• YAKHAK HOEJI
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• v.47 no.4
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• pp.230-233
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• 2003

Previously, protoberberine alkaloids such as berberine and palmatine have been found to lower dopamine content in PC12 cells (Shin et at., 2000). In this study, the effects of berberine and palmatine on L-DOPA-induced increase in dopamine level and cytotoxicity in PC12 cells were investigated. Treatment of PC12 with L-DOPA at concentration ranges of 20∼50 $\mu$M increased dopamine content and the increase in dopamine levels by L-DOPA was inhibited by 10∼40 $\mu$M berberine and 10∼80 $\mu$M palmatine, which the concentration ranges did not show a cytotoxicity. However, berberine and palmatine at concentrations higher than 50 $\mu$M and 100 $\mu$M caused a cytotoxicity, respectively. In addition, berberine (10∼20 $\mu$M) and palmatine (10∼50 $\mu$M) at non-cytotoxic concentration ranges aggravated L-DOPA-induced cytotoxicity in PC12 cells (L-DOPA concentration ranges, 20∼50 $\mu$M). The L-DOPA-induced cytotoxicity was also significantly potentiated by berberine (50 $\mu$M) and palmatine (100 $\mu$M) with cytotoxic ranges. These data demonstrate that berberine and palmatine inhibit L-DOPA-induced increase in dopamine content and stimulate L-DOPA-induced neurotoxicity. Therefore, the possibility that the long-term L-DOPA treated patients with berberine and palmatine could be checked the adverse symptoms.

• Nutrition Research and Practice
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• v.7 no.4
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• pp.249-255
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• 2013

In this study, the protective effects of EGCG on L-3,4-dihydroxyphenylalanine (L-DOPA)-induced oxidative cell death in catecholaminergic PC12 cells, the in vitro model of Parkinson's disease, were investigated. Treatment with L-DOPA at concentrations higher than $150{\mu}M$ caused cytotoxicity in PC12 cells, as determined using the 3-(4,5-dimetylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry detection. The apoptotic ratio was similar in cells treated with $100{\mu}M$ EGCG plus $150{\mu}M$ L-DOPA (5.02%) and the control (0.96%) (P > 0.05), and was lower than that of cells treated with L-DOPA only (32.24%, P < 0.05). The generation level of ROS (% of control) in cells treated with EGCG plus L-DOPA was lower than that in cells treated with L-DOPA only (123.90% vs 272.32%, P < 0.05). The optical density in production of TBARS in cells treated with L-DOPA only was higher than that in the control ($0.27{\pm}0.05$ vs $0.08{\pm}0.04$, P < 0.05), and in cells treated with EGCG only ($0.14{\pm}0.02$, P < 0.05), and EGCG plus L-DOPA ($0.13{\pm}0.02$, P < 0.05). The intracellular level of GSH in cells treated with EGCG plus L-DOPA was higher than that in cells treated with L-DOPA only ($233.25{\pm}16.44$ vs $119.23{\pm}10.25$, P < 0.05). These results suggest that EGCG protects against L-DOPA-induced oxidative apoptosis in PC12 cells, and might be a potent neuroprotective agent.

• KSBB Journal
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• v.5 no.2
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• pp.191-194
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• 1990

Tyrosine is a monohydrolic aromatic amino acid and DOPA is a tyrosine derivative containing dihydroxy group. DOPA can be synthesized from tyrosine by enzymatic reaction. The separation and quantitative determination of each component are very difficult in the reaction mixture. In the present study, two wavelengths giving maximum absorbance difference of each amino acid were determined using UV/VIS spectrophotometer by wavelength scanning and simple assay method was developed for the analysis of the reaction mixture of tyrosine and DOPA by measuring absorbances of reaction mixture. This method can be simply used for the analysis of the tyrosine and DOPA mixture because it does not require and procedure for the pretreatment of the reaction mixture.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.817-821
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• 2016

Levodopa or L-3,4-dihydroxyphenylalanine (L-DOPA) is the direct precursor of the neurotransmitter dopamine. L-DOPA is a well-known neuroprotective agent for the treatment of Parkinson's disease symptoms. L-DOPA was synthesized using the enzyme, tyrosinase, as a biocatalyst for the conversion of L-tyrosine to L-DOPA and an electrochemical method for reducing L-DOPAquinone, the product resulting from enzymatic synthesis, to L-DOPA. In this study, three electrode systems were used: A glassy carbon electrode (GCE) as working electrode, a platinum, and a Ag/AgCl electrode as auxiliary and reference electrodes, respectively. GCE has been modified using electropolymerization of pyrrole to facilitate the electron transfer process and immobilize tyrosinase. Optimum conditions for the electropolymerization modified electrode were a temperature of $30^{\circ}C$ and a pH of 7 producing L-DOPA concentration 0.315 mM. After 40 days, the relative activity of an enzyme for electropolymerization remained 38.6%, respectively.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.2
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• pp.147-155
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• 1999

Antioxidant effects of serotonin and L-DOPA on neuronal tissues were examined by studying the oxidative damages of brain synaptosomal components. The study further explored the mechanism by which they exert protective actions. Serotonin and L-DOPA (1 ${\mu}M$ to 1 mM) significantly inhibited lipid peroxidation of brain tissues by either $Fe^{2+}$ and ascorbate or t-butyl hydroperoxide in a dose dependent fashion. Protective effect of serotonin on the peroxidative actions of both systems was greater than that of L-DOPA. Protein oxidation of synaptosomes caused by $Fe^{2+}$ and ascorbate was attenuated by serotonin and L-DOPA. Protein oxidation more sensitively responded to L-DOPA rather than serotonin. Serotonin and L-DOPA (100 ${\mu}M$) decreased effectively the oxidation of synaptosomal sulfhydryl groups caused by $Fe^{2+}$ and ascorbate. The production of hydroxyl radical caused by either $Fe^{3+},$ EDTA, H_2O_2$ and ascorbate or xanthine and xanthine oxidase was significantly decreased by serotonin and L-DOPA (1 mM). Equal concentrations of serotonin and L-DOPA restored synaptosomal $Ca^{2+}$ uptake decreased by $Fe^{2+}$ and ascorbate, which is responsible for SOD and catalase. Protective effects of serotonin and L-DOPA on brain synaptosomes may be attributed to their removing action on reactive oxidants, hydroxyl radicals and probably iron-oxygen complex, without chelating action on iron.

• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1251-1254
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• 2005

It has been proposed that oxidation of L-3,4-dihydroxyphenylalanine (DOPA) may contribute to the pathogenesis of neurodegenerative disease. In this study, L-DOPA-Fe(III)-mediated DNA cleavage and the protection by carnosine and homocarnosine against this reaction were investigated. When plasmid DNA was incubated with L-DOPA in the presence of Fe(III), DNA strand was cleaved. Radical scavengers and catalase significantly inhibited the DNA breakage. These results suggest that $H_2O_2$ may be generated from the oxidation of DOPA and then $Fe^{3+}$ likely participates in a Fenton’s type reaction to produce hydroxyl radicals, which may cause DNA cleavage. Carnosine and homocarnosine have been proposed to act as anti-oxidants in vivo. The protective effects of carnosine and homocarnosine against L-DOPA-Fe(III)-mediated DNA cleavage have been studied. Carnosine and homocarnosine significantly inhibited DNA cleavage. These compounds also inhibited the production of hydroxyl radicals in L-DOPA/$Fe^{3+}$ system. The results suggest that carnosine and homocarnosine act as hydroxyl radical scavenger to protect DNA cleavage. It is proposed that carnosine and homocarnosine might be explored as potential therapeutic agents for pathologies that involve damage of DNA by oxidation of DOPA.

• Natural Product Sciences
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• v.10 no.3
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• pp.124-128
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• 2004

Previously, $(1R,9S)-{\beta}-Hydrastine$ hydrochloride has been found to lower dopamine content in PC12 cells (Kim et al., 20001). In this study, the effects of $(1R,9S)-{\beta}-Hydrastine$ hydrochloride on L-DOPA-induced cytotoxicity in PC12 cells were investigated. Treatment with $(1R,9S)-{\beta}-Hydrastine$ hydrochloride at concentrations higher than $500\;{\mu}M$ caused cytotoxicity in PC12 cells. In addition, $(1R,9S)-{\beta}-Hydrastine$ hydrochloride at non-cytotoxic or cytotoxic concentrations significantly enhanced L-DOPA-induced cytotoxicity (L-DOPA concentration, $50\;{\mu}M$). Treatment of PC12 cells with $750\;{\mu}M$ $-1R,9S)-{\beta}-Hydrastine$ hydrochloride and $50\;{\mu}M$ L-DOPA, alone or in combination, also induced cell death via a mechanism which exhibited morphological and biochemical characteristics of apoptosis, including chromatin condensation and membrane blebbing. Exposure of PC12 cells to $(1R,9S)-{\beta}-Hydrastine$ hydrochloride, L-DOPA and $(1R,9S)-{\beta}-Hydrastine$ hydrochloride plus L-DOPA for 48 h resulted in a marked increase in the cell loss and percentage of apoptotic cells compared with exposure for 24 h. These data indicate that $(1R,9S)-{\beta}-Hydrastine$hydrochloride at higher concentration ranges aggravates L-DOPA-induced neurotoxicity cytotoxicity in PC12 cells. Therefore, it is proposed that the long-term L-DOPA therapeutic patients with $(1R,9S)-{\beta}-Hydrastine$ hydrochloride could be checked for the adverse symptoms.

• Korean Journal of Pharmacognosy
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• v.42 no.4
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• pp.341-347
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• 2011

The neuroprotective effects of herbal ethanol extracts from Gynostemma pentaphyllum (GP-EX) in 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease treated with L-DOPA were investigated. Rats were prepared for the Parkinson's disease model by 6-OHDA-lesioning for 14 days. The rats were then treated with L-DOPA (10 and 20 mg/kg) with or without the oral administration of GP-EX (30 mg/kg, daily) for 28 days. L-DOPA (20 mg/kg) treatment for 28 days enhanced dopaminergic neuronal cell death in 6-OHDA-lesioned rat groups, but L-DOPA (10 mg/kg) did not. However, the oral administration of GP-EX (30 mg/kg) for 28 days ameliorated the enhanced neurotoxic effects induced by chronic L-DOPA treatment in 6-OHDA-lesioned rat groups by increasing tyrosine hydroxylase (TH)-immunohistochemical staining and the number of TH-immunopositive cells surviving in the substantia nigra. In addition, GP-EX administration (30 mg/kg) for 28 days recovered the levels of dopamine and norepinephrine of the striatum in 6-OHDA-lesioned rat groups, which were markedly reduced by L-DOPA treatment (20 mg/kg). GP-EX (30 mg/kg) did not produce any signs of toxicity, such as weight loss, diarrhea, or vomiting in rats during the 28-day treatment period. These results suggest that GP-EX has protective functions against chronic L-DOPA-induced neurotoxic reactions in dopaminergic neurons in the 6-OHDA-lesioned rat model of Parkinson's disease. Therefore, GP-EX may be beneficial in the prevention of adverse symptoms in parkisonian patients.

• Archives of Pharmacal Research
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• v.29 no.8
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• pp.645-650
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• 2006

Tributyltin chloride (TBTC) at concentrations of $0.5-1.0\;{\mu}M$ inhibits dopamine biosynthesis in PC12 cells. In this study, the effects of TBTC on L-3,4-dihydroxyphenylalanine (L-DOPA)-induced cytotoxicity in PC12 cells were investigated. TBTC at concentrations up to $1.0\;{\mu}M$ neither affected cell viability, nor induced apoptosis after 24 or 48 h in PC12 cells. However, TBTC at concentrations higher than $2.0\;{\mu}M$ caused cytotoxicity through an apoptotic process. In addition, exposure of PC12 cells to non-cytotoxic (0.5 and $1.0\;{\mu}M$) or cytotoxic $(2.0\;{\mu}M)$ concentrations of TBTC in combination with L-DOPA (20, 50 and $100\;{\mu}M$) resulted in a significant increase in cell loss and the percentage of apoptotic cells after 24 or 48 h compared with TBTC or L-DOPA alone. The enhancing effects of TBTC on L-DOPA-induced cytotoxicity were concentration- and treatment time-dependent. These data demonstrate that TBTC enhances L-DOPA-induced cytotoxicity in PC 12 cells.

• The Korean Journal of Nuclear Medicine
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• v.13 no.1_2
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• pp.37-43
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• 1979

This is an analysis of 39 patients studied at the Yonsei Medical Center from January, 1976 to March 1979. Of these35 patient were suspected of having hypothalamic insufficiency and subjected to the L-Dopa stimulation test to observe growth hormone sceretory function while four acromegaly patient received the glucose loading test and L-Dopa stimulation test. The results are as follows: 1. The basal level of GH in the various disease was as follows: a. The basal level was lower than the control level but was not statistically significant b. In diabetes the mean value tended to be higher than the control level but was not significant statistically c. In all four acromegaly patients the GH level was significantly higher than the control level 2. Of 13 patients with diabetes, nine had diabetic retinopathy, and of those nine, sir showed increased L-Dopa response. However, of the four non retinopathic DM patients, only one showed increased response to L-Dopa. 3. Two patients out of ten with Sheehan's syndrome responded to L-Dopa stimulation. 4. One Patient of eight with pituitary chromophobe adenoma responded to L-Dopa stimulation. 5. Four acromegaly patients revealed 3 acidophilic adenoma and one chromophobe adenoma histologically. Of patients receiving the L-Dopa stimulation test. Two showed a paradoxical response. Two patients who received the glucose loading test showed supressed response. 6. Of two craniopharyngioma patients, one showed increased GH response after L-Dopa stimulation. Increased response of GH after L-Dopa stimulation was seen in one of two craniopharyngioma patients and also in one of two patients with