Luciana K. Kohn

Cytotoxicity of tamoxifen in normal and tumoral cell lines and its ability to induce cellular transformation in vitro

Tamoxifen (TAM) is a non‐steroidal anti‐estrogen used to treat patients with estrogen receptor‐positive breast cancer and as a chemopreventive agent against breast cancer in high risk pre‐ and post‐menopausal women. However, recent studies have shown that tamoxifen causes endometrial and hepatic cancer. In this study, we examined the effects of tamoxifen (5, 10, 25 and 50 μM) on the growth and proliferation of nine tumoral cell lines (UACC62, MCF‐7, NCI‐460, K‐562, OVCAR‐03, PC‐03, HT‐29, 786‐0, NCI‐ADR) and non‐tumoral cell lines (3T3, V79, MDCK, VERO). Chinese hamster lung fibroblasts (V79) were the most sensitive lineage to tamoxifen, with 21.6% of the cells showing apoptosis at 50 μM TAM. Microscopic analysis showed that, the cellular transformation caused by TAM in V79 cells was similar to that seen with 7,12‐dimethylbenz(a)anthracene, thus indicating the carcinogenicity of TAM.

Antiproliferative effect of benzophenones and their influence on cathepsin activity.

The antiproliferative activity of two prenylated benzophenones isolated from Rheedia brasiliensis, the triprenylated garciniaphenone and the tetraprenylated benzophenone 7‐epiclusianone, was investigated against human cancer cell lines. The antiproliferative activity on melanoma (UACC‐62), breast (MCF‐7), drug‐resistant breast (NCI‐ADR), lung/non‐small cells (NCI460), ovarian (OVCAR 03), prostate (PC03), kidney (786‐0), lung (NCI‐460) and tongue (CRL‐1624 and CRL‐1623) cancer cells was determined using spectrophotometric quantification of the cellular protein content. The effect of these benzophenones on the activity of cathepsins B and G was also investigated. Garciniaphenone displayed cytostatic activity in all cell lines, whereas 7‐epiclusianone showed a dose‐dependent cytotoxic effect. The IC50 values for cell proliferation revealed that 7‐epiclusianone is more active than garciniaphenone against most of the cell lines. Furthermore, the antiproliferative effects demonstrated by garciniaphenone and 7‐epiclusianone were related to their cathepsin inhibiting properties. In conclusion, 7‐epiclusianone is a promising naturally occurring agent which displays multiple inhibitory effects which may be working in concert to inhibit cancer cell proliferation in vitro. The putative pathway by which 7‐epiclusianone affects cancer cell development may involve cathepsin inhibition. Copyright

New antitumoral agents I: In vitro anticancer activity and in vivo acute toxicity of synthetic 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadien-3-one and derivatives

This paper describes a new method for the preparation of 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadien-3-one 1 and its derivatives 2-5. This set of synthetic compounds exhibited high antitumoral activities regarding in vitro screening against several human tumor cell lines as lung carcinoma NCI-460, melanoma UACC-62, breast MCF-7, colon HT-29, renal 786-O, ovarian OVCAR-03 and ovarian expressing the resistance phenotype for adriamycin NCI-ADR/RES, prostate PC-3, and leukemia K-562. Compounds were also tested against murine tumor cell line B16F10 melanoma and lymphocytic leukemia L1210 as well as to their effect toward normal macrophages. Specific activity against colon cancer cells HT-29 was observed for all tested compounds and suggests further studies with models of colon cancer. Compounds 1, 2, and 4 showed significant cytotoxic activity with IC(50) values 2.3 microM for all human cancer cell lines. Intraperitoneal acute administration of compound 1 and 2 showed very low toxicity rate.

Antiviral Activity of Bacillus sp. Isolated from the Marine Sponge Petromica citrina against Bovine Viral Diarrhea Virus, a Surrogate Model of the Hepatitis C Virus

The Hepatitis C virus causes chronic infections in humans, which can develop to liver cirrhosis and hepatocellular carcinoma. The Bovine viral diarrhea virus is used as a surrogate model for antiviral assays for the HCV. From marine invertebrates and microorganisms isolated from them, extracts were prepared for assessment of their possible antiviral activity. Of the 128 tested, 2 were considered active and 1 was considered promising. The best result was obtained from the extracts produced from the Bacillus sp. isolated from the sponge Petromica citrina. The extracts 555 (500 µg/mL, SI>18) and 584 (150 µg/mL, SI 27) showed a percentage of protection of 98% against BVDV, and the extract 616, 90% of protection. All of them showed activity during the viral adsorption. Thus, various substances are active on these studied organisms and may lead to the development of drugs which ensure an alternative therapy for the treatment of hepatitis C.

A novel sunscreen agent having antimelanoma activity.

A novel series of eight dibenzoylmethane derivatives having both sunscreen and cytotoxic activity has been obtained by derivatizing commercial dibenzoyl methanes. Four human cancer cell lines (MCF 7 (breast), NCI ADR (breast expressing the multidrug resistance phenotype), NCI 460 (lung) and UACC 62 (melanoma)) were used for the cytotoxic assay. Eight among the 19 dibenzoylmethane derivatives showed cytotoxicity against these four cell lines. Absorption spectroscopies revealed that these compounds can be used as sunscreens against UV radiation.

Asymmetric total synthesis and antiproliferative activity of goniothalamin oxide isomers

Goniothalamin oxide (1) is a styryl lactone which was isolated from bark and leaves of several Goniothalamus species. This natural product has some interesting biological properties such as larvicidal and tripanocidal activities. However, no studies on the antiproliferative profile of goniothalamin oxide (1) and its stereoisomers have been reported yet. Here, goniothalamin epoxide (1), isogoniothalamin epoxide (2) and their enantiomers were prepared via epoxidation of (R)-and (S)-goniothalamin (4). A 3:2 molar ratio in favor of goniothalamin oxide (1) and ent-1 was observed from (R)- and (S)-4, respectively, when 3-chloroperbenzoic acid (mCPBA) was employed while an increase to 6:1 molar ratio was achieved with (S,S)-Jacobsens catalyst. Antiproliferative activity of these epoxides revealed that ent-isogoniothalamin oxide (ent-2) was the most active against the eight cancer cell lines studied. These results indicate that 6S, 7R and 8R absolute configurations are beneficial for the activity of these epoxides.

Synthesis and antiproliferative activity of novel limonene derivatives with a substituted thiourea moiety

A series of R-(+)-limonene derivatives bearing a substituted thiourea moiety (3-13) and five S-methyl analogs (14-18) were synthesized and evaluated for their in vitro antiproliferative activity against human cancer cell lines. Compounds bearing aromatic substituents (3-6) exhibit cytotastic activity in the full panel of cell lines tested, with GI50 values in the range of 2.5 to 24 µmol L-1. Compounds 3, 10, 12 and 16 were the most active with GI50 values in the range of 0.41 to 3.0 µmol L-1, against different cell lines.

In vitro antiviral activity of Brazilian plants (Maytenus ilicifolia and Aniba rosaeodora) against bovine herpesvirus type 5 and avian metapneumovirus

Context: Medicinal plants are well known for their use in traditional folk medicine as treatments for many diseases including infectious diseases. Objective: Six Brazilian medicinal plant species were subjected to an antiviral screening bioassay to investigate and evaluate their biological activities against five viruses: bovine herpesvirus type 5 (BHV-5), avian metapneumovirus (aMPV), murine hepatitis virus type 3, porcine parvovirus and bovine respiratory syncytial virus. Materials and methods: The antiviral activity was determined by a titration technique that depends on the ability of plant extract dilutions (25 or 2.5 µg/mL) to inhibit the viral induced cytopathic effect and the extracts’ inhibition percentage (IP). Results: Two medicinal plant species showed potential antiviral activity. The Aniba rosaeodora Ducke (Lauraceae) extract had the best results, with 90% inhibition of viral growth at 2.5 µg/mL when the extract was added during the replication period of the aMPV infection cycle. The Maytenus ilicifolia (Schrad.) Planch. (Celastraceae) extracts at a concentration of 2.5 µg/mL exhibited antiviral activity during the attachment phase of BHV-5 (IP = 100%). Discussion and conclusion: The biomonitored fractionation of the active extracts from M. ilicifolia and A. rosaeodora could be a potential tool for identifying their active compounds and determining the exact mechanism of action.

Antiproliferative activity of Luehea candicans Mart. et Zucc. (Tiliaceae)

Luehea candicans Mart. et Zucc. (Tiliaceae) is known as ‘açoita-cavalo’ and is one of the most important medicinal plants found in the Brazilian cerrado. The crude methanolic extracts of the branches and leaves and their fractions were evaluated using the following cancer cell lines: MCF-7 (breast), NCI-ADR (breast expressing the multidrug resistance phenotype), NCI-460 (lung), UACC-62 (melanoma), 786-0 (kidney), OVCAR (ovarian), PCO-3 (prostate), HT-29 (colon) and K-562 (leukaemia). The crude methanolic extracts from the branches (B) and leaves (L) were able to inhibit the growth of the K-562 and 786-0 cell lines in a dose-dependent manner, with GI50 values of 8.1 and 5.4 µg mL−1, respectively. The hexane (L1), chloroform (L2) and methanol (L4) fractions derived from extract L showed a high selectivity and pronounced cytostatic activity against 786-0 (GI50 ∼ 40 µg mL−1). A significant amount of lupeol was isolated from fraction L2. The chloroform (B2) and methanol (B3) fractions derived from extract (B) exhibited less selectivity, showing the highest cytostatic activity against K-562, NCI-ADR, OVCAR, MCF-7 and NCI-460 cells, with GI50 values between 27 and 40 µg mL−1. Lupeol, betulin, a mixture of steroids, (−)-epicatechin, vitexin and liriodendrin were isolated from these active fractions.

Photoinactivation of different human tumor cell lines and sheep red blood cells in vitro by liposome-bound Zn(II) Phthalocyanine: Effects of cholesterol.

The in vitro photoinactivation of human tumor cell lines and sheep red blood cells (SRBC) by Zinc (II) Phthalocyanine (ZnPc) was investigated using unilamellar liposome (LUV) as delivery system, in the presence and absence of cholesterol (CHOL) in the formulation. The presence of CHOL improves the stability of the system showing to be essential for the photodynamic action of ZnPc. LUVs prepared without CHOL did not present any antiproliferative effects neither induced significant photohaemolysis. The presence of ZnPc in the culture medium caused total cell growth inhibition (TGI) only at concentrations higher than 250 micromol dm(-3). For ZnPc in LUV/CHOL (mass ratio=3:1), the mean TGI values for almost all studied cells were around 80 micromol dm(-3), and 14 micromol dm(-3) for human ovarian carcinoma (NIH: OVCAR-3) cells. The cytoplasmic components of OVCAR-3 and SRBC when irradiated in presence of ZnPc in LUV/CHOL were completely destroyed, culminating in cell swelling, lysis and death by necrosis.