Synthesis, Characterization, and Anticancer Activity of Novel Lipophilic Emodin Cationic Derivatives

Cationic lipid-conjugated bis-arylidene oxindole derivatives as broad-spectrum breast cancer-selective therapeutics

Breast cancer is a heterogeneous malignancy with wide-ranging variations in therapeutic responses, overall survival etc. Major challenges for available chemotherapeutic agents in achieving clinical success are in maintaining systemic bio-distribution and avoiding non-specific adverse effects. Bis-arylidene oxindoles are estrogen receptor (ER)-selective bioactive molecules with moderate potency. In here, we have designed, synthesized and evaluated a series of twin aliphatic chain cationic lipid-conjugated bis-arylidene oxindole molecules with variations in nature of linker, lengths of carbon spacer and hydrophobic twin chains. We observed that among the various structural analogues, C8 twin-chain containing molecules, PGC8, S2C8 and S3C8 showed effective cancer cell-selective cytotoxicity in different cancer cell lines with an IC₅₀ ranging from 4 to 7 µM. These molecules selectively induced apoptosis, ROS production and cell cycle inhibition at G1/S phase in ER + breast cancer cells but not in non-cancer cells. Additionally, these molecules formed homogenous self-assemblies exhibiting effective hydrodynamic diameter with positive surface charge. The self-assemblies also showed prominent cancer cell-selective uptake and DNA-binding abilities. Hence, we have shown successful incorporation of dexamethasone to the self-assemblies, and its enhanced cytotoxicity even in ER-negative breast cancer cells. All these results indicate that PGC8, S2C8 and S3C8 molecules, albeit their potent and selective ER-positive anti-breast cancer activity, can be repurposed as targeted delivery systems and hold promise as unique, broader spectrum breast cancer cell-selective therapeutic payloads.

Diosgenin Derivatives as Potential Antitumor Agents: Synthesis, Cytotoxicity, and Mechanism of Action

Thirty-two new diosgenin derivatives were designed, synthesized, and evaluated for their cytotoxic activities in three human cancer cell lines (A549, MCF-7, and HepG2) and normal human liver cells (L02) using an MTT assay in vitro. Most compounds, especially 8, 18, 26, and 30, were more potent when compared with diosgenin. The structure-activity relationship results suggested that the presence of a succinic acid or glutaric acid linker, a piperazinyl amide terminus, and lipophilic cations are all beneficial for promoting cytotoxic activity. Notably, compound 8 displayed excellent cytotoxic activity against HepG2 cells (IC₅₀ = 1.9 μM) and showed relatively low toxicity against L02 cells (IC₅₀ = 18.6 μM), showing some selectivity between normal and tumor cells. Studies on its cellular mechanism of action showed that compound 8 induces G0/G1 cell cycle arrest and apoptosis in HepG2 cells. Predictive studies indicated that p38α mitogen-activated protein kinase (MAPK) is the optimum target of 8 based on its 3D molecular similarity, and docking studies showed that compound 8 fits well into the active site of p38α-MAPK and forms relatively strong interactions with the surrounding amino acid residues. Accordingly, compound 8 may be used as a promising lead compound for the development of new antitumor agents.

Synthesis and anti-inflammatory effects of novel emodin derivatives bearing azole moieties

Twelve azole derivatives of emodin were designed to possess anti-inflammatory activity and synthesized via a two-step sequence composed of the Williamson ether reaction and N-alkylation. The anti-inflammatory properties of these compounds were evaluated in RAW264.7 cells by measuring lipopolysaccharide (LPS)-induced nitric oxide (NO) production. The introduction of imidazole and four carbons into the scaffold of emodin led to the discovery of the potent compound 7e, which showed the best inhibition of NO production among twelve analogs. In our experiential setting, the IC₅₀ of compound 7e in NO production is 1.35 µM, which is lower than that of indomethacin. Mechanically, compound 7e effectively inhibited the protein and messenger RNA expressions of cyclooxygenase-2 and inducible NO synthase, as well as that of the proinflammatory cytokine interleukin-6, and the cytokines interleukin-1β and tumor necrosis factor-α in the LPS-stimulated RAW 264.7 macrophages. Compound 7e exerted inhibitory effects on the nuclear factor κB pathway by reducing the LPS-induced phosphorylation of the inhibitor of NF-κB and the nuclear translation of p-p65. These results suggest the potential of compound 7e in improving inflammatory conditions and diseases.