Synthesis, Anion Recognition, and Transmembrane Anionophoric Activity of Tripodal Diaminocholoyl Conjugates

Abstract

In this paper, we present the synthesis, anion recognition, and anionophoric activity of 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene-based tripodal 3α-hydroxy-7α,12α-diamino-5β-cholan-24-oate conjugate 1 and the corresponding tris(2-aminoethyl)amine-based analogue 2 and choloyl analogue 3. Their affinity toward anions was evaluated by means of competitive displacement assay using 5-carboxyfluorescein (5-FAM) as a fluorescent indicator. The results indicate compounds 1 and 2 exhibit strong recognition toward a wide range of biologically important anions, in particular, toward sulfate and phosphate anions. In MeOH-HEPES (4/1, pH 7), the binding constants of compounds 1 and 2 are 416- and 168-fold higher for sulfate than for chloride and 35- and 25-fold higher for phosphate than for chloride, respectively. The anion transport activity was measured by use of pH discharge assay and chloride-ion-selective electrode technique. The results indicate that compounds 1 and 2 function as effective anion-selective transporters in the order of ClO > I > NO > Br > Cl > SO > HPO and exhibit anionophoric activity via a process of major anion exchange and minor anion/cation symport. In addition, some insights into the correlation of the anion binding affinity with the transport efficiency are also briefly discussed.

Synthesis and mechanism of biological action of morpholinyl-bearing arylsquaramides as small-molecule lysosomal pH modulators

“…To gain insight into the probable mechanism of action of compounds 1–12 , we chose compound 12 to re-carry out the chloride efflux experiments in the presence of different alkali metal ions (Li + , Na + , K + , Rb + or Cs + ) or anions (NO 3 − , HCO 3 − or SO 4 2− ). 33,34 The results are shown in Fig. 3c and d, and clearly indicate that the chloride efflux activity of compound 12 is essentially independent of group I alkali metal ions, but varies with the anions.…”

“…). 33,34 The results are shown in Fig. 3c and d, and clearly indicate that the chloride efflux activity of compound 12 is essentially independent of group I alkali metal ions, but varies with the anions.…”

“…Literature procedures were adopted to carry out the chloride efflux; 29,30,34,52 calcein leakage; 30,52 U-tube experiments; 30,35 MQAE and MQAE-MP assays; 40,49,52 AO assays; 41,42,52 LysoSensor Green DND-189 assays; 23,44,45 BCECF-AM assays; 47 dextran, fluorescein and tetramethylrhodamine assays 38,42 and Magic Red Cathepsin assays. 23,42 Detailed experimental procedures may be found in the ESI †…”

“…This result excludes the determining role of those metal ions in the permeation process, and strongly suggests that the efflux of chloride anions proceeds via an anion exchange process. 33,34 Then we carried out a U-tube experiment to address whether compound 12 functions as a channel or a carrier. 35 In this experiment, the chloride-donating phase was separated from the chloride-receiving phase by a bulky organic phase.…”

Inhibition of autophagic flux by cyclometalated iridium(iii) complexes through anion transportation

“…Next, we tested the anion transport ability of Ir1 and Ir2 by a conventional method 46. Vesicles made of egg-yolk l -α-phosphatidylcholine (EYPC) containing 500 mM NaCl and 5 mM citric-phosphate buffer (pH 7.2) were suspended in isotonic and chloride-free 500 mM NaNO 3 solutions with citric-phosphate buffer (pH 7.2).…”