Synthesis and antitumor activity of goniofufurone analogues.

Synthesis and antitumor activity of goniofufurone analogues 15, 16, 17, 33, and 46 is reported. Key step in the synthesis is Pd (II) mediated oxidative cyclisation of vinyl-(hydroxy) furans 18, 19 to the corresponding lactols 32, 43. Cytotoxicities of 15, 16, 17, 33, and 46 tested against six human cancer cell lines are reported. Change of stereochemistry at C-5, C-6 and C-7 position of goniofufurone (1) did not enhance the cytotoxicities significantly.     

Novel nucleotide phosphonate analogues with potent antitumor activity

We have identified several nucleotide phosphonates demonstrating in vitro antiproliferative activity in several human cancer cell lines with IC(50) values in the microM range. The synthesis as well as structure-activity relationship are described.     

3Beta-hydroxy-6-aza-cholestane and related analogues as phosphatidylinositol specific phospholipase C (PI-PLC) inhibitors with antitumor activity

6-Aza steroid analogues were synthesized as PI-PLC inhibitors. The most active compound, 3beta-hydroxy-6-aza-cholestane (1) showed potent PI-PLC inhibition (IC50 = 1.8 microM), similar to that of the commercially available steroid analogue U73122 (IC50 = 1-2.1 microM). Compound 1 exhibited significant growth inhibition effects (IC50 = 1.3 microM in each case) against MCF-7 and HT-29 cancer cells in in vitro cell culture. Compound 1 also inhibited the in vitro adhesion and transmigration of HT-1080 fibrosarcoma cells at 2.5 and 5.0 microM, respectively. In vivo, compound 1, at 1 mg/kg/day, reduced the volume of MCF-7 tumors in xenograft models, without weight loss in mice. Structure activity relationships of this series of compounds revealed that a hydrophobic cholesteryl side chain, 3beta-hydroxy group and a C-6 nitrogen containing a hydrogen atom at position-6 are crucial for activity. N-Maleic amidoacid derivative 11 also exhibited weak inhibition (IC50 = 16.2 microM).     

Synthesis and antitumor activity of novel 20s-camptothecin analogues

In an effort to decrease the toxicity and improve the stability of labile lactone ring of camptothecin, nitrogenous heterocyclic aromatic groups were introduced into 20-position of camptothecin and seventeen new 20s-camptothecin derivatives were obtained in quantitative yield. The cytotoxicity in vitro on three cancer cell lines and the stability of the lactone in phosphate-buffered solution (PBS) of these derivatives were evaluated. Most of these tested derivatives possessed better cytotoxicity than topotecan. Analogues 6, 12 exhibited the best antitumor activity in vivo in all derivatives we prepared. The results suggested that introduction of pyrazole in 10- or 20-position of camptothecin could promote antitumor activity in vitro and in vivo, simultaneously bring much increase of the stability of lactone.     

Synthesis of aristolactam analogues and evaluation of their antitumor activity

A series of natural aristolactams and their analogues have been prepared and evaluated for antitumor activity against human cancer cells, including multi-drug resistant cell lines. Naturally occurring aristolactams, such as aristolactam BII (cepharanone B), aristolactam BIII, aristolactam FI (piperolactam A), N-methyl piperolactam A, and sauristolactam showed moderate antitumor activities in selected cell lines. However, several synthetic aristolactam derivatives exhibited potent antitumor activities against a broad array of cancer cell lines with GI₅₀ values in the submicromolar range.     

Synthesis and antitumor activity of novel 10-substituted camptothecin analogues

In an attempt to improve the antitumor activity and decrease the cytotoxicity of camptothecin, 18 new 10-substituted camptothecin derivatives were prepared. The cytotoxicity in vitro on cancer cell lines and antitumor activity in vivo, and inhibitory properties of topoisomerase I of these derivatives were evaluated. Most of these derivatives possessed lower cytotoxicities than CPT, and the compounds 13, 21, 22, 23, and 24 showed similar topoisomerase I inhibitory activity to CPT. Analogues 13 exhibited the best antitumor activity in vivo among all derivatives we prepared.     

Synthesis and antitumor activity of cyclodepsipeptide zygosporamide and its analogues

The synthesis and structure–activity relationships of zygosporamide, a known potent and selective cytotoxic natural product against SF-268 and RXF 393 cell lines, are described. The potencies of the synthetic zygosporamide are similar to those reported for the natural product toward all cancer cell lines examined with the exception of SF-268, the underlying cause of which remains to be elucidated.     

Peptides and antitumor activity. Development and investigation of some peptides with antitumor activity

We developed a group of synthetic analogs of GnRH and Somatostatin to inhibit the tumor growth of different kind. The GnRH analogs decreasing the gonadotroph and steroid hormone levels act on the hormone dependent tumors and influence their growth. One of the most effective antitumor analog was patented under the name FOLLIGEN which inhibited the breast cancer caused by DMBA in rats without any side-effects. Other inhibitory analogs of GnRH with long-lasting effect were effective in the treatment of breast, ovary and prostate tumors. Another analog [alpha-Asp(DEA)]6,Gln8-hGnRH showed a very low endocrine but high antitumor effect in both in vitro and in vivo experiments. Its tritium labeled derivative exhibited specific binding sites on human tumor cell lines. We synthesized the analogs of GnRH-III with effective selective antitumor activity which does not alter the ovarian cycle of rats but inhibits the colony-formation of human breast cancer cell lines and has a significant antiproliferative effect. We also synthesized conjugates of potent GnRH analogs with a branched chain polylysine backbone which induce a 33-35% decrease of cell numbers of MCF-7 and MDA-MB-231 human breast cancer cell lines and 45-50% inhibition of cell proliferation. Another conjugate decreased the tumor growth of MDA-MB-231 xenografts by 80% in a treatment of 9 weeks and even tumor free animals could be found among the ones treated. Using these radiolabeled peptide hormone analogs we found that human tumor cell lines and xenografts specifically bind the GnRH conjugates. We also synthesized a series of Somatostatin analogs which inhibit tyrosine kinases and the growth of several breast, prostate and colon tumor cell lines. One of our best analogs was a heptapeptide, TT-232, which strongly inhibited the tyrosine kinase activity and the cell-proliferation in different colon tumor cells. However, it did not inhibit the growth hormone release either in vitro or in vivo from rat pituitary cells. The TT-232 was found to be effective on 60 human tumor cell lines, it significantly inhibited the tumor growth on different animal tumor models, and induced apoptosis, as a result of which some animals became tumor free. The TT-232 inhibited the tumor growth of PC3 prostate xenografts with 60% and caused a 100% survival of mice 60 days after the transplantation. It is being preclinically tested at present. We have shown that the new GnRH analogs acting without any hormonal effect and the Somatostatin analogs with strong antitumor and tyrosine kinase inhibitory activity but no hormonal effect may represent a breakthrough in the research of the antitumor peptides, having direct effect on tumor cells.     

Synthesis of novel psoralen analogues and their in vitro antitumor activity

New tetracyclic benzofurocoumarin (benzopsoralen) analogues were synthesized and their inhibitory effect on the growth of tumor cell lines was evaluated. The human tumor cell lines used were MDA MB231 (breast adenocarcinoma), HeLa (cervix adenocarcinoma) and TCC-SUP (bladder transitional cell carcinoma). The in vitro antitumor activity of the new benzopsoralens was discussed in terms of structure–activity relationship. Molecular docking studies with human-CYP2A6 enzymes were also carried out with the synthesized compounds in order to evaluate the potential of these compounds to interact with the heme group of the enzymes. The results have demonstrated that the linear compounds have the most pronounced activity against tumor cell lines and this might be related to the better accessibility that these compounds have to the active site in relation to the angular ones that have shown in the majority of the cases multiple binding poses in the active site of CYP2A6.     

Natural withanolide-based lysine-specific demethylase 1 inhibitors for antitumor metastasis activity

Lysine specific demethylase 1 (LSD1), which is overexpressed in several human cancers and acts as a demethylase of histone 3, lysine 4 and lysine 9, has become an attractive therapeutic target for cancer therapy. Based on our previous systematic studies, withanolides are important secondary metabolites mostly from the Solanaceae family of plants, which are crucial agents for cancer treatment. Here, withanolides were characterized as LSD1 inhibitors, especially withaferin A, with an IC₅₀ value of 3.04 μM. In vitro bioactivity assays and virtual molecular docking indicated that withaferin A could inhibit MDA-MB-231 cell migration by inhibiting intracellular LSD1 activity. These findings provide a new withanolide-based natural molecular skeleton for LSD1 inhibitors with potential antitumor activity.     

Potent DNA gyrase inhibitors; novel 5-vinylpyrazole analogues with Gram-positive antibacterial activity

In this study, we designed and synthesized novel 5-vinylpyrazole analogues by decreasing the lipophilicity of the parent compounds 1a,b; 3-[(3-methoxycarbonyl)cyclohexylaminomethyl]indazoles while keeping the van der Waals interaction with the lipophilic area of DNA gyrase B. The selected compound 8bb exhibited good antibacterial activity against staphylococci and enterococci, including multi-drug resistant strains.     

New indolicidin analogues with potent antibacterial activity.

Indolicidin is a 13-residue antimicrobial peptide amide, ILPWKWPWWPWRR-NH2, isolated from the cytoplasmic granules of bovine neutrophils. Indolicidin is active against a wide range of microorganisms and has also been shown to be haemolytic and cytotoxic towards erythrocytes and human T lymphocytes. The aim of the present paper is two-fold. First, we examine the importance of tryptophan in the antibacterial activity of indolicidin. We prepared five peptide analogues with the format ILPXKXPXXPXRR-NH2 in which Trp-residues 4,6,8,9,11 were replaced in all positions with X = a single non-natural building block; N-substituted glycine residue or nonproteinogenic amino acid. The analogues were tested for antibacterial activity against both Staphylococcus aureus American type culture collection (ATCC) 25923 and Escherichia coli ATCC 25922. We found that tryptophan is not essential in the antibacterial activity of indolicidin, and even more active analogues were obtained by replacing tryptophan with non-natural aromatic amino acids. Using this knowledge, we then investigated a new principle for improving the antibacterial activity of small peptides. Our approach involves changing the hydrophobicity of the peptide by modifying the N-terminus with a hydrophobic non-natural building block. We prepared 22 analogues of indolicidin and [Phe(4,6,8,9,11)] indolicidin, 11 of each, carrying a hydrophobic non-natural building block attached to the N-terminus. Several active antibacterial analogues were identified. Finally, the cytotoxicity of the analogues against sheep erythrocytes was assessed in a haemolytic activity assay. The results presented here suggest that modified analogues of antibacterial peptides, containing non-natural building blocks, are promising lead structures for developing future therapeutics.     

Synthesis and antitumor activity of indolylpyrimidines: marine natural product meridianin D analogues

Marine indole alkaloid meridianin D analogues have been synthesized starting from the appropriate 3-cyanoacetyl indole. A facile two-step conversion of 3-cyanoacetyl indole to the corresponding cyano meridianin D analogue by treatment with dimethylformamide-dimethylacetal and further cyclization of the resulting enaminonitrile with aminoguanidine is described. Then, alkaline hydrolysis of cyano meridianin D afforded the carboxylic acid analogue. The treatment of acid with 75% H(2)SO(4) afforded the desired 6-debromomeridianin D. Simply treatment of cyano meridianin D analogue with hydrazine hydrate afforded the amidrazone analogue. The biological evaluation indicated that cyano analogue showed good cytotoxic activity with IC(50) values of 0.85 and 2.65microg (against MCF7 and HeLa, respectively), but acid and amidrazone analogues showed high cytotoxicity with IC(50) values of 0.75 and 0.25microg, respectively (against MCF7).     

New analogues of AHMA as potential antitumor agents: synthesis and biological activity

A series of new analogues of 3-(9-acridinylamino)-5-hydroxymethylaniline (AHMA, 1) and AHMA-ethylcarbamate (2) were synthesized by introducing an O-alkylcarboxylic acid esters to the CH(2)OH function, displacing the CH(2)OH function with a dimethylaminocarboxamido group or with a methyl function introduced at the meta-, para- or ortho-position to the NH(2) group to form 5-(9-acridinylamino)-m-toluidines (AMTs), 5-(9-acridinylamino)-p-toluidines (APTs) or 5-(9-acridinylamino)-o-toluidines (AOTs), respectively. The inhibitions of a variety of human tumor cell growth, interactions with DNA as well as inhibitory effect against topoisomerase II (Topo II) of these new agents were studied. Among AMT, APT and AOT derivatives with dimethylaminoethylcarboxamido and Me at C4 and C5 of acridine moiety (i.e., 21c, 23c and 26c) were more cytotoxic than AHMA (1) and AHMA-ethylcarbamate (2), depending upon the tumor cell line tested. Detailed structure-activity relationships of the new analogues were studied.     

Antisense oligonucleotides with antitumor activity

Antisense oligonucleotides (AONs) provide an efficient approach for developing target-selective anticancer drugs, because they can inhibit gene expression sequence specifically. To improve the therapeutic effenciency of AONs, two new types of the compounds have been developed. The first group of antisense oligodeoxynucleotides investigated contains base modified nucleotide units. Incorporation of 5-substituted pyrimidines into AONs increases cell membrane permeability (a), duplex stability (b), and nuclease resistance (c). These properties were studied using a large number of model oligonucleotides. The application of 5-(1-hexynyl)dU has been found to be the best modification. Application of MMP-9 collagenase inhibitor oligonucleotides (potential metastasis inhibitors) containing these nucleotide units instead of thymidines increased the collagenase inhibition potency by one order of magnitude compared to that of parental oligonucleotide including thymine bases. The second group of the compounds investigated represents a new type of antisense oligonucleotide synthesized by the antisense directed prodrug therapy (ADPT) conception. According to this principle, a telomerase inhibitor AON was conjugated with 5-fluoro-2'-deoxyuridine (FdU) and oligo-FdUs by phosphodiester bond at the 3'-terminus. The antitumor activities of conjugates in comparison with that of FdU were tested in HT1080 human fibrosarcoma and HT29 human colon adenocarcinoma cell lines. In HT29 cell culture the antiproliferative activity of prodrugs significantly increased with increasing length of the 3'-(FdU)n tail. The conjugate with one FdU unit was about 5 times, while the AON-(FdU)3 analogue was almost 19 times more active than FdU. Antitumor activity of the prodrug containing six FdU units was extremely high (relative efficiency = 26.6), therefore, in vivo testing of this analogue seems to be reasonable and promising. Antiproliferative activity of (FdU)n conjugated with a telomerase inhibitor increased by 5-13 times in HT1080 cells as compared to FdU administered in nucleoside form.     

Daunomycin-polypeptide conjugates with antitumor activity

We have developed a group of water-soluble drug conjugates in which daunomycin (Dau) is coupled to cationic, amphoteric or anionic branched polypeptides and a new conjugate containing a cationic polypeptide carrier modified with a cell penetrating octaarginine. We investigated in vitro physiological activity of these conjugates in several aspects: in vitro cytotoxicity and cytostatic effect, adhesion and cellular uptake were examined on murine (J774 and L1210) and human (MonoMac6 and HL-60) leukemia cell lines and on murine bone marrow derived macrophages. We found that these processes are dependent on the properties of the carrier, on experimental conditions like concentration and incubation time. We found that attachment of polypeptide and cell penetrating peptide to the bioactive agent, depending on the cell line, could significantly improve the antitumor activity of the drug.     

Synthesis,molecular docking and antitumor activity of novel pyrrolizines with potential as EGFR-TK inhibitors

A new series of pyrrolizine derivatives 4–8c were synthesized, their structures were confirmed by spectral and elemental analyses. Cytotoxic activity of these compounds was evaluated against breast (MCF7), colon (HCT116) and liver (HEPG2) cancer cell lines using sulphorhodamine-B (SRB) assay method. All the tested compounds showed highly potent activity against MCF7 cell line with IC₅₀ range equal 8–194 nM/ml and compound 8c was the best active one (IC₅₀ = 8.6 nM/ml). 8b was the best active compound on both HCT116 and HEPG-2 cancer cell lines; its IC₅₀ is 26.5 and 12.3 nM/ml respectively. Docking studies into ATP binding site of EGFR tyrosine kinase were performed to predict their scores and mode of binding to amino acids, moreover, inhibitory activity of these compounds against EGFR-TKs was evaluated; their inhibitory percent ranged from 40.4 to 97.6, compound 8c and 8b showed inhibitory activity at 97.6% and 88.4% respectively.