Acute toxicity and sub-chronic toxicity of steroidal saponins from Dioscorea zingiberensis C.H.Wright in rodents

Ethnopharmacological relevance

Steroidal saponins from Dioscorea zingiberensis are widely used in China for curing cardiovascular diseases. However, there was little toxicological information available on them.

Aim of the study

The study evaluated potential toxicity of the steroidal saponins and analyzed the metabolites in rats.

Materials and methods

For the acute study, the steroidal saponins were administered to kunming mice in single doses of 112.5–9000 mg/kg given by gavage. General behavior adverse effects, mortality and liver histopathological changes were examined. For the sub-chronic toxicity study, Sprague–Dawley rats were gavaged at doses of 127.5, 255 and 510 mg/kg/day for 30 days, then examined the biochemical and hematological parameters. Metabolites in serum were analyzed by HPLC–MS.

Results

The steroidal saponins caused dose-dependent general behavior adverse effects, mortality and liver histopathological changes in the acute toxicity study. In the sub-chronic toxicity study, 510 mg/kg/day of steroidal saponins increased total bilirubin (TBIL) in serum and decreased protein content in liver significantly. The metabolic process of TBIL in liver includes TBIL intaking, conjugated bilirubin forming, conjugated bilirubin excreting to biliary passage. Treatment with high dose of the steroidal saponins in vivo may lead to vacuolization of the cytoplasm of hepatocytes and canalicular cholestasis. In all doses used in the experiment, the steroidal saponins decreased aspartate aminotransferase (GOT), alanine aminotransferase (ALT) and alkaline phosphatase (AKP) in serum and increased reduced glutathione hormone (GSH), glutathione reductase (GR) and glutathione S-transferases (GST) in liver. Diosgenin was the main metabolite in serum.

Conclusions

The steroidal saponins did not show any sign of toxicity up to oral dose of 562.5 mg/kg in mice. No significant changes of biochemical and hematological parameters in rats (except at 510 mg/kg/day), it was concluded that the steroidal saponins did not appear to have significant toxicity in their traditional uses.     

Studies on the mechanism of paracetamol-induced protection against paracetamol hepatotoxicity.

In rats, 3 days treatment with paracetamol (1 oral dose of 1 g/kg daily) produced a complete protection against the hepatotoxic actions of a further dose of paracetamol as documented by determination of serum enzyme activities (glutamic-oxaloacetic transaminase, (GOT), glutamic-pyruvic transaminase (GPT), sorbitol dehydrogenase (SDH), bromsulphthalein retention and histological investigations. Subacute paracetamol treatment decreased liver glutathione levels by 46%, liver microsomal cytochrome P-450 content by 23%, hepatic hydroxylation of aniline by 29% and hepatic demethylation of aminopyrine by 46%. It afforded also some protection against the hepatotoxic actions of carbon tetrachloride, bromobenzene and thioacetamide, but did not influence the antiphlogistic activity of paracetamol (carrageenan paw edema test). Plasma and liver concentrations of free paracetamol after oral administration of 1 g/kg paracetamol were somewhat higher in the subacutely paracetamol-pretreated rats than in the non-pretreated control animals whereas no differences in the concentrations of conjugated paracetamol were found between the 2 groups. Pretreatment with paracetamol did not influence the urinary excretion of free paracetamol but caused some shift in the urinary excretion of paracetamol conjugates: pretreated rats excreted 23% less of the paracetamol glucuronide and sulfate and 33% more of the paracetamol mercapturate than the control animals. A depression of the microsomal mixed-function oxidase activity is presumed to be the main cause of the paracetamol-induced protection against paracetamol hepatotoxicity.     

N-acetylcysteine-induced inhibition of gastric emptying: A mechanism affording protection to mice from the hepatotoxicity of concomitantly administered acetaminophen

Swiss Webster male mice, 22 ± 3 g, killed 17–18 h following the concomitant oral administration of acetaminophen (350 mg/kg) and N-acetylcysteine (NAC, 100–500 mg/kg, treated) had statistically significant lower plasma transaminases (GOT and GPT) than control mice (acetaminophen + water). Possible mechanisms underlying this protective effect of NAC were examined. NAC (500 mg/kg) reduced [¹⁴C]acetaminophen-derived radioactivity in the blood and tissues but increased the percentage of the dose in the gastrointestinal tract. Depletion of hepatic sulphydryl compounds below 75% of the control value was prevented by NAC treatment, whereas urinary excretion of mercapturate and sulfate, metabolites derived from sulphydryls, were proportionally increased and excretion of unchanged drug was decreased by NAC. Absorption of acetaminophen from the small intestine was prevented by NAC and this was attributed to an inhibition in gastric emptying. Since all changes observed following NAC treatment could be attributed to inhibition of gastric emptying, it was considered the major mechanism responsible for affording in mice protection from acetaminophen-induced hepatocellular damage following concomitant oral administration.     

Evaluation of oxidative stress during apoptosis and necrosis caused by D-galactosamine in rat liver

Eighteen and twenty-four hours after intraperitoneal administration of D-galactosamine (1g/kg body weight) to rats, the activity of caspase-3-like protease in the liver increased significantly compared with that in the control group given saline. Histological examinations including the in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method found apoptotic hepatocytes 18 hr after the administration of D-galactosamine. Caspase-3 activity was barely detectable in the plasma of control rats, but increased significantly 24 hr after drug administration along with a dramatic increase in glutamate-oxaloacetate transaminase (GOT). These results indicated that D-galactosamine causes apoptosis in the liver by activating caspase-3, which is released to the plasma by secondary necrosis. The concentration of lipid hydroperoxides in the liver increased significantly 24 hr after D-galactosamine administration. In contrast, the concentration of vitamin C in the liver decreased significantly 18 and 24 hr after D-galactosamine administration. These results suggest that D-galactosamine induces severe oxidative stress in the liver, leading to extensive necrosis.     

Impact of certain flavonoids on lipid profiles--potential action of Garcinia cambogia flavonoids

Flavonoids from Cocos nucifera, Myristica fragrance, Saraka asoka and Garcinia cambogia exerted hypolipidaemic activity in rats. Lipid lowering activity was maximum in rats administered flavonoids (10 mg/kg BW/day) from Garcinia cambogia. A dose response study revealed biphasic activity. Higher doses were less effective in reducing lipid levels in serum and tissues, although devoid of toxic effects.     

新生儿窒息所致的心肌损伤及心肌酶谱的改变

报告１００例窒息江苏后的新生儿心电图检查，异常的６０例，其同日血清ＧＯＴ，ＬＤ－ＨＣＰＫ均值均明显高于脐血对照组，单项测定值高于对照组者达８８．３％。血清心肌酶谱的峰值在窒息复苏后１～７天，以后随复苏后的天数的增加而逐渐下降，心肌酶憎的高低还与窒息有无各种并发症成正比。随访心电田及心肌瞩谱均于复苏后２～３月内恢复正常，提示新生儿窒息会对心肌造成损伤，及时治疗是可以复原的。     

钉螺转氨酶的初步研究

纸层析法证明丙氨酸、天门冬氨酸及精氨酸经过钉螺匀浆作用后可使α-酮戊二酸转变成谷氨酸,说明钉螺存在谷-丙、谷-草及谷-精转氨酶。比色法也测得谷-草转氨酶和谷-丙转氨酶的活力。溴乙酰胺对上述两酶活力无明显影响,而烟酰苯胺有抑制钉螺谷-丙转氨酶作用。小剂量溴乙酰胺与烟酰苯胺盐酸盐伍用,无增强杀螺作用。     

Blood glutamate grabbing does not reduce the hematoma in an intracerebral hemorrhage model but it is a safe excitotoxic treatment modality

Recent studies have shown that blood glutamate grabbing is an effective strategy to reduce the excitotoxic effect of extracellular glutamate released during ischemic brain injury. The purpose of the study was to investigate the effect of two of the most efficient blood glutamate grabbers (oxaloacetate and recombinant glutamate oxaloacetate transaminase 1: rGOT1) in a rat model of intracerebral hemorrhage (ICH). Intracerebral hemorrhage was produced by injecting collagenase into the basal ganglia. Three treatment groups were developed: a control group treated with saline, a group treated with oxaloacetate, and a final group treated with human rGOT1. Treatments were given 1 hour after hemorrhage. Hematoma volume (analyzed by magnetic resonance imaging (MRI)), neurologic deficit, and blood glutamate and GOT levels were quantified over a period of 14 days after surgery. The results observed showed that the treatments used induced a significant reduction of blood glutamate levels; however, they did not reduce the hematoma, nor did they improve the neurologic deficit. In the present experimental study, we have shown that this novel therapeutic strategy is not effective in case of ICH pathology. More importantly, these findings suggest that blood glutamate grabbers are a safe treatment modality that can be given in cases of suspected ischemic stroke without previous neuroimaging.     

头部重点低温对完全性缺血后兔脑细胞胞浆酶变化的影响

本研究观察了头部重点低温（ＳＨＣ）对兔脑完全性缺血后再灌流时胞浆酶变化的影响。结论：再灌流后尽早实施ＳＨＣ，仍能有效防止脑胞浆酶的泄漏，这将有利于脑细胞的复苏。