Ipriflavone, a synthetic phytoestrogen, enhances intestinal calcium transport in vitro

Ipriflavone (IP), a synthetic isoflavone, prevents bone loss associated wit h ovarian hormone deficiency in women and animal models. This protective ef fect of IP may be partly due to its ability to enhance calcium absorption. The purpose of this study was to examine the effects of IP and 17 beta-estr adiol (E-2) on in vitro intestinal calcium transport in an ovariectomized r at model using E-2 as a positive control. Forty-eight 90-day-old female Spr ague-Dawley rats were divided into four groups: one sham-operated (sham) an d three ovariectomized groups. The ovx groups were either control (ovx), su pplemented with IP (100 mg/kg body weight daily) via Savaging (ovx+IP), or injected with E-2 (10 mu g/kg body weight) (ovx+E-2). Animals were fed diet s containing 0.4% calcium, 0.3% phosphorus, and 0.195 nmol vitamin D-3/g fo r 35 days from the date of surgery. Animals were exsanguinated, and isolate d cells from the duodenum, jejunum, ileum, and colon were used to measure i n vitro calcium uptake. Calcium uptake by duodenal cells was significantly greater in the IP and E-2-related animals compared with the ovx control gro up. In addition, calcium uptake by the ileal and colonic cells of the E-2-t reated animals was significantly greater compared with all the other groups . The results confirm our earlier findings implicating a role for estrogen in duodenal calcium uptake. The findings also indicate that IP, although le ss potent than estrogen, significantly enhances calcium uptake in the duode num, the active site of calcium absorption.