Lupane triterpenoids--betulin and betulinic acid derivatives induce apoptosis in tumor cells.

In the present investigation the antiproliferative activity of thirteen derivatives of betulinic acid and betulin was tested against five different tumor cell lines. The toxicity against normal human fibroblasts (WWO70327) and the mode of cell death on HT-29 (colon cancer) as well as caspase activity induced by the most active compounds, 9 (3-O-chloroacetylbetulinic acid) and 15 (28-O-chloroacetylbetulin) were determined. Investigated derivatives exerted a dose dependent antiproliferative action at micromolar concentrations toward target tumor cell lines. Treatment of HT-29 cells for 24 h with 9 and 15 induced apoptosis, as observed by dye exclusion test (trypan blue) and confirmed by the appearance of a typical ladder pattern in the DNA fragmentation assay.

Cytotoxicity, apoptosis and study of the DNA-binding properties of bi- and tetranuclear gallium(III) complexes with heterocyclic thiolato ligands.

The reaction of the heterocyclic thiol derivatives, 2-mercapto-1-methylimidazole (SH-imi), 5-mercapto-1-methyltetrazole (SH-tet), 2-mercaptobenzothiazole (SH-ben) and 5-phenyl-1,3,4-oxadiazole-2-thiol (SH-oxa), with trimethylgallium (1:1) afforded the dimeric or tetrameric complexes [Me(2)Ga(S-imi)](2) (1), [Me(2)Ga(S-tet)](2) (2), [Me(2)Ga(S-ben)](2) (3) and [Me(2)Ga(S-oxa)](4) (4), respectively. Molecular structures of 2 and 4 were determined by X-ray diffraction studies. The cytotoxicity of the gallium(III) complexes 1-4 was tested against human cell lines 8505C anaplastic thyroid cancer, A253 head and neck tumor, A549 lung carcinoma, A2780 ovarian cancer, DLD-1 colon carcinoma and compared with those of cisplatin and Ga(NO(3))(3). Compound 4 seems to be slightly more active against 8505C, A253 and A2780 and substantially more active than all the other complexes against DLD-1, with an IC(50) value of 5.49 ± 0.16 µM, very close to that of cisplatin (5.14 ± 0.12 µM). Complexes 1-4 were less toxic on normal human fibroblasts (WWO70327) than on the investigated tumor cell lines and more selective to cancer cells than cisplatin. DNA laddering method showed that treatment of the DLD-1 cell line with IC(90) doses of 1-4 resulted in the induction of apoptosis. Compound 1 caused apoptosis by upregulation of caspases 2, 3 and 8. Since no activity of caspase 9 is observed, complex 1 is causing apoptosis triggered by an extrinsic pathway. DNA-interaction tests have been also carried out. Solutions of all the studied complexes have been treated with different concentrations of fish sperm DNA (FS-DNA). Modifications of the UV spectra which gave intrinsic binding constants of 3.03 × 10(5), 4.44 × 10(5), 3.02 × 10(6) and 5.56 × 10(5) M(-1) for 1-4 were observed, however, no notable interaction with pBR322 plasmid DNA was detected.

Carbamate derivatives of betulinic acid and betulin with selective cytotoxic activity.

Synthesis and antiproliferative activity of eight new derivatives of betulinic acid (1) and betulin (2) are described. The compounds were tested against fifteen tumor cell lines. The toxicity against normal human fibroblasts and the mode of cell death on lung cancer cell line induced by the most active compounds 9 (bis(ethylcarbamate)betulin) and 11 (3-O-ethylcarbamate of 28-O-acetylbetulin) was investigated. Caspase 3 activity on lung cancer cell line (A549) was determined for 1, 5 (3-O-ethylcarbamate of betulinic acid), 9 and 11. All derivatives exerted a dose dependent antiproliferative action at micromolar concentrations toward target tumor cell lines. Treatment of lung cancer cells for 24h with 9 and 11 induced apoptosis, as observed by the appearance of a typical ladder pattern in the DNA fragmentation assay.

Synthesis and biological evaluation of antitumor-active gamma-butyrolactone substituted betulin derivatives.

The plant triterpenes betulin and betulinic acid (BA) are triterpenes featuring interesting pharmacological properties. Starting from substituted betulinic aldehydes, we used them as lead structures for the synthesis of several gamma-butyrolactones and butenolides. Their antitumor activity was examined for 15 cancer cell lines using a SRB-assay and their apoptotic action was documented by trypan-blue test and DNA laddering. Several compounds revealed a higher activity than betulinic acid.

Synthesis and biological evaluation of antitumour-active betulin derivatives.

The reaction of betulinic aldehydes with various carbon nucleophiles gave a series of new betulin derivatives, among them epoxides, glycidic derivatives and beta-hydroxy carbonyl compounds. Subsequent transformations of the beta-hydroxy carbonyls lead to 1,3-diketo- and alpha,beta-unsaturated betulin derivatives. These compounds were assayed for cytotoxicity using 15 human cancer cell lines and a colorimetric SRB-assay. Several compounds revealed significant antitumour activity.

Synthesis and anticancer activity of novel betulinic acid and betulin derivatives.

A series of novel betulinic acid derivatives 3-11 and betulin derivatives 12-17 were synthesized. The compounds were characterized by the means of (1)H- and (13)C-NMR spectroscopy as well as mass spectrometry. The compounds have been tested on ten tumor cell lines of different histogenic origin. The most active derivatives, containing a chloroacetyl group on C-3 in betulinic acid 9 and C-28 in betulin 15, were up to ten times more cytotoxic and many fold more selective towards tumor cells in comparison to normal cells (fibroblasts) than betulinic acid. Furthermore, compound 15 was found to possess cell growth inhibition even when treated for a short time on anaplastic thyroid cancer cells (SW1736).

Liposomes as vehicles for water insoluble platinum-based potential drug: 2-(4-(tetrahydro-2H-pyran-2-yloxy)-undecyl)-propane-1,3-diamminedichloroplatinum(II).

Formulation of liposome delivery system loaded with water insoluble 2-(4-(tetrahydro-2H-pyran-2-yloxy)-undecyl)-propane-1,3-diamminedichloroplatinum(II), LipoTHP-C11 was carried out. The particle size distributions were determined by dynamic light scattering and asymmetrical flow field-flow fractionation indicating size of around 120 nm. Stability study showed that LipoTHP-C11 was stable at 4 °C for more than two months. To test suitability of chosen formulation, LipoTHP-C11 was investigated against several tumor cell lines: H12.1, 1411HP, 518A2, A549, HT-29, MCF-7 and SW1736. Furthermore, toxicity against normal fibroblasts was examined. LipoTHP-C11 may be used as an attractive candidate for further assessment in vivo as antitumor agent.

Carbaboranes as pharmacophores: similarities and differences between aspirin and asborin.

In medicinal chemistry carbaboranes have been used almost exclusively as boron carriers for boron neutron capture therapy (BNCT). Recent developments extended the carrier approach and use carbaboranes as scaffolds for radiodiagnostic or therapeutic agents. Most recent studies, however, focus on carbaboranes as modern hydrophobic pharmacophores. This research employs preferably meta- and para-carbaborane, because these isomers are extremely hydrophobic and very stable. In this paper we therefore investigated the pharmacophoric behavior of the ortho isomer as putative phenyl mimetic by comparing aspirin to asborin, its ortho-carbaborane analogue. Special emphasis is placed on the impact of the cluster properties on the pharmacological profile. Subjects under study are the mode of cyclooxygenase (COX) inhibition, stability, and toxicity. The straightforward syntheses of the corresponding nido compounds as well as their contribution to the pharmacology of the closo precursors will be highlighted. Finally, proof will be given that the ortho-carbaborane core of asborin merits the designation "pharmacophore" by definition and is a multifunctional group rather than just a hydrophobic, bulky spectator.

Increased betulinic acid induced cytotoxicity and radiosensitivity in glioma cells under hypoxic conditions.

BACKGROUND: Betulinic acid (BA) is a novel antineoplastic agent under evaluation for tumor therapy. Because of the selective cytotoxic effects of BA in tumor cells (including gliomas), the combination of this agent with conservative therapies (such as radiotherapy and chemotherapy) may be useful. Previously, the combination of BA with irradiation under hypoxic conditions had never been studied. METHODS: In this study, the effects of 3 to 30 µM BA on cytotoxicity, migration, the protein expression of PARP, survivin and HIF-1α, as well as radiosensitivity under normoxic and hypoxic conditions were analyzed in the human malignant glioma cell lines U251MG and U343MG. Cytotoxicity and radiosensitivity were analyzed with clonogenic survival assays, migration was analyzed with Boyden chamber assays (or scratch assays) and protein expression was examined with Western blot analyses. RESULTS: Under normoxic conditions, a half maximal inhibitory concentration (IC50) of 23 µM was observed in U251MG cells and 24 µM was observed in U343MG cells. Under hypoxic conditions, 10 µM or 15 µM of BA showed a significantly increased cytotoxicity in U251MG cells (p = 0.004 and p = 0.01, respectively) and U343MG cells (p < 0.05 and p = 0.01, respectively). The combination of BA with radiotherapy resulted in an additive effect in the U343MG cell line under normoxic and hypoxic conditions. Weak radiation enhancement was observed in U251MG cell line after treatment with BA under normoxic conditions. Furthermore, under hypoxic conditions, the incubation with BA resulted in increased radiation enhancement. The enhancement factor, at an irradiation dose of 15 Gy after treatment with 10 or 15 µM BA, was 2.20 (p = 0.02) and 4.50 (p = 0.03), respectively. Incubation with BA led to decreased cell migration, cleavage of PARP and decreased expression levels of survivin in both cell lines. Additionally, BA treatment resulted in a reduction of HIF-1α protein under hypoxic conditions. CONCLUSION: Our results suggest that BA is capable of improving the effects of tumor therapy in human malignant glioma cells, particularly under hypoxic conditions. Further investigations are necessary to characterize its potential as a radiosensitizer.

Small structural changes of pentacyclic lupane type triterpenoid derivatives lead to significant differences in their anticancer properties.

In the present investigations five new derivatives of betulinic and betulonic acid were synthesized and the effect of this structural variations on anticancer activity was studied and discussed. The antiproliferative activity of betulinic and betulonic acid derivatives was studied against eight tumor cell lines of different histogenic origin. The derivatives exerted a dose dependent antiproliferative action at micromolar concentrations toward target tumor cell lines. The apoptotic mode of cell death on colon cancer cell line HT-29 was induced by the most active compounds 5, 2-amino-3-hydroxy-2-(hydroxymethyl)propyl (3-O-acetyl)betulinate, and 9, 2-amino-3-hydroxy-2-(hydroxymethyl)propyl betulonate. Treatment of HT-29 cells with 5 and 9 induced apoptosis, as observed by dye exclusion test (trypan blue) and by the appearance of a typical ladder pattern in the DNA fragmentation assay and FITC annexin V assay. Cell cycle perturbations caused by compound 5 are also presented.

In vitro anticancer studies of alpha- and beta-D-glucopyranose betulin anomers.

Four derivatives of betulin containing a D-glucopyranosyl moiety at C3 position were synthesized and characterized by (1)H and (13)C NMR spectroscopy as well as mass spectrometry. The crystal structure of 28-O-acetylbetulin-3-yl-beta-D-(2',3',4',6'-tetra-O-acetyl)glucopyranoside was determined. The compounds were tested against fifteen tumor cell lines of different histogenic origins. The alpha- and beta-anomers of 28-O-acetylbetulin-3-yl-D-glucopyranoside, exerted a dose dependent antiproliferative action towards the tumor cell lines. Treatment of HCT-116 cells for 24h induced apoptosis, which was confirmed by the appearance of a typical ladder pattern in the DNA fragmentation assay and cell cycle analysis. The alpha- and beta-anomers of 28-O-acetylbetulin-3-yl-D-glucopyranoside seem to induce apoptosis by activation of different upstream caspases on colon cancer HCT-116 cell line.

Synthesis and biological applications of ionic triphenyltin(IV) chloride carboxylate complexes with exceptionally high cytotoxicity.

The reaction of N-phthaloylglycine (P-GlyH), N-phthaloyl-l-alanine (P-AlaH), and 1,2,4-benzenetricarboxylic 1,2-anhydride (BTCH) with triethylamine led to the formation of the corresponding ammonium salts [NHEt(3)][P-Gly] (1), [NHEt(3)][P-Ala] (2) and [NHEt(3)][BTC] (3) in very high yields. The subsequent reaction of 1-3 with triphenyltin(iv) chloride (1 : 1) yielded the compounds [NHEt(3)][SnPh(3)Cl(P-Gly)] (4), [NHEt(3)][SnPh(3)Cl(P-Ala)] (5), and [NHEt(3)][SnPh(3)Cl(BTC)] (6), respectively. The molecular structure of 4 was determined by X-ray diffraction studies. The cytotoxic activity of the ammonium salts (1-3) and the triphenyltin(iv) chloride derivatives (4-6) were tested against human tumor cell lines from five different histogenic origins: 8505C (anaplastic thyroid cancer), A253 (head and neck cancer), A549 (lung carcinoma), A2780 (ovarian cancer) and DLD-1 (colon cancer). Triphenyltin(iv) chloride derivatives (4-6) show very high activity against these cell lines while the ammonium salts of the corresponding carboxylic acids (1-3) are totally inactive. The most active compound is 4 which is 50 times more active than cisplatin. Compound 4 is found to induce apoptosis via extrinsic pathways on DLD-1 cell lines, probably by accumulation of caspases 2, 3 and 8. Furthermore, compound 4 seems to cause disturbances in G1 and G2/M phases in cell cycle of DLD-1 cell line.

Synthesis, characterization, in vitro antitumoral investigations and interaction with plasmid pBR322 DNA of R2eddp-platinum(IV) complexes (R = Et, n-Pr).

The studies on synthetic, spectroscopic and biological properties of platinum(IV) complexes, [PtCl(4)(R(2)eddp)] (R = Et, 1; n-Pr, 2), containing kappa(2)N,N' bidentate ligands, esters of ethylenediamine-N,N'-di-3-propionic acid (HOOCCH(2)CH(2)NHCH(2)CH(2)NHCH(2)CH(2)COOH, H(2)eddp), are reported. Complexes have been characterized by infrared, (1)H and (13)C NMR spectroscopy and elemental analysis and it was concluded that the coordination of the ligands occurs via nitrogen donor atoms of the ester ligands (R(2)eddp). Cytotoxicity studies were performed for ligand precursors and corresponding platinum(IV) complexes. Although the n-Pr(2)eddp.2HCl itself showed no activity (IC(50) values > 125 microM) in selected cell lines, the activity of complex 2, via apoptotic mode of cell death, has increased significantly for a broad range of cancer cell lines tested in vitro (IC(50) = 8.6-49 microM). As it was found that complexes 1 and 2 are able to interact with pBR322 plasmid DNA, platinum(IV) complexes of this type may act as drugs and pro-drugs.