Thirayudh Glinsukon

Acute and subacute toxicity of piperine in mice, rats and hamsters

Piperine is acutely toxic to mice, rats and hamsters. The LD50 values for a single i.v., i.p., s.c., i.g. and i.m. administration of piperine to adult male mice were 15.1, 43, 200, 330 and 400 mg/kg body wt, respectively. The i.p. LD50 value was increased to 60 mg/kg body wt in adult female and 132 mg/kg body wt in weanling male mice. In adult female rats, the i.p. LD50 value was 33.5 mg/kg body wt whereas the i.g. LD50 value was increased to 514 mg/kg body wt. Most animals given a lethal dose died of respiratory paralysis within 3-17 min. In subacute toxicity studies, the rats died within 1-3 days after treatment. Histopathologic changes included severe hemorrhagic necrosis and edema in gastrointestinal tract, urinary bladder and adrenal glands. Death of these animals may be attributable to multiple dysfunctions in their organs.

Acute toxicity of nimbolide and nimbic acid in mice, rats and hamsters

Nimbolide and nimbic acid are toxic to mice only when given i.p. and i.v. but they are less toxic to rats and hamsters. The LD50 values of a single i.p. administration of nimbolide to adult male, female and weanling mice were 225, 280 and 240 mg/kg body wt, respectively, and its i.v. LD50 value was decreased to 24 mg/kg body wt in adult male mice. No fatality was observed when nimbolide was given i.g., i.m. and s.c. to adult male mice. Estimated LD50 values of nimbolide in rats and hamsters were somewhat higher than 600 and 500 mg/kg body wt. After 12-23 h i.p. administration of a lethal dose, most animals died of possible dysfunctions in kidney (tubular necrosis), small intestine (hemorrhagic necrosis), pancreas (acinar cell necrosis) and liver (mild fatty infiltration and focal necrosis). In contrast, mice and rats given a lethal dose of nimbolide (i.v.) died of a marked and sudden drop in arterial blood pressure and respiratory paralysis within about 1-18 min. Nimbic acid was less toxic to mice with an i.v. LD50 value of 265 mg/kg body wt and i.p. and i.g. LD50 values of higher than 600 mg/kg body wt. The possible cause of death induced by nimbic acid may be similar to that of nimbolide given i.v. and this is a sudden hypotensive shock.

Antifertility effect of Citrus hystrix DC.

An alcohol and chloroform extract of Citrus hystrix DC. fruit peel was investigated for antifertility activity in pregnant rats by oral administration at different periods of gestation. The extracts were found to effectively inhibit implantation, produce abortion and slightly hasten labor time when it was given from day 2 to 5, day 8 to 12 and day 15 until labor, respectively. At the same dose level which interrupted pregnancy, the extract did not affect the estrous cycle. Neither uterotrophic effects nor induction of vaginal cornification was observed when it was given to spayed rats. However, the extract enhanced the uterotrophic effect of estradiol when both were simultaneously given. Additionally, the extract stimulated uterine contractions observed in an in situ study. It is suggested that these two effects may be responsible for the interruption of pregnancy associated with the extract.

Effect of ethanol on the in vivo covalent binding and in vitro metabolism of aflatoxin B1 in rats

The binding of [3H]aflatoxin B1 (AFB1) to the DNA, RNA and protein of liver after i.p. administration to rats with and without ethanol pretreatment was studied. The quantities of AFB1 binding to DNA and RNA were significantly increased by ethanol pretreatment but the formation of protein adducts was not affected. AFB1 metabolism by hepatic microsomes from ethanol-treated rats to aflatoxins M1 (AFM1) and Q1 (AFQ1) was increased when compared to those of control microsomes. These results suggest that an increase in AFB1 binding to liver nucleic acids and AFB1 metabolism after pretreatment of ethanol resulted from an increase in hepatic mixed-function oxidases and a possible decrease in hepatic glutathione (GSH) content which subsequently lead to an increase in hepatotoxicity of AFB1.

Comparative toxicity in the rat of cytochalasins B and E

Abstract T. Glinsukon and S. Lekutai . Comparative toxicity in the rat of cytochalasins B and E. Toxicon 17, 137–144, 1979.—Cytochalasins B and E, produced by molds, were acutely toxic to rats. The ld 50 values for a single i.p. administration of cytochalasin B were: one-day-old rats, 10.6 mg/kg and weanling rats, > 15 mg/kg. Comparable values for cytochalasin E were: one-day-old rats, 1.28 mg/kg and weanling rats 3·5–5·0 mg/kg. One-day-old rats receiving a lethal i.p. dose of either cytochalasin B or E died within 2–8 hr with 0·3 ml fluid in the peritoneal cavity. Histopathologic changes with cytochalasin E included severe congestive necrosis of the liver and kidney whereas cytochalasin B caused congestion only at the edge of the liver. Cytochalasins E (0·5 mg/kg) and B (1·5 mg/kg) produced a maximum decrease of 46·2% and 45·4% respectively in total plasma protein concentrations when a single i.p. dose was given to adult male rats. Cytochalasin B caused a transient reduction in plasma volume within the first hr after administration and the volume gradually increased to the normal value. Maximum reduction of plasma volume and mean arterial pressure occurred 90 min after treatment with either cytochalasin B or E. Cytochalasin B appears to act directly on the walls of blood capillaries permitting extravascular effusion of plasma fluid. It also induces qualitatively different histopathologic changes in the liver and kidney than cytochalasin E.

Hepatic mitochondrial function and lysosomal enzyme activity in ethanol-potentiated aflatoxin B1 hepatotoxicity

The possible role of hepatic mitochondrial function and lysosomal enzyme activity in ethanol-enhanced aflatoxin B1 (AFB1) hepatotoxicity was studied in male rats. Hepatic ATP content was significantly decreased in rats treated with ethanol (4.0 g/kg body wt.) and AFB1 (2.0 mg/kg body wt.) compared with rats treated with AFB1 alone at 12-72 h after AFB1 administration. The decrease in hepatic ATP content was due to the decrease in the activity of NADH-cytochrome c reductase whereas cytochrome oxidase activity did not differ in rats treated with ethanol and AFB1 when compared to AFB1 alone. Total and free activities of hepatic lysosomal enzymes (glucuronidase, arylsulfatase and acid phosphatase) were significantly increased in rats treated with ethanol and AFB1 at 24-36 h after AFB1 administration when compared to AFB1 alone. The increase in hepatic lysosomal enzyme activities correlated well with the increase in the lipid peroxide level of lysosomes in rats treated with ethanol and AFB1. These findings indicate that the decrease in hepatic mitochondrial respiratory enzyme activities and the increase in lipid peroxide level of lysosomes might lead to a decrease in hepatic ATP content, and that the increase in the activities of hepatic lysosomal enzymes, respectively, enhance the AFB1 hepatotoxicity of ethanol.

Mutagenic activity of newly synthesized sulfa drugs to Salmonella typhimurium

The mutagenic activity of seven newly synthesized sulfa drugs was studied in Salmonella typhimurium, using forward mutation to 8-azaguanine (8-AG) resistance and reversion mutation assays (Ames test) both in the absence and presence of Aroclor induced rat liver S9. In forward mutation assays, N1-methylsulfanilamide, N4-acetyl-N1-methylsulfanilamide and N4-acetyl-N1-diethylsulfanilamide were mutagenic to S. typhimurium TM677 both in the presence and absence of metabolic activation while N4-acetylsulfanilamide, N1-diethylsulfanilamide and 4-nitro-N-2-pyridinylbenzenesulfonamide [2-(p-nitrobenzenesulfonamido)pyridine] were mutagenic only in the presence of metabolic activation. But 2-(N4-acetylsulfanilamido)pyridine was mutagenic in neither the presence nor the absence of metabolic activation. However, none of the seven compounds had any mutagenic effect on S. typhimurium TA98 or TA100 in the absence or presence of metabolic activation, by the Ames test preincubation method. The relationship between the structure of the compounds and their mutagenic activity is also discussed.

Time-course effects of ethanol pretreatment on hepatic necrosis and fat accumulation induced by aflatoxin B1 in the rat.

Effect of ethanol pretreatment on acute hepatotoxicity and hepatic fat accumulation induced by aflatoxin B1 (AFB1) was followed up to 120 h in male Wistar rats. Pretreatment with 4 oral doses of ethanol (4.0 g/kg body wt. each) at 48, 45, 24 and 21 h prior to AFB1 (2.0 mg/kg body wt.) single intraperitoneal administration caused a significant increase in the activity of plasma glutamic oxaloacetic transaminase (PGOT, 2.4-fold), plasma glutamic pyruvic transaminase (PGPT, 2.8-fold), liver triglycerides (2.3-fold) and the severity of liver necrosis at 72 h after AFB1 administration. The effect of ethanol pretreatment on an increase in the accumulation of liver cholesterol and cholesterol esters induced by AFB1 is additive in nature. In a time-course study, it was shown that liver necrosis and triglyceride, cholesterol and cholesterol ester accumulation occurred simultaneously in both groups of rats treated with AFB1 and ethanol-AFB1. These results suggest that fat accumulation per se is not a primary cause of liver necrosis induced by AFB1 and ethanol-AFB1.

Enhanced hepatotoxicity of aflatoxin B1 in the rat by ethanol: ultrastructural changes

The effect of ethanol pretreatment on aflatoxin B1 (AFB1)-induced ultrastructural alteration in hepatocytes was investigated in male Wistar rats. Pretreatment with 4 oral doses of ethanol (4.0 g/kg body wt. each) at 48, 45, 24 and 21 h prior to a single intraperitoneal administration of AFB1 (2.0 mg/kg body wt.) produced an alteration of fine structure more extensive than that observed after administration of AFB1 or ethanol alone. The organelles most affected were the mitochondria, endoplasmic reticulum and nucleus. The degree of nuclear edema, rough endoplasmic reticulum dilatation and mitochondrial swelling in hepatocytes from rats treated with ethanol and AFB1 was much greater than that of hepatocytes from rats treated with AFB1 or ethanol alone. Thus, ethanol may play a specific role in the potentiation of hepatic injury induced by AFB1 at the mitochondrial, endoplasmic reticular and nuclear level.

Effects of cytochalasin E on H+ and volume secretion in gastric fistula rats

Effects of cytochalasin E on the secretion of H+ and volume of gastric juice were investigated in gastric fistula rats. Direct exposure of the gastric mucosa to cytochalasin E (5-20 micrograms/ml) inhibited H+ secretory rate in all of the pentagastrin-, histamine- as well as non-stimulated rats but it did not affect the secretory volume of gastric juice. The inhibitory action of cytochalasin E on H+ secretion had a rapid onset and showed a dose-dependent pattern. The mechanism of inhibitory action was not related to its interaction with plasma membrane receptors or membrane enzyme, K+-stimulated ATPase. Interference with cellular energy production as well as alteration of microfilament function, which are essential for H+ production and secretion respectively, are likely to be the bases of the cytochalasin inhibition.