- November 2015 (2)
- September 2015 (1)
- July 2015 (1)
- June 2015 (3)
- May 2015 (1)
- January 2015 (1)
- December 2014 (1)
- November 2014 (2)
- September 2014 (4)
- August 2014 (2)
- July 2014 (3)
- June 2014 (1)
- May 2014 (3)
- April 2014 (2)
- February 2014 (2)
- January 2014 (1)
- December 2013 (2)
- November 2013 (3)
- October 2013 (1)
- September 2013 (1)
- August 2013 (2)
- July 2013 (2)
- May 2013 (1)
- April 2013 (1)
- February 2013 (2)
- January 2013 (1)
- December 2012 (2)
- November 2012 (1)
- October 2012 (2)
- July 2012 (2)
- May 2012 (4)
- April 2012 (2)
- March 2012 (2)
- January 2012 (3)
- 3D7 IC50 Avery Lab (3)
- AstraZeneca (2)
- Potencies Guy (1)
- Syngene (5)
- UCSD (1)
- Biology (37)
- DMPK (2)
- GSH-EE - Chapman Lab (2)
- GSK PRR Assay (1)
- Imperial DGFA (1)
- Kirk Lab (5)
- MetID (3)
- Potencies GSK (1)
A further set of Series 4 Triazolopyrazine compounds have been sent to have their efficacy evaluated against Plasmodium falciparum in-vitro at Syngene.
Some compounds were synthesised by the SSP group at The University Sydney and then purified in the research lab.
Structures are as follows and data will be published in due course:
General assay principle:
"This protocol assesses compound efficacy against Plasmodium falciparum in-vitro. This assay is using [3H]-hypoxanthine incorporation or DNA labeling by SYBR Green as a markers of parasite growth.
This procedure is designed for use with culture adapted P. falciparum strains or clones only. On one 96-well plate typically 03 drugs are tested in duplicate. Standard strains: Plasmodium falciparum, NF54 (sensitive to all known drugs), Plasmodium falciparum, K1 (chloroquine and pyrimethamine resistant). The assay can be performed in dose response mode (12 concentrations in duplicate, 24 data points) which allows determining IC50, or in single concentration mode (one concentration in triplicate, 3 data points) which allows determining the percentage of growth inhibition.
For more information, see Desjardins et al. (Antimicrob. Agents Chemother., 16(6), 710, 1979)."
(Post originally authored by Alice Williamson)
Four OSM Series 1 compounds were evaluated in a P. falciparum dual gamete formation assay, with data in the attached report. Literature on this assay is in this paper. The assay was performed by the original Imperial team.
All compounds were found to be inactive (low activity) against both male and female gametocytes, though the levels of activity for some compounds were higher vs. female than any antimalarials originally tested in the above-linked paper (where the maximum % inhibition at this concentration was 27%).
These data are a little surprising given that several of these compounds had previously displayed very high levels of activity in a late stage gametocyte assay:
Late Stage Gametocyte Assay (OSM-S-111)
it might have been expected that there would have been more activity vs (the more susceptible) males.
CC(N1C2=CC=C(F)C=C2)=C(C(OCC(N)=O)=O)C=C1C InChI=1S/C15H15FN2O3/c1-9-7-13(15(20)21-8-14(17)19)10(2)18(9)12-5-3-11(16)4-6-12/h3-7H,8H2,1-2H3,(H2,17,19) YSUCFIZUNLQZDX-UHFFFAOYSA-N
CC1=CC(/C=C(C(N/2)=O)\SC2=N/C3=CC=CC=C3)=C(C)N1C(C=C4)=CC=C4C(F)(F)F InChI=1S/C23H18F3N3OS/c1-14-12-16(15(2)29(14)19-10-8-17(9-11-19)23(24,25)26)13-20-21(30)28-22(31-20)27-18-6-4-3-5-7-18/h3-13H,1-2H3,(H,27,28,30)/b20-13- YBBWTVGRVHTTDD-MOSHPQCFSA-N
CC1=CC(/C=C(C(N/2)=O)\SC2=N/C3=CC=CC=C3)=C(C)N1C4=CC(C(F)(F)F)=CC(C(F)(F)F)=C4 InChI=1S/C24H17F6N3OS/c1-13-8-15(9-20-21(34)32-22(35-20)31-18-6-4-3-5-7-18)14(2)33(13)19-11-16(23(25,26)27)10-17(12-19)24(28,29)30/h3-12H,1-2H3,(H,31,32,34)/b20-9- GVGNOLWIUGQIHW-UKWGHVSLSA-N
CC1=CC(/C=C(C(N/2)=O)\SC2=N/C3=CC=CC=C3)=C(C)N1C4=CC=C(OC)C=C4 InChI=1S/C23H21N3O2S/c1-15-13-17(16(2)26(15)19-9-11-20(28-3)12-10-19)14-21-22(27)25-23(29-21)24-18-7-5-4-6-8-18/h4-14H,1-3H3,(H,24,25,27)/b21-14- KXIVXNPEYYNDHE-STZFKDTASA-N
This post originally authored by Mat Todd
Recent analysis was undertaken by Corey Nislow (see GHI20) on predicting the mechanism of action of Series 1 compounds. In discussions that took place by email (sorry) which are being incorporated into the final draft of the paper about to be submitted on Series 1, a suggestion was made by Corey that the different compounds in Series 1 may have different MoAs. To verify whether this might be true, one arylpyrrole and several Near Neighbours were sent for evaluation in a Parasite Reduction Ratio (PRR) (colloquially, Rate of Killing) assay at GSK Tres Cantos. Thank you to Benigno Crespo and Laura Sanz for doing this, and to Javier Gamo for signing off on the report, which is attached.
The PRR assay can reveal possible MoA based on a comparison of the killing profile of the compounds. If the pattern of parasite ratio, followed over several days, matches the profile found using an existing compound, it's possible they may share a MoA.
Here are the compounds analysed:
Here are the combined results.
Within the noise of this experiment it would seem as though the compounds share a common MoA. A suggestion was made by Corey that, based on the HipHop results, one compound (OSM-S-39) may share commonalities with artemisinin. Though artemisinin was not evaluated in the present assay run, it is known to possess a very rapid rate of killing that would not match the profiles obtained for the present compounds.
MMV019247 OSM-S-5 FC1=CC=C(N2C(C)=CC(C(OCC(N)=O)=O)=C2C)C=C1 InChI=1S/C15H15FN2O3/c1-9-7-13(15(20)21-8-14(17)19)10(2)18(9)12-5-3-11(16)4-6-12/h3-7H,8H2,1-2H3,(H2,17,19) YSUCFIZUNLQZDX-UHFFFAOYSA-N
MMV689017 OSM-S-10 FC1=CC=C(N2C(C)=CC(/C=C3S/C(NC\3=O)=N\C4=CC=CC=C4)=C2C)C=C1 InChI=1S/C22H18FN3OS/c1-14-12-16(15(2)26(14)19-10-8-17(23)9-11-19)13-20-21(27)25-22(28-20)24-18-6-4-3-5-7-18/h3-13H,1-2H3,(H,24,25,27)/b20-13- IMCPBTMVWRMBHR-MOSHPQCFSA-N
MMV689018 OSM-S-35 CC1=C(/C=C2S/C(NC\2=O)=N\C3=CC=CC=C3)C=C(C)N1C4=CC=CC=C4 InChI=1S/C22H19N3OS/c1-15-13-17(16(2)25(15)19-11-7-4-8-12-19)14-20-21(26)24-22(27-20)23-18-9-5-3-6-10-18/h3-14H,1-2H3,(H,23,24,26)/b20-14- QTDBAHFMTAMGMZ-ZHZULCJRSA-N
MMV689019 OSM-S-37 CC1=C(/C=C2S/C(NC\2=O)=N\C3=CC=CC=C3)C=C(C)N1C4=CC=C(C)C=C4 InChI=1S/C23H21N3OS/c1-15-9-11-20(12-10-15)26-16(2)13-18(17(26)3)14-21-22(27)25-23(28-21)24-19-7-5-4-6-8-19/h4-14H,1-3H3,(H,24,25,27)/b21-14- XCTPMKNSBDOHRB-STZFKDTASA-N
MMV689020 OSM-S-39 CC1=C(/C=C2S/C(NC\2=O)=N\C3=CC=CC=C3)C=C(C)N1C4=CC(C(F)(F)F)=CC(C(F)(F)F)=C4 InChI=1S/C24H17F6N3OS/c1-13-8-15(9-20-21(34)32-22(35-20)31-18-6-4-3-5-7-18)14(2)33(13)19-11-16(23(25,26)27)10-17(12-19)24(28,29)30/h3-12H,1-2H3,(H,31,32,34)/b20-9- GVGNOLWIUGQIHW-UKWGHVSLSA-N
MMV689021 OSM-S-51 CC1=C(/C=C2S/C(NC\2=O)=N\C3=CC=CC=C3)C=C(C)N1C4=NC=CC=C4 InChI=1S/C21H18N4OS/c1-14-12-16(15(2)25(14)19-10-6-7-11-22-19)13-18-20(26)24-21(27-18)23-17-8-4-3-5-9-17/h3-13H,1-2H3,(H,23,24,26)/b18-13- WFGBKPBKZGJAHY-AQTBWJFISA-N
What are the best strategies for minimizing metabolic clearance in OSM Series 4? This has been, and remains, a key scientific issue for us, along with maintaining potency and improving solubility.
We're devising the next set of compounds to make (also GHI301) and we're meeting next week (GHI317), so this is a good time to re-engage with metabolic clearance.
Separate Issues will be created for each relevant To Do item on Github, but here are all the background data:
1) All the current clearance data are in the wiki. Some data inherited, others obtained more recently. For the moment we are deprioritising the amide series (top row of data in the main wiki scheme) because of a probable hERG liability. So let's focus mostly on the non-amides.
2) Chris Swain predicted metabolic hotspots (in red, below) for three Series 4 compounds, MMV669844, MMV669848 and MMV670936.
When Chris ran the same compounds through a Cyp predictor the same sites came up minus those on the ring, suggesting the ring could be a substrate for another enzyme such as aldehyde oxidase. However, measured AO clearance values suggest MMV669844, for example, is not an AO substrate (see below).
3) Met and MetID work on these same three compounds above from Sue Charman's lab suggested that oxidation on the triazolopyrazine-aromatic system was occurring in most cases, with other liabilities shown above. The analog of MMV669844 with a CHF2 group in place of the CH3 (MMV670652, 17 nM) was tested in microsomal studies, giving CLint HLM<8, RLM 30.
4) Aldehyde Oxidase Screen. Performed, with summary data. Amides appeared to be more susceptible to AO oxidation, but in general several potent members of the ether class were found not to be substrates for AO. We should both not worry about AO for this series and yet periodically re-assess Series 4 compounds in the assay.
5) The nature of the core heterocyclic ring has a major effect on clearance - compare the parent triazolopyrazine MMV639565 with the imidazopyrazines MMV669846 and MMV670250.
The potency and reasonable clearance of MMV669846 make it interesting to look at again. The very high clearance of MMV670250 suggests...what?
6) We know that blocking the pyrazine ring in the 8-position reduces potency and that the N-oxide in the pyrazine ring is inactive (below), and we also now know that replacement of the pyrazine southwest N with CH lowers potency. Is there any reason to investigate these further, e.g. for metabolic clearance rate on these compounds?
6) To Do/Questions
i) Benzylic Blocking: Are there blocking groups in the northwest benzylic position we ought to include that might improve metabolic stability? Is it possible to run some of these through predictive software to see if such structures might help?
ii) Acquiring New Metabolic Data on Existing Compounds: MMV670652 (above) has not yet been studied in hepatocytes, and has not had MetID performed. Is there justification for this, to confirm that we see improvements over MMV669844, or can this be assumed?
iii) Acquiring New Metabolic Data on New Compounds: Of the newer compounds synthesised (1, 2, 3), are there any that ought to be evaluated at the Charman lab for microsomal stability (GHI213) (and solubility: GHI260)? Should we re-run Chris Swain's analysis on any new target compounds?
iv) Trends in the Data: In general the newer Monash data (in green in the wiki) shows that a number of the analogs with blocking groups in the northwest benzylic position and OCHF2 in the northeast have higher than expected clearance rates vs. what might be expected given the data for the analogs with similar blocking groups in the benzylic position and a cyano group in the northeast. Is it possible that the northeast Ar substituent is playing a role in metabolic liability of the aromatic system?
v) Triazole Mods: We should resynthesise the imidazopyrazine MMV669846 shown above to verify potency and microsomal stability. Underway. Are there other groups that could be entertained on the triazole, or in place of it? What is known of good mimics of such a ring system?
vi) Pinning Down Site of Oxidation: Is it worth establishing where on the triazolopyrazine-Ar structure the oxidation is occurring, given the prediction that Cyp will not oxidise on the TP ring and given the low AO clearance experimentally determined? (Related to GHI124).
Post originally authored by Mat Todd
Stephan Meister from Elizabeth Winzeler's laboratory at UCSD tested two Series 1 Compounds in a liver stage assay to provide some greater context for the first Open Source Malaria Paper.
The aryl pyrrole OSM-S-5 and near neighbour OSM-S-38 were both blood-stage active compounds from Series 1 and were both evaluated in this assay. OSM-S-5 showed an IC50 of 23 uM, whilst OSM-S-38 had an activity of 19 nM with no HepG2 cytotoxicity. These data may provide some evidence that these two series of compounds may have distinct mechanisms of action.
Previously OSM-S-111, another of the near neighbours (analogous to OSM-S-38) had shown moderate potency in the same assay:
General assay principle:
This assay is based on the murine Plasmodium berghei species transformed with Luciferase. Hepatic human transformed cells (HepG2), pretreated for two hours with the compound to investigate, are infected with freshly dissected P. berghei Luciferase sporozoites. After 48 hours of incubation with the compound to investigate, the viability of P. berghei exoerythrocytic forms (EEF) is measured by bioluminescence.
This assay allows us to identify compounds with an eventual activity against sporozoite infection of liver cell as well the viability of liver schizonts.
Update Sept 10th 2015
The compounds were re-tested by Stephan and Jenya Antonova, giving broadly similar results: OSM-S-5 showed an IC50 of 14 uM, whilst OSM-S-38 had an activity of 13 nM.
This raises the question of whether OSM-S-38 should be tested in the Pc liver stage assay at the BPRC in the Netherlands.
This post originally authored by Alice Williamson. Edited by Mat Todd. Updated with new data by Mat Todd.
Plasmodium berghei Luciferase sporozoites were obtained by dissection of infected A. stephensi mosquito salivary glands supplied by the New York University Insectary. Dissected salivary glands were homogenized in a glass tissue grinder and filtered twice through Nylon cell strainers (40 μm pore size, BD Falcon) and counted using a hemocytometer. The sporozoites were kept on ice until needed.
OSM-S-5: TCMDC-123812 CC(N1C2=CC=C(F)C=C2)=C(C(OCC(N)=O)=O)C=C1C InChI=1S/C15H15FN2O3/c1-9-7-13(15(20)21-8-14(17)19)10(2)18(9)12-5-3-11(16)4-6-12/h3-7H,8H2,1-2H3,(H2,17,19) YSUCFIZUNLQZDX-UHFFFAOYSA-N
OSM-S-38: CC1=CC(/C=C(C(N/2)=O)\SC2=N/C3=CC=CC=C3)=C(C)N1C(C=C4)=CC=C4C(F)(F)F InChI=1S/C23H18F3N3OS/c1-14-12-16(15(2)29(14)19-10-8-17(9-11-19)23(24,25)26)13-20-21(30)28-22(31-20)27-18-6-4-3-5-7-18/h3-13H,1-2H3,(H,27,28,30)/b20-13- YBBWTVGRVHTTDD-MOSHPQCFSA-N
OSM-S-111: O=C(/C(S/1)=C/C2=C(C)N(C3=CC=C(OC)C=C3)C(C)=C2)NC1=N\C4=CC=CC=C4 InChI=1S/C23H21N3O2S/c1-15-13-17(16(2)26(15)19-9-11-20(28-3)12-10-19)14-21-22(27)25-23(29-21)24-18-7-5-4-6-8-18/h4-14H,1-3H3,(H,24,25,27)/b21-14- KXIVXNPEYYNDHE-STZFKDTASA-N