N-alpha-Aminoacyl Colchicines as Promising Anticancer Agents.

BACKGROUND: In the last years, many efforts have been made to find colchicine derivatives with reduced toxicity. Additionally, the deregulation of amino acid uptake by cancer cells provides an opportunity to improve anticancer drug effectiveness. OBJECTIVE: To design new colchicine derivatives with reduced cytotoxicity and enhanced selectivity by means of introducing aminoacyl groups. METHODS: 34 colchicine analogues bearing L- and D-amino acid pendants were synthetized and characterized by NMR, IR and MS techniques. Cytotoxicity and antimitotic properties were assessed by spectrophotometry and cell cycle assays. Oncogene downregulation was studied by RTqPCR whereas in vivo studies were performed in SCID mice. RESULTS: Compounds exhibit high antiproliferative activities at the nanomolar level while being, in general, less cytotoxic than colchicine. Most compounds inhibit the polymerization of tubulin in a way similar to colchicine itself, with L-amino acid derivatives being the most active in the inhibition of tubulin polymerization. All selected compounds caused cell cycle arrest at the G2/M phase when tested at 1 µM. More specifically, Boc-L-proline derivative 6 arrested half of the population and showed one of the highest Selectivity Indexes. Derivatives 1 (Boc-glycine), 27 (D-leucine) and 31 (Boc-glycine-glycine) proved fairly active in downregulating the expression of the c-Myc, hTERT and VEGF oncogenes, with compound 6 (Boc-L-proline) having the highest activity. This compound was shown to exert a potent anti-tumor effect when administered intraperitoneally (LD50 > 100 mg/kg for 6, compared with 2.5 mg/kg for colchicine). CONCLUSION: Compound 6 offers an opportunity to be used in cancer therapy with less toxicity problems than colchicine.

Novel multitarget inhibitors with antiangiogenic and immunomodulator properties.

By means of docking studies, seventeen compounds T.1-T17 have been designed and evaluated as multitarget inhibitors of VEGFR-2 and PD-L1 proteins in order to overcome resistance phenomena offered by cancer. All these designed molecules display a urea moiety as a common structural feature and eight of them (T.1-T8) further contain a 1,2,3-triazol moiety. The antiproliferative activity of these molecules on several tumor cell lines (HT-29, MCF-7, HeLa, A549, HL-60), on the endothelial cell line HMEC-1 and on the non-tumor cell line HEK-293 has been determined. The urea derivatives were also evaluated for their antiangiogenic properties, whereby their ability to inhibit tubulogenesis and kinase activity employing flow cytometry, ELISA, immunofluorescence and western blot techniques was measured. In addition, these techniques were also employed to investigate the immunomodulator action of the synthetic compounds on the inhibition of PD-L1 and c-Myc proteins. Compound T.2, 1-(3-chlorophenyl)-3-(2-(4-(4-methoxybenzyl)-1H-1,2,3-triazol-1-yl)ethyl)urea, has shown similar results to sorafenib in both down-regulation of VEGFR-2 and inhibition of the kinase activity of this receptor. Furthermore, compound T.14, (E)-1-(4-chlorophenyl)-3-(3-(4-methoxystyryl)phenyl)urea, improves the effect of T.2 as regards tube formation of endothelial cells and inhibition of VEGFR-2 tyrosine kinase activity. In addition, T.14 improves the effect of the experimental drug BMS-8 in the inhibition of PD-L1 and c-Myc proteins.

Arylpyridines, arylpyrimidines and related compounds as potential modulator agents of the VEGF, hTERT and c-Myc oncogenes.

Twenty-four derivatives structurally related to honokiol have been synthesized and biologically evaluated. IC50 values were determined towards the HT-29, MCF-7 and HEK-293 cell lines. Some of these derivatives exhibited comparable or lower IC50 values than honokiol towards the HT-29 and MCF-7 cell lines or else higher selectivity indexes than the natural product. Twelve selected derivatives were evaluated for their ability to inhibit the expression of the VEGFA, hTERT and c-Myc genes and also to inhibit the production of total c-Myc protein and the secretion of the VEGF protein. One of the most promising compounds, 3-(2,4-dimethoxyphenyl)pyridine, may be a good candidate for further studies as an anticancer agent as it is able to improve the effect shown by honokiol in downregulating all gene expression and protein production at a safe concentration for non-tumor cells.

Synthesis and in-vitro Evaluation of S-allyl Cysteine Ester - Caffeic Acid Amide Hybrids as Potential Anticancer Agents.

We have synthesized a series of S-allyl cysteine ester-caffeic acid amide hybrids and evaluated them in order to determine their possible anticancer activity and selectivity in colorectal cancer, which is still one of the leading causes of morbidity and mortality worldwide. All compounds were tested against SW480 human colon adenocarcinoma cells and the non-malignant CHO-K1 cell line. Among the tested compounds, hybrids 6e, 9a, 9b, 9c, and 9e exhibited the highest effect on viability (IC50 SW480-48h= 0.18, 0.12, 0.12, 0.11, and 0.12 mM, respectively) and selectivity (SI = 10.3, 1.5, >83.33, >90.91 and >83.33, respectively) in a time- and concentration-dependent manner. Besides, our results were even better as regards lead compounds (S-allyl cysteine and caffeic acid) and the standard drug (5-FU). Additionally, these five compounds induced mitochondrial depolarization that could be related with an apoptotic process. Moreover, hybrids 6e, 9a, and 9e induced cell cycle arrest in G2/M phase, and compound 9c in S- phase, which suggests that these hybrid compounds could have also a cytostatic effect in SW480 cell line. The SAR analysis showed that hydroxyl groups increased the activity. Besides, there was not a clear relationship between the antitumor properties and the length of the alkyl chain. Since hybrid compounds were much more selective than the conventional drug (5-FU), this makes them promising candidates for further studies against colorectal cancer.

Synthesis and biological evaluation as antiangiogenic agents of ureas derived from 3'-aminocombretastatin A-4.

Twenty-six compounds derived from 3'-aminocombretastatin A-4 (AmCA-4) containing a urea fragment mimicking the structure of Sorafenib, have been synthesized and evaluated as antiangiogenic compounds. Antiproliferative activity of all the synthetic ureas has been measured on tumor cell lines HT-29, MCF-7, HeLa, A-549 and HL-60 as well as on the endothelial cell line HMEC-1 and on the non-tumor cell line HEK-293. Preliminary docking studies were developed in order to predict which ureas show better interactions with the protein VEGFR-2. Then, the selected derivatives were evaluated in terms of their apoptotic effect and antiangiogenic properties. In this regard, VEGFR-2/ligand interactions were determined by flow cytometry and immunofluorescence techniques. Inhibition of VEGFR-2 tyrosine kinase activity in both the A-549 and HMEC-1 cell lines was also carried out. In addition, tube formation inhibition was studied in endothelial cells. Ortho-chloro substituted urea 5 and ortho-bromo substituted urea 8 were the most active ones in both down-regulation of VEGFR-2 and inhibition of the kinase activity of this receptor, with better results than those obtained with sunitinib and sorafenib.

Synthesis and biological evaluation of carbamates derived from aminocombretastatin A-4 as vascular disrupting agents.

A series of twenty-six carbamates derived from aminocombretastatin A-4 (AmCA-4) were synthesized and evaluated for their capacity to affect cell proliferation, tubulin polymerization, mitotic cell arrest, microtubule network organization, apoptosis and endothelial tubular structures in vitro. The anti-proliferative activity of the synthetic carbamates was measured on several human tumor cell lines (i.e. HT-29, MCF-7, HeLa, A-549, MDA-MB-231, HL-60) as well as on the endothelial cell line HMEC-1 and the non-tumor cell line HEK-293. The compounds showed anti-proliferative activity in the nanomolar range thereby exceeding by far the activity of combretastatin A-4 (CA-4) and, in some cases, the activity of AmCA-4. The most active compounds proved to be the carbamates bearing chloro, bromo or methoxy groups in the meta position of the phenyl ring. Moreover, all carbamates inhibited in vitro tubulin polymerization, in a similar manner to that of CA-4 and AmCA-4 by interacting with the colchicine binding site in tubulin. The synthetic carbamates proved as active as AmCA-4 in causing mitotic arrest, as assessed in A549 human lung cancer cells, and disruption of the microtubule cellular network. Some selected carbamates induced apoptosis at concentrations as low as 10 nM, being more active than AmCA-4. Finally, these selected carbamates displayed a vascular disrupting activity on endothelial cells in a dose-dependent manner. In conclusion, our data indicate that carbamates derived from aminocombretastatin A-4 represent interesting lead compounds for the design of vascular disrupting agents.