Riboflavin placenta

Recently, Prasad et al. cloned a mammalian Na+-dependent multivitamin transporter (SMVT) from rat placenta [305], This transporter is very highly expressed in intestine and transports pantothenate, biotin, and lipoate [305, 306]. Additionally, it has been suggested that there are other specific transport systems for more water-soluble vitamins. Takanaga et al. [307] demonstrated that nicotinic acid is absorbed by two independent active transport mechanisms from small intestine one is a proton cotransporter and the other an anion antiporter. These nicotinic acid related transporters are capable of taking up monocarboxylic acid-like drugs such as valproic acid, salicylic acid, and penicillins [5], Also, more water-soluble transporters were discovered as Huang and Swann [308] reported the possible occurrence of high-affinity riboflavin transporter(s) on the microvillous membrane. 

Dancis J, Lehanka J, Levitz M. Placental transport of riboflavin differential rates of uptake at the maternal and fetal surfaces of the perfused human placenta. Am J Obstet Gynecol 1988 158 204-10. 

J Zempleni, G Link, W Kiibler. The transport of thiamine, riboflavin and pyridoxal 5 -phosphate by human placenta. Int J Vitam Nutr Res 62 165-172, 1992. 

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