The rhamnogalacturonan-II dimer decreases intestinal absorption and tissueaccumulation of lead in rats

The rhamnogalacturonan-II dimer (dRG-II) forms strong complexes in vitro wi th lead (Pb) and other selected cations. We examined the in vivo bioavailab ility of Pb complexed with dRG-II and the effect of unleaded dRG-II on the intestinal absorption and tissue retention of Pb in rats. Forty male Wistar rats were divided into four groups. Each group consumed a purified control diet for 3 wk or the same diet supplemented with: i) 3 mg of Pb/kg, ii) 0. 5 g of leaded dRG-II/kg, or iii) 0.5 g of leaded dRG-II/kg and 4.5 g of unl eaded dRG-II/kg. The leaded dRG-II provided similar to 3 mg of Pb/kg of die t. A chemical balance study was conducted during the last 5 d of the 3-wk s tudy, and blood and organs were sampled for Pb and mineral analyses. The ap parent intestinal absorptions of Pb were 62.3, 15.2, 11.8 and -0.1%, and Pb balances were 1.9, 9.6, 5.6 and -0.2 mu g/d for the control and the three experimental groups, respectively. The Pb complexed with dRG-II was less av ailable than Pb acetate, as reflected by significantly lower blood and tiss ue Pb levels. The addition of unleaded dRG-II decreased the intestinal abso rption and the tissue retention of Pb significantly. We further found that the apparent absorption and status of magnesium, zinc and iron were unaffec ted by Pb treatment or dRG-II addition. We conclude that dRG-II may be usef ul in decreasing toxicity related to chronic Pb exposure. Human studies wil l be necessary however, to further evaluate the clinical utility of this be neficial effect.