Synergic actions of polyphenols and cyanogens of peanut seed coat (Arachis hypogaea) on cytological, biochemical and functional changes in thyroid

In animals, long-term feeding with peanut (Arachis hypogaea) seed coats causes hypertrophy and hyperplasia of the thyroid gland. However, to date there have been no detailed studies. Here, we explored the thyroidal effects of dietary peanut seed coats (PSC) in rats. The PSC has high levels of pro-goitrogenic substances including phenolic and other cyanogenic constituents. The PSC was mixed with a standard diet and fed to rats for 30 and 60 days, respectively. Animals fed with the PSC-supplemented diet showed a significant increase in urinary excretion of thiocyanate and iodine, thyroid enlargement, and hypertrophy and/or hyperplasia of thyroid follicles. In addition, there was inhibition of thyroid peroxidase (TPO) activity, 5'-deiodinase-I (DIO1) activity, and (Na+-K+)-ATPase activity in the experimental groups of rats as compared to controls. Furthermore, the PSC fed animals exhibited decreased serum circulating total T4 and T3 levels, severe in the group treated for longer duration. These data indicate that PSC could be a novel disruptor of thyroid function, due to synergistic actions of phenolic as well as cyanogenic constituents.

[Determination of the thyreostats in animal muscle tissue by matrix solid-phase dispersion (MSPD) and liquid chromatography-tandem mass spectrometry]

BACKGROUND

The residues ofthyreostats must not be present in the edible animal tissues. The proposed in the EU minimum required performance limit (MPRL) in the animal tissues is 10 microg/kg. This implies the decision limit (CCalpha) and decision capability (CCbeta) of the analytical methods used for the determination of these compounds lower than 10 microg/kg.

OBJECTIVE

This study aimed at the development, basing on the literature data and own studies the analytical method allowing for the identification and quantification of five thyreostats: tapazole (TAP), thiouracil (TU), methylotiouracil (MTU), propylothiouracil (PTU) and phenylotiouracil (FTU)) in the bovine muscle tissue, which would meet the criteria set in the Commission Decision No 2002/657/EC.

MATERIAL AND METHODS

The developed method used liquid chromatography-tandem mass spectrometry (LC-MS/MS). The sample was extracted and cleaned using the matrix solid-phase dispersion (MSPD) method. The LC was equipped with column Luna C18 Phenomenex. Dimetylotiouracyl was used as internal standard. The samples were fortified at levels: 5, 10 and 20 microg/kg. The method was validated according to the criteria laid down in Commission Decision No. 2002/657/EC.

RESULTS

At the levels, mean relative recoveries was in the range 90 - 109% and repeatability (CV %) was less than 10%. Decision limit (CCalpha) and detection capability (CCbeta) calculated for all thyreostats were below the recommended minimum required performance limit (MRPL) - 10 microg/kg.

CONCLUSIONS

The developed and validated LC-ESI-MS/MS method allows for the identification and quantification of five thyreostats in the bovine muscle tissue in the quantities below 10 microg/kg. Analytical procedure meets the criteria of Commission Decision No 2002/657/EC.

Thyroid inhibitory, antiperoxidative and hypoglycemic effects of stigmasterol isolated from Butea monosperma

Stigmasterol, isolated from the bark of Butea monosperma was evaluated for its thyroid hormone and glucose regulatory efficacy in mice. Its administration at 2.6 mg/kg/d for 20 days reduced serum triiodothyronine (T(3)), thyroxin (T(4)) and glucose concentrations as well as the activity of hepatic glucose-6-phophatase (G-6-Pase) with a concomitant increase in insulin indicating its thyroid inhibiting and hypoglycemic properties. A decrease in the hepatic lipid peroxidation (LPO) and an increase in the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) suggested its antioxidative potential. The highest concentration tested (5.2 mg/kg) evoked pro-oxidative activity.

An ultrasensitive method for the determination of thiouracil and phenylthiouracil using capillary zone electrophoresis and laser-induced fluorescence detection

This paper reports the development of a method based on capillary electrophoresis with laser-induced fluorescence detection for the simultaneous determination of thiouracil (TU) and phenylthiouracil (PhTU) with high sensitivity (nanomolar range, i.e., attomoles detected). After derivatization with 5-iodoacetamidofluorescein, the analytes were separated by capillary zone electrophoresis using 20 mM phosphate buffer (pH 10.0) and quantified by fluorescence detection. The linearity range, precision, recovery, and detection limits were determined, and the method was shown to be applicable for the determination of TU and PhTU in spiked feed samples and urine.

Simultaneous determination of thyreostatic residues in animal tissues by matrix solid-phase dispersion and gas chromatography–mass spectrometry

A method for determination of thyreostatic residues in animal tissues by matrix solid-phase dispersion (MSPD) and gas chromatography-mass spectrometry in selected ion detection mode was developed. Thyreostatic compounds in different matrices were extracted and purified by combination of MSPD and subsequent solid-phase extraction. Silica gel was selected as the solid support of both procedures and the conditions of the procedures were optimized. Thyreostats were derivatized with pentafluorobenzylbromide (PFBBr) in strong basic medium and then with N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA), which can improve the yields of derivatization for thyreostats, the repeatability, and therefore the limits of detection (LOD) of thyreostats. The limits of detection reached 10 microg/kg (2-thiouracil, 6-methyl-2-thiouracil and 6-propyl-2-thiouracil), 20 microg/kg (6-phenyl-2-thiouracil) and 50 microg/kg (tapazole) with high recoveries (more than 70% for most of thyreostats) and relative standard deviations between 4.5% and 8.7%.

Solubilities of phenazopyridine, propranolol, and methimazole in supercritical carbon dioxide

The equilibrium solubilities of three drugs (phenazopyridine, propranolol and methimazole) were determined at temperatures ranging from 308 to 348 K and pressures from 122 to 355 bar in supercritical CO2 by a simple and reliable static method. The crossover region was observed for phenazopyridine, propranolol and methimazole at 180 bar. The solubilities were correlated using a semi empirical model. Correlation of the results shows good self-consistency of the data obtained.

Separation of a thyroid-active fraction from unheated soya bean flour

An agent depressing thyroid function present in soya beans has been described. It is soluble at pH 4.2, in 2 vol. of acetone and 10% trichloroacetic acid and insoluble in 90% acetone, 90% ethanol and in ethyl ether. It is not precipitated by saturated ammonium sulphate and resists pancreatic digestion and boiling for 2 h, but is apparently destroyed by autoclaving. Evidence of its small molecular weight includes its dialysability and retardation on a Sephadex G25 column. It decreases iodine uptake by the thyroid gland and its incorporation into the diet increases the tri‐iodothyronine‐binding capacity of rat serum.