H-Asp-OH

L-Aspartic acid is is an amino acid, shown to be a suitable prodrug for colon-specific drug deliverly.

L-Aspartic acid is shown to be a suitable prodrug for colon-specific drug deliverly[1]. L-[3H]Asp remaining in the brain at 5 min is increased by 206 and 178% by preadministration of 100 mM L-Aspartic acid and 100 mM L-Glu, respectively, whereas 100 mM D-Asp does not affect L-[3H]Asp efflux transport. That value for L-[3H]Glu at 20 min is increased by 145 and 156% by coadministration with 100 mM L-Aspartic acid and 100 mM L-Glu, respectively, but not by D-Asp. It is interesting that the apparent efflux rate of L-Aspartic acid across the BBB is sevenfold faster than that of L-Glu[2].

References:
[1]. Leopold CS, et al. In vivo pharmacokinetic study for the assessment of poly(L-aspartic acid) as a drug carrier for colon-specific drug delivery. J Pharmacokinet Biopharm. 1995 Aug;23(4):397-406.
[2]. Hosoya K, et al. Blood-brain barrier produces significant efflux of L-aspartic acid but not D-aspartic acid: in vivo evidence using the brain efflux index method. J Neurochem. 1999 Sep;73(3):1206-11.