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In situ imaging and proteome profiling indicate andrographolide is a highly promiscuous compound.

Li L, Wijaya H, Samanta S, Lam Y, Yao SQ - Sci Rep (2015)

Bottom Line: Natural products represent an enormous source of pharmacologically useful compounds, and are often used as the starting point in modern drug discovery.Many biologically interesting natural products are however not being pursued as potential drug candidates, partly due to a lack of well-defined mechanism-of-action.We caution its potential therapeutic effects should be further investigated in detail.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemistry, National University of Singapore, Singapore 117543 [2] Key Laboratory of Flexible Electronics (KLOFE) &Institute of Advanced Materials (IAM), National Jiangsu Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing 211816, P. R. China.

ABSTRACT
Natural products represent an enormous source of pharmacologically useful compounds, and are often used as the starting point in modern drug discovery. Many biologically interesting natural products are however not being pursued as potential drug candidates, partly due to a lack of well-defined mechanism-of-action. Traditional in vitro methods for target identification of natural products based on affinity protein enrichment from crude cellular lysates cannot faithfully recapitulate protein-drug interactions in living cells. Reported herein are dual-purpose probes inspired by the natural product andrographolide, capable of both reaction-based, real-time bioimaging and in situ proteome profiling/target identification in live mammalian cells. Our results confirm that andrographolide is a highly promiscuous compound and engaged in covalent interactions with numerous previously unknown cellular targets in cell type-specific manner. We caution its potential therapeutic effects should be further investigated in detail.

No MeSH data available.


Overall strategy of dual-purpose probes for real-time imaging of target-drug interaction and in situ proteome profiling/target identification.
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f1: Overall strategy of dual-purpose probes for real-time imaging of target-drug interaction and in situ proteome profiling/target identification.

Mentions: Natural products represent an enormous source of pharmacologically useful compounds1. They are the active components of many traditional medicines, and often used as the starting point in modern drug discovery2. Approximately 50% of FDA-approved drugs are directly derived from or inspired by natural products. Many biologically interesting natural products, however, have not been pursued as potential drug candidates due to a variety of reasons, including accessibility, cost, structural complexity, and a lack of well-defined mechanism-of-action3. Traditionally, in vitro methods based on affinity protein enrichment from crude cellular lysates are used to identify potential targets of natural products, but they are highly limited and cannot recapitulate protein-small molecule interactions in situ (e.g., in living cells)4. Consequently, wrong cellular targets might be identified5. Therefore, the field of natural product drug discovery can clearly benefit from innovative chemical tools capable of proteome-wide target identification under native cellular environments6. Inspired by concepts developed in activity-based protein profiling (ABPP)7, we recently introduced the so-called “in situ drug profiling“ approach in which protein-small molecule interactions were directly interrogated in living cells by using cell-permeable probes minimally modified from their parental bioactive compounds89, The strategy is applicable to compounds that form either irreversible or reversible complexes with their cellular targets, and has been adopted by others for both on- and off-target studies101112131415. Few natural products, however, have been studied in this way, partly due to limited synthetic accessibility615. More recently, dual-purpose small molecule probes capable of both in situ imaging and target identification have been developed16; by combining information obtained from both the sub-cellular localization and large-scale cell-based proteome profiling of such probes, high-confidence cellular targets of bioactive compounds could be delineated. Notwithstanding, since the imaging capability of such probes was driven by non-covalent interaction with their intended cellular targets, they fell short of reporting real-time target engagement. Bogyo and co-workers developed fluorescently quenched activity-based probes based on peptide acyloxymethylketones which were capable of real-time imaging of protease activities in mammalian cells17. Herein, by successfully uniting natural product drug discovery, in situ drug profiling and real-time bioimaging of target-drug interaction for the first time, we report dual-purpose probes based on andrographolide (a natural product; Fig. 1). Detailed in situ bioimaging and proteome profiling confirmed that andrographolide is a highly promiscuous compound engaged in covalent interactions with numerous previously unidentified cellular targets in cell type-specific manner.


In situ imaging and proteome profiling indicate andrographolide is a highly promiscuous compound.

Li L, Wijaya H, Samanta S, Lam Y, Yao SQ - Sci Rep (2015)

Overall strategy of dual-purpose probes for real-time imaging of target-drug interaction and in situ proteome profiling/target identification.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4478469&req=5

f1: Overall strategy of dual-purpose probes for real-time imaging of target-drug interaction and in situ proteome profiling/target identification.
Mentions: Natural products represent an enormous source of pharmacologically useful compounds1. They are the active components of many traditional medicines, and often used as the starting point in modern drug discovery2. Approximately 50% of FDA-approved drugs are directly derived from or inspired by natural products. Many biologically interesting natural products, however, have not been pursued as potential drug candidates due to a variety of reasons, including accessibility, cost, structural complexity, and a lack of well-defined mechanism-of-action3. Traditionally, in vitro methods based on affinity protein enrichment from crude cellular lysates are used to identify potential targets of natural products, but they are highly limited and cannot recapitulate protein-small molecule interactions in situ (e.g., in living cells)4. Consequently, wrong cellular targets might be identified5. Therefore, the field of natural product drug discovery can clearly benefit from innovative chemical tools capable of proteome-wide target identification under native cellular environments6. Inspired by concepts developed in activity-based protein profiling (ABPP)7, we recently introduced the so-called “in situ drug profiling“ approach in which protein-small molecule interactions were directly interrogated in living cells by using cell-permeable probes minimally modified from their parental bioactive compounds89, The strategy is applicable to compounds that form either irreversible or reversible complexes with their cellular targets, and has been adopted by others for both on- and off-target studies101112131415. Few natural products, however, have been studied in this way, partly due to limited synthetic accessibility615. More recently, dual-purpose small molecule probes capable of both in situ imaging and target identification have been developed16; by combining information obtained from both the sub-cellular localization and large-scale cell-based proteome profiling of such probes, high-confidence cellular targets of bioactive compounds could be delineated. Notwithstanding, since the imaging capability of such probes was driven by non-covalent interaction with their intended cellular targets, they fell short of reporting real-time target engagement. Bogyo and co-workers developed fluorescently quenched activity-based probes based on peptide acyloxymethylketones which were capable of real-time imaging of protease activities in mammalian cells17. Herein, by successfully uniting natural product drug discovery, in situ drug profiling and real-time bioimaging of target-drug interaction for the first time, we report dual-purpose probes based on andrographolide (a natural product; Fig. 1). Detailed in situ bioimaging and proteome profiling confirmed that andrographolide is a highly promiscuous compound engaged in covalent interactions with numerous previously unidentified cellular targets in cell type-specific manner.

Bottom Line: Natural products represent an enormous source of pharmacologically useful compounds, and are often used as the starting point in modern drug discovery.Many biologically interesting natural products are however not being pursued as potential drug candidates, partly due to a lack of well-defined mechanism-of-action.We caution its potential therapeutic effects should be further investigated in detail.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemistry, National University of Singapore, Singapore 117543 [2] Key Laboratory of Flexible Electronics (KLOFE) &Institute of Advanced Materials (IAM), National Jiangsu Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing 211816, P. R. China.

ABSTRACT
Natural products represent an enormous source of pharmacologically useful compounds, and are often used as the starting point in modern drug discovery. Many biologically interesting natural products are however not being pursued as potential drug candidates, partly due to a lack of well-defined mechanism-of-action. Traditional in vitro methods for target identification of natural products based on affinity protein enrichment from crude cellular lysates cannot faithfully recapitulate protein-drug interactions in living cells. Reported herein are dual-purpose probes inspired by the natural product andrographolide, capable of both reaction-based, real-time bioimaging and in situ proteome profiling/target identification in live mammalian cells. Our results confirm that andrographolide is a highly promiscuous compound and engaged in covalent interactions with numerous previously unknown cellular targets in cell type-specific manner. We caution its potential therapeutic effects should be further investigated in detail.

No MeSH data available.