TY - JOUR
T1 - Irreversible binding of an anticancer compound (BI-94) to plasma proteins
AU - Gautam, Nagsen
AU - Thakare, Rhishikesh
AU - Rana, Sandeep
AU - Natarajan, Amarnath
AU - Alnouti, Yazen
N1 - Funding Information:
This work was supported National Institutes of Health (Grants DA028555-01 and CA127239). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
Publisher Copyright:
© 2015 Informa UK Ltd.
PY - 2015/10/3
Y1 - 2015/10/3
N2 - 1. We investigated the mechanisms responsible for the in vivo instability of a benzofurazan compound BI-94 (NSC228148) with potent anti-cancer activity.2. BI-94 was stable in MeOH, water, and in various buffers at pHs 2.5-5, regardless of the buffer composition. In contrast, BI-94 was unstable in NaOH and at pHs 7-9, regardless of the buffer composition. BI-94 disappeared immediately after spiking into mice, rat, monkey, and human plasma. BI-94 stability in plasma can be only partially restored by acidifying it, which indicated other mechanisms in addition to pH for BI-94 instability in plasma.3. BI-94 formed adducts with the trapping agents, glutathione (GSH) and N-acetylcysteine (NAC), in vivo and in vitro via nucleophilic aromatic substitution reaction. The kinetics of adduct formation showed that neutral or physiological pHs enhanced and accelerated GSH and NAC adduct formation with BI-94, whereas acidic pHs prevented it. Therefore, physiological pHs not only altered BI-94 chemical stability but also enhanced adduct formation with endogenous nucleophiles. In addition, adduct formation with human serum albumin-peptide 3 (HSA-T3) at the Cys34 position was demonstrated.4. In conclusion, BI-94 was unstable at physiological conditions due to chemical instability and irreversible binding to plasma proteins.
AB - 1. We investigated the mechanisms responsible for the in vivo instability of a benzofurazan compound BI-94 (NSC228148) with potent anti-cancer activity.2. BI-94 was stable in MeOH, water, and in various buffers at pHs 2.5-5, regardless of the buffer composition. In contrast, BI-94 was unstable in NaOH and at pHs 7-9, regardless of the buffer composition. BI-94 disappeared immediately after spiking into mice, rat, monkey, and human plasma. BI-94 stability in plasma can be only partially restored by acidifying it, which indicated other mechanisms in addition to pH for BI-94 instability in plasma.3. BI-94 formed adducts with the trapping agents, glutathione (GSH) and N-acetylcysteine (NAC), in vivo and in vitro via nucleophilic aromatic substitution reaction. The kinetics of adduct formation showed that neutral or physiological pHs enhanced and accelerated GSH and NAC adduct formation with BI-94, whereas acidic pHs prevented it. Therefore, physiological pHs not only altered BI-94 chemical stability but also enhanced adduct formation with endogenous nucleophiles. In addition, adduct formation with human serum albumin-peptide 3 (HSA-T3) at the Cys34 position was demonstrated.4. In conclusion, BI-94 was unstable at physiological conditions due to chemical instability and irreversible binding to plasma proteins.
KW - Glutathione
KW - LC-MS/MS
KW - N-acetylcysteine
KW - irreversible protein binding
KW - isotopic filtering
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U2 - 10.3109/00498254.2015.1025250
DO - 10.3109/00498254.2015.1025250
M3 - Article
C2 - 25869245
AN - SCOPUS:84940557888
VL - 45
SP - 858
EP - 873
JO - Xenobiotica
JF - Xenobiotica
SN - 0049-8254
IS - 10
ER -