Palmatine, a Bioactive Protoberberine Alkaloid Isolated from Berberis cretica, Inhibits the Growth of Human Estrogen Receptor-Positive Breast Cancer Cells and Acts Synergistically and Additively with Doxorubicin

Palmatine (PLT) is a natural isoquinoline alkaloid that belongs to the class of protoberberines and exhibits a wide spectrum of pharmacological and biological properties, including anti-cancer activity. The aim of our study was to isolate PLT from the roots of Berberis cretica and investigate its cytotoxic and anti-proliferative effects in vitro alone and in combination with doxorubicine (DOX) using human ER⁺/HER2⁻ breast cancer cell lines. The alkaloid was purified by column chromatography filled with silica gel NP and Sephadex LH-20 resin developed in the mixture of methanol: water (50:50 v/v) that provided high-purity alkaloid for bioactivity studies. The purity of the alkaloid was confirmed by high resolution mass measurement and MS/MS fragmentation analysis in the HPLC-ESI-QTOF-MS/MS-based analysis. It was found that PLT treatment inhibited the viability and proliferation of breast cancer cells in a dose-dependent manner as demonstrated by MTT and BrdU assays. PLT showed a quite similar growth inhibition on breast cancer cells with IC₅₀ values ranging from 5.126 to 5.805 µg/mL. In contrast, growth of normal human breast epithelial cells was not affected by PLT. The growth inhibitory activity of PLT was related to the induction of apoptosis, as determined by Annexin V/PI staining. Moreover, PLT sensitized breast cancer cells to DOX. Isobolographic analysis revealed synergistic and additive interactions between studied agents. Our studies suggest that PLT can be a potential candidate agent for preventing and treating breast cancer.

Palmatine hydrochloride mediated photodynamic inactivation of breast cancer MCF-7 cells: Effectiveness and mechanism of action

Breast cancer is one of the commonest malignant tumors threatening to women. The present study aims to investigate the effect of photodynamic action of palmatine hydrochloride (PaH), a naturally occurring photosensitizer isolated from traditional Chinese medicine (TCM), on apoptosis of breast cancer cells. Firstly, cellular uptake of PaH in MCF-7 cells was measured and the cytotoxicity of PaH itself on breast cancer MCF-7 cells was estimated using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Subcellular localization of PaH in MCF-7 cells was observed using confocal laser scanning microscopy (CLSM). For photodynamic treatment, MCF-7 cells were incubated with PaH and then irradiated by visible light (470nm) from a LED light source. Photocytotoxicity was investigated 24h after photodynamic treatment using MTT assay. Cell apoptosis was analyzed 18h after photodynamic treatment using flow cytometry with Annexin V/PI staining. Nuclear was stained using Hoechst 33342 and observed under a fluorescence microscope. Intracellular production of reactive oxygen species (ROS) was studied by measuring the fluorescence of 2, 7-dichlorofluorescein (DCF) using a flow cytometry. Results showed that PaH treatment alone had no or minimum cytotoxicity to MCF-7 cells after incubation for 24h in the dark. After incubation for 40min, the cellular uptake of PaH reached to the maximum, and PaH mainly located in mitochondria and endoplasmic reticulum of MCF-7 cells. Photodynamic treatment of PaH demonstrated a significant photocytotoxicity on MCF-7 cells, induced remarkable cell apoptosis and significantly increased intracellular ROS level. Our findings demonstrated that PaH as a naturally occurring photosensitizer induced cell apoptosis and significantly killed MCF-7 cells.

Simultaneous determination of corynoline and acetylcorynoline in human urine by LC-MS/MS and its application to a urinary excretion study

Corynoline and acetycorynoline, the major active components derived from Corydalis bungeana Herba, showed multiple pharmacological activities. However, quantification of the two compounds in human urine has not been reported. A simple liquid chromatography with tandem mass spectrometry method for the simultaneous determination of corynoline and acetycorynoline in human urine has been developed and fully validated. The analytes were extracted from urine samples by simple liquid-liquid extraction. Chromatographic separation was achieved on a Hedera ODS-2C18 column with the mobile phase of water (containing 0.5% formic acid) and acetonitrile (28:72, v/v) at a flow rate of 0.4mL/min. A tandem mass spectrometric detection was conducted using multiple reaction monitoring via an electrospray ionization source in positive mode. The monitored ion transitions were m/z 368.1→289.1 for corynoline, m/z 410.2→289.2 for acetycorynoline and m/z 380.2→243.2 for donepezil (internal standard), respectively. The calibration curves were linear (correlation coefficients>0.9970) over the concentration ranges of 3.0-3000pg/mL for corynoline and 3.0-1000pg/mL for acetycorynoline. The established method was highly sensitive with the lower limit of quantification (LLOQ) of 3.0pg/mL for both analytes. The intra- and inter-day precision was lower than 10% in terms of relative standard deviation for the low, medium, and high quality control samples, and lower than 16% for the LLOQ samples of the analytes. The accuracy was within ±10% in terms of relative error for both analytes. The method was successfully applied to a urinary excretion study after oral administration of the Chinese medicine formula Shuanghua Baihe tablets in healthy volunteers. The urinary excretion profiles of corynoline and acetycorynoline in human were first reported. The results of this study suggest that renal excretion was not the main excretion pathway of corynoline and acetycorynoline in humans.

Influence of Palmatine on Bone Metabolism in Ovariectomized Mice and Cytokine Secretion of Osteoblasts

BACKGROUND/AIM

Receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG), regulate the cognate receptor RANK on osteoclast precursor cells. Herein we examined the inhibitory effects of palmatine on bone metabolism using ovariectomized (OVX) mice.

MATERIALS AND METHODS

The first experimentaI set was designed to histologically and biochemically examine mice randomly divided into four groups: sham-operated, OVX, and OVX-palmatine intake groups (1 mg/kg and 10 mg/kg). The second experimental set examined the influence of palmatine on osteoblast-like cells in vitro.

RESULTS

Palmatine caused significant suppression of osteoclast numbers in tissues. In palmatine-treated mice, RANKL and OPG expression decreased. In the culture supernatant of MC3T3-E1 cells, RANKL and OPG levels were significantly reduced by palmatine addition.

CONCLUSION

Palmatine may attenuate osteoclast differentiation through inhibition of RANKL and OPG expression by osteoblasts. Therefore, palmatine might be a candidate anti-resorptive agent for osteoporosis therapy.

[Study on effect of oligochitosan in promoting intestinal absorption of protoberberine alkaloids in extracts from Corydalis saxicola total alkaloids]

OBJECTIVE

To investigate the effect of oligochitosan in promoting intestinal absorption of protoberberine alkaloids in extracts from Corydalis saxicola total alkaloids.

METHOD

The in vitro single-pass intestinal perfusion model in rats was established to study the changes in absorption kinetic parameters of dehydrocavidine, berberine hydrochloride and palmatine chloride in C. saxicola total alkaloids after the addition of different concentrations oligochitosan and evaluate the effect of oligochitosan in promoting intestinal absorption of the drugs.

RESULT

The concentration of oligochitosan had different effects on the absorption rate constant (Ka) and apparent permeability coefficient (Peff) of the three active component in rat intestines. Ka and Peff in 0.5% oligochitosan group significantly increased, indicating a stronger effect in promoting the absorption.

CONCLUSION

Oligochitosan has a certain effect in promoting the intestinal absorptions of protoberberine alkaloids in C. saxicola total alkaloids.

Integrated pharmacokinetics of five protoberberine-type alkaloids in normal and insomnic rats after single and multiple oral administration of Jiao-Tai-Wan

ETHNOPHARMACOLOGICAL RELEVANCE

Jiao-Tai-Wan (JTW), an important herbal formula consists of Rhizoma coptidis and Cortex cinnamomi powder, is a famous prescription which has been used for centuries to treat insomnia in Traditional Chinese Medicine. The purpose of this study is to compare the pharmacokinetic properties of five protoberberine-type alkaloids (i.e. berberine, palmatine, coptisine, epiberberine and jatrorrhizine), the main bioactive constituents in JTW, between normal and insomnic rats. We also investigate the differences between single-dose and multiple-dose pharmacokinetics of five protoberberine-type alkaloids.

MATERIALS AND METHODS

The insomnic rat models were induced by intraperitoneal injection of one-dose para-chlorophenylalanine acid (PCPA). Quantification of five protoberberine-type alkaloids in rat plasma was achieved by using a rapid LC-MS/MS method. Plasma samples were collected at different time points to construct pharmacokinetic profiles by plotting drug concentration versus time and estimate pharmacokinetic parameters. An unpaired Student׳s t test was used for comparisons with SPSS 17.0.

RESULTS

The five protoberberine-type alkaloids of single-dose normal groups had slow absorption and low bioavailability, as well as a delay of peak time. In the single-dose oral administration, the Cmax and Tmax of five ingredients in insomnic rats had significant differences compared with those of normal rats. In the multiple-dose oral administration, the pharmacokinetic parameters of five protoberberine-type alkaloids varied greatly in insomnic rats. In the normal rats, there were significant differences (P<0.05) in the principal pharmacokinetic parameters such as Cmax and Tmax between single-dose and multiple-dose oral administration. In the insomnic rats, the five ingredients of multiple-dose groups showed better absorption than the single-dose groups. Particularly, three peaks were observed in multiple-dose model group of plasma-concentration curves.

CONCLUSIONS

The pharmacokinetic behavior of five protoberberine-type alkaloids was described in this paper. In both normal groups and model groups, the pharmacokinetic behavior of multiple-dose had significant differences comparing with the single-dose; either single-dose or multiple-dose, the pharmacokinetic behavior of insomnic rats had significant differences comparing the normal rats. Multiple dosing may improve the absorption of JTW in insomnic rats, which will increase the bioavailability and bring into active role in therapeutical effect.

Pharmacochemistry and integrated pharmacokinetics of six alkaloids after oral administration of huang-lian-jie-du-tang decoction

Pharmacochemistry and integrated pharmacokinetics of six alkaloids (groenlandicine, berberine, palmatine, epiberberine, jatrorrhizine, and columbamine) after oral administration of Huang-Lian-Jie-Du-Tang (HLJDT) decoction were investigated in this paper. The method of plasma pharmacochemistry was applied to predict the potential bioactive components in HLJDT decoction. Based on the accurate molecular weight, 10 components including 2 flavonoids (baicalin and wogonoside), 1 iridoid glycoside (geniposide), and 7 alkaloids (above-mentioned 6 alkaloids and coptisine) were structurally identified. Then, integrated pharmacokinetics of the alkaloids in Sprague-Dawley rats after oral administration of HLJDT decoction was investigated by HPLC method. The results showed that the pharmacokinetic behaviors of the alkaloids were different although their chemical structures were similar. This study developed a method to predict the potential bioactive components in HLJDT decoction and research the pharmacokinetic behaviors of the potential bioactive components.

Extraction optimization of Tinospora cordifolia and assessment of the anticancer activity of its alkaloid palmatine

OBJECTIVE

To optimize the conditions for the extraction of alkaloid palmatine from Tinospora cordifolia by using response surface methodology (RSM) and study its anticancerous property against 7,12-dimethylbenz(a)anthracene (DMBA) induced skin carcinogenesis in Swiss albino mice.

METHODS

The effect of three independent variables, namely, extraction temperature, time, and cycles was investigated by using central composite design. A single topical application of DMBA (100 μg/100 μL of acetone), followed 2 weeks later by repeated application of croton oil (1% in acetone three times a week) for 16 weeks, exhibited 100 percent tumor incidence (Group 2).

RESULTS

The highest yield of alkaloid from Tinospora cordifolia could be achieved at 16 hours of extraction time under 40°C with 4 extraction cycles. Alkaloid administration significantly decreases tumor size, number, and the activity of serum enzyme when compared with the control (Group 2). In addition, depleted levels of reduced glutathione (GSH), superoxide dismutase (SOD), and catalase and increased DNA damage were restored in palmatine treated groups.

CONCLUSION

The data of the present study clearly indicate the anticancer potential of palmatine alkaloid in DMBA induced skin cancer model in mice.

[Study on effects of Corydalis yanhusuo and L-THP on dopamine of reward circuitry in conditioned place preference rats and comparison]

OBJECTIVE

To study and compare the effect of Corydalis yanhusuo and L-THP on dopamine neurotransmitter and D2 receptor of reward circuitry in various cerebral areas of conditioned place preference model rats and the comparison of their effects.

METHOD

The CPP model was established by injecting morphine in rats with increasing doses for 10 days. The initial dose of 10 mg x kg(-1), and the final dose of 100 mg x kg(-1), with 10 mg x kg(-1) increased each day. At 48 h after the final training, CPP was adopted to detect the successful establishment of the model. On the same day (12 d), they were orally administered with 2, 1, 0.5 g x kg(-1) C. yanhusuo (containing 0.153, 0.077 and 0.038 mg L-THP) and L-THP (3.76, 1.88, 0.94 mg x kg(-1)) for six days. On 18 d, CPP test was performed again. Next day, HPLC was adopted to determine the content of dopamine neurotransmitters of reward circuitry in VTA-NAc-PFC; Immunohistochemistry and Western blotting were adopted to detect the expression of D2 receptors.

RESULT

Compared with the physiological saline treatment group, C. yanhusuo (2, 1 g x kg(-1)) and L-THP (3.76, 1.88 mg x kg(-1)) groups showed that rats stayed in a notably shorter period in white boxes (morphine-accompanied boxes) (P < 0.01 or P < 0.05), and revealed a remarkably lower dopamine content in VTA, NAc and PFC and the significant increase in the expression of D2 receptor (P < 0.01 or P < 0.05).

CONCLUSION

The down-regulation of the increased dopamine content in reward nervous circuitry and the up-regulation of the expression of D2 receptor may be one of mechanisms of C. yanhusuo and L-THP in accelerating the recession of morphine's CPP effect Regarding the inhibition of morphine's CPP effect and the effect on dopamine system, the effect of C. yanhusuo traditional Chinese medicine containing one-fold L-THP monomer is equal to that of the independent application of around 24-fold L-THP monomer.

[Study on in vitro release and percutaneous absorption for Zhitong cataplasm]

To evaluate in vitro release and transdermal behaviors of Zhitong cataplasm, modified Franz diffusion cell method was applied to investigate in vitro transdermal absorption of Zhitong cataplasm and the content of tetrahydropalmatine was determined by HPLC. In 24 hours, accumulative release rate of tetrahydropalmatine was 81. 9%, transmission rate was 2.26 microg x cm(-2) x h(-1). In 48 hours, accumulative transdermal rate and transmission rate of tetrahydropalmatine were 20.31%, 0.22 pg x cm(-2) x h(-1). So Zhitong cataplasm had a good release and transdermal properties and transdermal actions were consistent with zero-order kinetics process.

[Tetrahydropalmatine's permeative properties of acupoint and non-acupoint transdermal administration of Baijiezi Tufang in vitro and in vivo]

OBJECTIVE

To study tetrahydropalmatine's permeative properties of acupoint and non-adupoint transdermal administration of baijiezi tufang in vitro and in vivo.

METHOD

Taking tetrahydropalmatine as an evaluative component to assess the permeative of baijiezi tufang in acupoint skin and non-acupoint skin with the modified Franz diffusion cell method and in vivo penetration studies. The content of tetrahydropalmatine was determined by a HPLC method.

RESULT

The 24 hours cumulative permeation amount through acupoint skin was (13.53 +/- 3.92) microg x cm(-2), about 4 times higher than non-acupoint skin. The steady-state infiltration rates of tetrahydropalmatine in acupoint skin was (0.659 1 microg x cm(-2) x h(-1)), 4.5 times higher than non-acupoint skin. The content in acupoint skin was signally higher than that in non-acupoint skin (P < 0.05). An accumulation of fluorescence can be clearly seen in the four layers: stratum corneum > viable epidermis > dermis > subcutaneous.

CONCLUSION

In vitro and in vivo studies show that the permeation of baijiezi tufang in acupoint skin was better than in non-acupoint skin, following a higher cumulative amount and skin content.

Correlation between rheological properties, in vitro release, and percutaneous permeation of tetrahydropalmatine

The aim of the present work was to investigate the influence of formulation factors including different grades of Carbopol® matrices and penetration enhancers on the percutaneous permeation of tetrahydropalmatine (THP), rheological properties, and in vitro release; and the correlation behind rheological properties, in vitro release, and percutaneous permeation. Transdermal penetration of THP through excised rabbit skin and in vitro release of THP across transparent Cellophane® were performed by vertical Franz diffusion cell. Rheological analyses were proceeded in terms of "steady flow tests", "oscillation stress sweep", and "creep recovery". The result of percutaneous penetration of THP indicated that, the emulgel prepared with Carbopol® 971P (Cp 971P) as the matrix and N-methyl-2-pyrrolidone (NMP) as the penetration enhancer had the highest cumulative permeation amount (118.19 μg/cm(2)). All the experimental data showed a good fit to the Casson model in viscosimetric studies no matter what the types of matrices or the kinds of penetration enhancers were. The release profile fitted the zero-order release kinetics model with Cp 971P as the matrix without any penetration enhancers. However, when adding penetration enhancers, in vitro release of THP presented anomalous (non-Fickian) release kinetics. Clarifying the relationship behind percutaneous permeation of THP, rheological properties, and in vitro release will provide us with profound insights and facilitate the design of specific emulgel.

[Enhancing effect of volatile oils of rhizoma zingiberis, flos magnoliae and fructus litseae on permeation of rotundine in vitro]

OBJECTIVE

To investigate the enhancing effect of volatile oils of Rhizoma Zingiberis (RZ), Flos Magnoliae (FM), Fructus Litseae (FL), Azone and pairwise combinations on the permeation of Rotundine in vitro.

METHODS

To screen out the volatile oils with the best percutaneous enhancing effect on Rotundine, a test of penetration through rats skin was conducted by using an improved Franz diffusion cell. The accumulative penetration amount of Rotundine was determined by UV and HPLC.

RESULTS

All of the 3 volatile oils had enhancing effect on Rotundine permeation. The average accumulative doses of Rotundine for 8 hours (Q8, mg/cm2) of 5% volatile oil of FL, 5% volatile oil of, RZ, 2.5% FL + 2.5% Azone were 6.0758, 6.1148, 6.5487, the enhancement ratios of 4 hours were 1.01, 1.00, 1.13 respectively.

CONCLUSION

2.5% FL + 2.5% Azone had the best effect of percutaneous enhancing on Rotundine.

[Study on vitro release and transdermal behaviors of Yulian cataplasm]

OBJECTIVE

To investigate the regularity of Yulian Cataplasm in vitro release and transdermal behaviors.

METHOD

Improved Franz diffusion devices was used with four index ingredients as evodiamine, rutaecarpine, palmatine and berberine that were determined by HPLC in one mobile phase.

RESULT

The release rates of evodiamine, rutaecarpine, palmatine and berberine were 0.0239, 0.0156, 0.0725, 0.8191 mg x cm(-2) x h(-1/2), respectivley. The transdermal rates of evodiamine, rutaecarpine, palmatine and berberine were 1.256, 1.0302, 2.8029, 20.919 microg x cm(-2) x h(-1), respectively.

CONCLUSION

The releasing process of all index is in accordance with Higuchi equation and the transdermal proccess is in accordance with zero-level equation.

Acetylcholinesterase and butyrylcholinesterase inhibitory compounds from Corydalis cava Schweigg. & Kort

In the course of screening plants used in Danish folk medicine as memory enhancers, a crude methanolic extract of tubers from Corydalis cava showed significant acetylcholinesterase inhibitory activity in a dose-dependent manner. Activity guided fractionation of the methanolic extract resulted in the isolation of three alkaloids, bulbocapnine (1), corydaline (2) and corydine (3) as active constituents. Bulbocapnine inhibited acetylcholinesterase as well as butyrylcholinesterase in a dose-dependent manner with IC(50) values of 40+/-2 microM and 83+/-3 microM, respectively. Corydaline inhibited acetylcholinesterase in a dose-dependent manner with an IC(50) value of 15+/-3 microM and corydine inhibited butyrylcholinesterase in a dose-dependent manner with an IC(50) value of 52+/-4 microM. Corydaline was considered inactive against butyrylcholinesterase and corydine against acetylcholinesterase, due to IC(50)>100 microM.

Levo-tetrahydropalmatine attenuates cocaine self-administration and cocaine-induced reinstatement in rats

RATIONALE

Levo-tetrahydropalmatine (l-THP) is an alkaloid constituent of plants from the botanical genera Corydalis and Stephania and is contained in many traditional Chinese herbal preparations. In addition to its low-affinity antagonism of D2 dopamine (DA) receptors, we report that l-THP functions as a higher-affinity antagonist at D1 DA receptors and interacts with D3 DA receptors, suggesting that it may be effective for the treatment of drug addiction. Accordingly, l-THP has been reported to reduce heroin craving and relapse in recovering addicts.

OBJECTIVE

This study investigated the effects of l-THP (3.75, 7.5, and 15.0 mg/kg, i.p.) on cocaine self-administration (SA) and cocaine-induced reinstatement.

MATERIALS AND METHODS

Rats were trained to self-administer cocaine and food by pressing separate response levers during sessions consisting of a multiple schedule of alternating 30-min FR4 cocaine and 15-min FR4 food reinforcement. During the cocaine components of each session, the available cocaine dose varied such that rats had access to low and high dose ranges in varying sequence on alternating days. After SA, cocaine-reinforced responding was extinguished, and effects of l-THP on cocaine-induced reinstatement (10 mg/kg, i.p.) were examined.

RESULTS

l-THP produced a rightward and downward shift in the dose-response curve for cocaine SA and attenuated cocaine-induced reinstatement. l-THP also reduced food-reinforced responding and locomotor activity. However, reductions in cocaine SA were found at doses that failed to alter food-reinforced responding, and significant effects were not observed on food responding during reinstatement.

CONCLUSIONS

These findings suggest that l-THP is potentially useful for treating cocaine addiction.

Brain pharmacokinetics and tissue distribution of tetrahydropalmatine enantiomers in rats after oral administration of the racemate

Tetrahydropalmatine (THP), a racemic mixture, is a biologically active ingredient isolated from a traditional Chinese herb Rhizoma Corydalis (yanhusuo). The main objective of this study was to determine the brain pharmacokinetics and tissue distribution of THP enantiomers in rats after oral administration of racemic THP (rac-THP). Rats (5 animals/group/per time) were given a single oral dose of rac-THP and killed after different post-treatment times. The concentrations of THP enantiomers in plasma, cortex, cerebellum, diencephalon, brain stem, striatum and hippocampus were measured using a validated chiral high performance liquid chromatographic (HPLC) method coupled with an achiral column. The pharmacokinetic profiles of the two enantiomers in six brain regions were significantly different. The peak concentrations (Cmax) and AUC(0-infinity) values of the (-)-enantiomer were significantly greater than the corresponding values for the (+)-enantiomer while the striatum contained the highest peak concentrations compared with the plasma and other brain regions. The tissue distribution studies also revealed significant differences between the two enantiomers in all tissues except the lung. The highest concentrations of both enantiomers were found in the liver. The (-)/(+)-THP ratios in six brain regions and other tissues were consistent with that observed in plasma indicating that the stereoselective disposition of THP in rat brain and other tissues reflects the situation in plasma.

[Effect of l-tetrahydropalmatine on expression of adhesion molecules induced by lipopolysaccharides in human umbilical vein endothelium cell]

OBJECTIVE

To investigate the effect of l-tetrahydropalmatine (l-THP) on adhesion molecule expression induced by LPS in human umbilical vein endothelium cell (HUVEC).

METHOD

HUVEC were obtained from the human umbilical cord vein and treated by LPS or LPS plus different concentration of l-THP. Expression of ICAM-1 and E-selectin was assayed by flow cytometer.

RESULT

l-THP(250 mg x L(-1)) markedly attenuated ICAM-1 and E-selectin expression induced by LPS(P <0.05). l-THP(50 mg x L(-1) inhibited E-selectin expression (P < 0.05) but had no effect on ICAM-1 (P > 0.05). l-THP (10 mg x L(-1)) had no effect on expression of both adhesion molecules. DXM (50 mg x L(-1)) completely inhibited both responses induced by LPS (P < 0.05).

CONCLUSION

l-THP depresses expression of ICAM-1 and E-selectin induced by LPS, which suggests that I-THP represent a promising candidate to be developed into therapies for the treatment of inflammation.

Effects of l-tetrahydropalmatine on locomotor sensitization to oxycodone in mice

AIM

Recent studies have shown that l-tetrahydropalmatine (l-THP), an active component of Corydolis yanhusuo, can inhibit the development of the conditional place preference induced by opioid receptor agonists, but the effects of l-THP on locomotor sensitivity induced by opioid receptor agonists have not been documented. In the present study, the effects of l-THP on locomotor sensitization to oxycodone, which is an opioid receptor agonist, were studied.

METHODS

Mice treated daily for 7 d with 5 mg/kg oxycodone and challenged with the same dose after 5 days of washout showed locomotor sensitization. In order to study the effects of l-THP on locomotor sensitization induced by oxycodone, l-THP was administered at doses of 6.25, 12.5, and 18.75 mg/kg, 40 min prior to treatment of oxycodone.

RESULTS

l-THP per se did not affect the locomotor activity at the doses of 6.25, 12.5, and 18.75 mg/kg, but could antagonize the hyperactivity induced by oxycodone (5 mg/kg). Co-administration of l-THP (18.75 mg/kg), 40 min prior to oxycodone, could inhibit the development of sensitization to oxycodone. In addition, l-THP (6.25, 12.5, and 18.75 mg/kg, i.g.) dose-dependently prevented the expression of oxycodone sensitization.

CONCLUSION

These results suggested that l-THP could attenuate the locomotor-stimulating effects of oxycodone and inhibit the development and expression of oxycodone behavioral sensitization.

Stereoselective pharmacokinetics of tetrahydropalmatine after oral administration of (?)-enantiomer and the racemate

Tetrahydropalmatine (THP) is a biologically active ingredient isolated from a traditional Chinese herb Rhizoma corydalis (yanhusuo). THP is a racemic mixture which contains 50% of the (+) and 50% of (-) enantiomer. The (-) enantiomer accounts for most of the analgesic effects. Plasma concentrations of THP enantiomers were analyzed by chiral high-performance liquid chromatography (HPLC) on a Chiralcel OJ column with quantification by UV at 230 nm. The method was used to determine the pharmacokinetics of THP enantiomers in rats and dogs after oral administration of rac-THP or (-)-THP. The pharmacokinetic profiles of the two enantiomers after dosing with rac-THP were significantly different both in rats and dogs. The mean C(max) and AUC(0-infinity) values in rats were 1.93 +/- 0.36 microg/ml and 6.65 +/- 2.34 microg x h/ml for the (-) enantiomer, and 1.11 +/- 0.25 microg/ml and 2.03 +/- 0.45 microg x h/ml for the (+) enantiomer. The mean C(max) and AUC(0-infinity) in dogs were 1.60 +/- 0.81 microg/ml and 9.88 +/- 2.58 microg x h/ml for the (-) enantiomer, while 0.36 +/- 0.21 microg/ml and 1.22 +/- 0.40 microg x h/ml for the (+) enantiomer. rac-THP at 40 mg/kg and (-)-THP at 20 mg/kg had very similar plasma concentration-time profiles, and C(max), AUC(0-infinity), and t(1/2) of the (-) enantiomer in both rats and dogs, indicating that the two treatments were equivalent with respect to the pharmacokinetic properties of the (-) enantiomer.

Antimicrobial activity ofMahonia aquifoliumcrude extract and its major isolated alkaloids

The crude extract of Mahonia aquifolium (Pursh) Nutt. stem bark and its two main protoberberine alkaloids, berberine and jatrorrhizine, were tested for their in vitro antimicrobial activity. Twenty strains of coagulase-negative staphylococci and 20 strains of Propionibacterium acnes isolated from skin lesions of patients with a severe form of acne, and 20 strains of Candida sp. isolated from chronic vulvovaginal candidoses were tested for their susceptibility to crude extract and two isolated alkaloids. The minimum inhibitory concentrations obtained in this study illustrate the varying degrees of antibacterial and antifungal activity of the tested agents. The results indicate a rational basis for the traditional use of Mahonia aquifolium for localized skin and mucosal infection therapy, as well as for the possible development of a preparation for supportive therapy of the diseases mentioned above.

Antifungal activity of Mahonia aquifolium extract and its major protoberberine alkaloids

The crude extract of Mahonia aquifolium (Berberidaceae) stem bark and its components berberine, palmatine and jatrorrhizine were screened for their inhibitory activity against a variety of dermatophytes and two Candida species of human origin using the in vitro dilution agar plate method. Jatrorrhizine was found to be the most effective against all fungal species tested (MIC ranges from 62.5 to 125 micro g/mL), while the crude extract, berberine, and palmatine exhibited only marginal activity (MIC 500 to >/= 1000 micro g/mL). Dermatophytes were more susceptible to jatrorrhizine than yeasts, and Scopulariopsis brevicaulis appeared the least sensitive species to all the compounds tested. The effects of the alkaloids were compared with those of fluconazole and bifonazole for which the MIC ranges were 12.5 to >100 micro g/mL. Our results suggest that jatrorrhizine may serve as a leading compound for further studies to develop new antifungal agents with highly potent antifungal activity and low host toxicity.

Anxiolytic-like action of orally administered dl-tetrahydropalmatine in elevated plus-maze

dl-Tetrahydropalmatine (dl-THP), a naturally occurring alkaloid, has been intensively studied for its sedative and hypnotic effects. Putative explanation for its mechanism and target of action involves the dopaminergic neurotransmission system. In view of the close interactions between the dopaminergic and the GABAergic neurons in the amygdala, pharmacological effects of dl-THP were tested for activity at the GABAA receptor benzodiazepine site (BDS). Effects of dl-THP were examined in mice employing the elevated plus-maze, the holeboard and the horizontal-wire tests. In the elevated plus-maze, mice treated with low doses of dl-THP (0.5-10 mg/kg) exhibited significant increase in the percentage of entries and time spent in open arms without altering the number of closed-arm entries when compared to the control group, indicative of its selective anxiolytic effect. In the holeboard and horizontal wire tests, where exploratory behavior and potential muscle relaxant effect were assessed, respectively, only mice treated with as much as 50 mg/kg dl-THP manifested sedation and myorelaxation, as observed in the significant decrease in the number of head dips and the decrease in the percentage of mice grasping wire in comparison to control. Notably, coadministration of the BDS antagonist flumazenil abolished the dl-THP-induced anxiolysis as seen in the reversal of the increase of both the number of entries and time spent in open arms back to basal levels in the elevated plus-maze test. The results suggest that dl-THP at defined low dosages acts as anxiolytics in mice, and the BDS mediates, at least in part, such anxiolytic effect of dl-THP.

Suppression of experimental autoimmune tubulointerstitial nephritis in BALB/c mice by berberine

Berberine (BB) is a protoberberine alkaloid derived from various representatives of the Berberidaceae family. Although used as a therapeutic agent, it has not been applied in the treatment of immune-mediated disorders. In the present study, BB was administered at a daily dose of 10 mg/kg for 3 consecutive days before the induction of tubulointerstitial nephritis (TIN) by injection of bovine tubular basement membrane (TBM) antigen in BALB/c mice. The animals were investigated 2 months after TBM inoculation. The intensity of pathological injuries in animals with TIN+BB decreased significantly, an effect that correlated with the improvement of renal function. Flow cytometric analysis of peripheral blood cells showed that BB caused a decrease in the number of CD3(+), CD4(+), CD8(+), and sIg(+) lymphocytes in comparison with TIN mice. The same tendency was noticed in the lymphocytes from kidney infiltrates of treated animals. The control animals treated only with BB showed a decrease in the number of CD3(+), CD4(+), CD8(+) T-lymphocytes in comparison with control nontreated mice. Our results, thus, indicate that BB has an immunosuppressive effect in the TIN model, which is an analogue of various human kidney autoimmune diseases.

DL-tetrahydropalmatine-produced hypotension and bradycardia in rats through the inhibition of central nervous dopaminergic mechanisms

The effects of DL-tetrahydropalmatine (THP; a main active substance of the Chinese herb corydalis), haloperidol (a dopamine D2 receptor antagonist), apomorphine and amphetamine on cardiovascular function and striatal dopamine (DA) release were compared in rats under general anesthesia. Intravenous administration of THP (1-10 mg/kg) or haloperidol (0.5-1.25 mg/kg) produced hypotension, bradycardia and increased DA release in the striatum. On the other hand, amphetamine (0.5-1.25 mg/kg) produced hypertension, tachycardia and increased striatal DA release. However, intravenous injection of apomorphine (0.5-1.25 mg/kg) produced hypotension, bradycardia and decreased striatal DA release. In addition, the THP-induced hypotension was attenuated by pretreatment with spinal transection or amphetamine, while the THP-induced bradycardia was attenuated by pretreatment with bilateral vagotomy or amphetamine. Thus, it appears that THP acts through DA D2 receptor antagonism to induce hypotension and bradycardia in rats.

Effects of palmatine on motor activity and the concentration of central monoamines and its metabolites in rats

We used behavioral and biochemical methods to investigate the sedative effect of palmatine on locomotor activity and the concentration of monoamine in rats. It was found that palmatine enhanced the hypomotility induced by alpha-methyl-p-tyrosine, reserpine and 5-hydroxytryptophan, but reduced the hypermotility produced by L-dopa plus benserazide and p-chlorophenylalanine. Furthermore, palmatine significantly decreased the concentration of dopamine and homovanillic acid in the cortex and the concentration of serotonin in the brain stem, and it increased the concentration of 5-HT in the cortex and 5-hydroxyindole acetic acid in the brain stem. These results suggest that the sedative mechanism of palmatine may be related to the decrease in the concentration of catecholamine in the cortex and serotonin in brain stem and the increase in the concentration of 5-HT in the cortex.

l-tetrahydropalmatine increases leucine enkephalin levels in corpus striatum of rats

The effect of chronic l-tetrahydropalmatine (l-THP) administration on the level of leucine enkephalin (Leu-Enk) in rat corpus striatum was studied. After l-THP sc injection once daily for 2 wk, the striatal Leu-Enk level was elevated dose-dependently. However, a single injection of l-THP failed to change the Leu-Enk level. When rats received sc Sch-23390, a selective D1 antagonist, 15 nmol.kg-1 tid for 2 wk, striatal content of Leu-Enk increased from 0.17 +/- SD 0.03 ng.mg-1 tissue in control group to 0.23 +/- SD 0.05 ng.mg-1 tissue in Sch-23390 group (n = 8, P less than 0.05). Sulpiride (Sul), a selective D2 antagonist, 140 mumol.kg-1 sc given bid for 2 wk had no significant effect on the striatal Leu-Enk content. The results suggested that the blockade of D1 receptors by l-THP might be responsible for the increase of the striatal Leu-Enk content in rat.

The disposition of coralyne sulphoacetate in rodents

1. The disposition of (14C) coralyne sulphoacetate has been examined in the mouse and rat at three dose levels. 2. In both species the major route of excretion is biliary following either intraperitoneal or intravenous administration. In rats, 18-24% of the 14C is eliminated in the bile in the first 24 h and only 1-2% in the urine. Transport into bile appears to be active and the transport system saturable at the doses employed. 3. The majority of the biliary 14C in the rats is unchanged parent compound and a minority is associated with a metabolite. The maximum amount of metabolite is 12% at 10-30 min following the administered dose. 4. The initial plasma decay of (14C) coralyne following intravenous administration is rapid. Half-life values are 12-3, 16-2 and 2-41 min after doses of 13, 26 and 52 mg/kg respectively. 5. No sex differences were found in the rat in the parameters studied.