Ring-Contracted Artemisinin Derivatives as Novel CDK 4/6 Inhibitors: Synthesis and Anti-Breast Cancer Evaluation

The endoperoxide group of artemisinins is universally accepted an essential group for their anti-cancer effects. In this study, a series of D-ring-contracted artemisinin derivatives were constructed by combining ring-contracted artemisinin core with fragments of functional heterocyclic molecules or classical CDK4/6 inhibitors to identify more efficacious breast cancer treatment agents. Twenty-six novel hybridized molecules were synthesized and characterized by HRMS, IR, 1H-NMR and 13C NMR. In antiproliferative activities and kinase inhibitory effects assays, we found that the antiproliferative effects of B01 were close to those of the positive control Palbociclib, with GI50 values of 4.87±0.23 μM and 9.97±1.44 μM towards T47D cells and MDA-MB-436 cells respectively. In addition, the results showed that B01 was the most potent compound against CDK6/cyclin D3 kinase, with an IC50 value of 0.135±0.041 μM, and its activity was approximately 1/3 of the positive control Palbociclib.

Synthesis and anti-glioblastoma effects of artemisinin-isothiocyanate derivatives

A series of novel artemisinin (ART) derivatives containing an isothiocyanate (ITC) group were synthesized. All the compounds showed more potent anti-tumor effects than those of parent dihydroartemisinin (DHA) towards glioblastoma multiforme U87 in vitro. Among them, 5b had the strongest cytotoxic activity which exerted its effects in a concentration-dependent but not time-dependent manner (IC₅₀ 7.41 μM for 24 h, 7.35 μM for 72 h). Pyknosis was observed in 5b-treated U87 cells. Multiple intrinsic apoptotic pathways were induced by 5b including the upregulation of caspase 9, the release of cytochrome c, an increase of the proapoptotic protein Bax, a decrease of the anti-apoptotic protein Bcl 2, and the activation of execution pathways by the upregulation of caspase 3. In addition to apoptosis, an autophagic mechanism was also involved in 5b-induced cytotoxicity to human GBM U87 cells by upregulating the expression of LC3-II and downregulating p62. Furthermore, 5b also significantly attenuated the migration of U87 cells. Therefore, our results suggest that 5b may be a promising molecule for the further development of a novel drug for the treatment of glioblastoma.

Synthesis of artemisinin-isothiocyanate derivatives; evaluation of the cytotoxic effects of these compounds on U87 human glioblastoma cells; compound 5b induced apoptosis and autophagy in U87 cells; compound 5b significantly inhibited the migration of U87 cells.

Synthesis and antiphytoviral activity of α-aminophosphonates containing 3, 5-diphenyl-2-isoxazoline as potential papaya ringspot virus inhibitors

α-Aminophosphonates compounds containing 3,5-diphenyl-2-isoxazoline were synthesized and evaluated for their bioactivity. Seventeen of them showed good bioactivity (protection effect > 50%) in vivo against papaya ringspot virus, while two of them (V29 and V45) exhibited excellent antiviral activity (both 77.8%). In the latter case, the antiviral activity was close to that of antiphytovirucides ningnanmycin and dufulin (both 83.3%) at 500 mg/L. The preliminary structure-activity relationships indicated that the bioactivity was strongly influenced by the substituents.