Preliminary study of the anticancer applications of mesoporous materials functionalized with the natural product betulinic acid

Dehydrated MCM-41 (S1) was functionalized under nitrogen with 3-chloropropyltriethoxysilane (CPTS) and 3-aminopropyltriethoxysilane (APTS) by grafting in toluene at 80 °C over 48 h to give the corresponding materials S2 and S3, respectively. Subsequently, S2 and S3 were suspended in methanol and reacted in a nitrogen atmosphere with betulinic acid (BA) for 48 h at 65 °C (in the presence of the triethylamine of S2) to give the BA-functionalized materials S4 and S5. All materials studied were characterized by powder X-ray diffraction, X-ray fluorescence, nitrogen gas sorption, multinuclear MAS NMR spectroscopy, thermogravimetry, UV spectroscopy, IR, SEM, and TEM. To study the release of BA, S4 and S5 were suspended in solutions simulating various body pH conditions (pH 7.4, 5.5, and 3.0). Results of the quantification of BA release by HPLC for S4 show a pH-dependent and very slow BA release following a logarithmic tendency, while S5 behaves differently, also pH-dependent but, in this case, fast release of BA which requires only days for total release of the therapeutic compound. In addition, the cytotoxic activity of all synthesized materials against various cancer cell lines was studied. The results show the absence of an antiproliferative effect on the surfaces without BA S1-S3, while an antiproliferative effect was observed with S4 and S5 and was attributed to the release of BA in the medium.

Study of the anticancer properties of tin(IV) carboxylate complexes on a panel of human tumor cell lines

A group of organotin(IV) complexes were prepared: [SnCy3 (DMNI)] (1), [SnCy3 (BZDO)] (2), [SnCy3 (DMFU)] (3), and [SnPh2 (BZDO)2 ] (4), for which DMNIH=2,6-dimethoxynicotinic acid, BZDOH=1,4-benzodioxane-6-carboxylic acid, and DMFUH=2,5-dimethyl-3-furoic acid. The cytotoxic activities of compounds 1-4 were tested against pancreatic carcinoma (PANC-1), erythroleukemia (K562), and two glioblastoma multiform (U87 and LN-229) human cell lines; they show very high antiproliferative activity, with IC50 values in the 150-700 nM range after incubation for 72 h. Distribution of cellular DNA upon treatment with 1-4 revealed that whereas compounds 1-3 induce apoptosis in most of the cell lines, compound 4 does not affect cell viability in any cell line tested, indicating a possible difference in cytotoxic mechanism. Studies with the daunomycin-resistant K562/R cell line expressing P-glycoprotein (Pgp) showed that compounds 1-4 are not substrates of this protein efflux pump, indicating that these compounds do not induce acquisition of multidrug resistance, which is associated with the overexpression of Pgp.

A sodium ferrocenyl-phosphanide polymer based on racemic primary aminoalkyl(bisphosphanyl)ferrocene

The primary aminoalkyl(bisphosphanyl)ferrocenes 2-(N,N-dimethylaminomethyl)-1,1'-bis(phosphanyl)ferrocene (3a) and N,N-dimethyl-1-[1',2-bis(phosphanyl)ferrocenyl]ethylamine (3b) are readily available in two steps from the corresponding aminoalkylferrocenes. Deprotonation of 3a gave the first alkali metal aminoalkyl(bisphosphanido)ferrocene (4) as a one-dimensional polymer.

Synthesis, characterization and structures of cyclic organorhodium complexes of the type [Rh{CH(SO₂Ph)CH₂CH₂YR₂-κC,κY}L₂] (YR₂ = PPh₂, NMe₂; L₂ = diphosphine, cyclooctadiene)

Reactions of dinuclear chloridorhodium(I) complexes [(RhL₂)₂(μ-Cl)₂] (L₂ = P[symbol: see text]P: Me₂P(CH₂)₂PMe₂, dmpe, 7a; Ph₂PCH₂PPh₂, dppm, 7b; Ph₂P(CH₂)₂PPh₂, dppe, 7c; Ph₂P(CH₂)₃PPh₂, dppp, 7d; L₂ = cycloocta-1,5-diene, cod, 5) with lithiated γ-phosphino- and γ-aminofunctionalized propyl phenyl sulfones (Li[CH(SO₂Ph)CH₂CH₂PPh₂], 2; Li[CH(SO₂Ph)CH₂CH₂NMe₂], 4) led to the formation of organorhodium inner complexes of the type [Rh{CH(SO₂Ph)CH₂CH₂PPh₂-κC,κP}(P[symbol: see text]P)] (8a-d), [Rh{CH(SO₂Ph)CH₂CH₂NMe₂-κC,κN}(P[symbol: see text]P)] (9a-d), [Rh{CH(SO₂Ph)CH₂CH₂PPh₂-κC,κP}(cod)]·LiCl (11·LiCl) and [Rh{CH(SO₂Ph)CH₂CH₂NMe₂-κC,κN}(cod)]·LiCl (12·LiCl), respectively. Single-crystal X-ray diffraction analysis of 9c·THF, 11 and 12 exhibited in all three compounds a distorted square planar coordination of the rhodium atoms having bidentately coordinated neutral co-ligands (cod, 11, 12; dppe, 9c) and anionic α-phenylsulfonyl γ-phosphinopropyl (κC,κP; 11) and γ-aminopropyl ligands (κC,κN; 12, 9c), thus being typical organorhodium inner complexes. Furthermore, organorhodium inner complexes of type 8 were obtained in reactions of the dinuclear chloridobridged rhodium complexes [(RhL₂)₂(μ-Cl)₂] (L₂ = P[symbol: see text]P, 7a-d; cod, 5; (C₂H₄)₂, 6) with the (non-lithiated) γ-phosphinofunctionalized propyl phenyl sulfone PhSO₂CH₂CH₂CH₂PPh₂ (1) resulting in the formation of complexes having the sulfone κP coordinated ([RhClL₂-(Ph₂PCH₂CH₂CH₂SO₂Ph-κP)] (L₂ = P[symbol: see text]P, 10a-d; cod, 13; (C₂H₄)₂, 14) which were deprotonated (10a-d, 13) at the α-C atom with lithium diisopropyl amide (LDA) in a subsequent reaction. Single-crystal X-ray diffraction analysis of 10c (P[symbol: see text]P = dppe) revealed the expected square-planar coordination geometry of Rh. The identities of all rhodium complexes have been unambiguously proved by microanalyses and NMR spectroscopy (¹H, ¹³C, ³¹P).

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.

2,2'-{1,1'-[2,2'-Oxalylbis(hydrazin-2-yl-1-yl-idene)]diethyl-idyne}dipyridinium bis-(perchlorate) dihydrate

The title salt, C₁₆H₁₈N₆O₂²⁺·2ClO₄⁻·2H₂O, was obtained unintentionally as a major product in the reaction of Zn(ClO₄)₂·6H₂O with the N′,N′²-bis­[(1E)-1-(2-pyrid­yl)ethyl­idene]ethanedihydrazide (H₂L) ligand. The (H₄L)²⁺ cation lies across a centre of inversion. The pyridiniumimine fragments of (H₄L)²⁺ adopt syn orientations. Intra­molecular N—H⋯N and N—H⋯O hydrogen bonds lead to the formation of S(5) motifs. In the crystal, neighbouring cations are connected by π–π inter­actions between pyridinium units with a centroid–centroid distance of 3.600 (1) Å. Moreover, the crystal components are assembled into two-dimensional layers via N—H⋯O and O—H⋯O hydrogen bonds, with no direct hydrogen-bonding inter­actions between cations.

Improvement of cytotoxicity of titanocene-functionalized mesoporous materials by the increase of the titanium content

The reaction of [Ti(eta(5)-C(5)H(5))(2)Cl(2)] (1), with 3-mercaptopropyltrimethoxysilane or 3-mercaptopropyltriethoxysilane in the presence of triethylamine leads to the formation of the thiolate complexes [Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OMe)(3)}(2)] (2) and [Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OEt)(3)}(2)] (3), respectively. Complexes 2 and 3 have been characterized by traditional methods, in addition, structural studies based on DFT calculations are reported. 1-3 have been grafted onto dehydroxylated MCM-41 to give the novel materials MCM-41/[Ti(eta(5)-C(5)H(5))(2)Cl(2)] (S1), MCM-41/[Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OMe)(3)}(2)] (S2) and MCM-41/[Ti(eta(5)-C(5)H(5))(2){SCH(2)CH(2)CH(2)Si(OEt)(3)}(2)] (S3) which have been characterized by powder X-ray diffraction, X-ray fluorescence, nitrogen gas sorption, multinuclear MAS NMR spectroscopy, thermogravimetry, UV spectroscopy, SEM and TEM. Materials S2 and S3 present much higher values of Ti wt% (ca. 3%) than S1 (ca. 1%), indicating the higher functionalization rate induced by the substitution of the chloro ligands by the thiolato ligands in the starting titanocene derivatives. The cytotoxicity of the non-functionalized MCM-41 and S1-S3 toward human cancer cell lines such as adenocarcinoma HeLa, human myelogenous leukemia K562 and human malignant melanoma Fem-x has been studied. In addition the cytotoxicity of these materials on normal immunocompetent cells such as stimulated (PBMC+PHA) and non-stimulated (PBMC-PHA) peripheral blood mononuclear cells have been also studied. M(50) values (quantity of material needed to inhibit normal cell survival by 50%) of the studied surfaces show that non-functionalized MCM-41 was not active against any of the studied cells, while the functionalized surfaces S1-S3 were active against all the tested human cancer cells. The cytotoxic activity of surfaces S2 and S3 were very similar, however, S1 showed lower cytotoxic activity. This phenomenon indicates that the cytotoxicity of the titanocene-functionalized materials strongly depends on the titanium content.

Anticancer activity of dinuclear gallium(III) carboxylate complexes

The reaction of 3-methoxyphenylacetic acid, 4-methoxyphenylacetic acid, mesitylthioacetic acid, 2,5-dimethyl-3-furoic acid and 1,4-benzodioxane-6-carboxylic acid with trimethylgallium (1:1) yielded the dimeric complexes [Me(2)Ga(micro-O(2)CCH(2)C(6)H(4)-3-OMe)](2) (1), [Me(2)Ga(micro-O(2)CCH(2)C(6)H(4)-4-OMe)](2) (2), [Me(2)Ga(micro-O(2)CCH(2)SMes)](2) (3) (Mes=2,4,6-Me(3)C(6)H(2)), [Me(2)Ga{micro-O(2)C(Fur)}](2) (4) (Fur=2,5-dimethylfuran) and [Me(2)Ga{micro-O(2)C(Bdo)}](2) (5) (Bdo=1,4-benzodioxane) respectively. The molecular structure of 5 was determined by X-ray diffraction studies. The cytotoxic activity of the gallium(III) complexes (1-5) was tested against human tumor cell lines 8505C anaplastic thyroid cancer, A253 head and neck tumor, A549 lung carcinoma, A2780 ovarian cancer, DLD-1 colon carcinoma and compared with that of cisplatin. Taking into account the standard deviation, there is no significant difference in the activity for any of the compounds in any cell line. However, complex 5 presents the best IC(50) value against A253 head and neck tumor (6.6+/-0.2 microM), while complex 3 seems to be the most active against A2780 ovarian cancer (12.0+/-0.4 microM) and marginally on DLD-1 colon carcinoma (12.4+/-0.1 microM).

A new generation of anticancer drugs: mesoporous materials modified with titanocene complexes

Dehydroxylated MCM-41 and SBA-15 surfaces were modified by the grafting of two different titanocene complexes ([Ti(eta(5)-C(5)H(4)Me)(2)Cl(2)] and [Ti{Me(2)Si(eta(5)-C(5)Me(4))(eta(5)-C(5)H(4))}Cl(2)]) to give new materials, which have been characterized by powder X-ray diffraction, X-ray fluorescence, nitrogen gas sorption, MAS-NMR spectroscopy, thermogravimetry, SEM, and TEM. The toxicity of the resulting materials toward human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x, and normal immunocompetent cells, such as peripheral blood mononuclear cells PBMC has been studied. Estimation of the number of particles per gram of material led to the calculation of Q(50) values for these samples, which is the number of particles required to inhibit normal cell growth by 50%. In addition, M(50) values (quantity of material needed to inhibit normal cell growth by 50%) of the studied surfaces is also reported. Nonfunctionalized MCM-41 and SBA-15 did not show notable antiproliferative activity, whereas functionalization of these materials with different titanocene based anticancer drugs led to very promising antitumoral activity. The best Q(50) values correspond to titanocene functionalized MCM-41 surfaces (MCM-41/[Ti(eta(5)-C(5)H(4)Me)(2)Cl(2)] (1) and MCM-41/[Ti{Me(2)Si(eta(5)-C(5)Me(4))(eta(5)-C(5)H(4))}Cl(2)] (2)) with Q(50) values between 3.8+/-0.6x10(8) and 24.5+/-3.0x10(8) particles. Titanocene functionalized SBA-15 surfaces (SBA-15/[Ti(eta(5)-C(5)H(4)Me)(2)Cl(2)] (3) and SBA-15/[Ti{Me(2)Si(eta(5)-C(5)Me(4))(eta(5)-C(5)H(4))}Cl(2)] (4)) gave higher Q(50) values, showing lower activity from 73.2+/-9.9x10(8) to 362+/-7x10(8) particles. The best response of the studied materials in terms of M(50) values was observed against Fem-x (309+/-42 microg for 4) and K562 (338+/-18 microg for 2), whereas moderate activities were observed in HeLa cells (from 508+/-63 microg of 2 to 912+/-10 microg of 1). In addition, the analyzed surfaces presented only marginal activity against unstimulated and stimulated PBMC, showing a slight selectivity on human cancer cells. Comparison of the in vitro cytotoxicity in solution of the titanocene complexes [Ti(eta(5)-C(5)H(4)Me)(2)Cl(2)] and [Ti{Me(2)Si(eta(5)-C(5)Me(4))(eta(5)-C(5)H(4))}Cl(2)] and the corresponding titanocene functionalized materials is also described.