Activity of aqueous extract of the bark of Vitex doniana on uterine muscle response to drugs.

The activity of Vitex doniana on the uterine muscle response was investigated. The bark of Vitex doniana was extracted in boiled water at 100 degrees C, and the extracted solution filtered and centrifuged with refrigeration. The extract prepared from the dry powder extract was tested on uterine muscle strip preparations. The bark extract of Vitex doniana was analysed elementally and found to contain much more potassium and phosphate than calcium, magnesium, zinc and iron. The presence of potassium ions in excess may also be partly responsible for the effect of the crude extract on uterine muscle activity. In another study, Vitex doniana extract induced graded uterine muscle contractions and also potentiated the contractile effects of prostaglandins, ergometrine and oxytocin. However, the potentiating effect was not significant on the contractile responses to acetylcholine and potassium chloride. The investigation therefore suggests that the effect of the Vitex doniana bark extract may be not only voltage operated but may act via uterotonic receptors. Therefore, the use of Vitex doniana to control postpartum bleeding after child birth may be justified.

The effect of Sacoglottis gabonensis stem bark extract, a Nigerian alcoholic beverage additive, on the natural antioxidant defences during 2,4-dinitrophenyl hydrazine-induced membrane peroxidation in vivo.

This study was designed to ascertain/verify whether Sacoglottis gabonensis stem bark extract has biological antioxidant activity in membrane lipid peroxidation using male weanling rats as the experimental animals and, if so, to attempt to establish/deduce the possible mechanism(s) of the antioxidant action of the bark extract. Lipid peroxidation was induced experimentally with a single intraperitoneal 2,4-dinitrophenyl hydrazine (2,4-DNPH) at the end of a 3-day administration with the bark extract in drinking water. Three hours later, the liver and red blood cells were analysed for the three primary antioxidant enzymes, namely catalase, superoxide dismutase (SOD) and glutathione peroxidase, and two nonenzymic antioxidants, namely vitamin E (alpha-tocopherol) and vitamin C (ascorbic acid) levels. Results showed that pretreatment with the bark extract exhibited divergent effects on natural antioxidant enzymes: It impaired the enzyme-inducing action of 2,4-DNPH (and of ethanol) on liver and red blood cell catalase but reduced the SOD depressing effect of the experimental oxidant (2,4-DNPH) and ethanol. Neither 2,4-DNPH nor the extract had any measurable effect on glutathione peroxidase. The bark extract also exerted a sparing effect on tissue antioxidant vitamins, ascorbic acid and vitamin E, effectively inhibiting their depletion by 2,4-DNPH or ethanol in the liver, red blood cells and brain. It is being concluded that the mechanism of antioxidant action of the bark extract against membrane peroxidation is multifactorial/multisystem, involving inhibition of catalase, enhancing the SOD capability of the liver and red blood cells and sparing tissue depletion/utilization of vitamins C (ascorbic acid) and E (alpha-tocopherol).

The influence of Sacoglottis gabonensis stem bark extract and its isolate bergenin, Nigerian alcoholic beverage additives, on the metabolic and haematological side effects of 2,4-dinitrophenyl hydrazine-induced tissue damage.

This study was designed to study the influence of Sacoglottis gabonensis stem bark extract on the metabolic and cytotoxic side effects of 2,4-dinitrophenyl hydrazine (2,4-DNPH) on the brain and blood using male weaving rats as the experimental model. This was after the effect of the bark extract and bergenin, its isolate, on membrane lipid peroxidation and tissue natural antioxidant defences was reported. Lipid peroxidation was induced experimentally with a single intraperitoneal phenylhydrazine (2,4-DNPH) administration at the end of 3 days exposure to the bark extract or bergenin in drinking water. Three hours later, the brain, liver and red blood cells of the experimental animals were analysed for glucose level and the blood was analysed for selected key indices of oxidative stress: red blood cell (RBC) count haemoglobin (Hb), packed cell volume (PCV) and white blood cell (WBC) count (total and differential). The bark extract exhibited a protective action on brain glucose, significantly inhibiting the glucose-depleting action of both 2,4-DNPH and ethanol. It also inhibited the lowering action of DNPH and ethanol on PCV, RBC and Hb concentration of rat blood, but inhibited proliferation of white blood cells (total and differential). The data on the effect of bergenin, on the side effects of 2,4-DNPH experimental lipid peroxidation and on ethanol followed an essentially similar trend to those of the bark extract on brain glucose. Bergenin, similar to the bark extract, exerted a protective action on the brain tissue, though to a lesser extent, against the oxidants, 2,4-DNPH and ethanol. It is evident that aqueous ethanol extract of S. gabonensis stem bark has biological antioxidant properties against 2,4-DNPH and ethanol-induced tissue damage exerting its action on the haematological and metabolic side effects of the oxidants. By virtue of its essentially similar activity under the same conditions, bergenin appears to be the phytochemical constituent that is largely responsible for the observed action of the bark extract.

In vivo inhibition of Fas ligand-mediated killing by TR6, a Fas ligand decoy receptor.

TR6, a member of the tumor necrosis factor (TNF) receptor superfamily, has recently been shown to bind to Fas ligand (FasL) and inhibit FasL-mediated cell killing in vitro. In the current study, we demonstrate that TR6 can block the lethal activity of FasL in multiple in vitro systems, and extend this finding to an in vivo model of hepatitis. The binding of human TR6 to human FasL was verified with BIAcore chip technology. Human primary hepatocytes, HT-29 cells and Jurkat cells were assayed for viability to demonstrate TR6 inhibition of FasL-mediated cytotoxicity in vitro. Human TR6 was also shown to cross-react with membrane-bound mouse FasL, since the in vitro cytotoxic activity of L929 cells transfected with murine FasL was inhibited in the presence of human TR6. In vivo, FasL-induced acute, lethal, fulminant hepatic apoptosis resulting in death within 2 h of intravenous injection into Fas+ mice, but not Fas- MRL/lpr mice. Pretreatment of mice with TR6 blocked FasL-induced mortality, presumably by attenuating FasL-induced hepatic apoptosis. Thus, in both in vitro and in vivo systems, TR6 acts as a functional FasL decoy receptor and may be clinically useful in the treatment of hepatitis and other diseases associated with FasL-mediated tissue injury.

Keratinocyte growth factor-2 (FGF-10) promotes healing of experimental small intestinal ulceration in rats.

Keratinocyte growth factor-2 (KGF-2, repifermin) is a homolog of KGF-1 with epithelial mitogenic activities. We investigated the therapeutic role of KGF-2 in intestinal ulceration and its mechanisms of protection. KGF-2 (0.3-5 mg/kg) was administered before or after induction of small intestinal ulceration by indomethacin (Indo) in prevention and treatment protocols. In acute studies, KGF-2 was injected for up to 7 days before or daily for 5 days after Indo. In a 15-day chronic study, KGF-2 was injected intravenously daily beginning before or 7 days after Indo. Injury was evaluated by blinded macroscopic and microscopic inflammatory scores, epithelial BrdU staining, tissue IL-1beta, PGE(2), and hydroxyproline concentrations, and collagen type I RNA expression. In vitro effects of KGF-2 were evaluated by epithelial cellular proliferation, restitution of wounded monolayers, PGE(2) secretion, and expression of COX-2 and collagen mRNA. Intravenous KGF-2 significantly decreased acute intestinal injury by all parameters and significantly decreased chronic ulceration. Pretreatment, daily infusion, and delayed treatment were effective. KGF-2 promoted in vitro epithelial restitution with only modest effects on epithelial cell proliferation, stimulated COX-2 expression in cultured epithelial cells, and upregulated in vitro and in vivo PGE(2) production. KGF-2 did not affect in vivo fibrosis, although it induced collagen expression in cultured intestinal myofibroblasts. These results suggest that KGF-2 inhibits intestinal inflammation by stimulating epithelial restitution and protective PGs.

The hepatoprotective cytochrome P-450 enzyme inhibitor isolated from the Nigerian medicinal plant Cochlospermum planchonii is a zinc salt.

Aqueous extracts of Cochlospermum planchonii Hook.f. (Cochlospermaceae) rhizomes are used by native medical practitioners in northern Nigeria to treat jaundice. An extract prepared by a laboratory adaptation of their method was hepatoprotective in carbon tetrachloride-treated rats (CCl4), and it inhibited cytochrome P-450 enzymes, which constitutes a plausible hepatoprotective mechanism. A crystalline inhibitor (0.3% of dry weight of rhizomes) was isolated using inhibition of two rat cytochrome P-450 enzymes, aminopyrine-N-demethylase and aniline hydroxylase, as bioassays to guide fractionation by solvent partitioning, polyamdie column chromatography, preparative thin layer chromatography and fractional crystallization. The inhibitor was identified as zinc formate by inductively coupled plasma atomic emission spectroscopy, nuclear magnetic resonance spectroscopy and comparison with synthetic material by power X-ray diffraction crystallography. Synthetic and plant-derived zinc formate were equally effective as inhibitors of cytochrome P-450 enzymes and as hepatoprotective agents in carbon tetrachloride-treated rats. Cochlospermum planchonii rhizomes contain unusually high levels of manganese and zinc, although much higher levels have been observed in plants considered to be hyperaccumulators of these metals.

Fusarium mycotoxins nivalenol and 4-acetyl-nivalenol (fusarenon-X) in mouldy maize harvested from farms in Jos district, Nigeria.

Twelve random samples of mouldy maize collected during the 1991 harvest season from farms at different locations in Jos district, Nigeria, were screened primarily for contamination by the Fusarium mycotoxins nivalenol, fusarenon-X and HT-2 toxin. All the three mycotoxins were detected: nivalenol in three samples, (0.8-1.0 mg), fusarenon-X in four samples (3.0-15.0 mg) and HT-2 in only one sample (3.0 mg/kg). Deoxynivalenol (three samples) and T-2 toxin (one sample) were also detected. Deoxynivalenol and nivalenol co-contaminated the same samples, with nivalenol being present at much lower levels than the former. The maize samples were not destined for human consumption.

An examination of the effect of pretreatment of rats with Sacoglottis gabonensis bark extract, a Nigerian palmwine additive, and ethanol on macromolecular binding of aflatoxin B1.

In a previous study (Okoye and Neal, Food and Chemical Toxicology 1988, 26, 679) enhanced ethanol-induced reductions in albumin-bound and unbound serum aflatoxin B1 (AFB1) and increased hepatic DNA-AFB1 binding were observed in rats treated with bark extract of Sacoglottis gabonensis, a Nigerian palmwine additive. The present study was designed to examine further the mechanism of these effects. Male weanling rats were pretreated with the bark extract or ethanol, or both, in drinking-water (at three times the levels used in the previous study) for 8 days before the ip administration of a single dose of [3H]AFB1. [In the previous study the rats were fed all three compounds simultaneously.] In contrast to the results of the previous study, when both the additive and ethanol were administered, there were no significant effects on [3H]AFB1 binding to liver or serum albumin or liver DNA. The levels of DNA-bound aflatoxin were reduced in rats given the additive or ethanol alone.

Enhanced ethanol-induced changes in disposition and toxic response to dietary aflatoxin B1 due to Sacoglottis gabonensis bark extract, a Nigerian alcoholic beverage additive.

The disposition of, and toxic response, to, dietary aflatoxin B1 (AFB1) was investigated in rats ingesting small doses of Sacoglottis gabonensis bark extract, ethanol, or both, in the drinking-water. Ingestion of ethanol alone or with the bark extract for 8 days resulted in a significant reduction in the level of AFB1 bound to serum albumin, but the level of unbound aflatoxin in the serum was significantly depressed only by concurrent ingestion of ethanol and the bark extract. In contrast, the bark extract alone or with ethanol significantly enhanced AFB1 binding to hepatic DNA. As with serum aflatoxin, concurrent ingestion of ethanol and the extract caused the most pronounced effect, suggesting synergism. All three treatments interfered with both the daily excretion pattern, and level, of aflatoxin in the urine. All three treatments enhanced AFB1-induction of liver gamma-glutamyltranspeptidase activity, suggesting potentiation of toxic response to AFB1. These data suggest that addition of the bark extract to alcoholic beverages may affect the biological response to dietary AFB1.

Synergistic effect ofSacoglottis gabonensis bark extract.

Aflatoxin B1 metabolism was studied using microsomal and cytosolic fractions isolated from weanling male Fischer F344 rats given in drinking water for 7 days an aqueous extract ofSacoglottis gabonensis bark, 0.1% ethanol solution, or a solution containing both extract and ethanolad libitum. Microsomal production of aflatoxin B1-dihydrodiol, aflatoxin Q1, aflatoxin M1, aflatoxin Pi and proteinaflatoxin adduct formation, and cytosolic aflatoxin B1-glutathione conjugation were assayed. Pretreatment with the extract alone or together with ethanol caused significant increases in aflatoxin M1 production as compared to controls given only water, but aflatoxin Q1 production was enhanced only by pretreatment with both extract and ethanol. All the three treatments caused significant reductions in liver glutathione content. The highest aflatoxin B1 metabolising activity as determined by aflatoxin M1 and aflatoxin Q1 production was observed in rats pretreated with both ethanol and the extract, suggesting synergism. The findings suggest that at relatively mild doses,S. gabonensis extract alone or in concert with ethanol may influence response to aflatoxin.

Stability of zearalenone in naturally contaminated corn during Nigerian traditional brewing.

The extent of carryover of zearalenone in mouldy substrate guinea-corn into native beer, burukutu, was determined using a laboratory adaptation of the traditional brewing procedure. Mean zearalenone carryover into finished product was 51.4 +/- 7.3% of that in the starting mixture, suggesting a moderate stability. Some 12.1 +/- 3.3% was removed with discarded solid residue.