• 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.

• 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.

• 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.34 no.3 s.134
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• pp.242-245
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• 2003

The effects of chelidonine, a benzophenanthridine isoquinoline alkaloid, on L-DOPA-induced cytotoxicity in PC12 cells were investigated. The treatment of PC12 cells with chelidonine $(1-4\;{\mu}M)$ decreased dopamine content in a dose-dependent manner (30.2% inhibition at $4\;{\mu}M)$. Chelidonine was not cytotoxic up to $4\;{\mu}M)$. However, chelidonine at concentrations higher than $5\;{\mu}M$ caused a cytotoxicity in PC12 cells. L-DOPA at concentrations higher than $50\;{\mu}M$ led to cell damage by oxidative stress in PC12 cells. Chelidonine at non-cytotoxic concentration ranges of $1-4{\mu}M$ aggravated L- DOPA $(20-50\;{\mu}M)$-induced cytotoxicity in PC12 cells. The L-DOPA-induced cytotocxicity was synergistically stimulated by chelidonine at concentrations grader than $5\;{\mu}M$. These data demonstrate that chelidonine exacerbates L-DOPA-induced cytotoxicity. Therefore, it is proposed that the long-term L-DOPA therapeutic patients with chelidonine may need to be checked for the adverse symptoms.

• Biomolecules & Therapeutics
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• v.16 no.2
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• pp.106-112
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• 2008

The effects of harman and norharman on dopamine content and L-DOPA-induced cytotoxicity were investigated in PC12 cells. Harman and norharman decreased the intracellular dopamine content for 24 h. The $IC_{50}$ values of harman and norharman were 20.4 ${\mu}M$ and 95.8 ${\mu}M$, respectively. Tyrosine hydroxylase (TH) activity and TH mRNA levels were also decreased by 20 ${\mu}M$ harman and 100 ${\mu}M$ norharman. Under the same conditions, the intracellular cyclic AMP levels were decreased by harman and norharman. In addition, harman and norharman at concentrations higher than 80 ${\mu}M$ and 150 ${\mu}M$ caused cytotoxicity at 24 h in PC12 cells. Non-cytotoxic ranges of 10-30 ${\mu}M$ harman and 50-150 ${\mu}M$ norharman inhibited L-DOPA (20-50 ${\mu}M$)-induced increases of dopamine content at 24 h. Harman at 20-150 ${\mu}M$ and norharman at 100-300 ${\mu}M$ also enhanced LDOPA (20-100 ${\mu}M$)-induced cytotoxicity at 24 h. These results suggest that harman and norharman decrease dopamine content by reducing TH activity and aggravate L-DOPA-induced cytotoxicity in PC12 cells.

• 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.

• YAKHAK HOEJI
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• v.55 no.6
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• pp.510-515
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• 2011

Isoquinoline compounds including berberine enhance L-DOPA-induced cytotoxicity in PC12 cells. In this study, the effects of berberine on L-DOPA therapy in unilateral 6-hydroxydopamine (6-OHDA)-induced rat models of parkinsonism were investigated. Rats were prepared for the models of Parkinson's disease by 6-OHDA-lesioning for 14 days and then treated with L-DOPA (10 mg/kg) with or without berberine (5 and 30 mg/kg, i.p.) for 21 days. Treatment with berberine (5 and 30 mg/kg, i.p.) showed a dopaminergic cell loss in substantia nigra of 6-OHDA-lesioned rats treated with L-DOPA: 30 mg/kg berberine was more intensive neurotoxic. The levels of dopamine were also decreased by berberine (5 and 30 mg/ kg) in striatum-substantia nigra of 6-OHDA-lesioned rats treated with L-DOPA. These results suggest that berberine aggravates cell death of dopaminergic neurons in L-DOPA-treated 6-OHDA-lesioned rat models of Parkinson's disease. Therefore, the long-term L-DOPA therapeutic patients with isoquinoline compounds including berberine may need to be checked for the adverse symptoms.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.85.2-85.2
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• 2003

In vivo aromatic ${\beta}$-carbolines, such as harman and norharman, may easily be formed by cyclization of indoleamines with e.g. aldehydes. Because of the structural similarity to MPTP, ${\beta}$-carbolines have been proposed as endogenous toxins. In this study, we have investigated the effects of harman and norharman on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells. Treatment of PC12 cells with harman and norharman showed 48.8% and 49.5% inhibition of dopamine content at a concentration of 20 ${\mu}$M and 100 ${\mu}$M for 48h. (omitted)

• Korean Journal of Pharmacognosy
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• v.40 no.4
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• pp.351-356
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• 2009

Many isoquinoline alkaloids including berberine lower dopamine content by reducing tyrosine hydroxylase (TH) activity and aggravate L-DOPA-induced cytotoxicity in PC12 cells. In this study, the effects of berberine on 6-hydroxydopamine (6-OHDA)-induced cytotoxicity in PC12 cells and on unilateral 6-OHDA-lesioned rat models were investigated. Berberine at 10-30 ${\mu}M$ did not affect cell viability in PC12 cells. However, berberine at concentrations higher than $50{\mu}M$ caused cytotoxicity at 24 h. Berberine (10-50 ${\mu}M$) also enhanced 6-OHDA (10-50 ${\mu}M$)-induced cytotoxicity at 24 h compared to 6-OHDA alone with an apoptotic process. In addition, treatment with berberine (5 and 30 mg/kg, i.p.) for three weeks showed a dopaminergic cell loss in substantia nigra of 6-OHDA-lesioned rats: 30 mg/kg berberine was more intensive cytotoxic. The levels of dopamine were also decreased by berberine (5 and 30 mg/kg) in the ipsilateral substantia nigra of 6-OHDA-lesioned rats. These results suggest that berberine aggravated 6-OHDA-induced cytotoxicity in PC12 cells and treatment with berberine (5 and 30 mg/kg) in 6-OHDA-lesioned rats also enhanced the degeneration of dopaminergic cell death and the decrease in dopamine levels in substantia nigra. Therefore, the long-term L-DOPA therapeutic patients with isoquinoline compounds including berberine may need to be checked for the adverse symptoms.

• Journal of Life Science
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• v.28 no.3
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• pp.331-338
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• 2018

Melanin is a polymer substance that plays an important role in the determination of hair growth and skin color in vivo. However, melanin, which is over-produced by reactive oxygen species, is known to cause stains, freckles, and hypercholesterolemia, which are associated with aging. Previous studies have shown that polyphosphate, one of the components of Rhynchosia Nulubilis, inhibits skin aging induced by ultraviolet rays. The aim of this study is to investigate the direct effect of Rhynchosia Nulubilis ethanolic extract (RNEE) on melanin synthesis. In this study, RNEE showed no antioxidative effects on scavenging activity of DPPH radical in addition to reducing power. The cytotoxicity of RNEE was increased in a dose-dependent manner in an MTT assay. In addition, RNEE increased tyrosinase activity and melanin synthesis in DOPA-oxidation experiments. RNEE did not promote the conversion L-DOPA into melanin in live cells, but melanin production was promoted in the RNEE-treated group after H2O2 pretreatment compared to the control group in which melanin production was reduced by treatment with H2O2. In addition, RNEE increased the expression level of tyrosinase related protein-2 (TRP-2) and increased the expression level of tyrosinase related protein-1 (TRP-1) at a concentration of $16{\mu}g/ml$. In particular, it was found that RNEE increased the expression level of SOD-3, by which superoxide anion is converted to hydrogen peroxide, higher than the control and ${\alpha}$-MSH used as a positive control at a concentration of more than $16{\mu}g/ml$. The results suggest that RNEE can induce melanogenesis related to black hair.