Assessment of bioavailability and risk of iron in phytomedicines Aconitum carmichaeli and Paeonia lactiflora.

Since n-octanol, a long-chain alkanol, presents a configuration similar to that of carbohydrates and lipids, the lipophilicity and absorptivity of organic medicines may be assessed from their distribution coefficients between octanol and water. n-octanol is used as a model of biomembrane. This strategy has been used in order to define the species of iron in two phytomedicines and to study the distribution of iron in decoctions of phytomedicines in the stomach and the intestine. The concentrations of iron in the original herbal materials and in n-octanol- and water-soluble species were determined by flame atomic spectrometry following mixed acid digestion. The acidities of digestive and absorptive juices (saliva, gastric juice, bile and intestine), the phytomedical composition and the compatibility of phytomedicines, i.e., the combination ratio of single phytomedicines, greatly affected the iron complexing ligands and determined the species and bioavailability of iron. The concentration of octanol-soluble iron could be used for the bioavailability assessment of iron in phytomedicines. The dosage of iron in phytomedicines could be designed according to the level of the octanol-soluble iron and the reference daily intakes for iron (18 mg/d). Risk assessment could be examined through the comparison between the level of the octanol-soluble iron and the tolerable upper intake level for iron (45 mg iron/d).