Amantadine mitigates the cytotoxic and genotoxic effects of doxorubicin in SH-SY5Y cells and reduces its mutagenicity.

Amantadine (AMA) is a useful drug in neuronal disorders, but few studies have been performed to access its toxicological profile. Conversely, doxorubicin (Dox) is a well-known antineoplastic drug that has shown neurotoxic effects leading to cognitive impairment. The aims of this study are to evaluate the cytotoxic, genotoxic, and mutagenic effects of AMA, as well as its possible protective actions against deleterious effects of Dox. The Salmonella/microsome assay was performed to assess mutagenicity while cytotoxicity and genotoxicity were evaluated in SH-SY5Y cells using MTT and comet assays. Possible modulating effects of AMA on the cytotoxicity, genotoxicity, and mutagenicity induced by Dox were evaluated through cotreatment procedures. Amantadine did not induce mutations in the Salmonella/microsome assay and decreased Dox-induced mutagenicity in the TA98 strain. AMA reduced cell viability and induced DNA damage in SH-SY5Y cells. In cotreatment with Dox, AMA attenuated the cytotoxicity of Dox and showed an antigenotoxic effect. In conclusion, AMA does not induce gene mutations, although it has shown a genotoxic effect. Furthermore, AMA decreases frameshift mutations induced by Dox as well as the cytotoxic and genotoxic effects of Dox in SH-SY5Y cells, suggesting that AMA can interfere with Dox mutagenic activity and attenuate its neurotoxic effects.

Preparation and characterization of a novel host-guest complex based on folate-modified ß-cyclodextrin and artesunate.

The purpose of this study was to develop a novel folate-modified host-guest complex to enhance antitumor activity of the artesunate and improve the solubility and stability by encapsulated in ß-cyclodextrin and linked with folate. In this work, we designed and prepared the inclusion complex of adamantanamine conjugated artesunate (AD-ATS) with folic acid-ethylenediamine-ß-cyclodextrin (FA-EN-ß-CD). This material was characterized by 1D and 2D NMR, XRD, TG and SEM. The results suggested that AD-ATS was encapsulated within the FA-EN-ß-CD cavity to form host-guest inclusion complex, and the water solubility of AD-ATS was improved in the form of inclusion complex with FA-EN-ß-CD. The assessment of antitumor activity showed that cytotoxicity of AD-ATS/FA-EN-ß-CD complex was significantly enhanced in comparison to free AD-ATS, ATS/ß-CD inclusion complex and ATS/FA-EN-ß-CD inclusion complex.

Cisplatin or LA-12 enhance killing effects of TRAIL in prostate cancer cells through Bid-dependent stimulation of mitochondrial apoptotic pathway but not caspase-10.

Searching for new strategies for effective elimination of human prostate cancer cells, we investigated the cooperative cytotoxic action of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and two platinum-based complexes, cisplatin or LA-12, and related molecular mechanisms. We demonstrated a notable ability of cisplatin or LA-12 to enhance the sensitivity of several human prostate cancer cell lines to TRAIL-induced cell death via an engagement of mitochondrial apoptotic pathway. This was accompanied by augmented Bid cleavage, Bak activation, loss of mitochondrial membrane potential, activation of caspase-8, -10, -9, and -3, and XIAP cleavage. RNAi-mediated silencing of Bid or Bak in Bax-deficient DU 145 cells suppressed the drug combination-induced cytotoxicity, further underscoring the involvement of mitochondrial signaling. The caspase-10 was dispensable for enhancement of cisplatin/LA-12 and TRAIL combination-induced cell death and stimulation of Bid cleavage. Importantly, we newly demonstrated LA-12-mediated enhancement of TRAIL-induced cell death in cancer cells derived from human patient prostate tumor specimens. Our results provide convincing evidence that employing TRAIL combined with cisplatin/LA-12 could contribute to more effective killing of prostate cancer cells compared to the individual action of the drugs, and offer new mechanistic insights into their cooperative anticancer action.

The Synthesis of α,α-Disubstituted α-Amino Acids via Ichikawa Rearrangement.

An approach to α,α-disubstituted α-amino acids is reported. The key step is allyl cyanate-to-isocyanate rearrangement. As demonstrated, the resultant allyl isocyanates can be directly trapped with various nucleophiles, for instance, alcohols, amines, and organometallic reagents, to provide a broad range of N-functionalized allylamines. The developed method has been successfully applied in the synthesis of two bioactive peptides: 2-aminoadamantane-2-carboxylic acid derived P2X7-evoked glutamate release inhibitor and 4-amino-tetrahydropyranyl-4-carboxylic acid derived dipeptide GSK-2793660, which is currently in clinical trials as cathepsin C inhibitor for the treatment of cystic fibrosis, noncystic fibrosis bronchiectasis, ANCA-associated vasculitis and bronchiectasis.

Loss of PTEN Facilitates Rosiglitazone-Mediated Enhancement of Platinum(IV) Complex LA-12-Induced Apoptosis in Colon Cancer Cells.

We demonstrated for the first time an outstanding ability of rosiglitazone to mediate a profound enhancement of LA-12-induced apoptosis associated with activation of mitochondrial pathway in human colon cancer cells. This effect was preferentially observed in the G1 cell cycle phase, independent on p53 and PPARγ proteins, and accompanied with significant changes of selected Bcl-2 family protein levels. Further stimulation of cooperative synergic cytotoxic action of rosiglitazone and LA-12 was demonstrated in the cells deficient for PTEN, where mitochondrial apoptotic pathway was more stimulated and G1-phase-associated dying was reinforced. Our results suggest that combined treatment with rosiglitazone and LA-12 might be promising anticancer strategy in colon-derived tumours regardless of their p53 status, and also favourable in those defective in PTEN function.

Chemically Bonding of Amantadine with Gardenamide A Enhances the Neuroprotective Effects against Corticosterone-Induced Insults in PC12 Cells.

Two amantadine (ATD)-gardenamide A (GA) ligands have been designed and synthesized. The bonding of ATD with GA through a methylene carbonyl brigde (L1) enhances the neuroprotective effect against corticosterone (CORT)-induced impairments in PC12 cells; while the bonding through a succinyl brigde (L2) does not. L1 reduces the level of reactive oxygen species (ROS) and cell apoptosis generated by CORT. It restores CORT-changed cell morphology to a state that is closed to normal PC12 cells. One mechanism of L1 to attenuate CORT-induced cell apoptosis is through the adjustment of both caspase-3 and Bcl-2 proteins. Like GA, both nNOS and eNOS might be involved in the neuroprotective mechanism of L1. All the evidences suggest that L1 may be a potential agent to treat depression.

The New Semisynthetic Cardenolide Analog 3ß-[2-(1-Amantadine)-1-on-ethylamine]-digitoxigenin (AMANTADIG) Efficiently Suppresses Cell Growth in Human Leukemia and Urological Tumor Cell Lines.

BACKGROUND/AIM: The use of cardenolides in the treatment of cardiac insufficiency is well-established. However, the potential of cardenolides in tumor therapy has not been comprehensively studied. The aim of the present study was to characterize the cytotoxic effects of the new semisynthetic cardenolide analog AMANTADIG (3ß-[2-(1-amantadine)-1-on-ethylamine]-digitoxigenin), and the cardenolide digitoxin on leukemia and urological tumor cell lines. MATERIALS AND METHODS: The anti-proliferative effects of AMANTADIG and digitoxin on leukemia and urological cancer cell lines were analyzed using (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction viability assay. RESULTS: AMANTADIG and digitoxin exhibited anti-proliferative activities against the leukemia cell lines in the low nanomolar range. The prostate cancer and renal cell carcinoma cell lines were equally sensitive to AMANTADIG and digitoxin, however, the leukemia cell lines were more sensitive to both cardenolides. CONCLUSION: The new cardenolide analog AMANTADIG appears effective in cell growth inhibition of leukemia and urological tumor cell lines.

Platinum(IV) complex LA-12 exerts higher ability than cisplatin to enhance TRAIL-induced cancer cell apoptosis via stimulation of mitochondrial pathway.

In search for novel strategies in colon cancer treatment, we investigated the unique ability of platinum(IV) complex LA-12 to efficiently enhance the killing effects of tumor necrosis factor-related apoptosis inducing ligand (TRAIL), and compared it with the sensitizing action of cisplatin. We provide the first evidence that LA-12 primes human colon cancer cells for TRAIL-induced cytotoxicity by p53-independent activation of the mitochondrial apoptotic pathway. The cooperative action of LA-12 and TRAIL was associated with stimulation of Bax/Bak activation, drop of mitochondrial membrane potential, caspase-9 activation, and a shift of the balance among Bcl-2 family proteins in favor of the pro-apoptotic members. In contrast to cisplatin, LA-12 was a potent inducer of ERK-mediated Noxa and BimL protein upregulation, and more effectively enhanced TRAIL-induced apoptosis in the absence of Bax. The cooperative action of LA-12 and TRAIL was augmented following the siRNA-mediated silencing of Mcl-1 in both Bax proficient/deficient cells. We newly demonstrated that LA-12 induced ERK-mediated c-Myc upregulation, and proved that c-Myc silencing inhibited the mitochondrial activation and apoptosis in colon cancer cells treated with LA-12 and TRAIL. The LA-12-mediated sensitization to TRAIL-induced apoptosis was demonstrated in several colon cancer cell lines, further underscoring the general relevance of our findings. The selective action of LA-12 was documented by preferential priming of cancer but not normal colon cancer cells to TRAIL killing effects. Our work highlights the promising potential of LA-12 over cisplatin to enhance the colon cancer cell sensitivity to TRAIL-induced apoptosis, and provides new mechanistic insights into their cooperative action.

Platinum anticancer drugs and photochemotherapeutic agents: recent advances and future developments.

Platinum-based chemotherapeutic drugs such as cisplatin, carboplatin and oxaliplatin are widely applied for the treatment of various types of tumours. Over the last few decades, a large variety of Pt(II) and Pt(IV) complexes have been developed to improve the applicability in a wider spectrum of cancers, increase their therapeutic window and reduce the dose-limiting side effects. Photodynamic therapy (PDT), which is the administration of a photosensitiser followed by visible light activation, is a promising route to avoid damage to healthy cells and the surrounding tissue. Transition metal complexes as photochemotherapeutic agents are an attractive option for further development in the field of photoactivated chemotherapy (PACT). These complexes exhibit different numbers and types of excited states which are easily accessible upon light irradiation, subsequently giving rise to the formation of various photoproducts that can enable a distinct mode of action. Platinum-diazido complexes are promising candidates for PACT due to the low cytotoxicity when irradiated with visible light. This review summarises the mode of action of current platinum anticancer drugs with cisplatin as a lead example and the development of non-conventional Pt(II) complexes. Background information regarding PDT the photophysical and photochemical properties of metal complexes is provided, as well as notable examples of photoactivated metal complexes with biological activity. Particular emphasis is placed on recent developments on platinum photoactivated drugs.

Higher anti-tumour efficacy of platinum(IV) complex LA-12 is associated with its ability to bypass M-phase entry block induced in oxaliplatin-treated human colon cancer cells.

OBJECTIVES: Therapeutic potential of conventionally used platinum-based drugs in treatment of colorectal tumours has been limited due to high incidence of tumour resistance to them and to their severe side effects. This evokes a search for more suitable anti-cancer drugs. We have compared ability of oxaliplatin and a novel platinum(IV) complex, LA-12, to modulate the cell cycle and induce apoptosis in human colon adenocarcinoma HCT116 wt and p53/p21 null cells, and have investigated molecular mechanisms involved. MATERIALS AND METHODS: Cell cycle-related changes were analysed by flow cytometry (bromodeoxyuridine/propidium iodide staining, histone H3 phosphorylation). Apoptosis was detected using flow cytometry (assays monitoring caspase activity) and fluorescence microscopy (nuclear morphology). Changes in levels of genes/proteins involved in cell cycle and apoptosis regulation were examined by RT-PCR and western blotting. RESULTS: Our results highlight the outstanding ability of LA-12 to induce effective elimination of colon cancer cells independently of p53/p21, and in significantly lower doses compared to oxaliplatin. While oxaliplatin induced p53- and p21-dependent G2 -phase arrest associated with downregulation of cyclin B1 and Cdk1, LA-12 allowed cells to enter M-phase of the cell cycle regardless of p53/p21 status. CONCLUSIONS: Higher malignant cell toxicity and ability to bypass cell cycle arrest important for the cell damage repair suggest LA-12 to be a more effective candidate for elimination of colon tumours from a variety of genetic backgrounds, compared with oxaliplatin.

Potentiation of azole antifungals by 2-adamantanamine.

Azoles are among the most successful classes of antifungals. They act by inhibiting α-14 lanosterol demethylase in the ergosterol biosynthesis pathway. Oropharyngeal candidiasis (OPC) occurs in about 90% of HIV-infected individuals, and 4 to 5% are refractory to current therapies, including azoles, due to the formation of resistant biofilms produced in the course of OPC. We reasoned that compounds affecting a different target may potentiate azoles to produce increased killing and an antibiofilm therapeutic. 2-Adamantanamine (AC17) was identified in a screen for compounds potentiating the action of miconazole against biofilms of Candida albicans. AC17, a close structural analog to the antiviral amantadine, did not affect the viability of C. albicans but caused the normally fungistatic azoles to become fungicidal. Transcriptome analysis of cells treated with AC17 revealed that the ergosterol and filamentation pathways were affected. Indeed, cells exposed to AC17 had decreased ergosterol contents and were unable to invade agar. In vivo, the combination of AC17 and fluconazole produced a significant reduction in fungal tissue burden in a guinea pig model of cutaneous candidiasis, while each treatment alone did not have a significant effect. The combination of fluconazole and AC17 also showed improved efficacy (P value of 0.018) compared to fluconazole alone when fungal lesions were evaluated. AC17 is a promising lead in the search for more effective antifungal therapeutics.

A comparative study of pharmacokinetics, urinary excretion and tissue distribution of platinum in rats following a single-dose oral administration of two platinum(IV) complexes LA-12 (OC-6-43)-bis(acetato)(1-adamantylamine)amminedichloroplatinum(IV) and satraplatin (OC-6-43)-bis(acetato)amminedichloro(cyclohexylamine)platinum(IV).

PURPOSE: This study compared the pharmacokinetics, tissue distribution, and urinary excretion of platinum in rats after single oral doses of LA-12 and satraplatin. METHODS: Both platinum derivatives were administered to male Wistar rats as suspensions in methylcellulose at four equimolar doses within the range of 37.5-300 mg LA-12/kg body weight. Blood sampling was performed until 72 h, and plasma and plasma ultrafiltrate were separated. Moreover, urine was collected until 72 h, and kidney and liver tissue samples were obtained at several times after administration. Platinum was measured by atomic absorption spectrometry. The pharmacokinetics of platinum was analyzed by population modelling and post hoc Bayesian estimation as well as using non-compartmental pharmacokinetic analysis of the mean concentration-time curves. RESULTS: Platinum was detected in all plasma and ultrafiltrate samples 15 min after oral administration of both compounds and peaked between 3-4 h and 1-3 h, respectively. Similar for LA-12 and satraplatin, the C (max) and AUC values of plasma and ultrafiltrate platinum increased less than in proportion to dose. The mean C (max) and AUC values of plasma platinum observed after administration of LA-12 were from 0.84 to 2.5 mg/l and from 20.2 to 75.9 mg h/l. For ultrafiltrate platinum, the corresponding ranges were 0.16-0.78 mg/l and 0.63-1.8 mg h/l, respectively. The AUC of plasma platinum was higher after satraplatin (P < 0.001). However, administration of LA-12 resulted in significantly higher AUC values of ultrafiltrate platinum after the doses of 150 mg and 300 mg/kg (P < 0.01), respectively, and the C (max) values were significantly higher starting from the dose of 75 mg/kg LA-12 and upward (P < 0.01). Cumulative 72-h urinary recovery of platinum dose was below 5% for both compounds, and it decreased with the dose of satraplatin (P < 0.01), while a numerical decrease was observed after administration of LA-12 that did not reach statistical significance (P = 0.41). The renal clearance of free platinum was similar regardless of the dose and compound administered. Platinum concentrations in the liver homogenate exceeded those in the kidney. Distribution of platinum to tissues was higher after LA-12 compared to satraplatin. The difference in kidney platinum increased with dose and was twofold after 350 mg/kg LA-12. Liver platinum was twofold higher after LA-12 across all four doses. CONCLUSIONS: In conclusion, this first comparative pharmacokinetic study with LA-12 and satraplatin shows that characteristics of platinum exposure evaluated in the plasma, plasma ultrafiltrate and kidney and liver tissues increase less than in proportion to dose following a single-dose administration of 37.5-300 mg/kg to Wistar rats. These findings together with the dose-related elevation in the pharmacokinetic characteristics V/F and CL/F of platinum and ultrafiltrate platinum as well as a drop in platinum urinary recovery are consistent with a dose-related decrease in the extent of oral bioavailability most likely due to saturable intestinal absorption.

Cisplatin and a potent platinum(IV) complex-mediated enhancement of TRAIL-induced cancer cells killing is associated with modulation of upstream events in the extrinsic apoptotic pathway.

TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) can selectively trigger apoptosis in various cancer cell types. However, many cancer cells are resistant to death receptor-mediated apoptosis. Combination therapy with platinum complexes may affect TRAIL-induced signaling via modulation of various steps in apoptotic pathways. Here, we show that cisplatin or a more potent platinum(IV) complex LA-12 used in 20-fold lower concentration enhanced killing effects of TRAIL in human colon and prostate cancer cell lines via stimulation of caspase activity and overall apoptosis. Both platinum complexes increased DR5 surface expression in colon cancer cells. Small interfering RNA-mediated DR5 silencing rescued cells from sensitizing effects of platinum drugs on TRAIL-induced caspase-8 activation and apoptosis, showing the functional importance of DR5 in the effects observed. In addition, both cisplatin and LA-12 triggered the relocalization of DR4 and DR5 receptors to lipid rafts and accelerated internalization of TRAIL, which may also affect TRAIL signaling. Collectively, modulations of the initial steps of the extrinsic apoptotic pathway at the level of DR5 and plasma membrane are important for sensitization of colon and prostate cancer cells to TRAIL-induced apoptosis mediated by LA-12 and cisplatin.

LA-12 overcomes confluence-dependent resistance of HT-29 colon cancer cells to Pt (II) compounds.

BACKGROUND: LA-12 is a new platinum (IV) drug with promising cytotoxic effects in a wide range of cancer cell lines. Its confluence-dependent effects were compared with cisplatin (CDDP) and oxaliplatin (L-OHP) in HT-29 cells. MATERIALS AND METHODS: Cytotoxicity was determined by MTT test, eosin exclusion assay, and cell number quantification. The cell cycle was analysed using propidium iodide DNA staining (flow cytometry), apoptosis by phosphatidylserine externalisation (annexin-V assay), mitochondrial membrane potential by flow cytometry, nuclear morphology by means of fluorescence microscopy, and PARP cleavage by Western blotting. RESULTS: While L-OHP and CDDP were practically inactive in the subconfluent cell population, LA-12 showed a similar toxicity in both subconfluent and growing populations. All compounds induced apoptosis, although with different potentials. CONCLUSION: LA-12 was able to overcome confluence-dependent resistance of HT-29 cells observed for other platinum compounds, which may have potential therapeutic use in slowly growing tumours.

The new platinum(IV) derivative LA-12 shows stronger inhibitory effect on Hsp90 function compared to cisplatin.

BACKGROUND: Cisplatin and its derivatives are commonly used anti-cancer drugs. However, cisplatin has clinical limitations including serious side effects and frequent emergence of intrinsic or acquired resistance. Thus, the novel platinum(IV) complex LA-12 represents a promising treatment modality, which shows increased intracellular penetration resulting in improved cytotoxicity in various cancer cell lines, including cisplatin resistant cells. RESULTS: LA-12 disrupts cellular proliferation regardless of the p53 status in the cells, however the potency of the drug is greatly enhanced by the presence of a functional p53, indicating several mechanisms of action. Similarly to cisplatin, an interaction of LA-12 with molecular chaperone Hsp90 was proposed. Binding of LA-12 to Hsp90 was demonstrated by Hsp90 immunoprecipitation followed by platinum measurement using atomic absorption spectrometry (AAS). An inhibitory effect of LA-12 on Hsp90 chaperoning function was shown by decrease of Hsp90-assisted wild-type p53 binding to p21WAF1 promoter sequence in vitro and by accelerated ubiqutination and degradation of primarily unfolded mutant p53 proteins in cells exposed to LA-12. CONCLUSIONS: To generalize our findings, LA-12 induced degradation of other Hsp90 client proteins such as Cyclin D1 and estrogen receptor was shown and proved as more efficient in comparison with cisplatin. This newly characterised molecular mechanism of action opens opportunities to design new cancer treatment strategy profitable from unique LA-12 properties, which combine DNA damaging and Hsp90 inhibitory effects.

The effect of cellular environment and p53 status on the mode of action of the platinum derivative LA-12.

In this study, we characterized the effects of LA-12 on tumor cell lines possessing wild type p53 and on p53-deficient/mutant cell lines and the results were compared to those obtained using cisplatin. We have determined changes of p53 levels, of its transcriptional activity, of its posttranscriptional modifications and the effect of the treatment on the cell cycle, on the induction of apoptosis and on gene expression. LA-12 induces weak accumulation of both transcriptionally active p53 tumor suppressor and of p21(WAF1/CIP1) protein. LA-12 and cisplatin also significantly differ in their effects on apoptosis and cell cycle and on gene expression spectra in studied cell lines. LA-12 induces higher apoptosis levels in comparison with those induced by cisplatin, especially in p53-deficient H1299 cells and in MCF-7DD cells with transcriptionally inactive p53. We suggest that LA-12-mediated apoptosis is not fully dependent on p53. This confirms the therapeutic potential of LA-12 as a more potent cytostatic agent for both tumor cells expressing wild type p53 and for p53-deficient or mutant cells.

The novel platinum(IV) complex LA-12 induces p53 and p53/47 responses that differ from the related drug, cisplatin.

The platinum(II)-based complex cisplatin is one of the most frequently used antitumour agents; however, a high incidence of harmful side effects and the frequent emergence of acquired resistance are the major clinical problems. The novel platinum(IV)-based complex LA-12 exhibits a high efficacy against cancer cell lines, including cisplatin-insensitive cells, but the mechanisms by which LA-12 perturbs cell growth are unclear. We tested the effects of LA-12 on the p53 response and demonstrate that LA-12 induces unique changes in the profile of gene expression compared with cisplatin and doxorubicin. Furthermore, the ability of LA-12 to disrupt cellular proliferation is greatly enhanced by the expression of p53 and p53/47 indicating both p53-dependent and p53-independent effects of LA-12. Exposure of the human cancer cell lines H1299, A2780, BT549 and BT474 to LA-12 alters the expression of p53 and p53/47 in both a time-dependent and dose-dependent manner. Treatment of cells with a low concentration of the drug results in accumulation of p53 and p53/47 concomitant with their posttranslational modification, whereas a high dose results in the disappearance of both the forms of p53. The distinct p53 activation profile of LA-12 compared with cisplatin and doxorubicin provides a molecular explanation for the ability of this drug to treat cisplatin-resistant cells and indicates its potential usefulness as an alternative antitumour agent in first-line therapy or as a second-line therapy in patients with acquired cisplatin resistance.

Cytotoxicity, mutagenicity, cellular uptake, DNA and glutathione interactions of lipophilic trans-platinum complexes tethered to 1-adamantylamine.

Cytotoxicity and mutagenicity of trans,trans,trans-[PtCl2(CH3COO)2(NH3)(1-adamantylamine)] [trans-adamplatin(IV)] and its reduced analog trans-[PtCl2(NH3)(1-adamantylamine)] [trans-adamplatin(II)] were examined. In addition, the several factors underlying biological effects of these trans-platinum compounds using various biochemical methods were investigated. A notable feature of the growth inhibition studies was the remarkable circumvention of both acquired and intrinsic cisplatin resistance by the two lipophilic trans-compounds. Interestingly, trans-adamplatin(IV) was considerably less mutagenic than cisplatin. Consistent with the lipophilic character of trans-adamplatin complexes, their total accumulation in A2780 cells was considerably greater than that of cisplatin. The results also demonstrate that trans-adamplatin(II) exhibits DNA binding mode markedly different from that of ineffective transplatin. In addition, the reduced deactivation of trans-adamplatin(II) by glutathione seems to be an important determinant of the cytotoxic effects of the complexes tested in the present work. The factors associated with cytotoxic and mutagenic effects of trans-adamplatin complexes in tumor cell lines examined in the present work are likely to play a significant role in the overall antitumor activity of these complexes.

[Synthesis and neuroprotective activity in cell culture of aminoadamantane analogues].

Seven novel derivatives of aminoadamantane with 1-aminosubstituted group were synthesized from amantadine or memantine individually in order to find new neuroprotective agent. Six of them are amides of two precursors, one is a 1-amino derivative of memantine substituted with 2-hydroxy propyl. Their chemical structures were confirmed by 1H NMR and HRMS. The neuroprotective activity in vitro was evaluated primarily with 500 micromol x L(-1) glutamate damaged SY5Y cell by measurement of MTT metabolic rate and LDH leakage rate. Glutamate reduced MTT metabolic rate, but increased LDH leakage rate significantly. The addition of new derivatives elevated the MTT value with their certain concentration, reduced cell death rate. Especially as for 3d and 4c, they fully normalized LDH leakage rate with concentration of 20 micromol x L(-1) during LDH measurement. These data indicated that 3d and 4c have significant protective effect on nerve cell against glutamate injury, deserved to be further tested and maybe helpful for treatment of neurodegenerative disease.

Apoptosis and inhibition of gap-junctional intercellular communication induced by LA-12, a novel hydrophobic platinum(IV) complex.

A new hydrophobic platinum(IV) complex, LA-12, a very efficient anticancer drug lacking cross-resistance with cisplatin (CDDP), is now being tested in clinical trials. Here we investigated the apoptogenic activity of LA-12 and its effect on gap-junctional intercellular communication (GJIC) in the rat liver epithelial cell line WB-F344. LA-12 induced apoptosis much more efficiently than did CDDP due to a combination of rapid penetration into the cell and attack on DNA, leading to fast activation of p53 and caspase-3. Exposure of WB-F344 cells to LA-12 led to rapid induction of the time- and dose-dependent decrease in GJIC. On the molecular level, loss of GJIC induced by LA-12 was mediated by activation of extracellular signal-regulated kinase (ERK)-1 and ERK-2, as demonstrated by the use of inhibitors of ERK activation. Inhibition of GJIC was linked to rapid hyperphosphorylation of connexin-43 and disappearance of connexon clusters from membranes, which was not observed in the case of CDDP.