Design, synthesis, and biological evaluation of novel molecules as potent inhibitors of PLK1.

Polo-like kinase 1 (PLK1) is an attractive therapeutic target for the treatment of tumors, as it is an essential cell-cycle regulator frequently overexpressed in tumor tissues. PLK1 can promote tumor invasion and metastasis, and is often associated with poor prognosis in cancer patients. However, no PLK1 inhibitor has been granted marketing approval until now. Therefore, more potentially promising PLK1 inhibitors need to be investigated. In this study, a series of novel inhibitors targeting PLK1 was designed and optimized derived from a new scaffold. After synthesis and characterization, we obtained the structure-activity relationship and led to the discovery of the most promising compound 30e for PLK1. The antiproliferative activity against HCT116 cells (IC50 = 5 nM versus 45 nM for onvansertib) and the cellular permeability and efflux ratio were significantly improved (PappA→B = 2.03 versus 0.345 and efflux ratio = 1.65 versus 94.7 for 30e and onvansertib, respectively). Further in vivo studies indicated that 30e had favorable antitumor activity with 116.2% tumor growth inhibition (TGI) in comparison with TGI of 43.0% for onvansertib. Furthermore, 30e improved volume of tumor tissue distribution in mice as compared to onvansertib. This initial study on 30e holds promise for further development of an antitumor agent.

The Design, Synthesis and Preliminary Pharmacokinetic Evaluation of d3-Poziotinib Hydrochloride.

To establish a synthetic route to d3-poziotinib hydrochloride. Treatment of 4-chloro-7-hydroxyquinazolin-6-yl pivalate (1) with d3-methyliodide afforded the etherization product, which reacted with 3,4-dichloro-2-fluoroaniline to generate the key intermediate d3-4-(3,4-dichloro-2-fluorophenylamino)-7-methoxyquinazolin-6-yl pivalate (3). Followed the de-protection reaction, the nucleophilic substitution (SN2) reaction with tert-butyl 4-(tosyloxy)piperidine-1-carboxylate (TSP), and the de-protection reaction of t-butoxycarbonyl (Boc) group, and the amide formation reaction with acrylyl chloride, d3-poziotinib was obtained, which was converted to hydrochloride salt by treatment with concentrated hydrochloric acid (HCl). Starting from a known compound 4-chloro-7-hydroxyquinazolin-6-yl pivalate (1), after 7 steps transformation, d3-poziotinib hydrochloride was obtained with a total yield of 9.02%. The structure of d3-poziotinib hydrochloride was confirmed by 1H-NMR, 13C-NMR, and high resolution (HR)-MS. Meanwhile, the in vitro microsomal stability experiment showed that d3-poziotinib had a longer half time (t1/2 = 4.6 h) than poziotinib (t1/2 = 3.5 h).

9-Cyclopropylmethoxy-dihydrotetrabenazine and its stereoisomers as vesicular monoamine transporter-2 inhibitors.

Aim: To separate and evaluate 9-cyclopropylmethoxy-dihydrotetrabenazine (13a) and its stereoisomers for their high affinity for vesicular monoamine transporter-2 (VMAT2). Method: Stereoisomers of 13a were separated and configurations were ascertained by chiral chromatography and crystal diffraction combined with 1H-1H NOESY assay. Possible binding modes of eight stereoisomers and VMAT2 were explored by molecular docking assays. The VMAT2 affinity of the stereoisomers, inhibition in vivo and pharmacokinetics in rats were evaluated. Results: Three stereoisomers were obtained: P1, P2 and P3, and all had similar VMAT2 binding modes. P2 [(2R, 3R, 11bR)-13a] showed the highest potential VMAT2 binding activity (Ki = 0.75 nM), decreased locomotor activity in rats and had an oral absolute bioavailability of 92.0%. Conclusion: P2 has good efficacy and pharmacokinetic properties and warrants further development to treat tardive dyskinesia.

LPM3770277, a Potent Novel CDK4/6 Degrader, Exerts Antitumor Effect Against Triple-Negative Breast Cancer.

Triple negative breast cancer (TNBC) is a subtype of breast cancer with significant malignancy and poor prognosis but effective treatments are limited. Given the critical role of CDK4/6 in cell cycle and the apparent success of CDK4/6 inhibitors against certain cancer, this study attempted to utilize hydrophobic tagging technology to develop a CDK4/6 degrader against TNBC. We based on the chemical structure of the major metabolite of a clinically approved CDK4/6 inhibitor, abemaciclib, to synthesize three compounds and evaluated their in vitro cytotoxicity. LPM3770277 stood out as the most promising compound which was further confirmed by a series of binding and CDK4/6 degradation studies. LPM3770277 was able to bind to CDK4/6, and time-dependently and dose-dependently increased CDK4/6 protein degradation. Mechanistic study revealed that LPM3770277 exerted its CDK4/6 degradation effect via two machineries: proteasome and lysosome-promoted autophagy. Using in vivo TNBC xenograft cancer model, we found that LPM3770277 demonstrated superior anti-tumor efficacy and safety as compared to abemaciclib, although both compounds exerted similar effects on cell cycle arrest. In conclusion, this study for the first time developed and characterized a CDK4/6 degrader against TNBC using hydrophobic tags, which strongly suggests the viability of hydrophobic tags as a strategy to develop potential treatments against TNBC.

Small Molecules as SIRT Modulators.

Sirtuins are a family of NAD+-dependent deacetylases (class III histone deacetylases). Seven mammalian sirtuins, SIRT1-7, are identified, as the functions and locations differ greatly. SIRT1 and SIRT2 locate in nucleus and cytoplasm, while SIRT3-5 in mitochondria. Sirtuins are not only involved in many important biological processes such as apoptosis, cellular senescence, endocrine signaling, glucose homeostasis, aging, and longevity, it can also control circadian clocks and mitochondrial biogenesis. Small molecules that can modulate the sirtuins activity have been shown to have potentials for treating many human diseases such as type II diabetes, cancer, rheumatoid arthritis, cardiovascular and other age-relating diseases. Some polyphenolic natural products such as Resveratrol, Fisetin, and Quercetin have demonstrated health benefits due to their SIRT1 activation effects. Some structurally diverse synthetic compounds, such as SRT1720, SRT1460, Selisistat (EX 527), and AGK2 were used as small molecular SIRT modulators (IC50 = 0.04-100 µM) to treat ischemic stroke, myocardial infarction, neurodegenerative diseases, cancer, aging, and obesity. In order to get better understanding of how the small molecules interact with the sirtuin, the small molecules that having SIRT inhibitory or activation effect, found by HTS or other modern medicinal chemistry techniques, are reviewed in this article.

Synthesis and antitumor activities of 3-substituted-analine derivatives: structure modifications of Tuv part of tubulysins.

BACKGROUND: Tubulysins family is a kind of natural compound with potent, antitumor activity. To simplify the synthesis route and find new antitumor compounds is becoming a hotspot of research recent years. RESULTS: Starting from 3-nitrobenzoic acid, after 7 steps transformations, 12 new tubulysin analogues were synthesized by the conformational restraint and bioisostere principle. These structures are featuring 3-substituted analine moieties. All these compounds are new compounds, and the structures were characterized by 1H NMR, 13C NMR, and HRMS. The antitumor activities were screened by the MTT method using MDA-MB-231and MCF7 cells. CONCLUSIONS: Compound IIb exhibited certain antitumor activity with the IC50 value of 7.6 and 11.8 µM against MDA-MB-231 and MCF7 cells respectively. Compounds IIa-IIe had moderate antitumor activities suggested that the thiazole ring in the Tuv could be replaced by the phenyl ring. However, Compounds Ia-Ie lose antitumor activity dramatically suggested that the conformation of the Tuv was crucial for the tubulysin analogues to maintain the biological activity.

A concise synthesis of Fingolimod: an orally available drug for treating multiple sclerosis.

A concise route for the synthesis of Fingolimod is reported. Starting from n-octylbenzene and 3-nitropropionic acid, a sequence of reactions consisting of Friedel-Crafts acylation, reduction, and double Henry reaction, followed by hydrogenation were applied to prepare Fingolimod with a yield of 31%, and an overall atom economy of 82.7%. Graphical AbstractStarting from 3-nitropropanyl chloride, Fingolimod was obtained in 4 steps with an overall yield of 31%.