compound K were infused (10 μg/10 μl/h) into rat brain lateral ventricle for 7 days, through pre-implanted cannula by osmotic minipumps (Alzet, model 2ML). The levels of [3H]MK-801 binding were highly decreased in almost all regions of frontal cortex and hippocampus by ginsenoside Rh2 and compound K. The levels of [3H]muscimol binding were elevated in part of frontal cortex and granule layer of cerebellum by the treatment of ginsenoside Rh2 and compound K. However, the [3H]flunitrazepam binding was not modulated by any tested ginsenosides. Ginsenoside Rh2 and compound K induced the downregulation of the [3H]MK-801 binding as well as upregulation of the and [3H]muscimol binding in a region-specific manner after prolonged infusion into lateral ventricle. However, ginsenoside Rg3 did not show the significant changes of ligand bindings. In addition, ginsenoside Rh2 decreased the expression of nNOS in the hippocampus although Rg3 decreased the expression in the cortex. These results suggest that biotransformed ginsenoside Rh2 and compound K could play an important role in the biological activities in the central nervous systems and neurodegenerative disease.

Synthesis and evaluation of biological properties of benzylideneacetophenone derivatives

A series of yakuchinone B1f and its analogs1a-e was synthesized and evaluated for free radical scavenging, suppression of LPS-induced NO generation, cytotoxicity and anti-excitotoxicity in vitro. Compound1c exhibited potent anti-excitotoxicity, while all compounds1a-f showed considerable effects of free radical scavenging, suppression of LPS-induced NO generation, and cytotoxicity in microglia.

Enhancement of Anxiety and Modulation of TH and pERK Expressions in Amygdala by Repeated Injections of Corticosterone.

Repeated stress induces corticosterone release. However, it is not clear that stress results in further elevation of corticosterone levels, and the roles of released corticosterone to aggravate stress-related symptoms are also not clear. This study investigated whether neuronal modulation was induced in the amygdala after two kinds of stress, that is, such as electric shock and corticosterone injection. It was found that stress by electric shock decreased the expression of tyrosine hydoroxylase (TH) in the amygdala while the expression of pERK was increased. However, there is no difference in the expressions of TH and pERK in the frontal cortex compared with those of the control group. The level of corticosterone was significantly increased in the serum after stress. To determine the effect of corticosterone on the induction of anxiety and the expression of TH, the rats received corticosterone (20 mg or 40 mg/kg i.p.) for 1 day, 1 week, 2 weeks and 3 weeks, respectively. The spent time in open arms of the EPM (elevated plus maze) test was significantly decreased after 1 week, 2 weeks and 3 weeks. The time spent in open arms of the EPM test after repeated injections of corticosterone was significantly decreased in a dose-dependent manner. The expression of TH in the amygdala was reduced after following repeated corticosterone treatment for 2 weeks and 3 weeks. Collectively, this study suggests that corticosterone has a major role in the induction of anxiety and the modulation of TH expression, at least, in the amygdala.

The Neuroprotective Effects of Benzylideneacetophenone Derivatives on Excitotoxicity and Inflammation via Phosphorylated Janus Tyrosine Kinase 2/Phosphorylated Signal Transducer and Activator of Transcription 3 and Mitogen-Activated Protein K Pathways

To search for new neuroprotective compounds, novel benzylideneacetophenone compounds (JCI, (3E)-4-(4-hydroxy-3-methoxyphenyl)but-3-en-2-one; JC2, (1E)-1-(4-hydroxy-3-methoxyphenyl)hept-1-en-3-one; JC3, (2E)-3-(4-hydroxy-3-methoxyphenyl)phenylpro-2-en-l-one; JC4, (1E)-1-(4-hydroxy-3-methoxyphenyl)-5-phenylpent-1-en-3-one; JC5, (1E)-3-(4-hydroxy-3-methoxyphenyl)-6-phenylhex-1-en-3-one; JC6, (1E)-1-(4-hydroxy-3-methoxyphenyl]-7-phenylhept-1-en-3-one) were synthesized, and their potential to prevent neurotoxicities were evaluated. All compounds (JC1–JC6) showed considerable effect on free radical scavenging, the inhibition of glutamate-induced neurotoxicity in cortical cells, and the suppression of lipopolysaccharide (LPS)-induced nitric oxide (NO) generation in microglia. (2E)-3-(4-Hydroxy-3-methoxyphenyl)-phenylpro-2-en-1-one (JC3) exhibited the most potent neuroprotective effect in ischemia model using organotypic hippocampal culture and middle cerebral artery occlusion (MCAO). Based on the above-mentioned results, the mechanisms underlying the biological activity of JC3, which exhibited potent antiexcitotoxic and anti-inflammatory effects, were determined using cortical neuronal cells and microglia. Compound JC3 exerted a neuroprotective effect on oxygen-glucose deprivation- and hydrogen peroxide-induced cytotoxicity in cultured cortical cells. In addition, it suppressed the generation of NO, proinflammatory cytokines, and reactive oxygen species in LPS-treated microglial cells. It also suppressed the activation of phosphorylated Janus tyrosine kinase 2/phosphorylated signal transducer and activator of transcription 3 and mitogen-activated protein kinase (MAPK) in activated microglia and in cortex and striatum after 3 days of the MCAO in mice. These results demonstrated that JC3 might affect a set of intracellular signaling cascades, including the Janus tyrosine kinase/signal transducers and activators of transcription and MAPK pathways. This study suggests that benzylideneacetophenone derivative could be useful antineurotoxic agents.

Alteration of sphingolipid metabolism and pSTAT3 expression by dietary cholesterol in the gallbladder of hamsters

Cholesterol and sphingolipids are major lipid constituents of the plasma membrane and have been implicated in a number of human diseases, such as atherosclerosis, fatty liver, diabetes mellitus, coronary heart disease, and hypertension. However, the relationship between cholesterol and sphingolipid metabolism has not been investigated. The purpose of this study was to determine whether dietary cholesterol would induce the alteration of sphingolipid metabolism in hamsters. Hypercholesterolemia was induced in hamsters by placing them on an experimental diet containing 0.5% cholesterol plus 0.5% choline chloride for 8 and 12 weeks. The serum profile of the hamsters showed that the administration of cholesterol increased the levels of total cholesterol, LDL cholesterol, and triglycerides as well as the activities of GOT and GPT. The levels of ceramide and sphingosine-1-phosphate (So-1-P) were remarkably elevated by 6-fold, respectively, in the bile juice of cholesterol-fed hamsters. Interestingly, the levels of iNOS and GFAP were increased in the gallbladders of cholesterol-fed hamsters. In addition, the immunostaining of pSTAT3 was increased on the gallbladder epithelium after cholesterol feeding. These results suggest that sphingolipid metabolism may be regulated in the bile juice during cholesterol feeding and may be a potential target for the treatment of hypercholesterolemia-induced diseases.