Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration
For drugs to be active they have to reach their targets. Within cells this requires crossing the cell membrane, and then free diffusion, distribution, and availability. Here, we explored the in-cell diffusion rates and distribution of a series of small molecular fluorescent drugs, in comparison to p...
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eLife Sciences Publications Ltd
2024-12-01
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| Online Access: | https://elifesciences.org/articles/97255 |
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| author | Debabrata Dey Shir Marciano Anna Poryval Ondřej Groborz Lucie Wohlrabova Tomás Slanina Gideon Schreiber |
| author_facet | Debabrata Dey Shir Marciano Anna Poryval Ondřej Groborz Lucie Wohlrabova Tomás Slanina Gideon Schreiber |
| author_sort | Debabrata Dey |
| collection | DOAJ |
| description | For drugs to be active they have to reach their targets. Within cells this requires crossing the cell membrane, and then free diffusion, distribution, and availability. Here, we explored the in-cell diffusion rates and distribution of a series of small molecular fluorescent drugs, in comparison to proteins, by microscopy and fluorescence recovery after photobleaching (FRAP). While all proteins diffused freely, we found a strong correlation between pKa and the intracellular diffusion and distribution of small molecule drugs. Weakly basic, small-molecule drugs displayed lower fractional recovery after photobleaching and 10- to-20-fold slower diffusion rates in cells than in aqueous solutions. As, more than half of pharmaceutical drugs are weakly basic, they, are protonated in the cell cytoplasm. Protonation, facilitates the formation of membrane impermeable ionic form of the weak base small molecules. This results in ion trapping, further reducing diffusion rates of weakly basic small molecule drugs under macromolecular crowding conditions where other nonspecific interactions become more relevant and dominant. Our imaging studies showed that acidic organelles, particularly the lysosome, captured these molecules. Surprisingly, blocking lysosomal import only slightly increased diffusion rates and fractional recovery. Conversely, blocking protonation by N-acetylated analogues, greatly enhanced their diffusion and fractional recovery after FRAP. Based on these results, N-acetylation of small molecule drugs may improve the intracellular availability and distribution of weakly basic, small molecule drugs within cells. |
| format | Article |
| id | doaj-art-9a1d5741eaaa49ec96a75047d1f463cb |
| institution | OA Journals |
| issn | 2050-084X |
| language | English |
| publishDate | 2024-12-01 |
| publisher | eLife Sciences Publications Ltd |
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| spelling | doaj-art-9a1d5741eaaa49ec96a75047d1f463cb2025-08-20T02:19:22ZengeLife Sciences Publications LtdeLife2050-084X2024-12-011310.7554/eLife.97255Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestrationDebabrata Dey0https://orcid.org/0000-0003-3794-6476Shir Marciano1Anna Poryval2Ondřej Groborz3Lucie Wohlrabova4Tomás Slanina5Gideon Schreiber6https://orcid.org/0000-0002-2922-5882Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, IsraelDepartment of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, IsraelInstitute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech RepublicInstitute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech RepublicInstitute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech RepublicInstitute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech RepublicDepartment of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, IsraelFor drugs to be active they have to reach their targets. Within cells this requires crossing the cell membrane, and then free diffusion, distribution, and availability. Here, we explored the in-cell diffusion rates and distribution of a series of small molecular fluorescent drugs, in comparison to proteins, by microscopy and fluorescence recovery after photobleaching (FRAP). While all proteins diffused freely, we found a strong correlation between pKa and the intracellular diffusion and distribution of small molecule drugs. Weakly basic, small-molecule drugs displayed lower fractional recovery after photobleaching and 10- to-20-fold slower diffusion rates in cells than in aqueous solutions. As, more than half of pharmaceutical drugs are weakly basic, they, are protonated in the cell cytoplasm. Protonation, facilitates the formation of membrane impermeable ionic form of the weak base small molecules. This results in ion trapping, further reducing diffusion rates of weakly basic small molecule drugs under macromolecular crowding conditions where other nonspecific interactions become more relevant and dominant. Our imaging studies showed that acidic organelles, particularly the lysosome, captured these molecules. Surprisingly, blocking lysosomal import only slightly increased diffusion rates and fractional recovery. Conversely, blocking protonation by N-acetylated analogues, greatly enhanced their diffusion and fractional recovery after FRAP. Based on these results, N-acetylation of small molecule drugs may improve the intracellular availability and distribution of weakly basic, small molecule drugs within cells.https://elifesciences.org/articles/97255diffusionsmall molecule drugsin-celllysosome |
| spellingShingle | Debabrata Dey Shir Marciano Anna Poryval Ondřej Groborz Lucie Wohlrabova Tomás Slanina Gideon Schreiber Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration eLife diffusion small molecule drugs in-cell lysosome |
| title | Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration |
| title_full | Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration |
| title_fullStr | Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration |
| title_full_unstemmed | Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration |
| title_short | Reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration |
| title_sort | reversing protonation of weakly basic drugs greatly enhances intracellular diffusion and decreases lysosomal sequestration |
| topic | diffusion small molecule drugs in-cell lysosome |
| url | https://elifesciences.org/articles/97255 |
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