[Preparation of Oenothera biennis Oil Solid Lipid Nanoparticles Based on Microemulsion Technique].

OBJECTIVE: To study the preparation of Oenothera biennis oil solid lipid nanoparticles and its quality evaluation. METHODS: The solid lipid nanoparticles were prepared by microemulsion technique. The optimum condition was performed based on the orthogonal design to examine the entrapment efficiency, the mean diameter of the particles and so on. RESULTS: The optimal preparation of Oenothera biennis oil solid lipid nanoparticles was as follows: Oenothera biennis dosage 300 mg, glycerol monostearate-Oenothera biennis (2: 3), Oenothera biennis -RH/40/PEG-400 (1: 2), RH-40/PEG-400 (1: 2). The resulting nanoparticles average encapsulation efficiency was (89.89 ± 0.71)%, the average particle size was 44.43 ± 0.08 nm, and the Zeta potential was 64.72 ± 1.24 mV. CONCLUSION: The preparation process is simple, stable and feasible.

[Preparation and authentication of beta-cyclodextrin complex of volatile oil from Ledum palustre].

OBJECTIVE: To study the optimum inclusion process conditions for the beta-cyclodextrin complex of volatile oil from Ledum palustre. METHODS: The utilization ratio of the volatile oil from Ledum palustre was set as the index, and four factors were selected including the ratio of the volatile oil to beta-cyclodextrin, the temperature of preparation, the inclusion time and the ratio of beta-cyclodextrin to water. The optimum conditions were investigated by the orthogonal test form L9 (3(4)). The inclusion compound was identified by the ways of Micro-imaging, Thin-layer chromatography (TLC), Ultraviolet Spectroscopy (UV)and Infrared Spectroscopy (IR). RESULTS: The optimum preparation conditions were as follows: volatile oils: beta-cyclodextrin was 1:8, the inclusion temperature and time was 50 degrees C and 30 min, respectively. Beta-cyclodextrin: water was 1:15. CONCLUSION: The inclusion technology is stable and its quality is adjustable.

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.

Enantio-selective inhibition of (1R,9S)- and (1S,9R)-beta-hydrastines on dopamine biosynthesis in PC12 cells.

The inhibitory effects of (1R,9S)- and (1S,9R)-enantiomers of beta-hydrastine (BHS) on dopamine biosynthesis in PC12 cells were investigated. (1R,9S)-BHS decreased the intracellular dopamine content with the IC50 value of 14.3 microM at 24 h, but (1S,9R)-BHS did not. (1R,9S)-BHS was not cytotoxic at concentrations up to 250 microM towards PC12 cells. In these conditions, (1R,9S)-BHS inhibited tyrosine hydroxylase (TH) activity mainly in a concentration-dependent manner (33% inhibition at 20 microM) and decreased TH mRNA level in PC12 cells. The inhibitory patterns of dopamine content and TH activity by (1R,9S)-BHS showed similar behavioral curves. (1R,9S)-BHS at 10-50 microM also reduced the intracellular cyclic AMP level and Ca2+ concentration. In addition, treatment of L-DOPA at 20-50 microM for 24 h increased the intracellular dopamine content to 198-251% compared with the control in PC12 cells. However, the increase in dopamine levels induced by L-DOPA (20-50 microM) was reduced when L-DOPA was combined with (1R,9S)-BHS (10-50 microM). These results indicate that (1R,9S)-BHS, but not (1S,9R)-BHS, reduced dopamine content and L-DOPA-induced increase in dopamine content, in part, through the inhibition of TH activity and TH gene expression in PC12 cells: thus, (1R,9S)-BHS proved to have a function to regulate dopamine biosynthesis.

Effects of (1R,9S)-beta-hydrastine on l-DOPA-induced cytotoxicity in PC12 cells.

(1R,9S)-beta-Hydrastine in lower concentrations of 10-50 microM inhibits dopamine biosynthesis in PC12 cells. In this study, the effects of (1R,9S)-beta-hydrastine on L-DOPA (L-3,4-dihydroxyphenylalanine)-induced cytotoxicity in PC12 cells were investigated. (1R,9S)-Hydrastine at concentrations up to 250 microM did not reduce cell viability. However, at concentrations higher than 500 microM it caused cytotoxicity in PC12 cells, as determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, TUNEL (terminal deoxynucleotidyltransferase dUTP nick-end labeling) method and flow cytometry. Exposure of PC12 cells to cytotoxic concentrations of (1R,9S)-beta-hydrastine (500 and 750 microM) in combination with L-DOPA (20, 50 and 100 microM) after 24 or 48 h resulted in a significant decrease in cell viability compared with the effects of (1R,9S)-beta-hydrastine or L-DOPA alone, and apoptotic cell death was observed. However, the decrease in cell viability induced by (1R,9S)-beta-hydrastine was not prevented by the antioxidant N-acetyl-L-cysteine, indicating that it is not mediated by membrane-based oxygen free radical damage. These data suggest that (1R,9S)-beta-hydrastine has a mild cytotoxic effect and at higher concentration ranges aggravates L-DOPA-induced cytotoxicity in PC12 cells.

Aggravation of L-DOPA-induced neurotoxicity by tetrahydropapaveroline in PC12 cells.

Tetrahydropapaveroline (THP) is formed in Parkinsonian patients receiving L-DOPA therapy and is detected in the plasma and urine of these patients. In this study, we have investigated the effects of THP on L-DOPA-induced neurotoxicity in cultured rat adrenal pheochromocytoma, PC12 cells. Exposure of PC12 cells up to 10 microM THP or 20 microM L-DOPA after 24 or 48 hr, neither affected the cell viability determined by MTT assay, nor induced apoptosis by flow cytometry and TUNEL staining. However, at concentrations higher than 15 microM, THP showed cytotoxicity through an apoptotic process. In addition, THP at 5-15 microM for both incubation time points significantly enhanced L-DOPA-induced neurotoxicity (L-DOPA concentration, 50 microM). Exposure of PC12 cells to THP, L-DOPA and THP plus L-DOPA for 48 hr resulted in a marked increase in the cell loss and percentage of apoptotic cells compared with exposure for 24hr. The enhancing effects of THP on L-DOPA-induced neurotoxicity were concentration- and treated-time-dependent. THP, L-DOPA and THP plus L-DOPA produced a significant increase in intracellular reactive oxygen species generation and decrease in ATP levels, supporting the involvement of oxidative stress in THP- and L-DOPA-induced apoptosis. The antioxidant N-acetyl-L-cysteine strongly inhibited changes in apoptosis, decreases in cell viability and ROS generation induced by THP associated with L-DOPA. These results suggest that THP aggravates L-DOPA-induced oxidative neurotoxic and apoptotic effects in PC12 cells. Therefore, Parkinsonian patients treated with L-DOPA for long-term need to be monitored for the relationship between plasma concentration of THP and the symptoms of neurotoxicity.

Inhibitory effects of tributyltin on dopamine biosynthesis in rat PC12 cells.

The inhibitory effects of tributyltin chloride (TBTC) on dopamine biosynthesis in PC12 cells were investigated. Twenty-four hour exposure to TBTC at 0.5 microM showed 32.9% inhibition of dopamine content: the IC(50) value of TBTC was 0.72 microM. Dopamine content decreased at 6 h and reached a minimal level at 24 h after exposure to TBTC at 0.5 microM. The decreased dopamine level was maintained for up to 48 h. Under these conditions, tyrosine hydroxylase (TH) activity was inhibited at 6 h following the treatment with TBTC and the activity was maintained at a reduced level for up to 48 h (20-35% inhibition at 0.5 microM of TBTC). TH mRNA level also started to decrease at about 6 h and reached a minimal level at 24 h after exposure of PC12 cells to TBTC. In addition, treatment with L-3,4-dihydroxyphenylalanine (L-DOPA) at 20-50 microM increased the intracellular dopamine content in PC12 cells and the increase of dopamine level by L-DOPA was significantly inhibited after exposure to TBTC at 0.5-2.0 microM for 24 h. These results indicate that TBTC decreases dopamine content by the inhibition of TH activity and TH mRNA level in PC12 cells. It is, therefore, proposed that TBTC may exacerbate the Parkinson's symptoms because of the inhibition of dopamine biosynthesis and dopamine increase induced by L-DOPA.