Amidization of doxorubicin alleviates doxorubicin-induced contractile dysfunction and reduced survival in murine cardiomyocytes.

Doxorubicin is an effective anthracycline used for cancer therapy. However, the clinical application of doxorubicin has been largely limited by its irreversible cardiotoxicity, which is mainly induced by the primary amine group. In this study, we structurally modified doxorubicin by converting the primary amine into an acid-labile amide before assessing the acute cardiac effect of doxorubicin (pristine or modified) on cardiomyocyte contractile function. Contractile properties of murine cardiomyocytes were analyzed including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR(90)) and maximal velocity of shortening/re-lengthening (+/-dL/dt). Cell toxicity and survival rate were evaluated using the MTT assay. The doxorubicin-free base was amidized by reacting with 3,4,5,6-tetrahydophthalic anhydride (THPA) or 3,3,4,4-tetramethylsuccinic anhydride (TMSA) to yield doxorubicin-THPA or -TMSA. Acute exposure of pristine doxorubicin (10(-9)-10(-5)M) for 30 min significantly prolonged TPS and TR(90) without affecting PS and +/-dL/dt. Interestingly, doxorubicin-induced prolongation of TPS and TR(90) was significantly attenuated or abrogated by amidization of doxorubicin. Neither doxorubicin-THPA nor -TMSA affected PS and +/-dL/dt. ROS and MTT assay revealed significantly reduced ROS production and cardiac cell toxicity from amidized doxorubicin compared with the pristine compound. Comparable cytotoxicity in human ovarian cancer SKOV-3 cells was observed between amidized and pristine doxorubicin compounds. These data provide evidence for the first time that structural modification of doxorubicin alleviates its cardiac toxicity.

Bioassay-guided isolation of vasorelaxant compounds from Ziziphora clinopodioides Lam. (Lamiaceae).

Ziziphora clinopodioides Lam. (Lamiaceae) is traditionally used in Uighur's medicine for the treatment of hypertension. Our study determined and evaluated the bioactive compounds by performing an activity-guided fractionation of a hydroalcoholic extract of the whole plant, using an in vitro model of rat isolated thoracic aortic rings. Seven compounds were identified as active principles: acacetin, apigenin, chrysin, thymonin, acetovanillone, 4-hydroxyacetophenone and ethyl 4-coumarate. Apigenin, chrysin and ethyl 4-coumarate were found to be the most effective. Our results provide the first evidence that the vasodilation induced by Z. clinopodioides Lam. is mediated, at least in part, by phenolic components.

Vasorelaxant and hypotensive effects of a hydroalcoholic extract from the fruits of Nitraria sibirica Pall. (Nitrariaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Fruits of Nitraria sibirica Pall. are traditionally used in Uighur medicine to treat hypertension. This study aimed to support that folk use by defining their vasoactive and hypotensive properties. MATERIALS AND METHODS: The vasorelaxant activity and the underlying mechanisms of a hydroalcoholic extract from the fruits of Nitraria sibirica Pall. (NSHE) were evaluated on thoracic aortic rings isolated from Wistar rats. In addition, the acute hypotensive effect of NSHE was assessed in anesthetized spontaneously hypertensive rats (SHR) and in their normotensive control Wistar Kyoto (WKY) rats. RESULTS: NSHE (0.1-10 g/l) was clearly more effective to induce vasodilation of phenylephrine- (PE, 1 µM) than high KCl- (60mM) pre-contracted aortic rings with respective E(max) values of 82.9±2.2% and 34.8±3.6%. The removal of endothelium almost abolished the relaxant effect of the extract. In addition, pre-treatment with N(w)-nitro-L-arginine-methyl ester (L-NAME, 100 µM), atropine (1 µM) or charybdotoxin (30 nM) plus apamin (30 nM), respective blockers of nitric oxide (NO) synthase, muscarinic receptors and endothelium-derived hyperpolarizing factor (EDHF), significantly reduced the observed effect of NSHE. By contrast, the cyclooxygenase (COX) inhibitor indomethacin (10 µM) or the K(+) channels blockers glibenclamide (10 µM), iberiotoxin (30 nM) and 4-amino-pyridine (4-AP, 1 mM) failed to modify the vasodilation. Finally, the acute intravenous injection of NSHE (1, 5, 10, 20 mg/kg) induced an immediate and transient hypotensive effect in anesthetized SHR and in WKY rats. CONCLUSIONS: This experimental animal study suggests that hydroalcoholic extract from the fruits of Nitraria sibirica Pall. induces vasorelaxation through an endothelium-dependent pathway involving NO synthase (NOS) activation, EDHF production and muscarinic receptor stimulation. Additionally, our results determine that this vasorelaxant effect is translated by a significant hypotensive effect.

Mechanisms of vasorelaxation induced by Ziziphora clinopodioides Lam. (Lamiaceae) extract in rat thoracic aorta.

AIM OF THE STUDY: Ziziphora clinopodioides Lam. (ZC) is widely used in Uyghur folk medicine for the treatment of hypertension diseases in Xinjiang, an autonomous region of China. To provide pharmacological basis for this traditional use, we explored the vasodilating effects of ZC and investigated the underlying mechanisms. MATERIALS AND METHODS: Activity of hexane (ZCHE), dichloromethane (ZCDE) and aqueous (ZCAE) extracts of ZC were evaluated on isolated rat aortic rings pre-contracted with phenylephrine (PE) or high KCl. The mechanisms were evaluated on ZCDE, the most potent extract. RESULTS: ZCDE-induced relaxation in endothelium-intact aortic rings pre-contracted with phenylephrine (PE, 10(-6) M) or high KCl (6×10(-2) M), with respective EC(50) values of 0.27±0.03 and 0.34±0.04 g/l. Mechanic removal of the endothelium did not significantly modify ZCDE-induced relaxation. In endothelium-denuded aorta pre-contracted with PE (10(-6) M), the vasorelaxant effect of ZCDE was significantly decreased by 4-amino-pyridine (10(-3) M), but not by glibenclamide (10(-4) M), iberiotoxin (3×10(-8) M) and thapsigargin (10(-7) M). In Ca(2+) free solution, ZCDE significantly inhibited extracellular Ca(2+)-induced contraction in high KCl and PE pre-contracted rings. Additionally ZDCE inhibited the intracellular Ca(2+) release sensitive to PE (10(-6) M). CONCLUSIONS: The results demonstrate that ZDCE exhibits endothelium-independent vasodilating properties that are mediated by inhibition of extracellular Ca(2+) influx through voltage- and receptor-operated Ca(2+) channels (VDDCs and ROCCs), by inhibition of Ca(2+) release from intracellular stores, and also by the opening of voltage-dependent K(+) channels.

Effects of pomegranate flowers polyphenols on liver PON expression of diabetes combining non-alcoholic fat liver diseases rats / 药学学报

To investigate the protective effects and possible mechanism of pomegranate flowers polyphenols (PFP) on liver function of rats with diabetes combining non-alcoholic fat liver diseases, diabetes combining nonalcoholic fat liver disease model rats were established with high calorie feeding and small dose intraperitoneal injection of streptozotocin (STZ). Model rats were randomly divided into: model group, metformin group, pomegranate flowers polyphenols low, medium and high dose group (75, 150 and 300 mg x kg(-1)). After four weeks treatment, the levels of FPG, blood fat profiles and serum insulin, ALT, AST levels, SOD and MDA in the liver and serum separately were analyzed with biochemical methods. Paraoxonase (PON1 and PON3) mRNA and protein expression in liver were checked by RT-PCR and immunohistochemical method. Pathological changes of the liver were observed. FPG, IRI, non-HDL-C and transaminase significantly reduced and HDL-C raised in the each PFP dose group; Furthermore, compared with model group, fat drops in liver cells significantly reduced, antioxidant ability enhanced, PON1 mRNA and protein expression level in liver increased significantly. The protective effects of PFP against diabetes combining non-alcoholic fat liver diseases rats might through the increase liver PON1 mRNA and protein expression further enhanced the body antioxidant capacity and reduced IRI so as to ameliorate the rat hepatic steatosis.

Biphasic effects of haloperidol on sodium currents in guinea pig ventricular myocytes.

AIM: To study the effects of haloperidol on sodium currents (I(Na)) in guinea pig ventricular myocytes. METHOD: Whole-cell patch clamp technique was employed to evaluate the effects of haloperidol on I(Na) in individual ventricular myocytes. RESULTS: Haloperidol (0.1-3 micromol/L) inhibited I(Na) in a concentration-dependent manner with an IC50 of 0.253+/-0.015 micromol/L. The inhibition rate of haloperidol (0.3 micromol/L) on I(Na) was 22.14%+/-0.02%, and the maximum conductance was reduced. Haloperidol significantly reduced the midpoints for the activation and inactivation of I(Na) by 2.09 and 4.09 mV, respectively. The time constant of recovery was increased. The increase in time intervals could only recover by 90.14%+/-1.4% (n=6); however, haloperidol at 0.03 micromol/L enhanced I(Na) conductance. The midpoints for the activation and inactivation of I(Na) were shifted by 1.38 and 5.69 mV, respectively, at this concentration of haloperidol. CONCLUSION: Haloperidol displayed a biphasic effect on I(Na) in guinea pig cardiac myocytes. High concentrations of haloperidol inhibited I(Na), while lower concentrations of haloperidol shifted the activation and inactivation curve to the left. Full recovery of recovery curve was not achieved after 0.3 micromol/L haloperidol administration, indicating that the drug affects the inactivated state of sodium channels.

Electrophysiological effects of haloperidol on isolated rabbit Purkinje fibers and guinea pigs papillary muscles under normal and simulated ischemia.

AIM: Overdoses of haloperidol are associated with major ventricular arrhythmias, cardiac conduction block, and sudden death. The aim of this experiment was to study the effect of haloperidol on the action potentials in cardiac Purkinje fibers and papillary muscles under normal and simulated ischemia conditions in rabbits and guinea pigs. METHODS: Using the standard intracellular microelectrode technique, we examined the effects of haloperidol on the action potential parameters [action potential amplitude (APA), phase 0 maximum upstroke velocity (V(max)), action potential amplitude at 90% of repolarization (APD(90)), and effective refractory period (ERP)] in rabbit cardiac Purkinje fibers and guinea pig cardiac papillary cells, in which both tissues were under simulated ischemic conditions. RESULTS: Under ischemic conditions, different concentrations of haloperidol depressed APA and prolonged APD(90) in a concentration-dependent manner in rabbit Purkinje fibers. Haloperidol (3 micromol/L) significantly depressed APA and prolonged APD(90), and from 1 micromol/L, haloperidol showed significant depression on V(max); ERP was not significantly affected. In guinea pig cardiac papillary muscles, the thresholds of significant reduction in APA, V(max), EPR, and APD(90) were 10, 0.3, 1, and 1 mumol/L, respectively, for haloperidol. CONCLUSION: Compared with cardiac conductive tissues, papillary muscles were more sensitive to ischemic conditions. Under ischemia, haloperidol prolonged ERP and APD(90) in a concentration-dependent manner and precipitated the decrease in V(max) induced by ischemia. The shortening of ERP and APD(90) in papillary muscle action potentials may be inhibited by haloperidol.

Effects of two different extracts of total saponins from Cicer arietinum on kidney of T2DM rats / 药学学报

Protective effects of two different extracts of TSCA (total saponins from Cicer arietinum) were studied on kidney of T2DM rats. The diabetic model group was established with high calorie feeding and small dose injection of streptozotocin (STZ, 45 mg x kg(-1)). DM rats were randomly assigned to model group (feed with propylene glycol 1 mL/100 g), TSCA high dose group (300 mg x kg(-1)), TSCA low dose group (100 mg x kg(-1)) and normal control group (feed with propylene glycol 1 mL/100 g). After four weeks treatment with TSCA I and II, the levels of FPG FIns, BUN, Scr, ATII, ET-1, TXB2 and 6-keto-PGF1alpha in blood and the activities of SOD, GSH-PX and MDA in kidney were analyzed by biochemical methods. After four weeks treatment with TSCA II, the levels of FPG FIns, BUN, Scr, ATII and ET-1 were reduced significantly; and the ratios of TXB2 to 6-keto-PGF1alpha and SOD were effectively alleviated in TSCA II group. While there is no significant change on FPG and BUN in comparison to the rats treated with TSCA I, Scr, ATII, ET-I, GSH-PX and SOD were alleviated. The results suggest that TSCA II could be used to reduce FPG and FIns. According to the result of vasoactive substances index, TSCA II is more effective than TSCA I on renal protection of DM rats.