Folic acid conjugate

Pteroylheptaglutamic acid. Synonyms Vitamin Be conjugate, pteroyl-glutamio acid conjugate, folic acid conjugate, chick antianemia factor. 

Wiener and co-workers used folic acid-conjugated Gd(DTPA)-PAMAM dendrimers for visualizing the high-affinity folate receptor, overexpressed in many tumors.201 The contrast agent accumulated in the cells, resulting in a remarkable contrast enhancement on 7)-weighted images. 

Fig. 10.14 Folic acid can be conjugated onto nanotubes fluorescently labeled nanotubes to target cells expressing folic acid receptors (a,b,c). Nanotubes conjugated with folic acid display a fluorescent signature indicating that nanotubes are internalized by cells expressing folic acid receptors (d). Without the folic acid conjugate, there is very little distribution of nanotubes within the cells as attributed by the lack of fluorescent signature in (e) (Reprinted from Kam et al., 2005. With permission from the National Academy of Sciences, USA) (See Color Plates)...

Folic acid (vitamin Bg) is a conjugate of a pteridine unit, p-aminobenzoic acid, and glutamic acid. Deficiency of folic acid leads to anaemia, and it is also standard practice to provide supplementation during pregnancy to reduce the incidence of spina bifida. 

Sandoval, R. M., Keimedy, M. D., Low, P. S., and Molitoris, B. A. 2004. Uptake and trafficking of fluorescent conjugates of folic acid in intact kidney determined using intravital two-photon microscopy. Am. J. Physiol.-Cell Physiol. 287(2) C517-26. 

Receptor-mediated transporters are excipients that serve as substrates to exploit specific receptors present on cell membranes. Examples of various receptors that have been explored for permeation enhancement include bile acids (45), vitamin Bi2 (46), amino acids (47), and folic acid (48). Most of the work in receptor-mediated transporters is conducted via the use of prodrugs. For example, a prodrug of acyclovir conjugated to bile acids was seen to have higher permeability as compared to the original drug, because of receptor-mediated transport of the prodrug via bile acid transporters (49). 

Much of the folacin in food is present as conjugated pteroyl polyglutamates. Soybean contains 40% monoglutamate analogues, but in cabbage 90% of folic acid is present in forms... 

Scheme 6. Folate-targeted dendrimeric contrast agent (a 2nd generation species is presented) on a 4th generation dendrimer, 3 to 5 peripheral amine groups are randomly substituted by folic acid, the rest being conjugated to Gd-DTPA chelates...

Folic acid, shown in Fig. 12.3, is a common component of food and vitamins.36 The receptor for the vitamin folic acid is known as the folate receptor or the high-affinity membrane folate-binding protein.37 These folate receptors typically are not present in normal cells, but in a variety of human tumors they are greatly overexpressed.36-38 In addition, folate receptors mediate internalization by endocytosis. For these reasons, folic acid has been examined as a homing device. In general, studies have shown that by simple conjugation of folic acid to macromolecules, internalization into cells can occur similarly to that of free folic acid.39... 

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