Synthesis and biological evaluation of oleanolic acid derivatives with electrophilic warheads as antitumor agents.

Aim: The oleanolic acid derivatives containing electrophilic warheads were synthesized, and their antitumor activities were investigated. Materials & methods: The cytotoxicity of compounds against tumor cells were determined by the MTT method. The antitumor effects of compounds 27a, Y03 and Y04 were evaluated in vitro through a wound-healing assay, apoptosis and cell circle analysis, and cellular reactive oxide species determination. The levels of related proteins in MCF-7 cells treated with Y03 was determined through Western blot analysis. Results & conclusion: Compounds 27a, Y03 and Y04 displayed high cytotoxicity against breast cancer cells and inhibited cell migration, induced apoptosis, arrest cell circle at G0/G1 and promoted cellular reactive oxide species generation. The antitumor mechanism involved inhibition of Akt/mTOR and induction of ferroptosis.

An ultrasound-driven immune-boosting molecular machine for systemic tumor suppression.

Exploring facile and effective therapeutic modalities for synergistically controlling primary tumor and metastasis remains a pressing clinical need. Sonodynamic therapy (SDT) offers the possibility of noninvasively eradicating local solid tumors, but lacks antimetastatic activity because of its limited ability in generating systemic antitumor effect. Here, we exploited a previously unidentified ultrasound-driven "molecular machine," DYSP-C34 (C34 for short), with multiple attractive features, emerging from preferential tumor accumulation, potent ultrasound-triggered cytotoxicity, and intrinsic immune-boosting capacity. Driven by the ultrasound, C34 functioned not only as a tumor cell killing reagent but also as an immune booster that could potentiate robust adaptive antitumor immunity by directly stimulating dendritic cells, resulting in the eradication of the primary solid tumor along with the inhibition of metastasis. This molecular machine, C34, rendered great promise to achieve systemic treatment against cancer via unimolecule-mediated SDT.

Synthesis and biological evaluation of NO-donor containing photosensitizers to induce ferroptosis of cancer cells.

Photodynamic therapy (PDT) is a non-invasive treatment method for tumors by exciting photosensitizers (PS) upon light irradiation to generate cytotoxic reactive oxygen species (ROS). However, the low oxygen concentration near the tumor tissue limits the therapeutic effect of PDT. Herein, we synthesized six chlorin e6 derivatives containing NO-donors to enhance their antitumor activity by synergistic effect of ROS and NO. The results revealed that the new NO-donor containing photosensitizers (PS-NO) exhibited more potent photodynamic activity than chlorin e6, and the introduction of NO donor moieties to chlorin e6 increased the level of NO and ROS in cells. The addition of Ferrostatin-1, a ferroptosis inhibitor, markedly reduced the photodynamic activity of PS-NO as well as the level of NO and ROS in cells. Mechanism studies further showed that PS-NO could reduce intracellular GSH level, inhibit GPX4 activity and promote malondialdehyde (MDA) accumulation upon light irradiation, which suggested the ferroptosis mechanism underlying the PDT effect of PS-NO.

Synthesis and evaluation of 3-(phenylethynyl)-1,1'-biphenyl-2-carboxylate derivatives as new HIF-1 inhibitors.

Selaginellins are a type of rare natural products from the genus Selaginella with unusual alkynyl phenol skeletons and extensive biological activities. Previous structural simplification of these natural compounds afforded a series of diaryl acetylene derivatives with hypoxia-inducible factor 1 (HIF-1) inhibitory activity. In this study, we synthesized thirty compounds by stepwise optimization using methyl 3-(4-methoxylphenyl ethynyl)-[4'-methoxyl-1,1'-biphenyl]-2-carboxylate (1a) as a lead compound and evaluated their HIF-1 inhibitory activity by dual luciferase reporter assay. Among them, compound 9i displayed the most potent HIF-1 inhibitory activity (IC50 = 1.5 ± 0.03 µM) with relatively low cytotoxicity. Under hypoxia, compound 9i showed no effect on the accumulation of HIF-1α protein in western blot analysis, but could down-regulate the expression of VEGF mRNA, the downstream target gene of HIF-1 pathway. Cell-based activity assay demonstrated that compound 9i could inhibit the hypoxia-induced migration, invasion and proliferation of HeLa cells at the concentrations of 1 ~ 5 µM. In mouse breast cancer xenograft model, compound 9i exhibited obvious tumor growth inhibition and very low toxicity at a dose of 15 mg/kg. The results suggested that compound 9i would be a potential antitumor agent via HIF-1 pathway inhibition.

Synthesis and antitumor activity of α,ß-unsaturated carbonyl moiety- containing oleanolic acid derivatives targeting PI3K/AKT/mTOR signaling pathway.

Oleanolic acid (OA) and its semi-synthetic derivatives have been reported to have a wide range of biological activities. The introduction of electrophilic Michael acceptor group can increase the reactivity of OA to cellular targets and thus improve the anti-tumor activity. In this work, a series of novel α,ß-unsaturated carbonyl derivatives of OA were designed and synthesized. Their in vitro cytotoxic activity against MCF-7, HepG2 and HeLa cells were tested. Most derivatives exhibited improved cell growth inhibitory activity, especially for 3d with an IC50 of 0.77 µM in MCF-7 cells. Moreover, 3d inhibited the migration of MCF-7 and HeLa cells at the concentration of 4 µM. Flow cytometric analysis revealed that 3d induced cell apoptosis and S phase arrest in a concentration-dependent manner. Western blotting experiment demonstrated that 3d inhibited the phosphorylation of AKT and mTOR. These results suggest that this series of OA derivatives bearing exocyclic methylene ketone pharmacophore are promising anticancer agents as potential PI3K/AKT/mTOR pathway inhibitors.

Zinc(ii)-catalyzed intramolecular hydroarylation-redox cross-dehydrogenative coupling of N-propargylanilines with diverse carbon pronucleophiles: facile access to functionalized tetrahydroquinolines.

Zinc(ii)-catalyzed intramolecular hydroarylation-redox cross-dehydrogenative coupling of N-propargylanilines with two types of carbon pronucleophiles (nitromethane as a sp3 carbon pronucleophile and phenylacetylenes as sp carbon pronucleophiles) proceeded to give the 2-substituted tetrahydroquinolines in good yields with 100% atomic utilization without any additional external oxidants.

Synthesis of novel natural product-like diaryl acetylenes as hypoxia inducible factor-1 inhibitors and antiproliferative agents.

The selaginellin derivatives are a type of novel natural pigments with an unusual alkynyl phenol skeleton from the genus Selaginella. Some of these natural compounds were previously reported to show important bioactivities, including anticancer activity, cardiovascular protection and phosphodiesterase-4 inhibition. We designed and synthesized fifteen biphenyl-containing diaryl acetylene derivatives mimicking the skeleton of natural alkynyl phenols. In MTT assay in cancer cells, compounds 1c, 2d, 2g, 2h, 2i and 2j exhibited potent antiproliferative activity. The evaluation of Hypoxia Inducible Factor-1 (HIF-1) pathway inhibitory activity in dual luciferase assay demonstrated that most tested compounds exhibited moderate to good activities. Compounds 1a, 2f and 2h displayed high HIF-1 inhibitory activities and relatively low cytotoxicity, demonstrating great potential as HIF-1 inhibitors. These results afford a new strategy for the discovery of new HIF-1 inhibitors and anti-proliferative agents from natural or synthetic diaryl acetylene derivatives.

Non-destructive geographical traceability of sea cucumber (Apostichopus japonicus) using near infrared spectroscopy combined with chemometric methods.

Sea cucumber is the major tonic seafood worldwide, and geographical origin traceability is an important part of its quality and safety control. In this work, a non-destructive method for origin traceability of sea cucumber (Apostichopus japonicus) from northern China Sea and East China Sea using near infrared spectroscopy (NIRS) and multivariate analysis methods was proposed. Total fat contents of 189 fresh sea cucumber samples were determined and partial least-squares (PLS) regression was used to establish the quantitative NIRS model. The ordered predictor selection algorithm was performed to select feasible wavelength regions for the construction of PLS and identification models. The identification model was developed by principal component analysis combined with Mahalanobis distance and scaling to the first range algorithms. In the test set of the optimum PLS models, the root mean square error of prediction was 0.45, and correlation coefficient was 0.90. The correct classification rates of 100% were obtained in both identification calibration model and test model. The overall results indicated that NIRS method combined with chemometric analysis was a suitable tool for origin traceability and identification of fresh sea cucumber samples from nine origins in China.

Synergistic antiproliferative effect of chemo-phototherapy: Synthesis and photodynamic activity evaluation of novel Chlorin e6-artesunate conjugates as antiproliferative agents.

In order to increase the photodynamic effect of Chlorin e6, four Chlorin e6-artesunate conjugates were designed and synthesized. Among them, three conjugates (3, 6, 9) contained single artesunate side chain at 152, 173 and 131 of Chlorin e6, respectively, and one conjugate (11) contained three artesunate side chains. In the in vitro evaluation of photodynamic effect, the four conjugates showed more potent phototoxicity against HepG2 cells than Chlorin e6. The introduction of artesunate side chain significantly increased the intracellular ROS production, although the production of singlet oxygen was not improved. Compound 11 exhibited much more potent phototoxicity than the other conjugates because the three artesunate side chains greatly enhanced the ROS production and cellular uptake. The results demonstrated that the conjugation of Chlorin e6 and artesunate could accomplish synergistic effects of chemo-phototherapy, and finally enhanced their antiproliferative effects.

Syntheses of new chlorin derivatives containing maleimide functional group and their photodynamic activity evaluation.

Nine new chlorin derivatives containing maleimide functional group and amino acid residue with chlorin e6 scaffold (compounds 1-6) or pheophorbide a scaffold (compounds 7-9) were synthesised from chlorophyll a. The all nine derivatives demonstrated increased photo cytotoxic activity in HepG2 cell (IC50 3.2-20.5 µM) comparing with chlorin e6 and its trimethyl ester. Their photo cytotoxicities were approximately dependent on their abilities to produce singlet oxygen ((1)O2) in the cells.

Synthesis and evaluation of effective photoaffinity probe molecule of furospinosulin-1, a hypoxia-selective growth inhibitor.

The synthesis and evaluation of a photoaffinity probe molecule for furospinosulin-1, a hypoxia-selective growth inhibitor that we identified from marine sponge, was studied. An analogue carrying an alkyne tail showed potent hypoxia-selective inhibitory activity exceeding that of the parent molecule, and exhibited in vivo anti-tumor activity following oral administration. The alkyne moiety in the analogue was also found to be a good anchoring group for the preparation of probe molecules; a photoaffinity probe molecule having an optimized spacer length was selected through the systematic synthesis of several probes and the evaluation of their hypoxia-selective growth inhibitory activity and electrophoretic mobility shift properties.

Probe molecule equipped with boronic acid moiety as a reversible cross-linking group improves its binding affinity.

Syntheses of biotinylated probe molecules of L-glutathione (GSH) equipped with boronic acid moiety and evaluation of their binding affinities against glutathione-S-transferase (GST) were described. It revealed that the presence of boronic acid moiety in an appropriate position enhances binding affinity of GSH probe toward GST probably by forming a reversible cross-link. Among prepared, the boronate-containing probe 8b exhibited the highest recovering ability of GST from Escherichia coli cell lysate.

A new eudesmane sesquiterpene lactone from Curcuma wenyujin.

The aim of the study was to investigate the sesquiterpene constituents from the rhizomes of Curcuma wenyujin Y. H. Chen et C. Ling. The isolation and purification of the constituents from the 50% EtOH extracts of the rhizomes were performed with repeated column chromatography over sillica gel and macroporous resin. Eight sesquiterpenes were obtained and identified as wenyujinlactone A (1), neolitamone A (2), zedoarondiol (3), isozedoarondiol (4), aerugidiol (5), curcumol (6), curdione (7) and (1R, 10R)-epoxy-(-)-1, 10-dihydrocurdine (8) by means of spectral analysis. Among them, compound 1 was found to be a new eudesmane sesquiterpene lactone, whilst compounds 2-5 were obtained from this plant for the first time.