Tetrahydroberberine Research Articles

Enantioseparation and quantitative analysis of three alkaloids in Rhizoma Corydalis by chiral LC-MS/MS

A chiral liquid chromatography-mass spectrometry (LC-MS/MS) approach was developed and verified for the first time in order to quantify the three alkaloids, namely tetrahydropalmatine (THP), tetrahydroberberine (THB) and tetrahydrocoptisine (THC) in Rhizoma Corydalis. Solid-phase extraction was used to prepare sample solution. Enantiomeric separation was obtained on a Chiralpak IC column using acetonitrile-water-ammonia (90:10: 0.1, v/v/v) as mobile phase. The detection was carried out in multiple reaction monitoring (MRM) mode with positive electrospray ionization source. Transitions of m/z 356.0→192.0, m/z 340.0→176.0 and m/z 324.1→176.0 were monitored for THP, THB and THC respectively. All calibration curves showed good linearity (r2 ≥0.9994) within the test ranges. The lower limit of quantification (LLOQ) was 1.0 ng mL−1 and 1.5 ng mL−1 for (+)- and (−)-THP, 1.0 ng mL−1 and 3.0 ng mL−1 for (+)- and (−)-THB, 1.5 ng mL−1and 1.8 ng mL−1 for (+)- and (−)-THC, respectively. The precision, repeatability, and stability tests all meet the requirements. The average recoveries of the analytes ranged from 98.9 % to 101.3 %. Ultimately, the established method was successfully applied to the quantitative analysis of these alkaloid enantiomers extracted from Rhizoma Corydalis of different habitats.

Synthesis of new dihydroberberine and tetrahydroberberine analogues and evaluation of their antiproliferative activity on NCI-H1975 cells.

Dihydroberberine (DHBER), the partially reduced form of the alkaloid berberine (BER), is known to exhibit important biological activities. Despite this fact, there have been only few studies that concern the biological properties of functionalized DHBER. Attracted by the potentiality of this latter compound, we have realized the preparation of new arylhydrazono-functionalized DHBERs, starting from BER and some α-bromohydrazones. On the other hand, also the fully reduced form of BER, namely tetrahydroberberine (THBER), and its derivatives have proven to present different biological activities. Therefore, the obtained arylhydrazono-functionalized DHBERs were reduced to the corresponding arylhydrazono-THBERs. The antiproliferative activity of both arylhydrazono-DHBERs and -THBERs has been evaluated on NCI-H1975 lung cancer cells.

Pharmaceutical salt of tetrahydroberberine with sulfamic acid prepared via CAHBs

In order to further explore the role of Charge-assisted hydrogen bonds (CAHBs) recognition in the formation of tetrahydroberberine (THB) pharmaceutical salt/cocrystal, based on the analysis of the molecular interactions in forming unit pharmaceutical salts/cocrystal of THB and sulfophenyl acids, we speculate that hydroxyl group of sulfamic acid (SA) may cocrystallize with N atom on the quinoline ring of THB via CAHBs. Consequently, an unreported pharmaceutical salt (C20H22NO4·NH2SO3, THB-SA) of the THB was designed and synthesized. The THB-SA was characterized by single crystal X-ray diffraction, XRPD and TG methods. As expected, structure analysis of the THB-SA revealed that the THB molecule binds to the SA molecule precisely through CAHBs (N+-H···O−) between the N atom on the quinoline ring and sulfonic acid group of SA in asymmetric unit of THB-SA. This successfully implemented work implies that in the preparation of THB pharmaceutical salts/cocrystals, cocrystal formers (CCFs) that can form CAHBs with THB should be selected, which will provide a facilitate way to prepare THB pharmaceutical salts/cocrystals.

Tetrahydroberberine pharmaceutical salts/cocrystals with dicarboxylic acids: Charge-assisted hydrogen bond recognitions and solubility regulation

With our consistent aim to further expand the solid-state landscape via molecular recognition and regulate solubility of tetrahydroberberine (THB), charge-assisted hydrogen bond (CAHB) recognitions and solubility regulation of pharmaceutical salts/cocrystals of THB are comprehensively investigated through exploring four pharmaceutical salts/cocrystals of THB. Four pharmaceutical salts/cocrystals of THB with oxalic acid, malonic acid, maleic acid and fumaric acid were obtained with solution evaporation approach. Comprehensive crystal structures and Hirshfeld surface analyses reveal CAHB recognitions between THBs and coformers are dominant intermolecular interactions to stabilize crystal packing. As expected, solubilities of four pharmaceutical salts/cocrystals of THB have been improved by dicarboxylic acids. Importantly, the dicarboxylic acid with higher solubility can modulate solubility of THB to become higher. The enthalpy of hydration for four pharmaceutical salts/cocrystals is greater than that for neutral pure THB when CAHBs (with electrostatic interactions) exist, which effectively improve solubility of THB. Solvent molecules can disrupt interactions of pharmaceutical salts/cocrystals by solvent···solute interactions when dicarboxylic acids are highly soluble thereby leading to enhancement of dissolution. Research results inspirationally enlightens that the solubility of insoluble APIs could be effectively regulated by utilizing gradient solubility coformers with simultaneously forming CAHBs between active pharmaceutical ingredients and coformers.

Synthesis and biological evaluation of novel heteroring-annulated pyrrolino-tetrahydroberberine analogues as antioxidant agents

Tetrahydroberberine (THB), otherwise known as canadine, is a natural alkaloid showing significant pharmacological properties and antioxidant protection against oxidative damage. Herein, we synthetized structurally complex THB analogues, namely pyrrolino-tetrahydroberberines (PTHBs) 4a–g, containing the pyrrolino[2,3-b]pyridine system, by means of the reactions of 1,2-diaza-1,3-dienes and 7,8-dihydroberberine. Aim of the study was to explore the in vitro antioxidant properties of PTHBs in comparison to THB thus to identify the most effective against free radical-induced oxidative injury, by using three different antioxidant tests: the ORAC method, the DNA nicking assay, and the DCFH-DA cellular assay. As a result, PTHB 4d emerged among the other THB analogues by exhibiting the best antioxidant properties. First, it was the only compound having an ORAC value completely comparable to that of THB, indicating the same ability to neutralize peroxyl radicals. Secondly, 4d showed an even better antioxidant capacity than THB in protecting DNA against ferrous ion-induced strand breaks. These observations were also confirmed in NCTC-2544 human keratinocytes exposed to hydrogen peroxide. Indeed, 4d protected cells against oxidation more efficiently than THB both in the short (1 and 3 h) and long (24 h) period of incubation, possibly suggesting increased cell membrane permeability and/or intracellular stability of 4d as compared to THB.

Evaluation of Diuretic Activity of Argemone mexicana

Argemone mexicana is reported to posses alkaloids, amino acids, phenolics and fatty acids as major phytochemical groups. A series of bioactive compounds have been reported and some of them are isolated from different parts of Argemone Mexicana. The whole plant of A. mexicana was reported to posses isoquinoline alkaloids such as berberine, cheilanthifoline, coptisine, muramine, scoulerine, stylopine, cryptopine, thalifone, sanguinarine, protopine, optisine, chelerytherine and benzylisoquinoline alkaloids. tetrahydrober berine, protopine and Benzophenanthridines have been isolated from the plant. Seed oil otherwise called as Argemone oil reported to contain sanguinarine and dihydrosanguinarine. It also contains palmitic, myristic, oleic and linoleic acids. However, no scientific record is available for the anticonvulsant activity of aerial part of the plant Argemone mexicana. Hence the present study was designed to evaluate these activities of chloroform, ethanol and aqueous extract of Argemone mexicana leaves by using experimental models in mice.

Effects of tetrahydroberberine and tetrahydropalmatine on hepatic cytochrome P450 expression and their toxicity in mice

The aim of this study was to investigate the effects of tetrahydroberberine (THB) and tetrahydropalmatine (THP) on the expression of mouse liver cytochrome P450s, and evaluate their liver toxicity in mice. Real-time polymerase chain reaction (PCR) and western blot analyses were used to analyze the expression of major P450 isoforms. Liver toxicity was evaluated by measuring serum biochemical parameters and performing histopathological analysis. The real-time PCR results showed that THB induced Cyp1a2 (1.66 ± 0.34 fold, P < 0.05), Cyp3a11 (1.57 ± 0.24 fold, P < 0.05), and Cyp2e1 (1.75 ± 0.97 fold, P < 0.05) mRNA expression, while THP inhibited Cyp1a2 (0.66 ± 0.12 fold, P < 0.05) mRNA expression. The western blot results confirmed that the expression of CYP1A2, CYP3A, and CYP2E1 proteins in the mouse liver was induced by THB, whereas that of CYP1A2 was inhibited by THP. Toxicological studies showed that THB (40 mg/kg, oral gavage) increased mouse serum aspartate transaminase and total bilirubin, and liver malondialdehyde levels, and induced liver edema. No obvious changes in serum and liver tissue biochemical parameters were found and no significant pathological changes were detected in liver tissues after THP administration. Our results provide more information on the toxicity of THB and THP, and their related drug-drug interactions.

Pharmacokinetics and brain distribution of tetrahydropalmatine and tetrahydroberberine after oral administration of DA-9701, a new botanical gastroprokinetic agent, in rats.

DA-9701, a new botanical gastroprokinetic agent, has potential for the management of delayed gastric emptying in Parkinson's disease if it has no central anti-dopaminergic activity. Therefore, we examined the pharmacokinetics of DA-9701 components having dopamine D2 receptor antagonizing activity, tetrahydropalmatine (THP) and tetrahydroberberine (THB), following various oral doses (80-328 mg/kg) of DA-9701. The distribution of THP and THB to the brain and/or other tissues was also evaluated after single or multiple oral administrations of DA-9701. Oral administration of DA-9701 yielded dose-proportional area under the plasma concentration-time curve (AUC0-8 h) and maximum plasma concentration (Cmax) values for THP and THB, indicating linear pharmacokinetics (except for THB at the lowest dose). THP and THB's large tissue-to-plasma concentration ratios indicated considerable tissue distribution. High concentrations of THP and THB in the stomach and small intestine suggest an explanation for DA-9701's potent gastroprokinetic activity. The maximum concentrations of THP and THB in brain following multiple oral DA-9701 for 7 d (150 mg/kg/d) was observed at 30 min after the last oral DA-9701 treatment: 131±67.7 ng/g for THP and 6.97±4.03 ng/g for THB. Although both THP and THB pass through the blood-brain barrier, as indicated by brain-to-plasma concentration ratios greater than unity (approximately 2-4), oral administration of DA-9701 at the effective dose in humans is not expected to lead to sufficient brain concentrations to exert central dopamine D2 receptor antagonism.

Chiral hplc determination and stereoselective pharmacokinetics of tetrahydroberberine enantiomers in rats

Tetrahydroberberine (THB), a racemic mixture of (+)- and (-)-enantiomer, is a biologically active ingredient isolated from a traditional Chinese herb Rhizoma corydalis (yanhusuo). A chiral high performance liquid chromatography method has been developed for the determination of THB enantiomers in rat plasma. The enantioseparation was carried out on a Chiral®-AD column using methanol:ethanol (80:20, v/v) as the mobile phase at the flow rate 0.4 ml/min. The ultraviolet detection was set at 230 nm. The calibration curves were linear over the range of 0.01-2.5 μg/ml for (+)-THB and 0.01-5.0 μg/ml for (-)-THB, respectively. The lower limit of quantification was 0.01 μg/ml for both (+)-THB and (-)-THB. The stereoselective pharmacokinetics of THB enantiomers in rats was studied after oral and intravenous administration at a dose of 50 and 10 mg/kg racemic THB (rac-THB). The mean plasma levels of (-)-THB were higher at almost all time points than those of (+)-THB. (-)-THB also exhibited greater C(max), and AUC(0-∞), smaller CL and V(d), than its antipode. The (-)/(+)-enantiomer ratio of AUC(0-∞) after oral and intravenous administration were 2.17 and 1.43, respectively. These results indicated substantial stereoselectivity in the pharmacokinetics of THB enantiomers in rats.

Simultaneous determination of tetrahydropalmatine and tetrahydroberberine in rat urine using dispersive liquid–liquid microextraction coupled with high‐performance liquid chromatography

Dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC)-UV detection was applied in rat urine for the extraction and determination of tetrahydropalmatine (THP) and tetrahydroberberine (THB), both active components in Rhizoma corydalis. Various parameters affecting the extraction efficiency, such as the type and volume of extraction and dispersive solvent, pH, etc. were evaluated. Under the optimal conditions (extraction solvent: 37 μL of chloroform, dispersive solvent: 100 μL of methanol, alkaline with 100 μL of 1 mol/L NaOH, and without salt addition), the enrichment factors of THP and THB were more than 30. The extraction recoveries were 69.8-75.8% and 72.7-77.6% for THP and THB in rat urine, respectively. Both THP and THB showed good linearity in the range of 0.025-2.5 μg/mL, and the limit of quantification was 0.025 μg/mL (S/N=10, n=6). The intra-day and inter-day precision of THP and THB were <12.6%. The relative recoveries ranged from 95.5 to 107.4% and 96.8 to 100.9% for THP and THB in rat urine, respectively. The method has been successfully applied to rat urine samples. The results demonstrated that DLLME is a very simple, rapid and efficient method for the extraction and preconcentration of THP and THB from urine samples.

Tetrahydroberberine, an Isoquinoline Alkaloid Isolated from Corydalis Tuber, Enhances Gastrointestinal Motor Function

Because delayed gastric emptying and impaired gastric accommodation are regarded as pathophysiological mechanisms underlying functional dyspepsia (FD), prokinetics and fundic relaxants have been suggested as a new treatment for FD. We isolated tetrahydroberberine (THB), an isoquinoline alkaloid (5,8,13,13a-tetrahydro-9,10-dimethoxy-6H-benzo[g]-1,3-benzodioxolo[5,6-a]quinolizine) from Corydalis tuber, and found that it has micromolar affinity for dopamine D(2) (pK(i) = 6.08) and 5-HT(1A) (pK(i) = 5.38) receptors but moderate to no affinity for other relevant serotonin receptors (i.e., 5-HT(1B), 5-HT(1D), 5-HT(3), and 5-HT(4); pK(i) < 5.00). Oral administration of THB not only resulted in significantly accelerated gastric emptying of normal rats in a bell-shaped relationship, with a maximal efficacy at a dose of 30 μg/kg, but also restored the delayed gastric emptying caused by apomorphine, which might be mediated by an antidopaminergic effect. Data from electromyography indicated enhanced motor function of the upper gastrointestinal tract by THB, which occurred through strengthening contractility and shortening the contraction interval. Furthermore, in rats stressed by repeated restraint, a significantly higher shift in the pressure-volume curve by THB (10 μg/kg, p < 0.05), which was inhibited by [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide trihydrochloride (WAY-100635), a 5-HT(1A) antagonist, and N(ω)-nitro-l-arginine methyl ester, a nitric-oxide synthase inhibitor but not a vasoactive intestinal peptide antagonist, was observed. Oral administration of THB resulted in a drastic increase of gastric accommodation in Beagle dogs. Area under the volume versus time curve was increased significantly by THB (30 μg/kg, p < 0.01) and comparable with that of sumatriptan (3 mg/kg), a potent fundic relaxant. Taken together, our data suggested that THB, with D(2) receptor antagonist and 5-HT(1A) receptor agonist properties, has significant potential as a therapeutic for treatment of FD.

Tetrahydroberberine blocks ATP-sensitive potassium channels in dopamine neurons acutely-dissociated from rat substantia nigra pars compacta

Tetrahydroberberine (THB) exhibits neuroprotective effects but its targets and underlying mechanisms are largely unknown. Emerging evidence indicates that ATP-sensitive potassium (K ATP) channels in the substantia nigra pars compacta (SNc) promote Parkinson disease (PD) pathogenesis, thus blocking K ATP channels may protect neurons against neuronal degeneration. In the present study, we tested a hypothesis that THB blocks K ATP channels in dopaminergic (DA) neurons acutely dissociated from rat SNc. Using perforated patch-clamp recording in current-clamp mode, the functional K ATP channels can be opened by persistent perfusion of rotenone, an inhibitor of complex I of the mitochondrial respiratory chain. Bath-application of THB reversibly blocks opened K ATP channels in a concentration-dependent manner, which is comparable to a classical K ATP channel blocker, Tol. Compared to THB analogs, l-stepholidine ( l-SPD) or l-tetrahydropalmatine ( l-THP), THB exhibits more profound blockade in K ATP channels. In addition, exposure of THB alone to the recorded neuron increases action potential firing, and THB also restores rotenone-induced membrane hyperpolarization in the presence of dopamine D2 receptor antagonist (sulpiride), suggesting that THB exhibits an excitatory effect on SNc DA neurons through the block of K ATP channels. Collectively, the blockade of neuronal K ATP channels by THB in SNc DA neurons is a novel pharmacological mechanism of THB, which may contribute to its neuroprotective effects in PD.

Antitumor activity of berberrubine derivatives.

The antitumor activity of berberine, berberrubine, and their derivatives against sarcoma-180 ascites was determined by the total packed cell volume method. Berbine and tetrahydroberberine derivatives had no antitumor activity, but berberrubine (9-demethylberberine) and the ester derivatives of berberrubine had a strong antitumor activity. ED90 of berberrubine, its acetate and benzoate, were 15, 23, and 44 mg/kg, respectively. The therapeutic indices (LD10/ED90 by the present method) of these compounds were as follows: Berberrubine hydrochloride, 6.7 approximately 9.4; 9-acetyl-9-demethylberberine (9-acetylberberrubine) chloride, 7.6 approximately 8.7; 9-benzoyl-9-demethylberberine (9-benzoylberberrubine) chloride, 3.4 approximately 4.9.

The medicinal plant goldenseal is a natural LDL-lowering agent with multiple bioactive components and new action mechanisms

Our previous studies have identified berberine (BBR), an alkaloid isolated from the Chinese herb huanglian, as a unique cholesterol-lowering drug that upregulates hepatic low density lipoprotein receptor (LDLR) expression through a mechanism of mRNA stabilization. Here, we demonstrate that the root extract of goldenseal, a BBR-containing medicinal plant, is highly effective in upregulation of liver LDLR expression in HepG2 cells and in reducing plasma cholesterol and low density lipoprotein cholesterol (LDL-c) in hyperlipidemic hamsters, with greater activities than the pure compound BBR. By conducting bioassay-driven semipurifications, we demonstrate that the higher potency of goldenseal is achieved through concerted actions of multiple bioactive compounds in addition to BBR. We identify canadine (CND) and two other constituents of goldenseal as new upregulators of LDLR expression. We further show that the activity of BBR on LDLR expression is attenuated by multiple drug resistance-1 (MDR1)-mediated efflux from liver cells, whereas CND is resistant to MDR1. This finding defines a molecular mechanism for the higher activity of CND than BBR. We also provide substantial evidence to show that goldenseal contains natural MDR1 antagonist(s) that accentuate the upregulatory effect of BBR on LDLR mRNA expression. These new findings identify goldenseal as a natural LDL-c-lowering agent, and our studies provide a molecular basis for the mechanisms of action.

Tetrahydroberberine blocks membrane K+ channels underlying its inhibition of intracellular message-mediated outward currents in acutely dissociated CA1 neurons from rat hippocampus

In the patch-clamp perforated whole-cell recording mode, tetrahydroberberine (THB), a novel dopamine (DA) receptor antagonist, inhibits not only DA-induced outward K+ currents, but also acetylcholine-, caffeine- or strychnine-induced outward current. However, THB does not affect either GABA- or glycine-induced Cl− currents, or non-NMDA receptor agonist-induced cation currents. As expected for a K+ channel blocker, THB evokes a downward current deflection accompanied by a decrease of conductance. It is concluded that the direct blockade of membrane K+ channels by THB underlies its inhibition of intracellular message-mediated outward currents.

Tetrahydroberberine inhibits acetylcholine-induced K + current in acutely dissociated rat hippocampal CA1 pyramidal neurons

The effects of a novel chemical type of dopamine receptor antagonist, the tetrahydroprotoberberine analogs (THPBs), on acetylcholine (ACh)-induced current were studied in freshly dissociated pyramidal neurons from rat hippocampal CA1 area using the nystatin perforated patch-clamp recording technique. Under voltage clamp conditions, the ACh-induced outward current ( I ACh) is sensitive to the muscarinic receptor antagonist, atropine and the K + channel blocker, TEA. The reversal potential of I ACh (−84.1±0.8 mV) is close to the K + equilibrium potential, indicating that the I ACh is mediated by a muscarinic receptor, and is carried mainly by K +. Tetrahydroberberine (THB) markedly reduced the I ACh while its chemical analogs, l-stepholidine ( l-SPD) or l-tetrahydropalmatine ( l-THP), had little effect on the I ACh. The half-maximal inhibitory concentration (IC 50) of THB was 1.3×10 −5 M for a 10 −5 M ACh-induced I ACh. THB suppressed the maximum of the ACh concentration-response curve without shifting the Hill coefficient, indicating a non-competitive inhibition. It is concluded that THB non-competitively inhibits the ACh-induced K + current in a concentration-dependent manner, and that this inhibitory effect provides further evidence that THB plays its pharmacological roles in the central nervous system by effects other than through blockade of dopamine receptors.

Tetrahydroprotoberberine analogs antagonize ?1-adrenoceptors and inhibit mobilization of intracellular calcium

Effect of tetrahydroprotoberberine (THPB) analogues 1-stepholidine (1-SPD), 1-tetrahydropalmatine (1-HTP), tetrahydroberberine (THB), and tetrahydroproberberine-18 (THPB-18) on α1-adrenoceptors and cellular Ca2+ dynamics were studied by radioligand binding assay and vascular contractile functional determination. In membrane preparations of rat cerebral cortex 1-SPD, 1-THP, THB, or THPB-18 inhibited 125I-BE 2254 binding to α1-adrenoceptors with pKi values (-log Ki) of 5.54 ± 0.36, 5.56 ± 0.47, 6.01 ± 0.60, and 5.75 ± 0.56, respectively. The Hill coefficients for the 4 analogs were not significantly different to unity. The computer analysis showed that the competitive curves for the 4 analogs were fit to a one binding site model. In isolated rat aortae 1-SPD, 1-THP, THB, or THPB-18 inhibited phenylephrine-induced contraction with pA2 values of 5.48 ± 0.58, 5.66 ± 0.54, 5.45 ± 0.76, and 5.64 ± 0.34, respectively; the slopes of the Schild plot were not significantly different from unity. 1-SPD (10 μM) and THB (10 μM) did not affect the CaCl2-induced contraction in calcium free Krebs solution containing 100 mM KCl. However, both of them noncompetitively inhibited vasocontraction induced by intracellular Ca2+ mobilizers phenylephrine, 5-HT, angiotensin II, or bradykinin. These results suggest that THPB analogs can non-subtype selectively antagonize α1-adrenoceptors and inhibit intracellular Ca2+ mobilization. Drug Dev. Res. 39:191–196. © 1997 Wiley-Liss, Inc.

Tetrahydroberberine suppresses dopamine-induced potassium current in acutely dissociated CA1 pyramidal neurons from rat hippocampus

Effects of tetrahydroberberine (THB) on dopamine (DA)-induced response have been investigated in single pyramidal neurons freshly dissociated from CA1 area of the hippocampus using the nystatin perforated patch-clamp, whole-cell recording technique under voltage-clamp configuration. At a holding potential ( V H) of −20 mV, DA-induced responses included a transient outward current, a slow inward current and a combination of the two. The outward current had a reversal potential of −83.5±8.0 mV which was close to K + equilibrium potential and was sensitive to TEA, suggesting that this outward current was carried by K +. Application of THB reversibly suppressed three type responses induced by DA with different degrees of inhibitory ratio. THB inhibited the DA-induced outward current in a concentration-dependent manner with an IC 50 of 13 μM. The maximal value of the concentration-response curve for DA-induced outward current was suppressed by THB, sugegsting a non-competitive inhibition. The results support the hypothesis that THB acts as a novel dopaminergic system antagonist. Furthermore, THB inhibits the DA-induced K + current non-competitively in single dissociated cells, implying that THB may exhibit other pharmacological action on the central nervous system.

Separation and characterization of cytokinin-inducible ( S)-tetrahydroberberine oxidases controlling berberine biosynthesis in Thalictrum minus cell cultures

Three forms of cytokinin-induced tetrahydroberberine (THB) oxidase from Thalictrum minus cell suspension cultures were individually separated by chromatography using DEAE-TOYOPEARL. Two of them were ( S)-THB-specific oxidases, whereas the third was found to be a non-stereopecific one. The stereospecific oxidases were different from each other not only in the K m value, but also in the time course of activation induced by 6-benzylaminopurine (BAP). The substrate specificity of these oxidases from T. minus cells was more similar to that reported for the ( S)-THB oxidase of Coptis japonica than that for Berberis stolonifera cell cultures.

Effects of tetrahydroberberine on isoproterenol-stimulated mitochondrial 45Ca uptake in rabbit myocardia.

Cardiac mitochondria of rabbit was prepared by differential centrifugation. Tetrahydroberberine (THB) 10 mumol/L inhibited isoproterenol 1 mumol/L induced 45Ca uptake in the mitochondria by 48.58%. The inhibition is concentration-dependent and may play an important role in the protection of mitochondrial function in cardiac ischemia and reperfusion injury.