Cytotoxic Activity

Aim of the study: Nine plants from Reunion Island, selected using ethnopharmacology and chemotaxonomy, were investigated for their potential antimalarial value. Materials and methods: Thirty-eight extracts were prepared by maceration using CH 2 Cl 2 and MeOH, and were tested for in vitro activity against the 3D7 and W2 strain of Plasmodium falciparum. The most active extracts were then tested for in vitro cytotoxicity on human WI-38 fibroblasts to determine the selectivity index. Those extracts were also investigated in vivo against Plasmodium berghei infected mice. Results: Most active of the extracts tested were the dichloromethane leaves extracts of Nuxia verticillata Lam. (Buddlejaceae), Psiadia arguta Voigt. (Asteraceae), Lantana camara L. (Verbenaceae), the methanol extracts from Aphloia theiformis (Vahl) Benn. (Aphloiaceae) bark, and Terminalia bentzoe L. (Combretaceae) leaves displaying in vitro IC 50 values ranging from 5.7 to 14.1 g/ml. Extracts from Psiadia, Aphloia at 200 mg/(kg day) and Teminalia at 50 mg/(kg day) also exhibited significant (p < 0.0005) parasite inhibition in mice: 75.5%, 65.6% and 83.5%, respectively. Conclusion: Two plants showed interesting antimalarial activity with good selectivity: Aphloia theiformis and Terminalia bentzoe. Nuxia verticillata still needs to be tested in vivo, with a new batch of plant material.

Griscelli syndrome (GS) is caused by mutations in the MYO5A (GS1), RAB27A (GS2), or MLPH (GS3) genes, all of which lead to a similar pigmentary dilution. In addition, GS1 patients show primary neurological impairment, whereas GS2 patients present immunodeficiency and periods of lymphocyte proliferation and activation, leading to their infiltration in many organs, such as the nervous system, causing secondary neurological damage. We report the diagnosis of GS2 in a 4-year-old child with haemophagocytic syndrome, immunodeficiency, and secondary neurological disorders. Typical melanosome accumulation was found in skin melanocytes and pigment clumps were observed in hair shafts. Two heterozygous mutant alleles of the RAB27A gene were found, a C-T transition (C352T) that leads to Q118stop and a G-C transversion on the exon 5 splicing donor site (G467+1C). Functional assays showed increased cellular activation and decreased cytotoxic activity of NK and CD8+ T cells, associated with defective lytic granules release. Myosin-Va expression and localization in the patient lymphocytes were also analyzed. Most importantly, we show that cytotoxic activity of the patient's CD8+ T lymphocytes can be rescued in vitro by RAB27A gene transfer mediated by a recombinant retroviral vector, a first step towards a potential treatment of the acute phase of GS2 by RAB27A transduced lymphocytes.

The occurrence of the two new cis-fused A/B rings furostanol saponins (25S)-26-O-β-Dglucopyranosyl-5β-furostan-1β,3β,22α,26-tetraol-1-O-β-D-glucopyranoside and (25S)-26-Oβ-D-glucopyranosyl-5β-furostan-1β,2β,3β,5β,22α,26-hexaol and the known compounds

A number of arylazophenols 1 were converted into the corresponding mono Mannich bases 2 from which two quaternary salts 3a.b and an ester 3c were prepared. A series of bis Mannich bases 4 were also synthesized. The angles (0) made between one of the aryl rings and the adjacent azo linkage were determined by electronic absorption spectroscopy. X-ray crystallographic data were obtained for some of the Mannich bases. The compounds were evaluated against murine P388 Dl and L 12 IO cells and two human T-lymphocyte (Molt 4, CEM) lines, and most of the derivatives were also screened against a panel of human tumour cell lines. A number of correlations were noted between cytotoxicity and various physicochemical constants as well as some structural features determined by X-ray crystallography. Several of the Mannich bases were shown to have mutagenic properties using the 1 RK mutatest; the compounds in series 2 and 4 have the ability to penetrate the central nervous system, as revealed by their anticonvulsant properties. While series 2-4 have the potential to deaminate forming ortho quinone methides which would be capable of alkylating cellular thiols, the results of stability studies suggest that the bioactivities noted were due to the molecules per se. arylazopbenol I Mannicb base / cytotoxicity 1 mutagenesis / X-ray crystallography J anticonvulsant / CNS activity References

Ruthenium compounds in general are well suited for medicinal applications. They have been investigated as immunosuppressants, nitric oxide scavengers, antimicrobial agents, and antimalarials. The aim of this study is to evaluate the immunomodulatory activity of cis-(dichloro)tetraammineruthenium(III) chloride (cis-[RuCl 2 (NH 3 ) 4 ]Cl) on human peripheral blood mononuclear cells (PBMC). The cytotoxic studies performed here revealed that the ruthenium(III) complex presents a cytotoxic activity towards normal human PBMC, only at very high concentration. Results also showed that cis-[RuCl 2 (NH 3 ) 4 ]Cl presents

a b s t r a c t CYT997 was discovered as a potent tubulin polymerization inhibitor possessing potent cytotoxic activity against a range of cancer cells. Details of SAR studies, pharmacokinetic investigations and synthesis of compounds leading to the discovery of CYT997 are reported.

Natural products play a major role in anticancer drug discovery as a unique source of original structures which can provide models for future drug design. Relevant examples currently used in the clinic include teniposide and etoposide derived from naturally occurring podophyllotoxin, taxotere based on the structure of the yew diterpene paclitaxel, topotecan and irinotecan developed from camptothecin, and semisynthetic vinca alkaloids such as vinorelbine and vinflunine originating from the lead structure vinblastine. 1) In this context, our group is interested in potential anticancer natural product-like compounds including an acridone or xanthone derived basic core and an additional fused dimethylpyran ring. Indeed, the fused dimethylpyran system, which arises in Nature from the condensation of a phenol with an active isoprene unit, appears as a privileged substructure present in numerous bioactive compounds exemplified by the insecticide chromenes precocenes, 2) the HIV-1 reverse transcriptase inhibitors calanolides, 3) and the antitumor acridone alkaloid acronycine (1). 4) Based on this latter model, we recently prepared the pentacyclic analogues benzo[a]acronycine (6methoxy-3,3,14-trimethyl-3,14-dihydro-7H-benzo[a]pyrano[3,2-h]acridin-7-one) (2) and and benzo[b]acronycine (6-methoxy-3,3,14-trimethyl-3,14-dihydro-7H-benzo[b]pyrano[3,2-h]acridin-7-one) (3), together with several series of corresponding 1,2-dihydrodiol diesters, which displayed significantly enhanced in vivo antitumor activity when compared to the parent alkaloid. 5-8) Such compounds are exemplified by cis-diacetate 4, developed under the code S23906-1, which is currently undergoing phase I clinical trials. 9) The mechanism of its action implies alkylation of the 2-amino group of DNA guanine residues by the carbocation resulting from the elimination of the ester leaving group at position 1 of the drug. 10-12) This mechanism is related to that implied in the cytotoxic and antitumor properties of the natural furanoxanthone psorospermine (5), isolated from Psorospermum febrifugum. 13-15) Actually, psorospermine has been shown to interact with DNA and to alkylate the N-7 of the guanine residues. 16,17) In a continuation of our studies on the structure activity relationships in the acronycine series, 18-24) we describe here the synthesis and biological activites of

The chemical composition of essential oils of six Stachys species, S. cretica L. ssp. vacillans Rech. fil., S. germanica L., S. hydrophila Boiss., S. nivea Labill., S. palustris L. and S. spinosa L., obtained by hydrodistillation, was studied by GC and GC–MS. All the oils have in common a great percentage of fatty acids and esters (24.2–58.5%) and a high

Fine balanced sequential changes of the levels of circulating hepatotrophic factors are essential for normal liver regeneration. Our recent studies have indicated that liver-resident natural killer (NK) cells are important regulators of liver regeneration and have raised the possibility that hepatotrophic factors might mediate their activities through NK cells. In the present study, we assessed the effects of in vivo administration of three hepatotrophic factors (augmenter of liver regeneration [ALR], insulin-like growth factor-II [IGF-II], and hepatocyte growth factor [HGF]) on NK cells in normal rats. Each of the three, given over a 1-day period in doses known to produce hepatotrophic activity, induced inhibition of NK cell cytotoxic activities in the population of mononuclear leukocytes (MNL) in the liver, but not in MNL from the spleen or peripheral blood. In contrast to these results obtained by the whole animal treatment, the three molecules had no effect on NK cell functions when added to cultures of MNL from the livers, spleens, or blood of untreated rats. These data support and extend our previously advanced hypothesis that ALR and other hepatotrophic factors play an important role in liver regeneration by regional regulation of NK cells through some as-yet-unknown intermediary mechanism.

The pathogenic slow-growing Mycobacterium ulcerans has, until now, been cultured in liquid media containing albumin. Here, we report the first description of use of Sauton medium and modified Reid medium, two protein-free media, in which M. ulcerans was able to grow and produce its toxin, a major virulence factor of this environmental organism which causes a skin disease commonly called Buruli ulcer. These results suggest that Sauton and modified Reid may be useful for certain fields of M. ulcerans research requiring protein-free growth conditions. ß

Cytotoxic granules were isolated from human lymphokine-activated killer (LAK) cells and analyzed for their biochemical properties. Isolated granules of approximately 85-95% purity were obtained by differential centrifugation followed by discontinuous Percoli gradient centrifugation. The murine lymphocyte granule marker /V-a-carbamazepine-L-lysine thiobenzyl ester-esterase as well as cytotoxic activity toward the human tumor cell lines K562, Raji, Daudi, and CEM were associated with LAK granule fractions. Granule-associated ¿V-a-carbamazepine-L-lysinethio benzyl ester-esterase activity increased in recombinant interleukin 2 expanded human LAK cells in parallel with cytotoxic activity for Raji tumor cell targets. Cytotoxic LAK cell granules mediated calcium-de pendent killing of the tumor cell lines K562, Raji, Daudi, and CEM. However, no calcium-dependent hemolytic activity was found. Preincubation of human granules with calcium, a treatment which totally inacti vates the hemolytic and cytotoxic activity of murine lymphocyte granules |porforili 1 (Pl)| had no effect on human LAK granule cytotoxicity for nucleated cells. Human LAK granules appear to contain PI detected as cross-reactive antigen detected by mouse anti-Pi and human anti-C9 in Western blot analysis. In addition, Northern blot analysis of polyadenylated RNA isolated from human LAK cells using a murine PI comple mentary DNA probe showed a cross-hybridizing 2.8-to 3.0-kilobase mRNA species identical in size to murine PI niKNA. These results demonstrate that despite similar biochemical composition, functional differences exist between human and murine cytotoxic granules. Human LAK granules were synthesized in response to rf combinant interleukin 2 activation and appeared in parallel with cytotoxicity for tumor targets, suggesting an important role for LAK granules in tumor cell cytotoxicity by human LAK cells.

PNU 151807 is a new synthetic α-bromoacryloyl derivative of distamycin A. In the present study we investigated the DNA interaction and the mechanism of action of this compound in parallel with the distamycin alkylating derivative, tallimustine. PNU 151807 possesses a good cytotoxic activity in in vitro growing cancer cells, even superior to that found for tallimustine. By footprinting experiments we found that PNU 151807 and tallimustine interact non-covalently with the same AT-rich DNA regions. However, differently from tallimustine, PNU 151807 failed to produce any DNA alkylation as assessed by Taq stop assay and N3 or N7-adenine alkylation assay in different DNA sequences. PNU 151807, like tallimustine, is able to induce an activation of p53, and consequently of p21 and BAX in a human ovarian cancer cell line (A2780) expressing wild-type p53. However, disruption of p53 function by HPV16-E6 does not significantly modify the cytotoxic activity of the compound. Flow cytometric analysis of cells treated with equitoxic concentrations of PNU 151807 and tallimustine showed a similar induction of accumulation of cells in the G2 phase of the cell cycle but with a different time course. When tested against recombinant proteins, only the compound PNU 151807 (and not tallimustine or distamycin A) is able to abolish the in vitro kinase activity of CDK2-cyclin A, CDK2-cyclin E and cdc2-cyclin B complexes. The results obtained showed that PNU 151807 seems to have a mechanism of action completely different from that of its parent compound tallimustine, possibly involving the inhibition of cyclin-dependent kinases activity, and clearly indicate PNU 151807 as a new non-covalent minor groove binder with cytotoxic activity against cancer cells.

AbstractÐThe synthesis of three isoprenylated derivatives of cyclo-l-Trp-l-Pro is described. These substances have been evaluated for cytotoxic activity in rat normal ®broblast 3Y1 cells and have also been evaluated in vitro for the inhibition of microtubule assembly. #

In invertebrates, cytotoxicity can be an efficient natural defence system. Lysins can be secreted in the body fluids or act at the mem brane level of the effector cells. Hemocytes appear to be responsible for the cytotoxic response to foreign, broad, or specific stimuli. The mechanisms by which Iysins are released and function are not yet very well characterized. The findings about cell mediated contact dependent cytotoxicity suggest that multiple mechanisms must be considered. In allo-and xenogeneic reactions the specificity of cytotoxic mechanisms have been shown. In tunicates, humoral Iysins have not been observed. Cytotoxic hemocytes, responsible for allo-and xenogeneic reactions, appear to be involved in graft rejections. Some properties of tunicate hemocyte cytotoxicity have been examined in Ciona intestinalis using erythrocyte targets. The reaction is fast, calcium-dependent, behaves sigmoidally according to temperature, reaches a maximum at 37° C, and depends on mem brane contact. Individual variability in lytic capacity of Ciona specimens suggests that, as in the other invertebrate species, not all the hemocytes are cytotoxic. Sphingomyelin capacity to inhibit the reaction shows functional analogies with the pore-forming hemolysins of echinoderm and polychaete species. However, it is not excluded that a hemocyte phospholipase may provoke the lysis of the target cell membrane. Thus the hypothesis is supported that a NK-like activity appears early in the evolution thus contributing to the maintenance of homeostasis, and developing immunity.

Ergosterol peroxide, the steroidal derivative with cytotoxic activity, has been isolated for the first time from the mycelium of edible and medicinal mushroom Hericium erinaceum (lion's mane mushroom) together with erinacine A. The new densitometric method was applied for the quantitative determination of ergosterol peroxide in n-hexane extracts of H. erinaceum, Laetiporus sulfureus (chicken mushroom), and Morchella esculenta (common morel) mycelia, as well as in Boletus edulis (king bolete), Suillus bovinus (Jersey cow mushroom), and B. badius (bay bolete) fruiting bodies. The ergosterol peroxide content reached 15.98 ± 0.78, 10.07 ± 0.75, 13.37 ± 0.56, 29.32 ± 1.43, 17.27 ± 0.84, and 12.60 ± 0.59 mg per 100 g, respectively. What is significant was that ergosterol peroxide was identified for the first time, to the best of our knowledge, in edible mushrooms mentioned above.

Extracts of cultures grown in liquid or on solid rice media of the fungal endophyte Ampelomyces sp. isolated from the medicinal plant Urospermum picroides exhibited considerable cytotoxic activity when tested in vitro against L5178Y cells. Chromatographic separation yielded 14 natural products that were unequivocally identified based on their 1 H and 13 C NMR as well as mass spectra and comparison with previously published data. Six compounds (2, 4, 5, 7, 9 and 11) were natural products. Both fungal extracts differed considerably in their secondary metabolites. The extract obtained from liquid cultures afforded a pyrone (2) and sulfated anthraquinones (7 and 9) along with the known compounds 1, 3, 6 and 8. When grown on solid rice medium the fungus yielded three compounds 4, 5 and 11 in addition to several known metabolites including 6, 8, 10, 12, 13 and 14. Compounds 4, 8 and 10 showed the strongest cytotoxic activity against L5178Y cells with EC 50 values ranging from 0.2-7.3 lg/ml. Furthermore, 8 and 10 displayed antimicrobial activity against the Grampositive pathogens, Staphylococcus aureus, S. epidermidis and Enterococcus faecalis at minimal inhibitory concentrations (MIC) of 12.5 lg/ml and 12.5-25 lg/ml, respectively. Interestingly, 6 and 8 were also identified as constituents of an extract derived from a healthy plant sample of the host plant U. picroides thereby indicating that the production of bioactive natural products by the endophyte proceeds also under in situ conditions within the host plant.

Co-culturing of immunological effector cells with antigen-pulsed DC leads to an increase of cytotoxic activity against antigen-expressing tumour cells. Using this approach, we could detect up to 2.8% antigenspecific CTLs after co-culture with antigen-pulsed DC. However, the required high effector cell numbers remain a major obstacle in immunotherapy. In this study, we show an approach for generating activated and antigenspecific effector cells that enables us to decrease effector to target cell ratios. We used an interferon-c secretion assay to enrich activated effector cells after co-culture with antigen-pulsed dendritic cells (DC). Purified immunological effector cells lysed 58.3% of antigenexpressing tumour cells at an effector to target ratio of 1:1. Furthermore, using MHC-IgG complexes, we enriched effector cells expressing antigen-specific T-cell receptor after co-culture with DC. Performing ELISpot, flow cytometry and TCR analysis, we could show a significant increase of activated and specific TCRexpressing effector cells after co-culture with DC.

Lysimachia vulgaris L. (Primulaceae) has been used in the folk medicine of Europe and Asia in the treatment of fever, ulcers, diarrhoea and as an analgesic and antiinflammatory agent. From the underground parts of the plant a benzoquinone pigment and triterpene saponosides were isolated. Cytotoxic and antifungal activity of these compounds were tested in vitro against human and mouse melanoma cells and the yeast Candida albicans respectively. The results showed that saponoside B exerted cytotoxicity especially towards human melanoma cells.

Levoglucosenone has been used as template for the synthesis of a wide variety of compounds with an impressive structural variability. However, scarce work has been done regarding the generation of new bioactive entities. Here we report the cytotoxic effect of levoglucosenone and some related derivatives against hepatocarcinoma cell lines. Compounds were obtained in only one synthetic step and one of them showed an activity within the range of IC 50 values of cisplatin, a frequently administered chemotherapy drug.

A new sesquiterpene, lauroxepine and six known sesquiterpene lactones, were obtained through bioactivity-directed isolation from a methanol extract of the fruits of Laurus nobilis. The hexane-soluble part of the methanol extract yielded lauroxepine, costunolide and gazaniolide, while the dichloromethane-soluble part of the methanol extract afforded costunolide and four other sesquiterpene lactones including santamarine, reynosin, 11,13-dehydrosantonin and spirafolide. The new sesquiterpene lauroxepine and spirafolide have a rare molecular structure carrying an oxepine ring. Structures of the compounds were determined through 1D and 2D NMR and mass (EI-MS) techniques. The extracts were investigated for both ovarian cytotoxic activity and DNA damaging properties against three yeasts. Among the three tested extracts prepared from flowers, leaves and fruits of L. nobilis, the most cytotoxic active extract against ovarian cancer cell line was found to be the fruit extract with 98% inhibition. Among all tested extracts, only the fruit extract showed marginal inhibition (63.2%) against one DNA repair-deficient yeast strain (pRAD52 Gal). Six known sesquiterpene lactones were found to be highly cytotoxic against the A2780 ovarian cancer cell line, however, lauroxepine was not found to be active in A2780.

The ozonized sunflower oil product (Oleozon Ò ) was investigated to explore its cytotoxic activity on Giardia duodenalis in vitro cultivated trophozites. Oleozon Ò produced inactivation of Giardia trophozoites in a dose-and cell density-dependent manner. Thirty microliter of Oleozon Ò with peroxide index value of 500 equivalent-mmol of activated oxygen per kilogram were used to achieve a 100% inhibition (<À4.00 log unit) of trophozoites from an initial inoculum of 15 Â 10 4 cells. This potent effect was confirmed by transmission electron microscopy where morphological deterioration of superficial structures mainly in the ventral disc, and formation of a great number of micro vesicles in the cytoplasm were found. We concluded that a direct chemical-oxidation attack by the active substances from Oleozon Ò is one of the causes of the parasitocidal effect of this product. We suggest that the dose and cell density-dependent effect must be taken into account when prescription of this product for giardiasis treatment in humans.

Annual discards from the world fisheries are estimated to be approximately 20 million metric tonnes (25%) per year. The main objective of this work is to increase the utilisation of by-products (notably skin) from fish species in order to isolate new biologically active compounds. This study presents the results of a screening program for antifungal, antibacterial and cytotoxic activities in epidermal mucus and epidermis extracts of thirteen fish species that are commonly caught in North Atlantic waters and generate an important amount of fish waste. Antimicrobial assays used five Gram-positive bacteria five Gram-negative bacteria and five fungi. Of the 78 extracts tested, 15 showed antibacterial and/or antifungal activities. None of the aqueous fractions were active. One third of the active extracts were ethanolic fractions and three fourth of extracts were dichloromethane fractions. One third of the active fractions were of epidermal origin and the remaining came from mucus fractions. The high levels of inhibitory activity and no apparent toxicity against mouse fibroblasts of extracts of Pollachius virens (CH 3 CH 2 OH/epidermis), Labrus bergylta (CH 2 Cl 2 / mucus), Platichthys flesus (CH 3 CH 2 OH/mucus), Solea solea (CH 2 Cl 2 /mucus) and Scophtalamus rhombus (CH 2 Cl 2 /mucus) suggest they may have potential as novel active therapeutic agents. #

Synthesis of 7, a ferrocene derivative of the antiestrogenic drug hydroxytamoxifen bearing a basic chain-O(CH 2 ) n N(CH 3 ) 2 with n= 4 is presented, together with both studies of its antiproliferative effect on the hormone-dependent MCF7 cell line (estrogen receptor positive cells) and of its genotoxicity. This molecule is easily prepared via a McMurry coupling reaction. The antiproliferative effect found for 7 at an incubation molarity of 1 mM was very close to that found for the usual reference molecule, namely OH-tamoxifen. In addition to its structural antiestrogenic effect, 7 showed cytotoxic activity probably due to the vectored ferrocene. This genotoxic component was confirmed by a 3D (damaged DNA detection) test, that permits identification and quantification of lesions induced on DNA. Some key interactions of 7 docked into the alpha-estrogen receptor binding site were also shown.

Cytokinin ribosides (N 6 -substituted adenosine derivatives) have been shown to have anticancer activity both in vitro and in vivo. This study presents the first systematic analysis of the relationship between the chemical structure of cytokinins and their cytotoxic effects against a panel of human cancer cell lines with diverse histopathological origins. The results confirm the cytotoxic activity of N 6 -isopentenyladenosine, kinetin riboside, and N 6 -benzyladenosine and show that the spectrum of cell lines that are sensitive to these compounds and their tissues of origin are wider than previously reported. The first evidence that the hydroxylated aromatic cytokinins (ortho-, meta-, para-topolin riboside) and the isoprenoid cytokinin cis-zeatin riboside have cytotoxic activities is presented.

Contradictory results exist in the literature about the antineoplastic activity of ferrocenes and their ferrocenium salts; additionally, little is known about the mechanism by which such drugs become active towards cancer cells. In the present paper we show that only ferrocenium species are able to inhibit the growth of Ehrlich ascites tumor cells in vivo and we propose that the cytotoxic activity of ferrocenium salts is not based on their direct linking to DNA, but on their ability to generate oxygen active species which induce oxidative DNA damage.

Background:  Thioredoxin  reductase  is  an  important  enzyme  in
antioxidant  defense and regulation of cell function, its inhibition has
cytotoxic effects.
Aim:  To predict if; there  is correlation  between the already  in vitro
cytotoxic studied Au (III) complexes & their docking studies
Material  &  Method:  The  enzyme  in  complex  with  a  potential
inhibitor will be downloaded from the Protein Data Bank (PDB). The
inhibitory  binding  site  of  the  enzyme  will  be  defined  as  the  8  A°-sphere of residues surrounding the inhibitor.
Four gold-based compounds along with cisplatin and XAN were then
docked into the defined site and their poses inside the active site were
analyzed.
Results:  These  compounds  have  already  shown  in  vitro  activity
against  the  Hep-2  cell  line  and  this  cytotoxicity  compared  with  the
results generated by the computer
Conclusion: Computer aided drug design is excellent & modern tool
to correlate between the structures & inhibition properties of Au  (III)
complexes.

The application of inorganic chemistry to medicine is a rapidly developing field, and novel therapeutic and diagnostic metal complexes are now having an impact on medical practice. Advances in biocoordination chemistry are crucial for improving the design of compounds to reduce toxic side effects and understand their mechanisms of action. Cisplatin, as one of the leading metal-based drugs, is widely used in the treatment of cancer. Significant side effects and drug resistance, however, have limited its clinical applications. Biological carriers conjugated to cisplatin analogs have improved specificity for tumor tissue, thereby reducing side effects and drug resistance. Platinum complexes with distinctively different DNA binding modes from that of cisplatin also exhibit promising pharmacological properties. This review focuses on recent advances in developing platinum anticancer agents with an emphasis on platinum coordination complexes.

Cytotoxic and cell-transforming activities of methyl thiophanate, a systemic fungicide capable of entering plant cells and Ž . thus controlling fungal diseases that have already started, were studied in an in vitro medium-term 6-8 weeks experimental model utilizing BALBrc 3T3 cells. Cells were exposed to the chemical, dissolved in dimethyl sulfoxide, in the absence or Ž . presence of an exogenous metabolizing system derived from rat livers supplemented with cofactors S9 mix . In the absence of metabolic activation, methyl thiophanate exerted cytotoxic activity, evidenced through the formation of cell colonies, at Ž . low doses ) 10 mgrml . However, the cytotoxic activity was greatly reduced by the S9 mix-induced metabolic activation of the chemical. Without bioactivation, cell-transforming potential, evidenced through the induction of transformation foci, Ž . Ž . was observable only at the highest weakly toxic dose employed 25 mgrml . On the contrary, in the presence of metabolic Ž . activation, the cell-transforming activity was detectable at all tested doses i.e. from 20 to 200 mgrml and it was particularly evident in a level-II transformation amplification test when the cells were allowed to perform active proliferative activity. These results, providing further information on the activity of methyl thiophanate in multistep carcinogenesis as possible genotoxic andror co-carcinogenic agent, may contribute to better evaluate the oncogenic risk to man. q 1997 Elsevier Science B.V.

The complexes [Me 2 (Meclo)SnOSn(Meclo)Me 2 ] 2 (2) and [Ph 3 Sn(Meclo)] (3) where HMeclo is meclofenamic acid, N-(2,6-dichloro-m-tolylanthranilic acid)], have been prepared and structurally characterized by means of vibrational, 1 H and 13 C NMR spectroscopies. The crystal structure of complexes (2) and (3) have been determined by X-ray crystallography. Three distannoxane rings are present to the dimeric tetraorganodistannoxane of planar ladder arrangement of (2). The structure is centro symmetric and features a central rhombus Sn 2 O 2 unit two additional tin atoms linked at the oxygen atoms. Five-and six-coordinated tin centers are present in the dimer distannoxane. X-ray analysis of (3) revealed a penta-coordinated structure containing Ph 3 Sn coordinated to the chelated carboxylato group. The polar imino hydrogen atom participates in intra-molecular hydrogen bonds. Complexes and (3) are self-assembled via p ? p, C-H-p, stacking interactions and intra-molecular hydrogen bonds. Meclofenamic acid and [Ph 3 Sn(Meclo)] have been evaluated for antiproliferative activity in vitro against three human cancer cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A-549 (non-small cell lung carcinoma) and a mouse L-929 (a fibroblast-like cell line cloned from strain L). The [Ph 3 Sn(Meclo)] complex exhibited high cytotoxic activity against all the cancer cell lines. Meclofenamic and [Ph 3 Sn(Meclo)]

In the present investigation the n-hexane, carbon tetrachloride and choloroform soluble fractions of crude methanolic extract of Samanea saman bark were tested for antioxidant, antimicrobial and cytotoxic potential. Antioxidant activity of the extracts was evaluated by DPPH radical scavenging assay and total antioxidant activity test. Antimicrobial activity was tested using disc diffusion method against thirteen bacteria and three fungi and cytotoxicity was tested by brine shrimp lethality bioassay. Chloroform and hexane soluble fraction showed IC50 value of 12µg/ml and 14µg/ml respectively in scavenging DPPH radical while the reference Butylated hydroxytoluene showed an IC50 value of 10µg/ml. The carbon tetrachloride fraction showed the highest total antioxidant capacity. The carbon tetrachloride fraction was also found to possess mild to moderate microbial growth inhibitory capacity. In the brine shrimp lethality bioassay, the n-hexane, carbon tetrachloride, chloroform soluble fractions showed LC50 value of 14.94µg/ml, 0.831µg/ml and 3.288µg/ml respectively. The results suggest good antioxidant and cytotoxic potential of chloroform and hexane soluble fractions and antimicrobial activity of carbon tetrachloride fraction of Samanea saman bark extract.

A dichloromethane extract of root celery yielded falcarinol, falcarindiol, panaxydiol, and the new polyacetylene 8-O-methylfalcarindiol. The structure of the new compound was established by oneand two-dimensional (1D and 2D) NMR, mass spectrometry, and optical rotation data. Nonpolar extracts of roots and bulbs of carrots, celery, fennel, parsley, and parsnip were investigated for their content of polyacetylenes by high-performance liquid chromatography with diode array detection (HPLC-DAD). All five species contained polyacetylenes, although carrots and fennel only in minor amounts. Additionally, the cytotoxicity of the four polyacetylenes against five different cell lines was evaluated by the annexin V-PI assay. Falcarinol proved to be the most active compound with a pronounced toxicity against acute lymphoblastic leukemia cell line CEM-C7H2, with an IC 50 of 3.5 µmol/L. The possible chemopreventive impact of the presented findings is discussed briefly.

The aim of this work was to investigate the involvement of caspases in apoptosis induced by L-amino acid oxidase isolated from Bothrops atrox snake venom. The isolation of LAAO involved three chromatographic steps: molecular exclusion on a G-75 column; ion exchange column by HPLC and affinity chromatography on a Lentil Lectin column. SDS-PAGE was used to confirm the expected high purity level of BatroxLAAO. It is a glycoprotein with 12% sugar and an acidic character, as confirmed by its amino acid composition, rich in "Asp and Glu" residues. It displays high specificity toward hydrophobic L-amino acids. The N-terminal amino acid sequence and internal peptide sequences showed close structural homology to other snake venom LAAOs. This enzyme induces in vitro platelet aggregation, which may be due to H 2 O 2 production by LAAOs, since the addition of catalase completely inhibited the aggregation effect. It also showed cytotoxicity towards several cancer cell lines: HL60, Jurkat, B16F10 and PC12. The cytotoxicity activity was abolished by catalase. A fluorescence microscopy evaluation revealed a significant increase in the apoptotic index of these cells after BatroxLAAO treatment. This observation was confirmed by phosphatidyl serine exposure and activation of caspases. BatroxLAAO is a protein with various biological functions that can be involved in envenomation. Further investigations of its function will contribute to toxicology advances.

Four new sesquiterpene lactones (1-4) and a new sesquiterpene (5) together with 20 known compounds were isolated from two Gonospermum species (G. gomerae Bolle and G. fruticosum Less). Their structures were determined by analysis of spectroscopic data, including 1D and 2D NMR. The cytotoxicity of several new and known natural and semisynthetic sesquiterpene lactones was also assessed against human myeloid leukemia cell lines (HL-60 and U937), human melanoma cells (SK-MEL-1), and human adenocarcinoma (A549).