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. Author manuscript; available in PMC: 2019 Sep 5.
Published in final edited form as: Eur J Med Chem. 2018 Aug 20;157:962–977. doi: 10.1016/j.ejmech.2018.08.052

Table 3:

Cytotoxicity and inhibition of human proteasomes (hCP) measured in Jurkat lysate for P1 analogs. Assays were performed in biological triplicate (n=3) and confirmed in technical triplicate. The IC50 values were calculated using a nonlinear dose response model in GraphPad Prism 6.0 and are reported with the corresponding SD. ND: Not determined

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IC50 (μM) ± SD
Substitution hCP Inhibition Cytotoxicity
Compound Pz hβ5 hβ2 MCF7 MDA-MB-231 RPMI 8226
2 sec-Bu 0.0070 ± 0.0003 1.430 ± 0.089 1.853 ± 0.261 0.287 ± 0.008 0.191 ± 0.015
4a cyc-Pr 0.0076 ± 0.0006 3.188 ± 0.164 >100 >100 73.86 ± 2.65
4b cyc- Bu 0.0132 ± 0.0005 4.070 ± 0.461 >50 >50 37.22 ± 3.19
4c cyc-Pent 0.0129 ± 0.0007 7.468 ± 0.748 50.62 ± 4.20 28.17 ± 3.88 2.346 ± 0.334
4d i-Bu 0.0197 ± 0.0010 4.580 ± 0.161 55.32 ± 4.94 30.32 ± 3.03 33.52 ± 1.31
Carfilzomib (Cfz)
 0.0096 ± 0.0006 0.203 ± 0.005 0.0041 ± 0.0001 0.0044 ± 0.0001 0.0067 ± 0.0002
Cystargolide B 0.90 ± 0.11 ND 84.7 ± 18.6 ND ND