Phyllanthus amarus Schum & Thonn is a medicinal herb widely used in tropical and subtropical countries for diabetes mellitus treatment. The effect of aqueous extract (AE) and hydroalcoholic extract (HAE) of this plant on blood glucose levels was investigated in fasting normal and glucose loaded hyperglycemic rats (oral glucose tolerance test, OGTT) during 2-3 h using metformin as reference drug. Qualitative and quantitative phytochemical screening revealed that P. amarus contains tannin, polysaccharide, saponin, flavonoid and alkaloid. The two extracts (2 g/kg) administered 30 min before glucose loading, decrease the blood glucose level in hyperglycemic rats within 30 min and 60 min after glucose loading (P < 0.001). When the extracts (1 g/kg) were administrated 1 h prior to glucose loading a maximum activity was observed after 30 min. HAE was more efficient in reducing hyperglycemic peak and contain more flavonoid than AE. Key words : Phyllanthus amarus, antihyperglycemic, intestinal glucose absorption. Phyllanthus amarus Schum & Thonn est une plante medicinale tres utilisee dans les pays tropicaux et subtropicaux pour le traitement du diabete sucre. L'effet de l'extrait aqueux (EA) et de l’extrait hydroalcoolique (EHA) de la plante sur la glycemie a ete evalue sur des rats normaux et en etat d’hyperglycemie provoquee par voie orale (HPVO) pendant 2-3 h avec metformine comme drogue de reference. L’etude qualitative et le screening phytochimique ont revele la presence de tanins, des polysaccharides, des saponines, des flavonoides et des alcaloides dans la plante. Administres 30 min avant la surcharge glucidique les deux extraits (2 g / kg) reduit l’hyperglycemie chez les rats en etat d’HPVO dans les 30 et 60 min apres la surcharge glucidique (P <0,001). Par contre, lorsque les extraits (1 g / kg) sont administres 1 h avant la surcharge glucidique, l’activite maximale a ete observee des 30 min. Compare a l’EA, l’EHA reduit plus significativement le pic hyperglycemique et contient beaucoup plus de flavonoides que l’EA. Mots cles : Phyllanthus amarus, antihyperglycemiante, absorption intestinal du glucose

Since 1994 the lagoon of Boughrara located in the south western coast of Tunisia was a seat of repeated episodes of harmful algal proliferation. Due to intoxications by shellfish harvested in this region the area was banned. In order to estimate the metal contribution to this phenomenon, seawater and bivalves collected from Boughrara during the algal bloom period were analysed for Cd, Cr, Hg, Pb, Cu and Al content using the atomic absorption spectrometry.The average of the metals and heavy metals concentrations in clams flesh and shells were lower or in the range of the European Union regularity limits and exhibited the following decreasing order: Al>Cu>Cd>Cr>Pb>Hg. Levels were ranging between 11.541 mg/kg and 0.025 mg/kg wet weights. For seawater and inter-shell water the order was approximately the same. The lagoon of Boughrara might be considered relatively unpolluted with metals and repeated toxic algal proliferations remained unexplained.

Ochratoxin A (OTA), is a mycotoxin contaminating food and feed stuffs, consisting of a chlorinated dihydroisocoumarin linked through a 7-carboxyl group tol-phenylalanine by an amide bond. When OTA (0.12–1.4 mM) is incubated with freshly isolated rat hepatocytes, it inhibits both the hydroxylation of phenylalanine (0.05 mM) to tyrosine, catalyzed by phenylalanine hydroxylase and the subsequent metabolism of tyrosine as measured by homogentisate oxidation. The IC50 of OTA for phenylalanine hydroxylation is 0.43 mM. OTα, (0.5–1.0 mM), the dihydroisocoumarin moiety of OTA, does not inhibit phenylalanine hydroxylase activity under these conditions. During incubations of hepatocytes with uniformly labelled [3H]-OTA and unlabelled phenylalanine, tyrosine-ochratoxin A is formed (up to 6% of the total mycotoxin added), indicating that ochratoxin can act as a substrate for phenylalanine hydroxylase. In vivo tyrosine-OTA is also found in liver of poisoned animals.

Un total de 49 muestras de frutas secas y aceitunas negras, adquiridas en mercados populares de Rabat (Marruecos), son extraidas y analizadas para la presencia de Ocratoxina A (OTA) por HPLC con deteccion fluorimetrica. La confirmacion de la presencia de OTA en muestras positivas se realizo por la division de la molecula OTA usando carboxipeptidasa con determinacion fluorimetrica de HPLC de ocratoxina ?? (OT??). Los resultados demuestran que un 66.6 y un 36% de frutas secas y aceitunas negras estan respectivamente contaminadas por OTA. Todas las muestras de frutas secas analizadas en este estudio estan un poco contaminadas y los valores obtenidos son mas bajos que los limites establecidos por la Union Europea. Las aceitunas negras estan mas contaminadas por OTA, la concentracion media es 1.43 ?Eg/kg (rango de 0.62 a 4.8 ?Eg/kg).

Magnesium and zinc are both involved in a high number of enzymic activities vital for mammals. They are found in prostate in remarkably high concentrations and released into seminal fluid. Furthermore, drastic reduction of Zn and Mg concentrations in the semen fluid may lead to disorders in male fertility. We aimed to analyse the differences in Mg and Zn levels in the seminal plasma of 213 males including 48 normozoospermic, 30 azoospermic, 28 oligoasthenozoospermic, 22 asthenozoospermic and 85 chronic prostatitis. Mg and Zn concentrations were measured using an atomic absorption spectrophotometer. While zinc levels did not show correlation either with the volume of the sperm or the percentage of pathological forms, magnesium concentrations in seminal plasma were significantly decreased in chronic prostatitis patients as compared to other groups or normozoospermic patients (p<0.001). We propose therefore magnesium as a marker of prostatitis.

Okadaic acid (OA) is a shellfish toxin produced by dinoflagellates, in mussels. It is a potent tumour promoter and represents a potential threat to human health even at low concentrations. OA targets mainly the gastrointestinal tract in acute poisoning, causing diarrhoea. Therefore the present investigations were designed to study the ability of okadaic acid to induce cytotoxicity and DNA lesions in a human colonic cell line (Caco-2). Incubation of Caco-2 cells with OA (3.75–60 ng/ml, i.e 4.6×10–3–7.5×10–2 µM) causes a significant reduction in cell viability. Moreover, okadaic acid inhibits protein and DNA synthesis with, respectively, IC50 of 16 and 6.5 ng/ml after 24 h incubation. It also provokes cell cycle arrest, characterised by an increase in the number of S phase cells, correlated with a significant decrease in G0/G1 phase cells at high concentration. One of the main results obtained in these investigations is the apoptosis induced by OA in Caco-2 cells of intestinal origin, shown by DNA laddering in agarose gel electrophoresis (250–1000 base pairs). OA also induces clastogenic effects evaluated by DNA fragmentation analysis using the method of Higuchi and Aggarwal (52% for 60 ng/ml) and comet assay (increase of the frequency of comets and their tails length). Therefore, the cell death induced by OA seems clearly to be concentration-dependent after 24 h of incubation. The cytotoxic properties of okadaic acid and its ability to damage DNA result in cell death, mainly by apoptosis. Since consumption of shellfish contaminated with acceptable okadaic acid concentrations exposes colonic cells to harmful concentrations of this toxin, the possibility that OA would display its toxic effects on intestinal cells in vivo should be evaluated in human primary intestinal cells and human intestinal slices for cytotoxic effects, DNA fragmentation and apoptosis.

Ochratoxin A (OTA) was found in cereals in the former Czechoslovakia as early as 1978. It was even the cause of mycotoxic nephropathy in pigs in a farm in the second half of the 1970s. Since then OTA has been monitored by the health authorities of Czechoslovakia and now the Czech Republic. OTA was detected in samples of various foodstuffs e.g. composite samples of cereals, pastry, coffee and raisins. OTA was also found in the blood serum of blood donors. A recent study of the accumulation of OTA in patients with chronic renal insufficiency (CHRI) has demonstrated that unlike in the control group of blood donors, the retention of OTA is significant in outpatients with stabilized CHRI and patients in the terminal stage of CHRI (who are regularly treated by dialysis). Because of the nephrotoxicity of OTA, such a retention may accelerate their disease. The study has also shown that a standard dialysis did not result in the decrease of OTA serum levels. Findings of OTA in biological materials have proven that the Czech population is exposed to this toxin to a certain degree.

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus ochraceus as well as other moulds. This mycotoxin contaminates animal feed and food. OTA is immunosuppressive, genotoxic, teratogenic, carcinogenic and is nephrotoxic in all animal species studied so far. OTA inhibits protein synthesis and induces lipid peroxidation. Since it seems impossible to avoid completely contamination of foodstuffs by toxigenic fungi, it is necessary to investigate the possible ways of limiting such toxicity. An attempt to prevent OTA-induced nephrotoxic and genotoxic effects, mainly the karyomegaly, has been made in vivo using aspartame (L-aspartyl-L-phenylalanine methyl ester), a structural analogue of both OTA and phenylalanine. Aspartame (25 mg/kg body weight) prevented most of the nephrotoxic effects induced by OTA (289 mug/kg body weight). It also showed some utility in preventing morphological and histological damage, mainly the karyomegaly. The protective effects of aspartame on OTA-induced nephrotoxicity could be based on several mechanisms related to competitive binding to plasma proteins, to transport or tissue distribution in the kidney or to the elimination of the toxin in the urine.

Capsaicin is a natural product of Capsicum peppers, excitatory effects of which have been shown to be mediated by the recently cloned vanilloid receptor 1 (VR1). Since previous studies have shown that capsaicin inhibits protein synthesis, experiments were performed to investigate whether this effect is mediated by VR1 receptor on cultured monkey kidney cells (Vero cells). The capsaicin uptake was assessed in cellular homogenate and in medium by high-performance liquid chromatography (HPLC) separation and quantification on C18 reverse-phase column and fluorescence detection. Toxic effects were assessed by incorporation of [3H]L-leucine into cellular proteins in the presence of capsazepine, the VR1 vanilloid receptor antagonist and Ruthenium red or tyrosine or calcium. Capsazepine (1 to 256 μM) did not modify the uptake rate of capsaicin for incubation times up to 24 h and did not antagonize capsaicin-induced protein synthesis inhibition. It rather inhibited protein synthesis per se from 100 to 256 μM. Ruthenium red which blocks mitochondrial calcium uptake, inhibited protein synthesis and did not antagonise or increase synergistically the effects of capsaicin. Interestingly in a medium deprived of calcium and supplemented by calcium chloride (10–50 μM) the protein synthesis inhibition induced by capsaicin is antagonised somehow. There was no prevention of capsaicin diffusion into the cells. Tyrosine, which seems to be the best preventive agent of capsaicin inhibitory effects, prevents its metabolism but not its diffusion. Capsaicin might enter cells by diffusion and interfere with protein synthesis machinery by competition with tyrosine which in turn prevents the metabolism of capsaicin. The results of the present study suggest that cell responses to capsaicin may be transduced through at least two molecular pathways, one involving VR1, since the receptor antagonist capsazepine fails to prevent the inhibitory effect of capsaicin in Vero cells of renal origin.

Cases of karyomegaly were described by Sclare 30 and by Mihatch 31 in patients affected with tubular-interstitial nephropathy. The Karyomegalic cells showed enlarged nuclei with accumulation of genetic material. No aetiology was suggested. Our study of rats experimentally intoxicated by ochratoxin A, a well-known nephrotoxic compound, indicates the presence of karyomegaly with alteration of the tubular tissue. In control animals no karyomegalic cells were detected. These observations suggest that karyomegaly with megacytosis may be caused by the nephrotoxic ochratoxin A in the kidney. In addition abnormal mitosis together with karyomegalic cells were observed at an earlier stage of the intoxication (30 days) suggesting possible regeneration if the OTA insults are stopped. After 90 days of treatment, the degeneration increased and only karyomegalic and apoptotic-like cells were observed indicating that the regeneration no longer occurs and that the degeneration becomes irreversible.

Okadaic acid (OA) is the main toxin produced by dinoflagellates which can accumulate in the hepatopancreas of mussels and cause diarrhetic shellfish poisoning in consumers. This toxin is also a tumour promoter and a specific potent inhibitor of protein phosphatases 1 and 2A. No specific target organ is known for this toxin. This study concerns the distribution of [3H]OA in organs and biological fluids of Swiss mice having received a single dose per os of AO (50 microg/kg). The determination of the toxin extracted from mouse organs 24 h after administration of [3H]OA and derivatised with 9-anthryldiazomethane (ADAM) before HPLC and fluorescent detection showed the highest concentration in intestinal tissue and stomach. This distribution was even more pronounced in intestinal tissue, when animal were given per os 90 microg/kg which induced diarrhoea. The high concentrations of [3H]OA in intestinal tissues and contents 24 h after administration demonstrates a slow elimination of OA. When the dose of OA was increased from 50-90 microg/kg, the concentrations of the toxin in the intestinal content and faeces increased proportionally. A good correlation was found between an increase of OA in the intestinal tissue and the diarrhoea in animals given 90 microg/kg orally. Moreover OA was present in liver and bile and in all organs including skin and also fluids. Altogether these results confirmed an enterohepatic circulation of OA as previously shown. These data also revealed that in acute OA intoxication the concentration of the toxin in the intestinal tissues reaches cytotoxic concentrations in accordance with the diarrhoea which is the main symptom of OA poisoning.

We have shown that zearalenone (Zen) induces sterility in female rats treated before or after fertilisation. It also causes hepatic and renal lesions and haematological and biochemical effects as evidenced by modification of several parameters. Its cytotoxicity has been confirmed in vitro in Vero cells (IC50 = 20 mu M), in which it causes inhibition of protein and DNA synthesis and production of malondialdehyde (MDA). It has been shown that Zen induces the formation of DNA adducts primarily in the liver in mice. Experiments have been designed to demonstrate the genotoxicity of Zen and its consequences, such as mutagenicity. In addition, the use of vitamin E as natural preventive agent has been studied. We have demonstrated that Zen (1.5 mM) induces the expression of genes of the SOS repair system in lysogenic E. coli which have integrated the 1 phage, indicating the induction of lesions in the DNA Vitamin E, which has some structural similarities with Zen, prevented all the observed effects, when preincubated in the medium (6-12 mM) 1h prior to the toxin. Thus vitamin E appears efficient in preventing cytotoxic, genotoxic and mutagenic effects of Zen and possibly the carcinogenic ones.