4 research outputs found
Targeted Antitumoral Dehydrocrotonin Nanoparticles With L-ascorbic Acid 6-stearate
Tumoral cells are known to have a higher ascorbic acid uptake than normal cells. Therefore, the aim of this study was to obtain polymeric nanoparticles containing the antitumoral compound trans-dehydrocrotonin (DHC) functionalized with L-ascorbic acid 6-stearate (AAS) to specifically target this system tumoral cells. Nanoparticle suspensions (NP-AAS-DHC) were prepared by the nanoprecipitation method. The systems were characterized for AAS presence by thin-layer chromatography and for drug loading (81-88%) by UV-Vis spectroscopy. To further characterize these systems, in vitro release kinetics, size distribution (100-140 nm) and Zeta potential by photon-correlation spectroscopic method were used. In vitro toxicity against HL60 cells was evaluated by tetrazolium reduction and Trypan blue exclusion assays. Cell death by apoptosis was quantified and characterized by flow cytometry and caspase activity. Zeta potential analyses showed that the system has a negatively charged outer surface and also indicate that AAS is incorporated on the external surface of the nanoparticles. In vitro release kinetics assay showed that DHC loaded in nanoparticles had sustained release behavior. In vitro toxicity assays showed that NP-AAS-DHC suspension was more effective as an antitumoral than free DHC or NP-DHC and increased apoptosis induction by receptor-mediated pathway. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association.981247964807Ziegler, D.S., Kung, A.L., Therapeutic targeting of apoptosis pathways in cancer (2008) Curr Opin Oncol, 20, pp. 97-103http://www.who.int, last access: 20/02/2008Sofou, S., Surface-active liposomes for targeted cancer therapy (2007) Nanomedicine, 2 (5), pp. 711-724. , http://www.futuremedicine.com/doi/pdf/10.2217/17435889.2.5.711, DOI 10.2217/17435889.2.5.711Castro, M.A., Pozo, M., Cortes, C., Garcia, M.D.L.A., Concha, I.I., Nualart, F., Intracellular ascorbic acid inhibits transport of glucose by neurons, but not by astrocytes (2007) Journal of Neurochemistry, 102 (3), pp. 773-782. , DOI 10.1111/j.1471-4159.2007.04631.xSavona, M., Talpaz, M., Getting to the stem of chronic myeloid leukaemia (2008) Nature Reviews Cancer, 8 (5), pp. 341-350. , DOI 10.1038/nrc2368, PII NRC2368McNulty, A.L., Stabler, T.V., Vail, T.P., McDaniel, G.E., Kraus, V.B., Dehydroascorbate transport in human chondrocytes in regulated by hypoxia and is a physiologically relevant source of ascorbic acid in the joint (2005) Arthritis Rheum, 52, pp. 2676-2685Agus, D.B., Vera, J.C., Golde, D.W., Stromal cell oxidation: A mechanism by which tumors obtain vitamin C (1999) Cancer Res, 18, pp. 4555-4558Marcato, P.D., Durán, N., New aspects of nanopharmaceutical delivery systems (2008) J Nanosci Nanotechnol, 8, pp. 1-4Duran, N., Marcato, P.D., Buffo, C.M.S., De Azevedo, M.M.M., Esposito, E., Poly(epsilon-caprolactone)/propolis extract: Microencapsulation and antibacterial activity evaluation (2007) Pharmazie, 62 (4), pp. 287-290. , DOI 10.1691/ph.2007.4.6058Lee, A.L., Wang, Y., Ye, W.H., Yoon, H.S., Chan, S.Y., Yang, Y.Y., Efficient intracellular delivery of functional proteins using cationic polymer core/shell nanoparticles (2008) Biomaterials, 29, pp. 224-232Jain, K.K., Recent advances in nanoocology (2008) Technol Cancer Res Treat, 7, pp. 1-13Har-El, Y.-E., Kato, Y., Intracellular delivery of nanocarriers for cancer therapy (2007) Current Nanoscience, 3 (4), pp. 329-338. , http://www.ingentaconnect.com/content/ben/cnano/2007/00000003/00000004/ art00005, DOI 10.2174/157341307782418612Arruebo, M., Fernández-Pacheco, R., Ibarra, M.R., Santamaría, J., Magnetic naoparticles for drug delivery (2007) Nanotoday, 2, pp. 22-32Durán, J.D.G., Arias, J.L., Gallardo, V., Delgado, A.V., Magnetic colloids as drug vehicles (2008) J Pharm Sci, 97, pp. 2948-2983Duran, N., Marcato, P.D., De Souza, G.I.H., Alves, O.L., Esposito, E., Antibacterial effect of silver nanoparticles produced by fungal process on textile fabrics and their effluent treatment (2007) Journal of Biomedical Nanotechnology, 3 (2), pp. 203-208. , DOI 10.1166/jbn.2007.022Nair, L.S., Laurencin, C.T., Biodegradable polymers as biomaterials (2007) Progr Polym Sci, 32, pp. 762-798Grynberg, N.F., Echevarria, A., Lima, J.E., Pamplona, S.S.R., Pinto, A.C., Maciel, M.A.M., Anti-tumor activity of two 19-nor-clerodane diterpenes, transdehydrocrotonin and trans-crotonin, from Croton cajucara (1999) Planta Med, 65, pp. 687-689Melo, P.S., Justo, G.Z., Duran, N., Haun, M., Natural killer cell activity and anti-tumour effects of dehydrocrotonin and its synthetic derivatives (2004) European Journal of Pharmacology, 487 (1-3), pp. 47-54. , DOI 10.1016/j.ejphar.2004.01.027, PII S0014299904000895Rodriguez, J.A., Hiruma-Lima, C.A., Brito, A.R.M.S., Antiulcer activity and subacute toxicity of trans-dehydrocrotonin from Croton cajucara (2004) Hum Exp Toxicol, 23, pp. 455-461Silva, R.M., Oliveira, F.A., Cunha, K.M.A., Maia, J.L., Maciel, M.A.M., Pinto, A.C., Nascimento, N.R.F., Rao, V.S.N., Cardiovascular effects of trans-dehydrocrotonin, a diterpene from Croton cajucara in rats Vasc Pharmacol, 43, pp. 11-18Anazetti, M.C., Melo, P.S., Duran, N., Haun, M., Dehydrocrotonin and its derivative, dimethylamide-crotonin induce apoptosis with lipid peroxidation and activation of caspases-2, -6 and -9 in human leukemic cells HL60 (2004) Toxicology, 203 (1-3), pp. 123-137. , DOI 10.1016/j.tox.2004.06.003, PII S0300483X04003282Souza Brito, A.R.M., Rodriguez, J.A., Hiruma-Lima, C.A., Haun, M., Nunes, D.S., Antiulcerogenic activity of trans-Dehydrocrotonin from Croton cajucara (1998) Planta Medica, 64 (2), pp. 126-129Yan, Y., Bornscheuer, U.T., Schmid, R.D., Lipase-catalyzed synthesis of vitamin C fatty acid esters (1999) Biotechnology Letters, 21 (12), pp. 1051-1054. , DOI 10.1023/A:1005620125533Cui, F., Shi, K., Zhang, L., Tao, A., Kawashima, Y., Biodegradable nanoparticles loaded with insulin-phospholipid complex for oral delivery: Preparation, in vitro characterization and in vivo evaluation (2006) Journal of Controlled Release, 114 (2), pp. 242-250. , DOI 10.1016/j.jconrel.2006.05.013, PII S0168365906002355, Third International Nanomedicine and Drug Delivery SymposiumHumeau, C., Girardin, M., Rovel, B., Miclo, A., Enzymatic synthesis of fatty acid ascorbyl esters (1998) Journal of Molecular Catalysis - B Enzymatic, 5 (1-4), pp. 19-23. , DOI 10.1016/S1381-1177(98)00090-3, PII S1381117798000903Gryparis, E.C., Mattheolabakis, G., Bikiaris, D., Avgoustakis, K., Effect of conditions of preparation on the size and encapsulation properties of PLGA-mPEG nanoparticles of cisplatin (2007) Drug Delivery, 14 (6), pp. 371-380. , DOI 10.1080/10717540701202937, PII 781274247Anazetti, M.C., Melo, P.S., Duran, N., Haun, M., Comparative cytotoxicity of dimethylamide-crotonin in the promyelocytic leukemia cell line (HL60) and human peripheral blood mononuclear cells (2003) Toxicology, 188 (2-3), pp. 261-274. , DOI 10.1016/S0300-483X(03)00089-1Freire, A.C.G., Melo, P.S., Aoyama, H., Haun, M., Durán, N., Ferreira, C.V., Cytotoxicity effect of lactone from Croton cajucara on human promyelocytic leukemia cells (2003) Planta Med, 69, pp. 67-69Galvao Freire, A.C., Fernandes De Assis, C., Frick, A.O., Da Silva Melo, P., Haun, M., Aoyama, H., Duran, N., Ferreira, C.V., Influence of protein phosphatase inhibitors on HL60 cells death induction by dehydrocrotonin (2003) Leukemia Research, 27 (9), pp. 823-829. , DOI 10.1016/S0145-2126(03)00013-4Stroh, C., Schulze-Osthoff, K., Death by a thousand cuts: An ever increasing list of caspase substrates (1998) Cell Death and Differentiation, 5 (12), pp. 997-1000Mosqueira, V.C.F., Legrand, P., Pinto-Alphandary, H., Puisieux, F., Barratt, G., Poly(D,L-Lactide) nanocapsules prepared by a solvent displacement process: Influence of the composition on physicochemical and structural properties (2000) Journal of Pharmaceutical Sciences, 89 (5), pp. 614-626. , DOI 10.1002/(SICI)1520-6017(200005)89:53.0.CO;2-7Kubo, I., Asaka, Y., Shibata, K., Insect growth inhibitory nor-diterpenes, cis-dehydrocrotonin and trans-dehydrocrotonin, from Croton cajucara (1991) Phytochemistry, 30, pp. 2545-2546Chen, Q., Espey, M.G., Sun, A.Y., Lee, J.-H., Krishna, M.C., Shacter, E., Choyke, P.L., Levine, M., Ascorbate in pharmacologic concentrations selectively generates ascorbate radical and hydrogen peroxide in extracellular fluid in vivo (2007) Proceedings of the National Academy of Sciences of the United States of America, 104 (21), pp. 8749-8754. , DOI 10.1073/pnas.0702854104Gruss-Fischer, T., Fabian, I., Protection by ascorbic acid from denaturation and release of cytochrome c, alteration of mitochondrial membrane potential and activation of multiple caspase induced by H2O2, in human leukemia cells (2002) Biochem Pharmacol, 63, pp. 1325-1335Fransson, L.A., Mani, K., Novel aspects of vitamin C: How important is glypican-1 recycling? (2007) Trends Mol Med, 13, pp. 143-149Czech Jr., M.P., Lawrence, J.C., Lynn, W.C., Evidence for the involvement of sulfhydryl oxidation in the regulation of fat cell hexose transport by insulin (1974) Proc Natl Acad Sci USA, 71, pp. 4173-4177Sagun, K.C., Cárcamo, J.M., Golde, D.W., Vitamin C enters mitochondria via facilitative glucose transporter 1 (Glut1) and confers mitochondrial protections against oxidative injury (2005) FASEB J, 19, pp. 1657-1667Xie, S.-Q., Liu, G.-C., Ma, Y.-F., Cheng, P.-F., Wu, Y.-L., Wang, M.-W., Ji, B.-S., Wang, C.-J., Synergistic antitumor effects of anthracenylmethyl homospermidine and alpha-difluoromethylornithine on promyelocytic leukemia HL60 cells (2008) Toxicology in Vitro, 22 (2), pp. 352-358. , DOI 10.1016/j.tiv.2007.09.017, PII S0887233307002615Dzietko, M., Boos, V., Sifringer, M., Polley, O., Gerstner, B., Genz, K., Endesfelder, S., Felderhoff-Mueser, U., A critical role for Fas/CD-95 dependent signaling pathways in the pathogenesis of hyperoxia-induced brain injury (2008) Ann Neurol, 64, pp. 664-67
Nanocytotoxicity: Violacein And Violacein-loaded Poly (d, L-lactide-co-glycolide) Nanoparticles Acting On Human Leukemic Cells
Violacein is a compound obtained from Chromobacterium violaceum, a bacterium found in the Amazonian region. Violacein-loaded poly (D, L-lactide-co-glycolide) nanoparticles has a similar inhibitory effect evaluated by trypan blue assay on leukemic HL60 cells than the free form. However, the cytotoxic effects evaluated by phosphatase activity and MTT reduction assays were lower for the encapsulated form than for free violacein. Based on morphological changes, violacein and violacein entrapped in nanoparticles were found to induce terminal differentiation (assessed by nitro blue tetrazolium reduction) in HL60 cells. Thus, both formulations inhibit HL60 cell growth in vitro, partly by inducing cytotoxic effects and cell differentiation. Flow cytometric analysis of HL60 cells after treatment for 12 h showed that violacein-loaded PLGA induced apoptosis, with maximum cell death at a concentration of 2 μM. Violacein and violacein/PLGA induced opposite effects on the mitochondrial swelling which indicates altered mitochondrial function. The mitochondrial activity was also checked by flow cytometry studies. Labelled cells with the probe JC1 displayed a basal hypopolarized status of the mitochondria in treated cells. Based on morphological changes, alterations in phospholipid asymmetry and changes in mitochondrial polarization, violacein and nanoparticles containing violacein were found to trigger cell death by apoptosis. These methodologies are promising as diagnostic and mechanistic effects of nanoparticles in cell cultures. Copyright © 2009 American Scientific Publishers All rights reserved.52192201Durán, N., Menck, C.F.M., Chromobacterium violaceum: A review of pharmacological and industrial perspectives (2001) Crit. Rev. Microbiol., 27, p. 201Melo, P.S., Justo, G.Z., De Azevedo, M.B.M., Durán, N., Haun, M., Violacein and its complexes induce apoptosis and differentiation in HL60 cells (2003) Toxicology, 186, p. 217Dessaux, Y., Elmerich, C., Faure, D., Violacein: A molecule of biological interest originating from the soil-borne bacterium Chromobacterium violaceum (2004) La Revue de Médecine Interne, 25, p. 659Saraiva, V.S., Marshall, J.C., Cools-Lartigue, J., Burnier, M.N., Cytotoxic effects of violacein in human uveal melanoma cell lines (2004) Melanoma Res., 14, p. 421Durán, N., Justo, G.Z., Ferreira, C.V., Melo, P.S., Cordi, L., Martins, D., Violacein: Properties and biological activities (2007) Biotechnol. Appl. Biochem., 48, p. 127Shenoy, D.B., Amiji, M.M., Poly(ethylene oxide)-modified poly(ε-caprolactone) nanoparticles for targeted delivery of tamoxifen in breast cancer (2005) Int. J. Pharm., 293, p. 261Rao, G.C., Kumar, M.S., Mathivanan, N., Rao, M.E., Nanosuspensions at the most promising approach in nanoparticulate drug delivery systems (2004) Pharmazie, 59, p. 5Jin, S., Ye, K.M., Nanoparticle-mediated drug delivery and gene therapy (2007) Biotechnol. Progr., 23, p. 32Kabanov, A.V., Batrakova, E.V., Miller, D.W., Pluronic block copolymers as modulators of drug efflux transporter activity in the blood-brain barrier (2003) Advan. Drug Deliv. Rev., 55, p. 151Minko, T., Batrakova, E.V., Li, S., Li, Y.L., Pakunlu, T.I., Alakhov, V.Y., Kabanov, A.V., Pluronic block copolymers alter apoptotic signal transduction of doxorubicin in drug-resistant cancer cells (2005) J. Control. Release, 105, p. 269Rapoport, N., Marin, A.P., Timoshin, A.A., Effect of a polymeric surfactant on electron transport in HL60 cells (2000) Arch. Biochem. Biophys., 384, p. 100Kohli, E., Han, H.Y., Zeman, A.D., Vinogradov, S.V., Formulations of biodegradable Nanogel carriers with 5′- triphosphates of nucleoside analogs that display a reduced cytotoxicity and enhanced drug activity (2007) J. Control. Release, 121, p. 19Uzunoglu, S., Uslu, R., Tobu, M., Saydam, G., Terzioglu, E., Buyukkececi, F., Omay, S.B., Augmentation of methylprednisolone-induced differentiation of myeloid leukemia cells by serine/threonine protein phosphatase inhibitors (1999) Leukaemia Res., 23, p. 507Anazetti, M.C., Melo, P.S., Durán, N., Haun, M., Comparative cytotoxicity of dimethylamide-crotonin in the promyelocytic leukemia cell line (HL60) and human peripheral blood mononuclear cells (2003) Toxicology, 188, p. 261Redmond, K.M., Wilson, T.R., Johnston, P.G., Longley, D.B., Resistance mechanisms to cancer chemotherapy (2008) Frontiers Biosci., 13, p. 5138Melet, A., Song, K., Bucur, O., Jagani, Z., Grassian, A.R., Khosravi-Far, R., Apoptotic pathways in tumor progression and therapy (2008) Advan. Exper. Med. Biol., 615, p. 47Debatin, K.M., Activation of apoptosis pathways by anticancer treatment (2000) Toxicol. Lett., 112, p. 41Inayat-Hussain, S.H., Osman, A.B., Din, L.B., Taniguchi, N., Altholactone, a novel styryl-lactone induces apoptosis via oxidative stress in human HL60 leukemia cells (2002) Toxicol. Lett., 131, p. 153Kim, R., Emi, M., Tanabe, K., The role of apoptosis in câncer cell survival and therapeutic outcome (2006) Cancer Biol. Ther., 30, p. 5Anuradha, C.D., Kanno, S., Hirano, S., Oxidative damage to mitochondria is a preliminary step to caspase-3 activation in fluoride-induced apoptosis in HL60 cells (2001) Free Radic. Biol. Med., 31, p. 367Stoetzer, O.J., Progrebniak, A., Pelka-Fleischer, R., Hasmann, M., Hiddemann, W., Nuessler, V., Modulation of apoptosis by mitochondrial uncouplers: Apoptosis-delying features despite intrinsic cytotoxicity (2002) Biochem. Pharmacol., 63, p. 471Ujihara, M., Nomura, K., Yamada, O., Deura, H., Establishment of a stable HL60 subline having the potential for monocytic differentiation using granulocyte-macrophage colony-stimulating factor: Possible use for the study of monocytic differentiation and oxidative stress (1998) Atherosclerosis, 139, p. 301Sokoloski, J.A., Sartorelli, A.C., Induction of the differentiation of HL60 promyelocytic leukemia cells by nonsteroidal anti-inflammatory agents in combination with low levels of vitamin D 3 (1997) Leukemia. Res., 22, p. 153Wyllie, A.H., Kerr, J.F.K., Currie, A.R., Cell Death: The significance of apoptosis (1980) Int. Rev. Cytol., 68, p. 251Israels, L.G., Israels, E.D., Apoptosis (1999) Steam Cells, 17, p. 306Kohroki, J., Norio, M.A., Tanaka, T., Itoh, N., Inada, A., Tanaka, K., Induction of differentiation and apoptosis by dithizone in human myeloid leukemia cell lines (1998) Leukemia Res., 22, p. 405Minko, T., Kopecková, P., Kopecek, J., Preliminary evaluation of caspases-dependent apoptosis signaling pathways of free and HPMA copolymer-bound doxorubicin in human ovarian carcinoma cells (2001) J. Control. Release, 71, p. 227Minko, T., Pakunlu, R.I., Wang, Y., Khandar, J.J., Saad, M., New generation of liposomal drugs for cancer (2006) Anticancer Agents Med. Chem., 6, p. 537Kodach, L.L., Bos, C.L., Durán, N., Peppelenbosch, M.P., Ferreira, C.V., Hardwick, J.C., Violacein synegistically increases 5-fluorouracil cytotoxicity, induces apoptosis and inhibits Akt-mediated signal transduction in humancolorectal cancer cells (2006) Carcinogenesis, 27, p. 508De Carvalho, D.D., Costa, F.T.M., Durán, N., Haun, M., Cytotoxic activity of violacein in human colon cancer cells (2006) Toxicol. in Vitro, 20, p. 1514Rettori, D., Durán, N., Production, extraction and purification of violacein: An antibiotic produced by Chromobacterium violaceum (1998) World J. Microbiol. Biotechnol., 14, p. 685Ferdous, A.J., Stembridge, N.Y., Singh, M., Role of monensin PLGA polymer nanoparticles and liposomes as potentiator of ricin a immunotoxins in vitro (1998) J. Control. Release, 50, p. 71Denizot, F., Lang, R., Rapid colorimetric assay for cell growth and survival, modifications to the tetrazolium dye procedure giving improved sensitivity and reliability (1986) J. Immunol. Methods, 89, p. 271Schneider, W.C., Hogeboom, G.H., Intracellular distribution of enzymes. V. Further studies of cytochrome c in rat liver homogenates (1950) J. Biol. Chem., 183, p. 123Anazetti, M.C., Melo, P.S., Durán, N., Haun, M., Dehydrocrotonin and its derivative, dimethylamide-crotonin induce apoptosis with lipid peroxidation and activation of caspases-2, -6 and -9 in human leukemic cells HL60 (2004) Toxicology, 203, p. 123Araragi, S., Kondoh, M., Kawase, M., Saito, S., Higashimoto, M., Sato, M., Mercuric chloride induces apoptosis via a mitochondrial-dependent pathway in human leukemia cells (2003) Toxicology, 184, p. 1Fillon, S., Lang, F., Jendrossek, V., Pseudomonas aeruginosa triggered apoptosis of human epithelial cells depends on the temperature during infection (2002) Cell Physiol. Biochem., 12, p. 207Melo, P.S., Maria, S.S., Vidal, B.C., Haun, M., Durán, N., Violacein cytotoxicity and induction of apoptosis in V79 cells (2000) In Vitro Cell. Develop. Biol.-Animal, 36, p. 539Pailard, F., Finot, F., Mouche, I., Prenez, A., Vericat, J.A., Use of primary cultures of rat hepatocytes to predict toxicity in the early development of new chemical entities (1999) Toxicol. in Vitro, 13, p. 693Mosmann, T., Rapid colorimetric assay for cellular growth and survival: Application to proliferation and cytotoxicity assay (1983) J. Immunol. Methods, 65, p. 55Freire, A.C.G., Aoyama, H., Haun, M., Ferreira, C.V., Relationship between phosphatase inhibitors, okadaic acid and pervanadate, on human myeloid leukaemia cell line (2003) J. Enzyme Inhib. Med. Chem., 18, p. 425Mehar, A., Macanas-Pirard, P., Mizokami, A., Takahashi, Y., Kass, G.E.N., Coley, H.M., The effects of cyclooxygenase-2 expression in prostate cancer cells: Modulation of response to cytotoxic agents (2008) J. Pharmacol. Exper. Ther., 324, p. 1181Rossi, D., Gaidano, G., Messengers of cell death: Apoptotic signalling in health and disease (2003) Haematologica, 88, p. 212Lee, J.Y., Hwang, W.I., Lim, S.T., Antioxidant and anticancer activities of organic extracts from Platycodon grandiflorum A. de Candolle roots (2004) J. Ethnopharmacol., 93, p. 409Facompré, M., Wattez, N., Kluza, J., Lansiaux, A., Bailly, C., Relationship between cell cycle changes and variations of the mitochondrial membrane potential induced by etoposide (2000) Mol. Cell Biol. Re. Comm., 4, p. 37Greenebaum, B., Blossfield, K., Hannig, J., Carrillo, C.S., Beckett, M.A., Weichselbaum, R.R., Lee, R.C., Poloxamer 188 prevents acute necrosis of adult skeletal muscle cells following high-dose irradiation (2004) Burns, 30, p. 539Luo, J., Borgens, R., Shi, R., Polyethylene glycol immediately repairs neuronal membranes and inhibits free radical production after acute spinal cord injury (2002) J. Neurochem., 83, p. 471Marks, J.D., Pan, C., Bushell, R., Cromie, W., Lee, R.C., Amphiphilic, tri-block copolymers provide potent, membrane-targeted neuroprotection (2001) FASEB J., 15, p. 1107Maskarinec, S.A., Lee, K.Y.C., Comparative study of poloxamer insertion into lipid monolayers (1809) Langmuir, 19, p. 2003Tharmalingam, T., Ghebeth, H., Wuerz, T., Butler, M., Pluronic enhances the robustness and reduces the cell attachment of mammalian cells (2008) Mol. Biotechnol., 39, p. 16
Diterpenes From Xylopia Langsdorffiana Inhibit Cell Growth And Induce Differentiation In Human Leukemia Cells
Two new diterpenes were isolated from stems and leaves of Xylopia langsdorffiana, entatisane-7α,16α-diol (xylodiol) and ent-7α-acetoxytrachyloban-18-oic acid (trachylobane), along with the known 8(17),12E,14-labdatrien-18-oic acid (labdane). We investigated their antitumour effects on HL60, U937 and K562 human leukemia cell lines. We found that xylodiol was the most potent diterpene in inhibiting cell proliferation of HL60, U937 and K562 cells, with mean IC 50 values of 90, 80 and 50 μM, respectively. Based on the nitroblue tetrazolium (NBT) reduction assay, all the diterpenes were found to induce terminal differentiation in HL60 and K562 cells, with xylodiol being the most effective. NBT reduction was increased by almost 120% after 12 h exposure of HL60 cells to xylodiol at a concentration lower than the IC 50 (50 μM). Thus, xylodiol inhibited human leukemia cell growth in vitro partly by inducing cell differentiation, and merits further studies to examine its mechanism of action as a potential antitumoural agent. © 2009 Verlag der Zeitschrift für Naturforschung, Tübingen.649-10650656Denizot, F., Lang, R., Rapid colorimetric assay for cell growth and survival, modifications to the tetrazolium dye procedure giving improved sensitivity and reliability (1986) J. Immunol. Methods, 89, pp. 271-277Dimas, K., Demetzos, C., Vãos, V., Ioannidis, P., Trangas, T., Labdane type diterpenes down-regulate the expression of c-Myc protein, but not of Bcl2, in human leukemia T-cells undergoing apoptosis (2001) Leukemia Res, 25, pp. 449-454Faulkner, D.F., Lebby, V., Waterman, P.G., Further diterpenes from stem bark of Xylopia aethiopica (1985) Planta Med, 4, pp. 354-355Graikou, K., Aligiannis, N., Skaltsounis, A.L., Chinou, I., Michel, S., Tillequin, F., Litaudon, M., New diterpenes from Croton insularis (2004) J. Nat. Prod, 67, pp. 685-688Jiang, H., Lin, J., Fisher, P.B., A molecular definition of terminal cell differentiation in human melanoma cells (1994) Mol. Cell Differ, 2, pp. 221-239Kohroki, J., Muto, N., Tanaka, T., Itoh, N., Inada, A., Tanaka, K., Induction of differentiation and apoptosis by dithizone in human myeloid leukemia cell lines (1998) Leukemia Res, 22, pp. 405-412Kondoh, M., Suzuki, I., Sato, M., Nagashima, F., Simizu, S., Harada, M., Fujii, M., Watanabe, Y., Kaurene diterpene induces apoptosis in human leukemia cells partly through a caspase-8-dependent pathway (2004) J. Pharmacol. Exp. Ther, 311, pp. 115-122Leszczyniecka, M., Roberts, T., Dent, P., Grant, S., Fisher, P.B., Differentiation therapy of human cancer: Basic science and clinical applications (2001) Pharmacol. Ther, 90, pp. 105-156Li, W.-X., Cui, C.-B., Cai, B., Yao, X.-S., Labdane-type diterpenes as new cell cycle inhibitors and apoptosis inducers from Vitex trifolia L (2005) J. Asian Nat. Prod. Res, 7, pp. 95-105Maas, P.J.M., Kamer, H.M.V., Junikka, L., Silva, R.M., Rainer, H., Annonnaceae from centraleastern Brazil (2001) Rodriguésia, 80, pp. 65-98Morais, M.P.L., Roque, N.F., Diterpenes from the fruits of Xylopia aromatica (1988) Phytochemistry, 27, pp. 3205-3208Newman, D.J., Cragg, G.M., Snader, K.M., Natural products as sources of new drugs over the period 1981-2002 (2003) J. Nat. Prod, 66, pp. 1022-1037Oliveira, A.P., Furtado, F.F., Silva, M.S., Tavares, J.F., Mafra, R.A., Araújo, D.A.M., Cruz, J.S., Medeiros, I.A., Calcium channel blockade as a target for the cardiovascular effects induced by the 8(17),12E,14-labdatrien-18-oic acid (labdane-302) (2006) Vasc. Pharmacol, 44, pp. 338-344Perry, N.B., Burgess, E.J., Baek, S.-H., Weavers, R.T., The first atisane diterpenoids from a liverwort: Polyols from Lepidolaena clavigera (2001) Org. Lett, 3, pp. 4243-4245Sun, I.C., Kashiwada, Y., Morris-Natschke, S.L., Lee, K.H., Plant-derived terpenoids and analogues as anti-HIV agents (2003) Curr. Top. Med. Chem, 3, pp. 155-169Tavares, J.F., Queiroga, K.F., Silva, M.V.B., Diniz, M.F.F.M., Barbosa-Filho, J.M., Da-Cunha, E.V.L., Simone, C.A., Silva, M.S., Ent-Trachylobane diterpenoids from Xylopia langsdorffiana (2006) J. Nat. Prod, 69, pp. 960-962Tavares, J.F., Silva, M.V.B., Queiroga, K.F., Diniz, M.F.F.M., Barbosa-Filho, J.M., Haun, M., Melo, P.S., Silva, M.S., Xylodiol, a new atisane diterpenoid from Xylopia langsdorffiana St.-Hil. & Tul. (Annonaceae) (2007) Z. Naturforsch, 62 c, pp. 742-74