One of the main directions of steroid research is the preparation of modified derivatives in which, in addition to changes in physicochemical properties, receptor binding is significantly altered, thus a bioactivity different from that of the parent compound predominates. In the frame of this work, 2-arylidene derivatives were first synthesized by regioselective modification of the A-ring of natural sex hormone, 5α-dihydrotestosterone (DHT). After Claisen-Schmidt condensations of DHT with (hetero)aromatic aldehydes in alkaline EtOH, heterocyclizations of the α,β-enones were performed with 3-amino-1,2,4-triazole, 3-aminopyrazole and 3-amino-5-methylpyrazole in the presence of t-BuOK in DMF to afford 7'-epimeric mixtures of A-ring-fused azolo-dihydropyrimidines, respectively. Depending on the electronic demand of the substituents of the arylidene moiety, spontaneous or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)-induced oxidation of the heteroring led to triazolo[1,5-a]pyrimidines and pyrazolo[1,5-a]pyrimidines in good yields, while, using the Jones reagent as a strong oxidant, 17-oxidation also occurred. The crystal structures of an arylidene and a triazolopyrimidine product have been determined by single crystal X-ray diffraction and both were found to crystallize in the monoclinic crystal system at P2₁ space group. Most derivatives were found to diminish the transcriptional activity of androgen receptor (AR) in reporter cell line. The candidate compound (17β-hydroxy-2-(4-chloro)benzylidene-5α-androstan-3-one, 2f) showed to suppress androgen-mediated AR transactivation in a dose-dependent manner. We confirmed the cellular interaction of 2f with AR, described the binding in AR-binding cavity by the flexible docking and showed the ability of the compound to suppress the expression of AR-regulated genes in two prostate cancer cell lines.

Therapy of FLT3-positive acute myeloid leukemia still remains complicated, despite the availability of newly approved kinase inhibitors. Various strategies to avoid the reduced efficacy of therapy have been explored, including the development of dual targeting compounds, which inhibit FLT3 and another kinase necessary for the survival and proliferation of AML cells. We have designed new 2,7,9-trisubstituted 8-oxopurines as FLT3 inhibitors and report here the structure-activity relationship studies. We demonstrated that substituents at positions 7 and 9 modulate activity between CDK4 and FLT3 kinase, and the isopropyl group at position 7 substantially increased the selectivity toward FLT3 kinase, which led to the discovery of compound 15a (9-cyclopentyl-7-isopropyl-2-((4-(piperazin-1-yl)phenyl)amino)-7,9-dihydro-8H-purin-8-one). Cellular analyses in MV4-11 cells revealed inhibition of autophosphorylation of FLT3 kinase in nanomolar doses, including the suppression of downstream STAT5 and ERK1/2 phosphorylation. We also describe mechanistic studies in cell lines and activity in a mouse xenograft model in vivo.

Taxanes and other tubulin‐targeting medications are essential for treating advanced malignancies, especially in patients undergoing less aggressive chemotherapy. However, their clinical efficacy is often limited by significant off‐target toxicity and adverse side effects. In this study, the synthesis and characterisation of novel steroidal A‐ring‐fused isoxazoles, which were obtained through iodine‐mediated oxidative cyclization of dihydrotestosterone (DHT)‐derived α,β‐unsaturated oximes, are reported. According to mechanistic studies, the most potent compounds induced mitotic arrest and disrupted cytoskeletal integrity at low micromolar concentrations. The lead compound, 2j , notably increased the rate of tubulin polymerisation in vitro and stabilised polymerised tubulin in the cells, leading to a G2/M block of the cell cycle. Molecular docking studies indicated that 2j is bound preferably to the taxane site on tubulin, forming conserved interactions. MicroScale Thermophoresis was used to further study this binding and showed a nanomolar K _D for 2j . The fact that 2j maintained its activity in docetaxel‐resistant prostate cancer cells, demonstrating its ability to circumvent resistance pathways linked to existing therapies with taxane‐like drugs, supports its clinical relevance. Therefore, our results encourage additional research and development for its potential therapeutic use in cancer treatment, particularly in resistant cases.

Therapy of FLT3-positive acute myeloid leukemia still remains complicated, despite the availability of newly approved kinase inhibitors. Various strategies to avoid reduced efficacy of therapy are explored including the development of dual targeting compounds, which inhibit FLT3 and another kinase necessary for survival and proliferation of AML cells. We have designed new 2,7,9-trisubstituted 8-oxopurines as FLT3 inhibitors and report here structure-activity relationship studies. We demonstrated that substituents at positions 7 and 9 modulate activity between CDK4 and FLT3 kinase and the isopropyl group at position 7 increased substantially the selectivity toward FLT3 kinase, which led to the discovery of compound 15a (9-cyclopentyl-7-isopropyl-2-((4-(piper-azin-1-yl)phenyl)amino)-7,9-dihydro-8 H -purin-8-one). Cellular analyses in MV4-11 cells revealed inhibition of autophosphorylation of FLT3 kinase in nanomolar doses including suppression of downstream STAT5 and ERK1/2 phosphorylation. We also describe mechanistic studies in cell lines and activity in a mouse xenograft model in vivo.