calcimycin and tetrandrine

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid from the root of Stephania tetrandra, is known to possess antitumor activity in various malignant neoplasms. However, the precise mechanism of TET-mediated immune modulation remains to be clarified. One of the possible mechanisms for its protective properties is by downregulation of the inflammatory responses. In the present study, the human mast cell line (HMC-1) was used to investigate this effect. TET significantly inhibited the induction of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-8 by phorbol 12-myristate 13-acetate (PMA) plus A23187. Moreover, TET attenuated expression of cyclooxygenase (COX)-2. In activated HMC-1 cells, the phosphorylation of extra-signal response kinase (ERK1/2) and c-jun N-terminal Kinase (JNK1/2), but not p38 mitogen-activated protein kinase, was decreased by treatment of the cells with TET. TET inhibited PMA plus A23187-induced nuclear factor (NF)-κB activation, IκB degradation and phosphorylation. Furthermore, TET suppressed the expression of TNF-α, IL-8, IL-6 and COX-2 through suppression of the ERK1/2, JNK1/2, IκBα degradation and phosphorylation, and NF-κB activation. These results indicated that TET exerted a regulatory effect on inflammatory reactions mediated by mast cells.

Topics: Benzylisoquinolines; Calcimycin; Cell Line; Cyclooxygenase 2; Humans; Interleukin-6; Interleukin-8; JNK Mitogen-Activated Protein Kinases; Mast Cells; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Tetradecanoylphorbol Acetate

To study the effects of tetrandrine (Tet) on platelet aggregation and platelet activating factor (PAF) generation in rabbit platelet-rich plasma (PRP).. The aggregation rate of platelets induced by calcimycin (Cal) and PAF and the inhibition rate of Tet on platelet aggregation were measured. The amount of PAF in PRP stimulated with Cal and treated with Tet was also measured.. Cal 1-8 mumol.L(-1) and PAF 9.5-190.5 pmol.L(-1) induced platelet aggregation. At the final concentrations of 4-64 mumol.L(-1), Tet inhibited the aggregation induced by Cal 4 mumol.L(-1) and PAF 142.9 pmol.L-1. The IC50 (95% confidence limits) were 8.6 (6.0-12.2) mumol.L-1 for Cal and 14.0 (6.4-30.4) mumol.L(-1) for PAF. In the PRP aggregation by Cal, there was a marked increase in PAF content. Tet dependented the release of PAF from platelets by Cal in a concentration-dependent manner, with IC50 of 21 (8-54) mumol.L(-1).. The inhibition effect of Tet on platelet aggregation might be concerned with the reduction of endogenous PAF generation.

Topics: Alkaloids; Animals; Benzylisoquinolines; Blood Platelets; Calcimycin; Platelet Activating Factor; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits

Calcimycin induced rabbit platelet adhesion to cultured bovine cerebral microvascular endothelial cells (CMEC) and its inhibition by triazelodiazepine (WEB 2086), 1,5-bis-(3,4-dimethoxyphenyl)-tetrahydro-(4H)-pyran (DMPP) and tetrandrine (Tet) were investigated. The results showed that calcimycin significantly increased platelet adhesion to CMEC. The platelet adhesion to CMEC was increased by 17.1% vs control after stimulation with calcimycin 0.01 mumol.L-1 for 25 min. WEB 2086 0.1, 1.0 and 10.0 mumol.L-1 or DMPP 0.1, 1.0 and 10.0 mumol.L-1 or Tet 0.1, 1.0 and 10.0 mumol.L-1 inhibited the calcimycin induced platelet adhesion to CMEC by 9.0, 22.9 and 23.1% or 9.7, 15.6 and 22.1% or 7.8, 15.6 and 24.6%, respectively. This indicates that DMPP and Tet may have perspectives in the prevention and treatment of cerebral vascular diseases.

Topics: Alkaloids; Animals; Azepines; Benzylisoquinolines; Brain; Calcimycin; Cattle; Cells, Cultured; Endothelium, Vascular; Male; Microcirculation; Platelet Activating Factor; Platelet Adhesiveness; Platelet Aggregation Inhibitors; Pyrans; Rabbits; Triazoles

The effects of tetrandrine (Tet) on the production of 2 major metabolites of arachidonic acid (AA), the leukotriene B4 (LTB4) and the thromboxane B2 (TXB2) in rabbit whole blood were investigated by reversed phase high pressure liquid chromatography (HPLC) and radioimmunoassay (RIA), respectively. After incubation with different doses of Tet for 15 min in vitro, the production of LTB4 and TXB2 by rabbit whole blood stimulated with calcimycin (20 mumol.L-1) was inhibited in a dose-dependent manner, with IC50 value of 17.8 +/- 8.6 and 17.7 +/- 9.2 mumol.L-1, respectively. In the presence of exogenous AA, the inhibitory effects of Tet were markedly lessened. The effects of Tet were much like those of calmodulin (CaM) antagonist fluphenazine (Flu). Dexamethasone (Dex) also inhibited the production of LTB4 and TXB2 when incubated with rabbit whole blood for 60 min. Tet iv 10 mg.kg-1 also inhibited the production of LTB4 and TXB2 in rabbit whole blood stimulated with calcimycin. These results suggest that Tet may be an antagonist of CaM, thus suppressing the release of AA which was catalyzed by CaM dependent phospholipase A2 (PLA2) from the membrane phospholipids of blood cells.

Topics: Alkaloids; Animals; Benzylisoquinolines; Calcimycin; Calcium Channel Blockers; Chromatography, High Pressure Liquid; Female; Leukotriene B4; Male; Rabbits; Radioimmunoassay; Thromboxane B2

Tetrandrine (TT) and other bisbenzylisoquinoline alkaloids have been used in China as a treatment for fibrotic lung diseases. Because of their potential use as pulmonary therapeutic agents, we studied the effects of some of these compounds on energy metabolism in isolated rat alveolar type II cells, i.e., cells which play a critical role in maintaining normal lung function. Incubation of type II cells with most of the alkaloids produces a reduction in cellular ATP content. However, there is no effect of the alkaloids on cellular oxygen consumption. All of the alkaloids which produce reductions in cell ATP levels cause increases in internal calcium levels of type II cells. Incubation of the cells with the calcium ionophore, 4-bromo A-23187, leads to increased amounts of intracellular calcium and reductions in ATP levels, but has no effect on oxygen consumption. Exposure of isolated lung mitochondria to calcium produces a concentration-dependent reduction in ATP synthesis with no effect on mitochondrial oxygen consumption. Direct exposure of mitochondria to TT has no effect on ATP synthesis. These results are consistent with the notion that the alkaloids produce an increase in type II cell internal calcium levels which, in turn, leads to reduced rates of mitochondrial ATP synthesis.

Topics: Adenosine Triphosphate; Alkaloids; Animals; Antineoplastic Agents, Phytogenic; Benzylisoquinolines; Calcimycin; Calcium; Cell Membrane; Cell Survival; Male; Mitochondria; Oxygen Consumption; Pulmonary Alveoli; Rats; Rats, Sprague-Dawley

The production of platelet activating factor (PAF) in bovine cerebral microvascular endothelial cells (CME cells) and the effects of tetrandrine (Tet) and dauricine (Dau) on the PAF production were investigated. PAF was determined by the aggregation of washed rabbit platelets. The results showed that the CME cells produced PAF 5.93 ng/8.5x 10(5) cells under the calcimycin 2.5 mumol.L-1 stimulation. Tet and Dau 1, 10, and 100 mumol.L-1 inhibited the production of PAF by 18.2%, 51.8%, 56.8%, and 26.3%, 63.3%, 65.9%, respectively. Tet concentration-dependently inhibited the PAF 9.1 nmol.L-1 induced washed rabbit platelets aggregation with the IC50 of 3.05 mumol.L-1 (95% confidence limits: 0.59-15.86 mumol.L-1). The binding of [3H]triazolodiazepine to the CME cells was partially displaced by Tet 0.02-33.00 mumol.L-1. It is suggested that the cerebrovascular system produces PAF at the pathological conditions and the inhibition of Tet and Dau.

Topics: Alkaloids; Animals; Benzylisoquinolines; Brain; Calcimycin; Cattle; Cells, Cultured; Endothelium, Vascular; Isoquinolines; Microcirculation; Platelet Activating Factor; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Tetrahydroisoquinolines

In the presence of KCl 19 mmol.L-1, calcium agonist Bay k 8644 0.47 mumol.L-1 elicited a strong contraction of isolated rabbit aortic strips, and this contraction was concentration-dependently inhibited by tetrandrine; but this antagonism was noncompetitive. Calcium ionophore calcimycin evoked contraction was markedly depressed by tetrandrine. The results suggested that tetrandrine might not only inhibit transmembrane influx of calcium via potential-dependent channels but also interfere with other processes related to calcium.

Topics: 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; Alkaloids; Animals; Aorta, Thoracic; Benzylisoquinolines; Calcimycin; Calcium Channel Blockers; Female; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth, Vascular; Rabbits

Neutrophils (NP) cytoplasmic free Ca2+ concentrations ([Ca2+]i) under several conditions were measured with Quin 2 in rats. The process of loading Quin 2-AM into the cells followed by its hydrolysis was assured by monitoring the shift of fluorescent emission spectrum of Quin 2-AM to that of Quin 2. The resting [Ca2+]i of NP in Ca2(+)-containing and Ca2(+)-free solutions were 186 +/- 45 and 46 +/- 16 nmol/L, respectively, indicating extracellular calcium concentration ([Ca2+]0) plays an important role on [Ca2+]i. Among agents tested, prostaglandin E2 (PGE2) 100 nmol/L did not change [Ca2+]i significantly. Calcimycin 25 mumol/L, leukotriene B4(LTB4) 60 nmol/L and platelet activating factor (PAF) 10 nmol/L increased [Ca2+]i of NP in Ca2(+)-containing solution from 185 +/- 54, 175 +/- 36 and 188 +/- 54 to 814 +/- 67, 577 +/- 229 and 540 +/- 174 nmol/L, respectively. But, compound 48/80 3.2 micrograms/ml, LTB4 300 nmol/L, PAF 10 nmol/L and PAF 5 nmol/L plus LTB4 150 nmol/L did not change significantly [Ca2+]i of NP in Ca2(+)-free solution, indicating that these agonists can not release intracellularly stored Ca2+ or no stored Ca2+ in NP is available. The rises of [Ca2+]i produced by calcimycin, PAF and LTB4 were markedly inhibited by tetrandrine (Tet) 65 mumol/L. These results, as a whole, show that Tet inhibits the rises of [Ca2+]i of NP induced by calcimycin, PAF and LTB4 via decreasing Ca2+ influx. The Ca2+ antagonism in this case may be related to its anti-allergic actions.

Topics: Alkaloids; Animals; Benzylisoquinolines; Calcimycin; Calcium; Calcium Channel Blockers; Leukotriene B4; Neutrophils; Platelet Activating Factor; Rats; Rats, Inbred Strains

Topics: Alkaloids; Animals; Benzylisoquinolines; Calcimycin; Calcium Channel Blockers; Calcium Chloride; Female; Histamine Release; Male; Mast Cells; p-Methoxy-N-methylphenethylamine; Peritoneal Cavity; Rats; Rats, Inbred Strains