Assessment of the mutagenic, antimutagenic and cytotoxic activities of ethanolic extract of araticum (Annona crassiflora Mart. 1841) by micronucleus test in mice.

A typical Brazilian plant, araticum (Annona crassiflora Mart.), is widely used in humans as therapeutic medicine to treat several diseases such as diarrhea, rheumatism and syphilis. It contains acetogenins which present cytotoxic, antitumogenic, and antiparasitic properties. In this study, mutagenic, antimutagenic and cytotoxic effects of araticum leaves ethanolic extract were evaluated by micronucleus test in mice. To evaluate the mutagenic activity, animals were treated with ethanolic extract of araticum (EEA) using 10, 20, 50, 100 and 160 mg.kg(-1). For all doses, micronucleated polychromatic erythrocytes (MNPCE) frequency was evaluated at 24, 48 and 72 hours after treatment. To evaluate the antimutagenic activity, animals were treated with 10, 20, 50 and 100 mg.kg(-1) of EEA and 4 mg.kg(-1) of MMC simultaneously. The frequency of MNPCE was evaluated 36 hours after exposure. Cytotoxicity was evaluated by the polychromatic and normochromatic erythrocytes ratio (PCE/NCE). In the mutagenicity assessment, all doses of EEA resulted in no significant increase of MNPCE (P > 0.05), compared to solvent- control group. Regarding administration time, no significant difference among three evaluation periods was observed (P > 0.05). Such results indicate that EEA did not exert mutagenic activity. Cytotoxicity was evident in doses of 50, 100 and 160 mg.kg(-1) at 24 and 48 hours after exposure. Concerning antimutagenicity, except the 10 mg.kg(-1) co-administered with 4 mg/kg of MMC, all doses reduced significantly the frequency of MNPCE compared to the positive control group (P < 0.05). These results, therefore, indicate an antimutagenic activity of the EEA. Cytotoxicity was significantly increased (P < 0.01) at 100 mg.kg(-1) EEA doses co-administered with 4 mg.kg(-1) of MMC.

Absence of antimutagenicity of Cochlospermum regium (Mart. and Schr.) Pilger 1924 by micronucleus test in mice.

Cochlospermum regium (Mart. and Schr.) Pilger, popularly known as "algodãozinho do campo", is a medicinal plant that grows in the Cerrado of Brazil. This plant has been used in traditional medicine against various diseases such as leucorrhoea, gastritis and ulcers. It has also been effective in treating skin problems like pimples, boils and blotches. In the present study, the in vivo antimutagenicity of aqueous extract of C. regium was evaluated. The Micronucleus Test was performed in polychromatic erythrocytes from Swiss male mice treated with one of the four doses of extract of the plant (19, 38, 76 and 114 mg.kg(-1) body weight), administered by intraperitonial injection (i.p.) simultaneously with cyclophosphamide (24 mg.kg(-1) b.w.) or mitomycin C (4 mg.kg(-1) b.w.). The cytotoxicity was evaluated by polychromatic and normochromatic erythrocytes ratio (PCE/NCE). The results showed no significant reduction of the micronucleated polychromatic erythrocytes frequency (P > 0.05). In conclusion, the data indicate that C. regium roots aqueous extract, for the conditions used, did not exhibit the antimutagenic effect.

Assessment of the mutagenic, antimutagenic and cytotoxic activities of ethanolic extract of araticum (Annona crassiflora Mart. 1841) by micronucleus test in mice

A typical Brazilian plant, araticum (Annona crassiflora Mart.), is widely used in humans as therapeutic medicine to treat several diseases such as diarrhea, rheumatism and syphilis. It contains acetogenins which present cytotoxic, antitumogenic, and antiparasitic properties. In this study, mutagenic, antimutagenic and cytotoxic effects of araticum leaves ethanolic extract were evaluated by micronucleus test in mice. To evaluate the mutagenic activity, animals were treated with ethanolic extract of araticum (EEA) using 10, 20, 50, 100 and 160 mg.kg-1. For all doses, micronucleated polychromatic erythrocytes (MNPCE) frequency was evaluated at 24, 48 and 72 hours after treatment. To evaluate the antimutagenic activity, animals were treated with 10, 20, 50 and 100 mg.kg-1 of EEA and 4 mg.kg-1 of MMC simultaneously. The frequency of MNPCE was evaluated 36 hours after exposure. Cytotoxicity was evaluated by the polychromatic and normochromatic erythrocytes ratio (PCE/NCE). In the mutagenicity assessment, all doses of EEA resulted in no significant increase of MNPCE (P > 0.05), compared to solvent- control group. Regarding administration time, no significant difference among three evaluation periods was observed (P > 0.05). Such results indicate that EEA did not exert mutagenic activity. Cytotoxicity was evident in doses of 50, 100 and 160 mg.kg-1 at 24 and 48 hours after exposure. Concerning antimutagenicity, except the 10 mg.kg-1 co-administered with 4 mg/kg of MMC, all doses reduced significantly the frequency of MNPCE compared to the positive control group (P < 0.05). These results, therefore, indicate an antimutagenic activity of the EEA. Cytotoxicity was significantly increased (P < 0.01) at 100 mg.kg-1 EEA doses co-administered with 4 mg.kg-1 of MMC.

O araticum (Annona crassiflora Mart.) é uma planta tipicamente brasileira, largamente utilizada em humanos como remédio para o tratamento de diversas doenças como diarréia, reumatismo e sífilis. Esta planta contém acetogeninas que apresentam propriedades citotóxica, antitumorigênica e antiparasitária. Neste estudo, foram avaliados os possíveis efeitos mutagênico, antimutagênico e citotóxico do extrato etanólico de folhas de araticum, pelo teste de micronúcleos em camundongos. Para a investigação da atividade mutagênica, os animais foram tratados com o extrato etanólico de araticum (EEA) utilizando 10, 20, 50, 100 e 160 mg.kg-1. Para todas as doses, as freqüências de eritrócidos policromáticos micronucleados (MNPCE) foram avaliadas em 24, 48 e 72 horas após o tratamento. Para a investigação da atividade antimutagênica, os animais foram tratados com 10, 20, 50 e 100 mg.kg-1 de EEA simultaneamente com 4 mg.kg-1 de MMC. A freqüência de MNPCE foi avaliada após 36 horas de exposição. A citotoxicidade foi avaliada pela razão de eritrócitos policromáticos e normocromáticos (PCE/NCE). Na avaliação da mutagenicidade, todas as doses de EEA não aumentaram significativamente o número de MNPCE (P > 0,05), comparativamente as do grupo solvente-controle. Em relação ao tempo de administração, não foi constatada diferença significativa entre os 3 períodos avaliados (P > 0,05). Esses resultados indicam que o EEA não exerceu atividade mutagênica.A citotoxicidade foi evidente nas doses de 50, 100 e 160 mg.kg-1 em 24 e 48 horas depois da exposição. Em relação à antimutagenicidade, exceto para a dose de 10 mg.kg-1 co-administrada com 4 mg.kg-1 de MMC, todas reduziram significativamente a freqüência de MNPCE, comparativamente as do grupo controle positivo (P < 0,05). Esses resultados, portanto, indicam uma atividade antimutagênica do EEA. A citotoxicidade foi significativamente aumentada (P < 0,01) na dose de 100 mg.kg-1 de EEA co-administrada com 4 mg.kg-1 de MMC.

Absence of antimutagenicity of Cochlospermum regium (Mart. and Schr.) Pilger 1924 by micronucleus test in mice

Cochlospermum regium (Mart. and Schr.) Pilger, popularly known as "algodãozinho do campo", is a medicinal plant that grows in the Cerrado of Brazil. This plant has been used in traditional medicine against various diseases such as leucorrhoea, gastritis and ulcers. It has also been effective in treating skin problems like pimples, boils and blotches. In the present study, the in vivo antimutagenicity of aqueous extract of C. regium was evaluated. The Micronucleus Test was performed in polychromatic erythrocytes from Swiss male mice treated with one of the four doses of extract of the plant (19, 38, 76 and 114 mg.kg-1 body weight), administered by intraperitonial injection (i.p.) simultaneously with cyclophosphamide (24 mg.kg-1 b.w.) or mitomycin C (4 mg.kg-1 b.w.). The cytotoxicity was evaluated by polychromatic and normochromatic erythrocytes ratio (PCE/NCE). The results showed no significant reduction of the micronucleated polychromatic erythrocytes frequency (P > 0.05). In conclusion, the data indicate that C. regium roots aqueous extract, for the conditions used, did not exhibit the antimutagenic effect.

Cochlospermum regium (Mart. & Schr.) Pilger, conhecido popularmente como "algodãozinho-do-campo", é uma planta medicinal que cresce no Cerrado brasileiro. Esta planta tem sido utilizada na medicina tradicional contra várias doenças como leucorréia, gastrites e úlceras. Esta também tem se mostrado efetiva no tratamento de doenças de pele como espinhas, furúnculos e manchas. No presente estudo, foi avaliada a antimutagenicidade do extrato aquoso de C. regium pelo Teste do Micronúcleo in vivo. Este ensaio foi realizado em eritrócitos policromáticos de camundongos machos Swiss tratados com quatro concentrações diferentes do extrato da planta (19, 38, 76 e 114 mg.kg-1 por peso corpóreo), administrado por injeção intraperitonial (i.p.) simultaneamente com ciclofosfamida (24 mg.kg-1 p.c.) ou mitomicina C (4 mg.kg-1 p.c.). A citotoxicidade foi avaliada pela razão eritrócitos policromáticos e normocromáticos (PCE/NCE). Os resultados obtidos não mostraram redução significativa da freqüência de eritrócitos policromáticos micronucleados (P > 0,05). Em conclusão, os resultados indicam que o extrato aquoso de raiz de C. regium, para as condições utilizadas, não exibiu efeito antimutagênico.

Antiproliferative activity of Pterodon pubescens Benth. seed oil and its active principle on human melanoma cells.

On a preliminary screening, relevant in vitro antiproliferative activity was observed to the crude ethanolic extract of Pterodon pubescens seed oil against the human melanoma cell line SK MEL 37. The diethyl ether fraction from crude ethanolic extract which exhibited stronger activity was submitted to fractionation by gradient elution with hexane/ethyl acetate. Subfraction A, eluted by hexane/ethyl acetate (80:20), was essentially the most active between all the assayed subfractions with an IC(50) of 37microg/ml calculated by the MTT colorimetric method. At this concentration, subfraction A caused morphological features and internucleosomal DNA fragmentation pattern of apoptosis. Through chromatographic separation, the furane diterpene 1 was isolated from this active subfraction and identified by spectral techniques. Compound 1 showed an IC(50) value of 32microM and fluorescence staining with DAPI revealed some typical nuclear changes which are characteristic of apoptosis. These findings support a role for diterpenoids vouacapan-type skeleton as a model to develop new anticancer agents.

The melanocortin-1 receptor carboxyl terminal pentapeptide is essential for MC1R function and expression on the cell surface.

The pigmentary actions of the melanocortins are mediated by the melanocortin-1 receptor (MC1R), a seven transmembrane domains receptor positively coupled to Gs and the cAMP cascade. In order to define the structure-function relationships of potentially relevant domains in MC1R, particularly its C-terminal cytosolic tail, we generated and analyzed several variants with C-terminal deletions, as well as point mutants in selected residues of the human MC1R. We show that the MC1R C-terminal pentapeptide is essential for proper receptor expression on the plasma membrane, and that residues Thr314, Cys315 and Trp317 are at least partially responsible for this effect.

Lipopolysaccharide and cytokines induce nitric oxide synthase and produce nitric oxide in cultured normal human melanocytes.

The role of nitric oxide in normal and pathological conditions of human skin is still poorly understood. In this study we have demonstrated by immunobloting the expression of an inducible nitric oxide synthase isoform (iNOS) in cultured normal human melanocytes treated with bacterial lipopolysaccharide, tumor necrosis factor-alpha and interferon-gamma. Nitric oxide was also detected in the culture medium and its formation was abolished upon treatment with N(G)-mono-methyl-L-arginine(L-NMMA), a competitive inhibitor of nitric oxide synthase. These results suggest that nitric oxide could led to autodestruction of melanocytes causing skin depigmentation. The therapeutic relevance of nitric oxide synthase inhibitors in treatment of vitiligo was suggested.

Recognition of melanoma cell antigens with antibodies present in sera from patients with vitiligo.

BACKGROUND: Patients with vitiligo show specific losses of integumentary melanocytes, probably due to autoimmunity against melanocytes. We attempted to determine the presence of antibodies against pigment cell antigens in the sera of vitiligo patients. METHODS: Detergent-solubilized human melanoma cells were submitted to electrophoretic separation and immunoblotted against serum samples obtained from 19 patients with vitiligo and from 20 age- and sex-matched healthy individuals. RESULTS: Eighty-nine per cent of patients with vitiligo had antibodies to one or more pigment cell antigens. Similar antibodies were detected in 20% of healthy individuals. Antigens of 165, 90, and 68 kDa were recognized by the antibodies present in sera from 11%, 26%, and 37% of vitiligo patients, respectively, and in none of the normal sera. All patients with familial vitiligo also had antibodies to these three proteins. CONCLUSIONS: Proteins of 165, 90, and 68 kDa are specifically recognized by antibodies present in the sera of vitiligo patients and in all patients with genetic vitiligo. Whether or not these proteins might be implicated in the destruction of melanocytes by the immune system in vitiligo remains to be evaluated.

Formation of cyclobutane thymine dimers from UVA photosensitization of pyridopsoralen monoadducted DNA.

The present report provides evidence that thymine dimerization can be UVA photosensitized at a tetranucleotide, 5'-TATT-3', by a 7-methyl-pyrido(3,4-c)psoralen monoadduct in DNA. The efficiency of the photoprocess depends on the tetranucleotide flanking sequences. These results demonstrate that one DNA lesion can originate the contiguous formation of a second type of lesion and emphasize the sequence-specific response to interaction of drugs with DNA. Results are related to the sensitivity of DNA to 1,10-phenanthroline-cuprous ion complex nucleolytic activity and discussed in terms of the major role of local deformability of DNA in interaction with ligands.

Selective DNA thymine dimerization during UVA irradiation in the presence of a saturated pyridopsoralen.

It has been recently shown that UVA (320-400 nm) irradiation of DNA in the presence of pyridopsoralens induces the formation of thymine cyclobutane dimers in addition to monoadducts. In this work, we measured the potency of a saturated pyridopsoralen to photosensitize DNA, despite its inability to covalently attach to DNA. First, from spectroscopic fluorescence measurements, we have shown that both analogs, saturated and unsaturated pyridopsoralens, namely 4',5'-dihydro-7-methyl-pyrido[3,4-c]psoralen (DH-MePyPs) and 7-methylpyrido[3,4-c]psoralen, exhibit a similar global affinity for DNA. Secondly, we demonstrated, by footprinting experiments, that exposure of a DNA sequence to 365 nm UV radiation in the presence of DH-MePyPs results in selective cyclobutane thymine dimerization. Thymines located in the immediate proximity of the 5'-TA-3' step are exclusively affected and the frequency of this photoprocess depends on flanking sequences. We thus probe a selective thymine dimer photosensitizer. Results are discussed in terms of drug affinity and physical properties of the helix at the binding site.

Detection of pyrimidine dimers and monoadducts induced by 7-methylpyrido(3,4-c) psoralen and UVA in Chinese hamster V79 cells by enzymatic cleavage and high-pressure liquid chromatography.

The photochemotherapeutically active psoralen derivative 7-methylpyrido(3,4-c) psoralen (MePyPs) has been recently shown to be able to photoinduce monoadducts of the C4-cycloaddition type as well as pyrimidine dimers in DNA in vitro. In the present study, we report on the induction of these two types of photolesions in mammalian cells in culture. The MePyPs photocycloadducts were quantified in V79 Chinese hamster cells after treatment with MePyPs plus UVA following enzymatic hydrolysis of the DNA by DNase I, S1 nuclease and acidic phosphatase treatments. Concomitantly induced pyrimidine dimers were determined by two methods, high-pressure liquid chromatography and alkaline gel electrophoresis after dimer-specific endonucleolytic cleavage. The results show that, in Chinese hamster cells treated with MePyPs plus UVA, the yield of pyrimidine dimers is approximately 5-10% that of MePyPs-DNA photocycloadducts. Because psoralen monoadditions to DNA alone are generally not considered as being very phototoxic, a synergistic interaction of monoadditions with pyrimidine dimers may be expected to occur in order to explain the high photobiological effectiveness of this psoralen derivative.

Interaction between enzyme-generated triplet carbonyls and molecules intercalated into DNA.

The phosphorescence from enzyme-generated and -protected triplet acetone is very efficiently quenched by dyes intercalated into DNA. The process is unlikely to be due to energy transfer and is tentatively ascribed to electron transfer occurring within the DNA helix complex with the acting enzyme. This quenching markedly protects DNA from breaks induced by triplet acetone. In the case of some barely emissive enzyme-generated triplet carbonyl species, it is possible to detect a weak emission resulting from the interaction with dye X DNA; this emission may be associated with back electron transfer.