A comprehensive study of Sansalvamide A derivatives: The structure-activity relationships of 78 derivatives in two pancreatic cancer cell lines

Abstract

We report an extensive structure-activity relationship (SAR) of 78 compounds active against two pancreatic cancer cell lines. Our comprehensive evaluation of these compounds utilizes SAR that allow us to evaluate which features of potent compounds play a key role in their cytotoxicity. This is the first report of 19 new second-generation structures, where these new compounds were designed from the first generation of 59 compounds. These 78 structures were tested for their cytotoxicity and this is the first report of their activity against two pancreatic cancer cell lines. Our results show that out of 78 compounds, three compounds are worth pursuing as leads, as they show potency of 55% in both cancer cell lines. These three compounds all have a common structural motif, two consecutive d-amino acids and an N-methyl moiety. Further, of these three compounds, two are second-generation structures, indicating that we can incorporate and utilize data from the first generation to design potency into the second generation. Finally, one analog is in the mid nanomolar range, and has the lowest IC(50) of any reported San A derivative. These analogs share no structural homology to current pancreatic cancer drugs, and are cytotoxic at levels on par with existing drugs treating other cancers. Thus, we have established Sansalvamide A as an excellent lead for killing multiple pancreatic cancer cell lines.

Figure 1

Retrosynthetic approach

Figure 2

Synthesis of Macrocycles Conditions: a) coupling agent*, DIPEA (4 equiv), DCM (0.1M), b)TFA (20%), Anisole (2 equiv), DCM, c) LiOH (4 equiv), MeOH d)LiOH (10 equiv), MeOH, e) HATU (0.7 equiv), DEPBT (0.7 equiv), TBTU (0.7 equiv), DIPEA (6 equiv), DMF:DCM:CH₃CN (2:2:1) 0.01M. *TBTU (1.2 equiv), and/or HATU (0.75 equiv)

Figure 3

Amino acids used in the synthesis of seventy-eight derivatives

Figure 4

Compounds with alterations at position I. Data is represented as % growth inhibition relative to 1% DMSO control. Each data point is an average of 4 wells run in three assays. All assays were run for 72 hours at 5µM compound concentration.

Figure 5

Compounds with alterations at positions II and/or I. Data is represented as % growth inhibition relative to 1% DMSO control. Each data point is an average of 4 wells run in three assays. All assays were run for 72 hours at 5µM compound concentration.

Figure 6

Compounds with alterations in positions III and/or I/II. Data is represented as % growth inhibition relative to 1% DMSO control. Each data point is an average of 4 wells run in three assays. All assays were run for 72 hours at 5µM compound concentration.

Figure 7

Compounds with alterations at positions IV and/or l-lll. Data is represented as % growth inhibition relative to 1% DMSO control. Each data point is an average of 4 wells run in three assays. All assays were run for 72 hours at 5µM compound concentration.

Figure 8

Compounds with alterations at position V and/or I-IV. Data is represented as % growth inhibition relative to 1% DMSO control. Each data point is an average of 4 wells run in three assays. All assays were run for 72 hours at 5µM compound concentration.

Figure 9

Compounds with N-methyl moieties and their enantiomers. Data is represented as % growth inhibition relative to 1% DMSO control. Each data point is an average of 4 wells run in three assays. Error = ±5%. All assays were run for 72 hours at 5µM compound concentration.

Figure 10

Most potent compounds and the compounds from which they were designed. Data is represented as % growth inhibition relative to 1% DMSO control. Each data point is an average of 4 wells run in three assays. All assays were run for 72 hours at 5µM compound concentration.

Figure 11

IC_50s of potent compounds. Each data point is an average of 4 wells run in three assays at 50, 10, 0.5, and 0.1 µM.

Figure 11

IC_50s of potent compounds. Each data point is an average of 4 wells run in three assays at 50, 10, 0.5, and 0.1 µM.