Boldine Inhibits Mouse Mammary Carcinoma In Vivo and Human MCF-7 Breast Cancer Cells In Vitro.

Boldine is an aporphine alkaloid widely consumed in the folk medicine of some regions. Its anticancer potential has been shown but not yet elucidated. We compared the antitumor effect of orally and parenterally applied boldine in mice bearing solid Ehrlich tumor. We also explored the effects of boldine on breast adenocarcinoma MCF-7 cells in vitro. Repeated i. p. injections of 30, 60, or 90 mg boldine/kg, either alone or combined with doxorubicin, slowed tumor growth in vivo. The latter two doses also prolonged the post-therapeutic survival of the mice. When fed food supplemented with boldine at a dose of 90 mg/kg, the tumor-bearing mice survived significantly longer, but there was no effect on tumor size. Interestingly, continuous p. o. administration did not produce detectable levels of boldine in plasma or tissue samples, in contrast to high but short-lived concentrations after i. p. injections. There was neither antagonism nor synergism between boldine and doxorubicin, except a possible synergism of i. p. boldine 90 mg/kg combined with doxorubicin when compared with doxorubicin alone.Boldine was cytotoxic to MCF-7 cells and reduced their viability and proliferation in vitro. Exposure to boldine decreased bromodeoxyuridine incorporation and histone H3 phosphorylation but did not induce apoptosis. Boldine treatment resulted in p38, ERK, and JNK activation in the mitogen-activated protein kinase pathway in a dose-dependent manner. Since bioavailability in mice seems to be different from that reported in rats, pharmacokinetic studies in humans are needed to evaluate the role of boldine in the beneficial effects of Boldo infusions.

Boldine enhances bile production in rats via osmotic and farnesoid X receptor dependent mechanisms.

Boldine, the major alkaloid from the Chilean Boldo tree, is used in traditional medicine to support bile production, but evidence to support this function is controversial. We analyzed the choleretic potential of boldine, including its molecular background. The acute- and long-term effects of boldine were evaluated in rats either during intravenous infusion or after 28-day oral treatment. Infusion of boldine instantly increased the bile flow 1.4-fold in healthy rats as well as in animals with Mrp2 deficiency or ethinylestradiol induced cholestasis. This effect was not associated with a corresponding increase in bile acid or glutathione biliary excretion, indicating that the effect is not related to stimulation of either bile acid dependent or independent mechanisms of bile formation and points to the osmotic activity of boldine itself. We subsequently analyzed bile production under conditions of changing biliary excretion of boldine after bolus intravenous administration and found strong correlations between both parameters. HPLC analysis showed that bile concentrations of boldine above 10 µM were required for induction of choleresis. Importantly, long-term pretreatment, when the bile collection study was performed 24-h after the last administration of boldine, also accelerated bile formation despite undetectable levels of the compound in bile. The effect paralleled upregulation of the Bsep transporter and increased biliary clearance of its substrates, bile acids. We consequently confirmed the ability of boldine to stimulate the Bsep transcriptional regulator, FXR receptor. In conclusion, our study clarified the mechanisms and circumstances surrounding the choleretic activity of boldine.

IL-1 receptor blockade alleviates endotoxin-mediated impairment of renal drug excretory functions in rats.

The aim of our study was to investigate whether two potent anti-inflammatory agents, dexamethasone and anakinra, an IL-1 receptor antagonist, may influence acute kidney injury (AKI) and associated drug excretory functions during endotoxemia (LPS) in rats. Ten hours after LPS administration, untreated endotoxemic rats developed typical symptoms of AKI, with reduced GFR, impaired tubular excretion of urea and sodium, and decreased urinary excretion of azithromycin, an anionic substrate for multidrug resistance-transporting proteins. Administration of both immunosuppressants attenuated the inflammatory response, liver damage, AKI, and increased renal clearance of azithromycin mainly by restoration of GFR, without significant influence on its tubular secretion. The lack of such an effect was related to the differential effect of both agents on the renal expression of individual drug transporters. Only dexamethasone increased the urinary clearance of bile acids, in accordance with the reduction of the apical transporter (Asbt) for their tubular reabsorption. In summary, our data demonstrated the potency of both agents used for the prevention of AKI, imposed by endotoxins, and for the restoration of renal drug elimination, mainly by the improvement of GFR. The influence of both drugs on altered tubular functions and the expression of drug transporters was differential, emphasizing the necessity of knowledge of transporting pathways for individual drugs applied during sepsis. The effect of anakinra suggests a significant contribution of IL-1 signaling to the pathogenesis of LPS-induced AKI.

Deferoxamine but not dexrazoxane alleviates liver injury induced by endotoxemia in rats.

The purpose of the present study was to compare the activity of two different clinically available iron chelators on the development of acute liver injury after administration of the bacterial endotoxin (lipopolysaccharide [LPS]) in rats. Lipopolysaccharide was administered either alone or after pretreatment with dexrazoxane (DEX) or deferoxamine (DFO). Control groups received only saline or its combination with either chelator. After 8 h, untreated LPS rats developed liver injury, with signs of inflammation and oxidative stress. Lipopolysaccharide reduced plasma iron concentrations in association with increased production of hepcidin and the reduced liver expression of ferroportin. Administration of chelating agents to LPS animals showed distinct effects. Although both drugs were able to reduce liver iron content, together with corresponding changes in hepcidin and ferroportin expressions, only DFO showed a protective effect against liver injury despite relatively small liver concentrations. In sharp contrast, DEX failed to improve any hallmark of liver injury and even worsened the GSH/GSSG ratio, the indicator of oxidative stress in the tissue. High-performance liquid chromatography-mass spectrometry analysis showed marked liver accumulation of iron-chelating metabolite of DEX (ADR-925), whereas the parent compound was undetectable. Further downregulation of transporters involved in bile formation was observed after DFO in the LPS group as well as in healthy animals. Neither chelator imposed significant liver injury in healthy animals. In conclusion, we demonstrated marked differences in the modulation of endotoxemic liver impairment between two iron chelators, implicating that particular qualities of chelating agents may be of crucial importance.

Cholestatic effect of epigallocatechin gallate in rats is mediated via decreased expression of Mrp2.

Epigallocatechin gallate (EGCG) has been shown to be protective in various experimental models of liver injury, although opposite effects have also been reported. Since its effect on biliary physiology has not been thoroughly investigated, the present study evaluated effect of EGCG on bile flow and bile acid homeostasis in rats. Compared to controls, EGCG treatment decreased bile flow by 23%. Hepatic paracellular permeability and biliary bile acid excretion were not altered by EGCG administration, but biliary glutathione excretion was reduced by 70%. Accordingly, the main glutathione transporter on the hepatocyte canalicular membrane, multidrug resistance-associated protein 2 (Mrp2), was significantly decreased at the protein level. EGCG administration also doubled plasma bile acid levels compared to controls. While protein levels of the main hepatic bile acid transporters were unchanged, the rate-limiting enzyme in the bile acid synthesis, Cyp7a1, was significantly increased by EGCG. Enhanced bile acid synthesis in these animals was also confirmed by a 2-fold increase in plasma marker 7α-hydroxy-4-cholesten-3-one. In contrast, EGCG markedly downregulated major bile acid transporters (Asbt and Ostα) and regulatory molecules (Shp and Fgf15) in the ileum. When EGCG was coadministered with ethinylestradiol, a potent cholestatic agent, it did not show any additional effect on the induced cholestasis. This study shows ability of EGCG to raise plasma bile acid concentrations, mainly through Cyp7a1 upregulation, and to decrease bile production through reduction in Mrp2-mediated bile acid-independent bile flow. In conclusion, our data demonstrate that under certain conditions EGCG may induce cholestasis.

Epigallocatechin gallate enhances biliary cholesterol secretion in healthy rats and lowers plasma and liver cholesterol in ethinylestradiol-treated rats.

The beneficial effect of the major green tea catechin, epigallocatechin gallate (EGCG), on cholesterol homeostasis has been studied mainly in relation to the intestinal absorption of cholesterol; however, how EGCG affects cholesterol metabolism in the liver is not entirely known. The present study investigated the effect of EGCG on liver cholesterol metabolism in healthy and ethinylestradiol-treated rats. EGCG treatment reduced plasma total cholesterol in ethinylestradiol-treated animals and very low density lipoprotein cholesterol in both groups receiving EGCG. In healthy rats, despite the decrease in bile flow, EGCG markedly enhanced biliary secretion of cholesterol and phospholipids. These changes were correlated with increased expression of ATP-binding cassette transporter G5 and G8 and scavenger receptor class B type 1, and decreased expression of acyl-CoA:cholesterol acyltransferase. Ethinylestradiol treatment caused marked hepatic cholesterol accumulation with a concomitant liver weight increase and plasma cholesterol reduction. In ethinylestradiol-treated rats, EGCG co-administration attenuated the increase in liver cholesterol and liver weight. Furthermore, EGCG blunted induction of acyl-CoA:cholesterol acyltransferase and raised reduced levels of ATP-binding cassette transporter G5 and G8 and 3-hydroxy-3-methyl-glutaryl-CoA reductase in ethinylestradiol-treated rats. In conclusion, this study has demonstrated for the first time the ability of EGCG to enhance biliary cholesterol secretion and to attenuate ethinylestradiol-induced liver cholesterol accumulation. Changes in the expression of relevant enzymes and transporters suggest evidence of another mechanism that may contribute to the overall effect of EGCG on cholesterol metabolism and imply new physiological consequences of this widely used compound.