Determination of anthocyanidins in berries and red wine by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) method for the determination of anthocyanidins from berries and red wine is described. Delphinidin, cyanidin, petunidin, pelargonidin, peonidin, and malvidin contents of bilberry (Vaccinium myrtillus), black currant (Ribes nigrum), strawberry (Fragaria ananassa cv. Jonsok), and a Cabernet sauvignon (Vitis vinifera) red wine were determined. The aglycon forms of the anthocyanins present in the samples were revealed by acid hydrolysis. A reversed phase analytical column was employed to separate the anthocyanidins before identification by diode array detection. The suitability of the method was tested by determining the recovery (95-102% as aglycons and 69-104% from glycosides) for each anthocyanidin. Method repeatability was tested by charting the total aglycon content of two samples over a period of 14 analyses and determining the coefficients of variation (1.41% for bilberry and 2.56% for in-house reference material). The method developed proved thus to be effective for reliable determination of anthocyanidins from freeze-dried berry samples and red wine. The total anthocyanidin content of the tested samples was as follows: in-house reference material, 447 +/- 8 mg/100 g; strawberry, 23.8 +/- 0.4 mg/100 g; black currant, 135 +/- 3 mg/100 g; bilberry, 360 +/- 3 mg/100 g; and Cabernet sauvignon red wine, 26.1 +/- 0.1 mg/100 mL.

Chromium content of foods and diets.

Comparatively few valid data are available on the chromium content of foods and on the dietary chromium (Cr) intake of various populations. This is chiefly because of the difficulties encountered in contamination control during sampling, sample pretreatment, and analysis. Moreover, there are several analytical problems involved that are mostly owing to the low concentration level of Cr in foods. However, with the recent establishment of food reference materials with certified low concentrations of Cr, the analytical validity of studies on Cr content of foods and on its dietary intake by various populations can be ascertained. With the exception of herbs and condiments, and certain other special food items with a relatively low average consumption rate, such as tea, coffee, and some candies, most foods contain Cr below 100 micrograms/kg. Staple foods, particularly cereals and milk, are very low (less than or equal to 10 micrograms/kg) in Cr, showing little or no geographic variation. Food processing may increase food Cr content depending on the process. Processes, such as meat grinding and homogenization using stainless-steel equipment, very strongly increase the Cr content of foods. Also, acidic fruit juices in contact with steel cans are high in Cr, whereas cooking in aluminium vessels reduces the Cr content of foods. Average dietary Cr intake seems to fluctuate considerably among countries. In many developing countries, such as Brazil, the Sudan, and Iran, the dietary intake is high, from 50-100 micrograms/d, whereas in certain developed countries, such as Finland, Sweden, Switzerland, and the US, the intake is 50 micrograms/d or lower and, consequently, at or below the estimated safe and adequate daily dietary intake range of 50-200 micrograms/d established by the US National Academy of Sciences. The average Cr content of human milk is below 0.5 micrograms/L, thus resulting in a very low average intake of 0.3 microgram Cr/d by exclusively breast-fed infants in the US and Finland.

Dietary selenium protects against acute toxicity of T-2 toxin in rats.

The efficacy of dietary selenium (Se) supplementation on acute toxicity of T-2 toxin was investigated. Wistar male rats were divided into six groups with 15 rats in each and fed for 6 weeks ad libitum a semi-synthetic diet containing either 0.03 (groups 1 and 2), 0.5 (groups 3 and 4) or 2.5 mg Se/kg (groups 5 and 6). By the end of the experiment the rats in groups 2, 4 and 6 were administered once per os 3.8 mg/kg body weight T-2 toxin, while the animals in groups 1, 3 and 5 received equal doses of the solvent. Twenty-four hours after administration of the toxin the surviving rats were sacrificed and the liver microsomes isolated and determined for activities of enzymes relating to xenobiotics metabolism and Se. The results showed that feeding the rats 2.5 mg Se/kg diet increased the deethylation rate of 7-ethoxycoumarin by 42% and slightly decreased (20%) glutathione-S-transferase activity. Twenty-four hours after the administration of T-2 toxin the lethality percentages in groups 2, 4 and 6 were 47%, 27% and 20%, respectively. Furthermore, administration of T-2 toxin to group 6 rats resulted in a significant decrease in the level of cytochrome P-450 and 7-ethoxycoumarin deethylase activity (to 78% and 51%, respectively) compared to the control group. At the same time a 72% increase in the UDP-glucuronosyltransferase activity and of 61% in epoxide hydrolase activity compared to the control group was found. Similarly, although somewhat smaller, changes were seen in the group 4 rats receiving 0.5 mg Se/kg diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of inorganic chromium supplementation on glucose tolerance, insulin response, and serum lipids in noninsulin-dependent diabetics.

A placebo-controlled double-blind cross-over study was carried out to assess the effect of chromium supplementation (200 micrograms trivalent chromium daily for 6 wk) on glucose tolerance, insulin response, long-term diabetic control, and serum lipids in 10 noninsulin-dependent diabetics aged 37 to 68 yr. After chromium supplementation 24-h urinary chromium excretion showed a 9-fold increase indicating a positive chromium balance in the subjects. There was no significant difference between chromium supplementation and placebo periods in glucose tolerance and in fasting or 2-h postglucose serum insulin levels but the 1-h postglucose serum insulin level was slightly lower on chromium supplementation than on the placebo (55 +/- 9.0 versus 64 +/- 11; p less than 0.01, paired t test). Serum total cholesterol and triglycerides and their high-density, low-density, and very low-density lipoprotein subfractions showed no change after chromium supplementation as compared to the placebo period.