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.

Goitrogenic content of Indian cyanogenic plant foods & their in vitro anti-thyroidal activity.

BACKGROUND & OBJECTIVES: Consumption of cyanogenic foods has been considered as one of the etiological factors in certain instances for the persistence of endemic goitre. The present study was undertaken to study the cyanogenic glucosides, glucosinolates and thiocyanate content in edible portion of certain selected plant foods of Indian origin. Further in vitro anti-thyroidal activity using raw, boiled and cooked extracts of these plants with and without excess iodide was also studied. METHODS: Cyanogenic plant foods generally vegetables were collected from different areas of West Bengal and Tripura. Cassava was obtained from Meghalaya and Kerala and their cyanogenic glucosides, glucosinolates and thiocyanate were estimated. Thyroid peroxidase activity (TPO) of human thyroid was assayed from microsomal fraction following I3- from iodide. The anti-TPO activities of the plants were assayed after adding raw, boiled and cooked extracts in the assay medium with and without extra iodide. Relative antithyroidal potency of the plant extracts was also evaluated in terms of the concentration (IC50) necessary to produce 50 per cent inhibition of TPO activity. PTU equivalence of the plant foods was also determined. RESULTS: Cabbage and cauliflower were rich in glucosinolates, bamboo shoot and cassava were rich in cyanogenic glucosides, mustard, turnip and radish were relatively rich in thiocyanate however all the constituents were present in each plant. Boiled extracts showed maximum inhibition of TPO activity followed by cooked and raw extracts. Excess iodide was found relatively effective for raw extract but less effective for boiled and cooked extracts in reversing anti-TPO activity. Inhibition constant (IC50) was found highest with bamboo shoot and least with cabbage. INTERPRETATION & CONCLUSION: Raw, boiled and cooked extracts of the plants showed anti-thyroidal activity in vitro. Excess iodide reversed the anti-TPO activity to same extent but could not neutralise it.

O processamento doméstico do feijão-comum ocasionou uma redução nos fatores antinutricionais fitatos e taninos, no teor de amido e em fatores de flatulência rafinose, estaquiose e verbascose / The domestic processing of the common bean resulted in a reduction in the phytates and tannins antinutritional factors, in the starch content and in the raffinose, stachiose and verbascose flatulence factors

The objective of this study was to evaluate the effect of the soaking step and the domestic processing of the common bean, on the chemical composition, the levels of phytate, tannin, starch and flatulence factors by utilizing the follows treatments: raw bean (FC), freeze-dried cooked unsoaked bean (FCSM), freeze-dried cooked bean without the non-absorbed soaking water (FCSAM), freeze-dried cooked bean with the non-absorbed soaking water (FCCAM) and the soaking water (AM). The beans were soaking for a period for 16 hours in the proportion 3:1 (water:beans) at room temperature. The effect of the phytates and tannins on the net protein efficiency ratio (NPR) and protein digestibility using male Wistar rats were studied. A decrease in the phytate content of the beans (85) with use of soaking was observed. In the case of the tannin content, only the cooking of the beans promoted high decomposition (84). In the (FCSAM) treatment a decrease in the raffinose (25.0), stachiose (24.8), verbascose (41.7) and starch (26.8) contents was observed. Diets containing casein (control), casein plus the soluble solids obtain from the soaking water showed no significant difference (p > 0.05) for the NPR, as well as for the different bean treatments, although these showing lower values. The treatment (FCSM) showed the higher digestibility (74.3 +/- 5.8) of the bean treatments, the casein diets showing 94.6 +/- 0.9. The reduction of the phytates, tannin, starch contents and flatulence factors in the common bean was most effective when the soaking water not absorbed was discarded (FCSAM).

Linamarin- the toxic compound of cassava

Cassava is a widely grown root crop which accumulates two cyanogenic glucosides, linamarin and lotaustralin. Linamarin accounts for more than 80 per cent of the cassava cyanogenic glucosides. It is a beta-glucoside of acetone cyanohydrin and ethyl-methyl-ketone-cyanohydrin. Linamarin beta-linkage can only be broken under high pressure, high temperature and use of mineral acids, while its enzymatic break occurs easily. Linamarase, an endogenous cassava enzyme, can break this beta-linkage. The enzymatic reaction occurs under optimum conditions at 25ºC, at pH 5.5 to 6.0. Linamarin is present in all parts of the cassava plant, being more concentrated on the root and leaves. If the enzyme and substrate are joined, a good detoxification can occur. All the cassava plant species are known to contain cyanide. Toxicity caused by free cyanide (CN-) has already been reported, while toxicity caused by glucoside has not. The lethal dose of CN- is 1 mg/kg of live weight; hence, cassava root classification into toxic and non-toxic depending on the amount of cyanide in the root. Should the cyanide content be high enough to exceed such a dose, the root is regarded as toxic. Values from 15 to 400 ppm (mg CN- of fresh weight) of hydrocyanic acid in cassava roots have been mentioned in the literature. However, more frequent values in the interval 30 to 150 ppm have been observed. Processed cassava food consumed in Brazil is safe in regard to cyanide toxicity.