Total Synthesis of Altissimacoumarin D, a Small Molecule Sirtuin1 Activator

The total synthesis of the plant natural product altissimacoumarin D was achieved by the Mitsunobu alkylation of isofraxidin by geraniol. Isofraxidin was prepared from 2,4-dihydroxybenzaldehyde in five steps. The key reaction was the Knoevenagel condensation of an ortho-hydroxybenzaldehyde with Meldrum’s acid under neutral conditions in water and one-pot acid catalyzed cyclization to the coumarin

Fluorinated tranylcypromine analogues as inhibitors of lysine-specific demethylase 1 (LSD1, KDM1A)

We report a series of tranylcypromine analogues containing a fluorine in the cyclopropyl ring. A number of compounds with additional m- or p- substitution of the aryl ring were micromolar inhibitors of the LSD1 enzyme. In cellular assays, the compounds inhibited the proliferation of acute myeloid leukemia cell lines. Increased levels of the biomarkers H3K4me2 and CD86 were consistent with LSD1 target engagement

Synthesis of calboxamide-containing tranylcypromine analogues as LSD1 (KDM1A) inhibitors targeting acute myeloid Leukemia

Lysine-specific demethylase 1 (LSD1/KDM1A) oxidatively removes methyl groups from histone proteins, and its aberrant activity has been correlated with cancers including acute myeloid leukemia (AML). We report a novel series of tranylcypromine analogues with a carboxamide at the 4-position of the aryl ring. These compounds, such as 5 a and 5 b with benzyl and phenethylamide substituents, respectively, had potent sub-micromolar IC 50 values for the inhibition of LSD1 as well as cell proliferation in a panel of AML cell lines. The dose-dependent increase in cellular expression levels of H3K4me2, CD86, CD11b and CD14 supported a mechanism involving LSD1 inhibition. The tert-butyl and ethyl carbamate derivatives of these tranylcypromines, although inactive in LSD1 inhibition, were of similar potency in cell-based assays with a more rapid onset of action. This suggests that carbamates can act as metabolically labile tranylcypromine prodrugs with superior pharmacokinetics

Synthesis of Carboxamide-Containing Tranylcypromine Analogues as LSD1 (KDM1A) Inhibitors Targeting Acute Myeloid Leukemia

Lysine-specific demethylase 1 (LSD1/KDM1A) oxidatively removes methyl groups from histone proteins, and its aberrant activity has been correlated with cancers including acute myeloid leukemia (AML). We report a novel series of tranylcypromine analogues with a carboxamide at the 4-position of the aryl ring. These compounds, such as 5 a and 5 b with benzyl and phenethylamide substituents, respectively, had potent sub-micromolar IC50 values for the inhibition of LSD1 as well as cell proliferation in a panel of AML cell lines. The dose-dependent increase in cellular expression levels of H3K4me2, CD86, CD11b and CD14 supported a mechanism involving LSD1 inhibition. The tert-butyl and ethyl carbamate derivatives of these tranylcypromines, although inactive in LSD1 inhibition, were of similar potency in cell-based assays with a more rapid onset of action. This suggests that carbamates can act as metabolically labile tranylcypromine prodrugs with superior pharmacokinetics

LSD1 inhibition attenuates androgen receptor V7 splice variant activation in castration resistant prostate cancer models

Background: Castrate resistant prostate cancer (CRPC) is often driven by constitutively active forms of the androgen receptor such as the V7 splice variant (AR-V7) and commonly becomes resistant to established hormonal therapy strategies such as enzalutamide as a result. The lysine demethylase LSD1 is a co-activator of the wild type androgen receptor and a potential therapeutic target in hormone sensitive prostate cancer. We evaluated whether LSD1 could also be therapeutically targeted in CRPC models driven by AR-V7. Methods: We utilised cell line models of castrate resistant prostate cancer through over expression of AR-V7 to test the impact of chemical LSD1 inhibition on AR activation. We validated findings through depletion of LSD1 expression and in prostate cancer cell lines that express AR-V7. Results: Chemical inhibition of LSD1 resulted in reduced activation of the androgen receptor through both the wild type and its AR-V7 splice variant forms. This was confirmed and validated in luciferase reporter assays, in LNCaP and 22Rv1 prostate cancer cell lines and in LSD1 depletion experiments. Conclusion: LSD1 contributes to activation of both the wild type and V7 splice variant forms of the androgen receptor and can be therapeutically targeted in models of CRPC. Further development of this approach is warranted

Synthesis of cyclic peptide natural products and inhibitors of histone modifying enzymes

Natural products have been the source of numerous leads for several drugs. As these natural products are often isolated in small quantities, it is necessary to produce them synthetically to allow testing for biological activity. Furthermore, synthesis allows the preparation of unnatural analogues for SAR studies. Cyclic peptides represent an important family of biologically active natural products. The hepta- and octacyclopeptides sanguinamide A and sanguinamide B were recently isolated in submicromolar amounts by the Molinski group. The lack of material prevented biological evaluation of the natural products. For this reason and to confirm the structural elucidation we have targeted the total synthesis of sanguinamides. In addition to two proline residues, sanguinamides A and B include heterocycles and natural L-amino acid residues. We have completed the total syntheses of sanguinamides A and B; however the synthetic rotamers differed in both cases from the natural rotamers. We have investigated the influence of macrocyclisation on cis/trans conformational preference of the proline residues for the synthesis of sanguinamide A. We attempted several isomerisations and calculated the relative energies of the different sanguinamide conformers. [D-Ile]-Sanguinamide A, Cys(tBu) analogue of sanguinamide A and the synthetic sanguinamide B displayed antibacterial activity while the synthetic trans, trans-sanguinamide A displayed mild tyrosine kinase inhibitory activity. While extracted stylissamide A showed inhibition of translation during the elongation step, even though being structurally identical to the natural product, the synthetic compound prepared by macrocyclisation from a linear precursor was found to be totally inactive. Histones undergo different types of covalent modifications on the N-terminal tails such as acetylation, phosphorylation and methylation. Histone modification is a major mechanism of regulation in gene expression, replication and repair. Deregulation of histone modifications leads to cancer progression and therefore, inhibitors of enzymes which are able to catalyse the addition and removal of these epigenetic marks have therapeutic potential for treating cancer. An enzyme of particular interest is the family of zinc-dependent histone deacetylases (HDACs) that remove acetyl groups from acetylated lysine residues. Depsipeptides were prepared as HDAC inhibitors. We will ii present our total synthesis of largazole along with a range of analogues and discuss the SAR obtained from HDAC and cell proliferation assays. We elucidated the stereochemistry of burkholdac B by total synthesis of three diastereomers. The diastereomers made along with the natural product were tested as HDAC inhibitors. We are interested in inhibitors of lysine-specific demethylase 1 (LSD1) which is a different kind of epigenetic enzyme involved in demethylation of histone proteins in chromatin. Tranylcypromine is known to be an LSD1 inhibitor. Analogues of PCPA have been synthesised in order to explore the structure-activity relationships of this inhibitor. Analogues were also prepared and tested as LSD1 inhibitors

Total Synthesis and Stereochemical Assignment of Burkholdac B, a Depsipeptide HDAC Inhibitor

Three diastereomers of burkholdac B were prepared by total synthesis, enabling the full stereochemical assignment of the natural product. It is proposed that burkholdac B is identical to thailandepsin A independently isolated by Cheng from the same strain of Burkholderia thailandensis. Burkholdac B is the most potent among depsipeptide histone deacetylase inhibitors in growth inhibition of the MCF7 breast cancer cell line with an IC50 of 60 pM. © 2011 American Chemical Society

Total synthesis of largazole and analogues: HDAC inhibition, antiproliferative activity and metabolic stability

The total synthesis of largazole and four analogues is reported. All analogues were nanomolar HDAC inhibitors. The antiproliferative activity is driven by lipophilicity and cell permeability. In murine liver homogenates, largazole is rapidly metabolized (half-life ?5 min) to the thiol which has a half-life of 51 min