Synthesis and evaluation of in vitro and in vivo anti-Toxoplasma gondii activity of tetraoxane-substituted ursolic acid derivatives.

A series of derivatives of ursolic acid (UA) were synthesised, the anti-Toxoplasma gondii activity was tested, and the selectivity index (SI) of these compounds was calculated to determine the derivative with the best anti-Toxoplasma gondii activity. Compound A7 showed the best activity against the Toxoplasma gondii (IC50 in T. gondii infected GES-1 cells: 9.1 ± 7.2 µM), better than the lead compound UA and the positive control drug Spiramycin. Compound A7 was selected for further in vivo research: A7 was tested for its effect on the inhibition rate of tachyzoites in mice and its biochemical parameters, such as alanine aminotransferase, aspartate aminotransferase, glutathione, and malondialdehyde were determined. Compound A7 was evaluated for its anti-Toxoplasma activity and partial damage to the liver. Therefore, the results show that compound A7 could be a potential lead compound for developing a novel anti-Toxoplasma gondii molecule.

Evaluation of the anti-Toxoplasma gondii Activity of Hederagenin in vitro and in vivo.

Toxoplasma gondii infection is widespread worldwide, not only posing a serious threat to human food safety and animal husbandry, but also endangering human health. The selectivity index was employed to measure anti-T. gondii activity. Hederagenin (HE) exhibited potent anti-T. gondii activity and low cytotoxicity. For this reason, HE was selected for in vivo experiments. HE showed 64.8%±13.1% inhibition for peritoneal tachyzoites in mice, higher than spiramycin 56.8%±6.0%. Biochemical parameters such as alanine aminotransferase, aspartate aminotransferase, glutathione, and malondialdehyde, illustrated that HE was a good inhibitor of T. gondii in vivo. This compound was also effective in relieving T. gondii-induced liver damage. Collectively, it was demonstrated that HE had potential as an anti-T. gondii agent.

Synthesis and Antimicrobial Activity Evaluation of Imidazole-Fused Imidazo[2,1-b][1,3,4]thiadiazole Analogues.

Three series of new imidazole-fused imidazo[2,1-b][1,3,4]thiadiazole analogues (compounds 20 a-g, 21 a-g, and 22 a-g) have been synthesized, and their antibacterial and antifungal activities have been evaluated. All the target compounds showed strong antifungal activity and high selectivity for the test fungus Candida albicans over Gram-positive and -negative bacteria. N-((4-(2-Cyclopropyl-6-(4-fluorophenyl)imidazo[2,1-b][1,3,4]thiadiazol-5-yl)-5-(6-methyl-pyridin-2-yl)-1H-imidazol-2-yl)methyl)aniline (21 a) showed the highest activity against C. albicans (MIC50 =0.16 µg/mL), 13 and three times that of the positive control compounds gatifloxacin and fluconazole, respectively. Compounds 21 a and 20 e did not show cytotoxicity against human foreskin fibroblast-1 cells, and compound 21 a was as safe as the positive control compounds in hemolysis tests. These results strongly suggest that some of the compounds produced in this work have value for development as antifungal agents.

Evaluation of ursolic acid derivatives with potential anti-Toxoplasma gondii activity.

Toxoplasma gondii is an important pathogen that causes serious public health problems. Currently, therapeutic drugs for toxoplasmosis cause serious side effects, and more effective and novel substances with relatively low toxicity are urgently needed. Ursolic acid (UA) has many properties that can be beneficial to healthcare. In this study, we synthesized eight series of UA derivatives bearing a tetrazole moiety and evaluated their anti-T. gondii activity in vitro using spiramycin as a positive control. Most of the synthesized derivatives exhibited better anti-T. gondii activity in vitro than UA, among which compound 12a exhibited the most potent anti-T. gondii activity. Furthermore, the results of biochemical parameter determination indicated that 12a effectively restored the normal body weight of mice infected with T. gondii, reduced hepatotoxicity, and exerted significant anti-oxidative effects compared with the findings for spiramycin. Additionally, our molecular docking study indicated that the synthesized compounds could act as potential inhibitors of T. gondii calcium-dependent protein kinase 1 (TgCDPK1), with 12a possessing strong affinity for TgCDPK1 via binding to the key amino acids GLU129 and TYR131.

Synthesis, in vitro and in vivo biological evaluation of dihydroartemisinin derivatives with potential anti-Toxoplasma gondii agents.

In this study, four series of dihydroartemisinin derivatives were designed, synthesized, and evaluated for anti-toxoplasma gondii activity, and calculated the selectivity index (SI). It was the higher the SI, the better the effect of this compound against Toxoplasma gondii. Our goal was to filter out compounds that were bigger SI than the lead compound. The compound with the highest SI was selected for the anti-toxoplasmosis test in mice in vivo. Among the synthesized compounds, the (3R,5aS,6R,8aS,9R,12R,12aR)-3,6,9-trimethyl-decahydro-12H-3,12-epoxy[1,2]di-oxepino[4,3 -i]isochromen-10-yl-(te-rt-butoxycarbonyl)-l-alaninate (A2) exhibited the most potent anti-T. gondii activity and low cytotoxicity (SI: 6.44), yielding better results than the lead compound DHA (SI: 1.00) and the clinically used positive-control drug spiramycin (SI: 0.72) in vitro. Furthermore, compound A2 had better growth inhibitory effects on T. gondii in vivo than spiramycin did and significantly reduced the number of tachyzoites in the peritoneal cavity of mice (P < 0.01). The evaluation of the data generated in the T. gondii mouse infection model indicates that compound A2 treatment was a good inhibitor of T. gondii in vivo and that it was effective in relieving the liver damage induced by T. gondii. In addition, the results of a docking study revealed that A2 could become a better T. gondii calcium-dependent protein kinase1 (TgCDPK1) inhibitor. For this reason, compound A2 has potential as an anti-parasitic drug. Further studies are required to elucidate the mechanism of the action of compound A2, as well as to develop drug delivery systems for patients.

Synthesis and Biological Evaluation of (+)-Usnic Acid Derivatives as Potential Anti-Toxoplasma gondii Agents.

Six series of (+)-usnic acid derivatives were synthesized. The IC50 values of these compounds were determined in T. gondii infected HeLa cells (µM) and in HeLa cells (µM), and their selectivity indexes (SI) were calculated. In vitro, most of the derivatives tested in this study exhibited more anti activity than that of the parent compound (+)-usnic acid and the positive control drugs. Among these derivatives, methyl (E)-(1-(6-acetyl-7,9-dihydroxy-8,9b-dimethyl-1,3-dioxo-3,9b-dihydrodibenzo[b,d]furan-2(1H)-ylidene)ethyl)phenylalaninate (D3) showed the most effective anti-T. gondii activity (selectivity >2.77). In comparison with the clinically used positive control drugs sulfadiazine (selectivity 1.15), pyrimethamine (selectivity 0.89), spiramycin (selectivity 0.72), and the lead compound (+)-usnic acid (selectivity 0.96), D3 showed better results in vitro. Furthermore, D3 and (E)-6-acetyl-7,9-dihydroxy-8,9b-dimethyl-2-(1-(quinolin-6-ylamino)ethylidene)dibenzo[b,d]furan-1,3(2H,9bH)-dione (F3) had greater inhibitory effects on T. gondii (inhibition rates 76.0% and 64.6%) in vivo in comparison to spiramycin (inhibition rate 55.2%); in the peritoneal cavity of mice, the number of tachyzoites was significantly reduced (p < 0.001) in vivo. Additionally, some biochemical parameters were measured and spleen indexes were comprehensively evaluated, and the results indicated that mice treated with both compound D3 and compound F3 showed reduced hepatotoxicity and significantly enhanced antioxidative effects in comparison to the normal group. Granuloma and cyst formation were effected by the inhibition of compound D3 and compound F3 in liver sections. Overall, these results indicated that D3 and F3 for use as anti-T. gondii agents are promising lead compounds.

Synthesis and biological evaluation of ursolic acid derivatives bearing triazole moieties as potential anti-Toxoplasma gondii agents.

Ursolic acid (UA), a plant-derived compound, has many properties beneficial to health. In the present study, we synthesised three series of novel UA derivatives and evaluated their anti-Toxoplasma gondii activity both in vitro and in vivo. Most derivatives exhibited an improved anti-T. gondii activity in vitro when compared with UA (parent compound), whereas compound 3d exhibited the most potent anti-T. gondii activity in vivo. Spiramycin served as the positive control. Additionally, determination of biochemical parameters, including the liver and spleen indexes, indicated compound 3d to effectively reduce hepatotoxicity and significantly enhance anti-oxidative effects, as compared with UA. Furthermore, our molecular docking study indicated compound 3d to possess a strong binding affinity for T. gondii calcium-dependent protein kinase 1 (TgCDPK1). Based on these findings, we conclude that compound 3d, a derivative of UA, could act as a potential inhibitor of TgCDPK1.

Synthesis and evaluation of novel arctigenin derivatives as potential anti-Toxoplasma gondii agents.

Four new series of arctigenin derivatives were designed, synthesised, and evaluated for their anti-Toxoplasma gondii activity in vitro and in vivo. Among the synthesised compounds, 4-(3,4-dimethoxybenzyl)-3-(4-((1-(2-fluorobenzyl)-1H- 1,2,3-triazol-4-yl)methoxy)-3-methoxybenzyl)dihydrofuran-2(3H)-one (D4) exhibited the most potent anti-T. gondii activity and low cytotoxicity (IC50 in T. gondii: 17.1 µM; IC50 in HeLa cells: ≥ 600.0 µM; Selectivity: 35.09), demonstrating better results than the lead compound arctigenin (IC50 in T. gondii: 586.4 µM; IC50 in HeLa cells: 572.7 µM; Selectivity: 0.98) and the clinically applied positive-control drug spiramycin (IC50 in T. gondi: 262.2 µM; IC50 in HeLa cells: 189.0 µM; Selectivity: 0.72) in vitro. Furthermore, 2-(4-((4-(3,4-dimethoxybenzyl)-2-oxotetrahydrofuran-3-yl)methyl)-2- methoxyphenoxy)N-phenylacetamide (E5) had better inhibitory effects on T. gondii in vivo than spiramycin did. Compound D4 and E5 not only significantly reduced the number of tachyzoites in the peritoneal cavity of mice, but also resulted in their partial malformation (P < 0.05) in vivo. The determination of liver and spleen index and biochemical parameters, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutathione (GSH) and malondialdehyde (MDA), were comprehensively evaluated for compound D4 and E5's anti-T. gondii activity and some damage to the liver. In addition, the results of a docking study of D4 into the T. gondii calcium-dependent protein kinase 1 (TgCDPK1) receptor protein-binding site revealed that its mode of action was possibly as a TgCDPK1 inhibitor. Overall, the results revealed that D4 and E5 are promising lead compounds for the further development and identification of arctigenin derivatives as anti-T. gondii agents.

Synthesis and Pharmacological Evaluation of New 3,4-Dihydroisoquinolin Derivatives Containing Heterocycle as Potential Anticonvulsant Agents.

Two novel series of 3,4-dihydroisoquinolin with heterocycle derivatives (4a-t and 9a-e) were synthesized and evaluated for their anticonvulsant activity using maximal electroshock (MES) test and pentylenetetrazole (PTZ)-induced seizure test. All compounds were characterized by IR, ¹H-NMR, 13C-NMR, and mass spectral data. Among them, 9-(exyloxy)-5,6-dihydro-[1,2,4]triazolo[3,4-a]isoquinolin-3(2H)-one (9a) showed significant anticonvulsant activity in MES tests with an ED50 value of 63.31 mg/kg and it showed wide margins of safety with protective index (PI > 7.9). It showed much higher anticonvulsant activity than that of valproate. It also demonstrated potent activity against PTZ-induced seizures. A docking study of compound 9a in the benzodiazepine (BZD)-binding site of γ-aminobutyric acidA (GABAA) receptor confirmed possible binding of compound 9a with the BZD receptors.

Synthesis and Biological Evaluation of Novel Benzothiazole Derivatives as Potential Anticonvulsant Agents.

New benztriazoles with a mercapto-triazole and other heterocycle substituents were synthesized and evaluated for their anticonvulsant activity and neurotoxicity by using the maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ), and rotarod neurotoxicity (TOX) tests. Among the compounds studied, compound 2-((1H-1,2,4-triazol-3-yl)thio)-N-(6-((3-fluorobenzyl) oxy)benzo[d]thiazol-2-yl)acetamide (5i) and 2-((1H-1,2,4-triazol-3-yl)thio)-N-(6-((4-fluorobenzyl)oxy) benzo[d] thiazol-2-yl)acetmide (5j) were the most potent, with an ED50 value of 50.8 mg/kg and 54.8 mg/kg in the MES test and 76.0 mg/kg and 52.8 mg/kg in the scPTZ seizures test, respectively. They also showed lower neurotoxicity and, therefore a higher protective index. In particular, compound 5j showed high protective index (PI) values of 8.96 in the MES test and 9.30 in the scPTZ test, which were better than those of the standard drugs used as positive controls in this study.

[Myanmar jadeitite low-temperature metamorphic water-rock reaction: eveidence from microscopic fourier transform infrared spectroscopy].

Weathering & transporting and depositing processes may improve the quality of some natural low-quality jadeite through reaction with surrounding water fluids. But the mechanism of such water-rock reaction has not been known clearly to date. Applying microscopic Fourier transform infrared spectroscopy (Micro-FTIR), this paper carried out comparatively in-situ research of jadeites' mineral composition before and after water-rock reaction. The results show that water-rock reaction cannot impact jadeites in their major and minor element composition, but greatly change their water content. Jadeites became richer, with even several times increase, in water content, after experiencing water-rock reaction, and hence show a shift of absorption peak at 3 550 cm(-1) to higher frequency. The mineral crystals of these jadeites showed reglar variation in water content from core to edge, and these jadeites have more water in marginal area than in center area, being opposite to the change in water content in jadeite during high temperature and pressure metamorphic process, hence implying that there are different mechanism and shift direction for H+/OH of jadeite between high pressure metamorphic process and low temperature water-rock reaction. We think that this finding may contribute to understanding the behavior of water in jadeite during metamorphic process and the mechanism of jadeite quality improvement.

The Methanol Extract of Azadirachta indica A. Juss Leaf Protects Mice Against Lethal Endotoxemia and Sepsis.

In the present study, the inhibitory effect of neem leaf extract (NLE) on lipopolysaccaride (LPS)-induced nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production was examined both in vitro and in vivo. In vitro study revealed that NLE treatment (100 µg/ml) inhibits LPS (100 ng/ml)-induced NO production by 96% and TNF-α production by 32%. The reduction in NO production is probably conferred by the complete suppression of inducible nitric oxide synthase (iNOS) expression. Interestingly, in vivo NLE significantly improved the survival rate of mice in an experimental sepsis model. Administration of NLE (100 mg/kg) 24 h before LPS treatment (20 mg/kg) improved the survival rate of mice by 60%. The inhibition of plasma NO and TNF-α production by NLE is likely to account for the improved survival of mice. Our results suggest that NLE may present a promising avenue in the development of therapeutic agents for the treatment of inflammatory diseases.

Anti-toxoplasmosis effects of oleuropein isolated from Fraxinus rhychophylla.

Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii, with very few therapeutic treatment options. Typically, the choices for treatment are pyrimethamine and sulfadiazine, however their utility is limited because of drug toxicity and serious side effects. For these reasons, new drugs with lower toxicity are urgently needed. In this study, the compound oleuropein isolated from Fraxinus rhynchophylla showed anti-T. gondii effects in vitro and in vivo. In Madin-Darby bovine kidney cells, the selectivity of oleuropein was 8.9, which was higher than sulfadiazine and pyrimethamine (3.8 and 2.5, respectively). In infected mice, the inhibition ratio of T. gondii in the peritoneal cavity was 55.4% compared to the negative control group after treatment with 300 mg/kg oleuropein. In addition, inhibitory effects on granuloma, apoptosis, necrosis and cyst-formation were shown in sections of spleen and liver. Oleuropein is therefore a potentially useful anti-T. gondii candidate for clinical application.

Effects of asimilobine on dopamine biosynthesis and l-DOPA-induced cytotoxicity in PC12 cells.

The effects of asimilobine, an aporphine isoquinoline alkaloid, on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells were investigated. Asimilobine at concentration ranges of 0.05-0.2 microM showed a significant inhibition of intracellular dopamine levels for 24 h in a concentration-dependent manner with an IC50 value of 0.13 microM. Asimilobine at 0.15 microM inhibited tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) activities at 24 h (73.2% inhibition of TH activity): the inhibition of TH activity was stronger and longer than that of AADC activity. Asimilobine also decreased TH mRNA levels and intracellular cyclic AMP levels, but not the basal Ca2+ concentrations. In addition, asimilobine at 0.05-5.0 microM, but not 10 microM, did not alter cell viability toward PC12 cells. A non-cytotoxic asimilobine (0.15 microM) associated with l-DOPA (20, 50, and 100 microM) for 24 h inhibited L-DOPA-induced increases in dopamine levels and enhanced L-DOPA-induced cell death when compared with L-DOPA alone. These results suggest that asimilobine inhibits dopamine biosynthesis by mainly reducing the TH activity and TH mRNA expression, and enhances L-DOPA-induced cytotoxicity in PC12 cells.

Induction of dopamine biosynthesis by l-DOPA in PC12 cells: implications of L-DOPA influx and cyclic AMP.

The effects of 3,4-dihydroxyphenylalanine (l-DOPA) on dopamine biosynthesis and cytotoxicity were investigated in PC12 cells. l-DOPA treatment (20-200 microM) increased the levels of dopamine by 226%-504% after 3-6 h of treatment and enhanced the activities of tyrosine hydroxylase (TH) and aromatic l-amino acid decarboxylase (AADC). l-DOPA (20-200 muM) treatment led to a 562%-937% increase in l-DOPA influx at 1 h, which inhibited the activity of TH, but not AADC, during the same period. The extracellular releases of dopamine were also increased by 231%-570% after treatment with 20 and 200 microM l-DOPA for 0.5-3 h. l-DOPA at a concentration of 100-200 microM, but not 20 microM, exerted apoptotic cytotoxicity towards PC12 cells for 24-48 h. l-DOPA (20-200 microM) increased the intracellular cyclic AMP levels by 318%-557% after 0.5-1 h in a concentration-dependent manner. However, the elevated cyclic AMP levels by l-DOPA could not protect against l-DOPA (100-200 microM)-induced cytotoxicity after 24-48 h. In addition, l-DOPA (20-200 microM)-induced increases in cyclic AMP and dopamine were significantly reduced by treatment with SCH23390 (dopamine D(1) receptor antagonist). The increased levels of dopamine by l-DOPA were also reduced by H89 (protein kinase A, PKA, inhibitor) and GF109203X (protein kinase C inhibitor); however, the reduction by GF109203X was not significant. l-DOPA at 20-200 microM stimulated the phosphorylation of PKA and cyclic AMP-response element binding protein and induced the biosynthesis of the TH protein. These results indicate that 20-200 microM l-DOPA induces dopamine biosynthesis by two pathways. One pathway involves l-DOPA directly entering the cells to convert dopamine through AADC activity (l-DOPA decarboxylation). The other pathway involves l-DOPA and/or released dopamine activating TH to enhance dopamine biosynthesis by the dopamine D(1) receptor-cyclic AMP-PKA signaling system (dopamine biosynthesis by TH).

Effects of harman and norharman on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells.

The effects of harman and norharman on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells were investigated. Harman and norharman at a concentration of 20 microM and 100 microM showed 49.4% and 49.5% inhibition of dopamine content for 48 h, respectively. The IC50 values of harman and norharman were 21.2 microM and 103.3 microM. Dopamine content, tyrosine hydroxylase (TH) activity and TH mRNA levels were decreased during the first 6 h, maintained for up to 48 h and then gradually recovered at 72 h after exposure to 20 microM harman and 100 microM norharman. Under the same conditions, the intracellular cyclic AMP levels and Ca2+ concentrations were also decreased by harman and norharman. In addition, harman and norharman at concentrations higher than 80 microM and 150 microM caused cytotoxicity at 48 h in PC12 cells. Non-cytotoxic ranges of 10-30 microM harman and 50-150 microM norharman inhibited L-DOPA (20-50 microM)-induced increases in dopamine content at 48 h. Harman at 20-150 microM and norharman at 100-300 microM also enhanced L-DOPA (20-100 microM)-induced cytotoxicity at 48 h with an apoptotic process. These results suggest that harman and norharman inhibit dopamine biosynthesis by reducing TH activity and enhance L-DOPA-induced cytotoxicity in PC12 cells.

Effects of anonaine on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells.

The effects of anonaine, an aporphine isoquinoline alkaloid, on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells were investigated. Anonaine at concentration ranges of 0.01-0.2 microM showed a significant inhibition of dopamine content at 24 h, with an IC(50) value of 0.05 microM. Anonaine at 0.05 microM inhibited tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) activities to 38.4-40.2% and 78.4-90.2% of control levels at 12-24 h and 3-6 h, respectively. TH activity was more influenced than AADC activity. Anonaine also decreased intracellular cyclic AMP levels, but not intracellular Ca(2+) concentrations. In addition, anonaine (0.05 microM) reduced L-DOPA (50 microM and 100 microM)-induced increases in dopamine content at 24 h. However, anonaine (0.05 microM) did not enhance L-DOPA (50 microM and 100 microM)-induced cell death after 24 h. These results suggest that anonaine inhibits dopamine biosynthesis by mainly reducing TH activity without aggravating L-DOPA-induced cytotoxicity in PC12 cells.

Liriodenine inhibits dopamine biosynthesis and L-DOPA-induced dopamine content in PC12 cells.

The inhibitory effects of liriodenine, an aporphine isoquinoline alkaloid, on dopamine biosynthesis and L-DOPA-induced dopamine content increases in PC12 cells were investigated. Treatment of PC12 cells with 5-10 microM liriodenine significantly decreased the intracellular dopamine content in a concentration-dependent manner (IC50 value, 8.4 microM). Liriodenine was not cytotoxic toward PC12 cells at concentrations up to 20 microM. Tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) activities were inhibited by 10 microM liriodenine to 20-70% and 10-14% of control levels at 3-12 h, respectively; TH activity was more influenced than AADC activity. The levels of TH mRNA, intracellular cyclic AMP and basal Ca2+ concentration were also decreased by 10 microM liriodenine. In addition, 10 microM liriodenine reduced L-DOPA (20-100 microM)-induced increases in dopamine content. However, 10 microM liriodenine resulted in a protective effect against L-DOPA (50-100 microM)-induced cytotoxicity. These results suggest that liriodenine regulates dopamine biosynthesis by partially reducing TH activity and TH gene expression and has protective effects against L-DOPA-induced cytotoxicity in PC12 cells.

Effects of (1R,9S)-beta-hydrastine on intracellular calcium concentration in PC12 cells.

(1R,9S)-beta-hydrastine (BHS) decreases the basal intracellular Ca(2+) concentration ([Ca(2+)](i)) in PC12 cells.(5) This study examined the effects of (1R,9S)-BHS on [Ca(2+)](i) in PC12 cells. (1R,9S)-BHS at 10-100 microM in combination with a high extracellular K+ level (56 mM) inhibited the release of dopamine in a concentration-dependent manner with an IC(50) value of 66.5 microM. BHS at 100 microM inhibited the sustained increase in [Ca(2+)](i) induced by a high K+ level (56 mM), and had an inhibitory effect on the 2 microM nifedipine-induced blockage of the K+ -stimulated sustained increase in [Ca(2+)](i). In addition, (1R,9S)-BHS at 100 microM prevented the rapid and sustained increase in [Ca(2+)](i) elicited by 20 mM caffeine, but did not have an effect on the increase induced by 1 microM thapsigargin, in the presence of external Ca(2+). These results suggest that the active sites of (1R,9S)-BHS are mainly L-type Ca(2+) channels and caffeine-sensitive Ca(2+)-permeable channels in PC12 cells.

Inhibitory effects of (1R,9S)-beta-Hydrastine on calcium transport in PC12 cells.

(1R,9S)-beta-Hydrastine (BHS), at 100 microM, has been shown to mainly reduce the K+-induced dopamine release and Ca2+ influx by blocking the L-type Ca2+ channel and inhibit the caffeine activated store-operated Ca2+ channels, but not those activated by thapsigargin, in PC12 cells. In this study, the effects of BHS on Ca2+ transport from Ca2+ stores in the absence of external Ca2+ were investigated in PC12 cells. BHS decreased the basal intracellular Ca2+ concentration ([Ca2+]i) in the absence of external Ca2+ in PC12 cells. In the absence of external Ca2+, pretreating PC12 cells with 100 microM BHS reduced the rapid increase in the [Ca2+]i elicited by 20 mM caffeine, but not that by 1 microM thapsigargin. In addition, BHS inhibited the increase in the [Ca2+]i elicited by restoration of 2 mM CaCl2 after the Ca2+ stores had been depleted by 20 mM caffeine, but not those depleted by 1 microM thapsigargin, in the absence of external Ca2+. These results suggested that BHS mainly inhibited Ca2+ leakage from the Ca2+ stores and the caffeine-stimulated release of Ca2+ from the caffeine-sensitive Ca2+ stores in PC12 cells.