Use of the intestinal bile acid transporter for the uptake of cholic acid conjugates with HIV-1 protease inhibitory activity.
OBJECTIVE
To investigate the ability of the human intestinal bile acid transporter to transport cholic acid conjugates with potential HIV-1 protease inhibitory activity.


METHODS
Cholic acid was conjugated at the 24 position of the sterol nucleus with various amino acids and amino acid analogs. The CaCo-2 cell line was used as a model to investigate the interaction of these bile acid conjugates with the human intestinal bile acid transporter. Interaction between the carrier and the conjugates was quantified by inhibition of taurocholic acid transport and confirmed by transport of radiolabelled conjugates in this cell line.


RESULTS
The highest interaction with the transporter, as quantified by inhibition of taurocholic acid transport, occurred when a single negative charge was present around the 24 to 29 region of the sterol nucleus. A second negative charge or a positive charge significantly reduced the interaction. Transport of radiolabelled cholyl-L-Lys-epsilon-tBOC ester and cholyl-D-Asp-beta-benzyl ester was inhibited by taurocholic acid. Of all tested compounds, only cholyl-D-Asp-beta-benzyl ester showed modest HIV-1 protease inhibitory activity with an IC50 of 125 microM.


CONCLUSIONS
Cholic acid-amino acid conjugates with appropriate stereochemistry are recognized and transported by the human bile acid transporter and show modest HIV-1 protease inhibitory activity. Transport of these conjugates by the bile acid carrier is influenced by charge and hydrophobicity around the 24 position of the sterol nucleus.
Kågedahl
M
M
Department of Pharmacy, University of California at San Francisco 94143-0446, USA.
Swaan
P W
PW
Redemann
C T
CT
Tang
M
M
Craik
C S
CS
Szoka
F C
FC
Oie
S
S
D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D001692:Biological Transport; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000378:metabolism*; D002793:Cholic Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D004848:Epithelium / Q000378:metabolism; D016333:HIV Protease / Q000187:drug effects; D017320:HIV Protease Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases; D008562:Membrane Glycoproteins; D012964:Sodium / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013656:Taurocholic Acid / Q000378:metabolism*; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)
D000596:Amino Acids; D002352:Carrier Proteins; D002793:Cholic Acids; D016333:HIV Protease; D017320:HIV Protease Inhibitors; D006913:Hydroxysteroid Dehydrogenases; D008562:Membrane Glycoproteins; D012964:Sodium; D013656:Taurocholic Acid; C037643:bile acid binding proteins; C435496:AKR1C2 protein, human; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)