Genotoxic effect of Physalis angulata L. (Solanaceae) extract on human lymphocytes treated in vitro

Physalis angulata L (Solanaceae) is a medicinal plant from North of Brazil, whose different extracts and infusions are commonly used in the popular medicine for the treatment of malaria, asthma, hepatitis, dermatitis and rheumatism. However, the genotoxic effects of P. angulata on human cells is not well known. The main purpose of the present study was to evaluate the in vitro genotoxic effects of aqueous extract of P. angulata using the comet assay and the micronucleus assay in human lymphocytes provided from 6 healthy donors. Treatments with P. angulata extracts were performed in vitro in order to access the extent of DNA damage. The comet assay has shown that treatments with P. angulata at 0.5, 1.0, 2.0, 3.0 and 6.0 microg/mL in culture medium were genotoxic. Lymphocytes treated with P. angulata at the concentrations of 3.0 and 6.0 microg/mL in culture medium showed a statistically significant increase in the frequency of micronucleus (p<0.05), however, the cytokinesis blocked proliferation index (CBPI) was not decreased after P. angulata treatment. In conclusion, the present work demonstrated the genotoxic effects of P. angulata extract on human lymphocytes in vitro.(AU)

Genotoxic effect of Physalis angulata L. (Solanaceae) extract on human lymphocytes treated in vitro

Physalis angulata L (Solanaceae) is a medicinal plant from North of Brazil, whose different extracts and infusions are commonly used in the popular medicine for the treatment of malaria, asthma, hepatitis, dermatitis and rheumatism. However, the genotoxic effects of P. angulata on human cells is not well known. The main purpose of the present study was to evaluate the in vitro genotoxic effects of aqueous extract of P. angulata using the comet assay and the micronucleus assay in human lymphocytes provided from 6 healthy donors. Treatments with P. angulata extracts were performed in vitro in order to access the extent of DNA damage. The comet assay has shown that treatments with P. angulata at 0.5, 1.0, 2.0, 3.0 and 6.0 microg/mL in culture medium were genotoxic. Lymphocytes treated with P. angulata at the concentrations of 3.0 and 6.0 microg/mL in culture medium showed a statistically significant increase in the frequency of micronucleus (p<0.05), however, the cytokinesis blocked proliferation index (CBPI) was not decreased after P. angulata treatment. In conclusion, the present work demonstrated the genotoxic effects of P. angulata extract on human lymphocytes in vitro.

Protective effect of thiourea, a hydroxyl-radical scavenger, on curcumin-induced chromosomal aberrations in an in vitro mammalian cell system.

Natural dietary antioxidants are extensively studied for their ability to protect cells from damage to DNA, protein, and lipids induced by antitumor agents or radiation that leads to the generation of free radical in normal cells in vivo and in vitro. Curcumin is a natural antioxidant known to possess therapeutic properties and has been reported to scavenge free radicals and to inhibit clastogenesis in mammalian cells. However, curcumin has been reported to induce a significant increase in the frequency of chromosomal aberrations in Chinese hamster ovary (CHO) cells. To investigate whether the clastogenic activity of curcumin in CHO cells in culture can be ascribed to a pro-oxidant behavior, mediated by free radical generation, experiments were carried out with the combination of curcumin (15 microg/ml) and thiourea (10, 20, or 40 microg/ml), a potent hydroxyl radical scavenger. The results showed that the clastogenic action of curcumin was statistically decreased in a dose-dependent manner in the presence of thiourea. These data have shown that curcumin-induced chromosomal damage in CHO cells can be mediated by hydroxyl radical generation in the present experimental conditions. Teratogenesis Carcinog. Mutagen. 21:175-180, 2001.

Potentiation by turmeric and curcumin of gamma-radiation-induced chromosome aberrations in Chinese hamster ovary cells.

The effect of turmeric and curcumin, two natural antioxidants, on the frequencies of chromosome aberrations induced in Chinese hamster ovary (CHO) cells by gamma-radiation was investigated. Cells were treated with three concentrations of each drug, turmeric (100, 250, and 500 microg/ml) and curcumin (2.5, 5, and 10 microg/ml), and then irradiated (2.5 Gy) during different phases of the cell cycle. Turmeric was not clastogenic by itself, whereas curcumin at 10 microg/ml enhanced the chromosomal damage frequency. Neither of the two antioxidants showed protective effect against the clastogenicity of gamma-radiation. Instead, an obvious increase in the frequencies of chromosome aberrations was observed when turmeric at 500 microg/ml was associated with gamma-radiation during G2/S phase, and curcumin at 10 microg/ml plus gamma-radiation during S and G2/S phases of the cell cycle. The results clearly indicate the exacerbated effect of turmeric and curcumin on radiation-induced clastogenicity, suggesting that these antioxidants are also potentiating agents depending on the experimental conditions.

Comparative study of the effects of vitamin C and bleomycin on smokers' and non-smokers' lymphocytes in clastogenicity assays.

Free radicals are products of metabolic reactions and of external factors that can injure different biological molecules. However, different antioxidant agents can prevent the action of these reactive species and the damage they cause. Vitamin C (VC) is an important micronutrient found in the diet, which presents defense mechanisms against the free radicals that challenge the cells of the organism. The objective of the present study was to investigate the effect of VC as a modulator of the damage induced in DNA by bleomycin (BLM) in lymphocytes from smokers and non-smokers. The difference in response to the mutagenic potential of BLM between smokers and non-smokers was also investigated. Peripheral blood lymphocyte cultures were treated simultaneously with BLM (20 microg/ml) and/or VC (100, 200, and 400 microg/ml) in the G2 phase of the cell cycle. The results obtained did not demonstrate a statistically significant difference in the response to the antitumor agent BLM between smokers and non-smokers. The data also showed that VC had no significant modulating effect on the frequency of chromosome aberrations induced by BLM in the cells of smokers and non-smokers under the experimental conditions used.

Evaluation of the genotoxic potential of the isocoumarin paepalantine in in vivo and in vitro mammalian systems.

Paepalantine is an isocoumarin isolated from Paepalanthus vellozioides which showed antimicrobial activity in in vitro experiments. In the present study, paepalantine was tested for possible clastogenic and cytotoxic action. Cultures from different individuals were treated with paepalantine at concentrations of 20, 40 and 80 microg/ml. The effect of isocoumarin was also tested in an in vivo assay using Wistar rat bone marrow cells. Paepalantine was administered intraperitoneally at concentrations of 6.25, 12.5 and 25 mg/kg body weight. Under these conditions paepalantine did not have a clastogenic effect, but was significantly cytotoxic in the in vitro and in vivo mammalian cell systems tested in the present work.

In vitro and in vivo study of the clastogenicity of the flavone cirsitakaoside extracted from Scoparia dulcis L. (Scrophulariaceae).

The mutagenic effect of the flavone cirsitakaoside extracted from the medicinal herb Scoparia dulcis was evaluated in vitro by using human peripheral blood cultures treated with doses of 5, 10, and 15 microg of the flavone/ml culture medium for 48 h. The compound proved to be mutagenic at the highest concentration tested (15 microg/ml). Furthermore, the proliferative index was significantly reduced in all cultures treated with the flavone, although the mitotic index was not reduced. However, the clastogenic activity of the flavone cirsitakaoside was not observed when Swiss mice were treated orally with doses of 10, 20, and 30 mg/animal for 24 h.

Mutagenic and cytotoxic activity of an isocoumarin (Paepalantine) isolated from Paepalanthus vellozioides.

A new isocoumarin with antimicrobial activity was isolated from Paepalanthus vellozioides (a native Brazilian plant) and called paepalantine. This study was carried out to assess the mutagenic activity of this new agent in assays with Salmonella typhimurium TA100, TA98, and TA102 and in Chinese hamster ovary (CHO) cell cultures, as well as cytotoxicity to McCoy cells. paepalantine caused a significant dose-dependent increase in the frequency of revertants in the three strains used in the assay, both with and without S9 mix, in concentrations varying from 2 to 128 micrograms/plate. The mutagenicity was confirmed in assays with CHO cells treated in the G1, S, and G2 phases of the cell cycle. There was an increase in the chromosomal aberration frequency, mainly in the G2 phase. Furthermore, the mitotic index of the treated cultures (40,80, and 160 micrograms/ml) was significantly lower, indicating cytotoxicity. The midpoint cytotoxicity values of McCoy cells by the neutral red (NR) and microculture tetrazolium (MTT) techniques resulted in a NR50 and MTT50 of 30 and 38 micrograms/ml, respectively. Alterations to the paepalantine structure are suggested to reduce its mutagenic and cytotoxic activity in investigations for its antineoplastic potential.

Genotoxicity of the natural cercaricides "sucupira" oil and eremanthine in mammalian cells in vitro and in vivo.

"Sucupira" oil and the lactone eremanthine, extracted from Pterodon pubescens and Eremanthus elaeagnus, respectively, are known for their cercaricidal action in experimental animals. Because of their biological effect, they have the potential to be used for the prophylaxis of schistosomiasis caused by Schistosoma mansoni. To test the clastogenicity of these agents, "sucupira" oil, either pure or diluted in corn oil, was tested in vivo on Wistar rat bone marrow cells following dermal application. Metaphase analysis showed that the compound did not induce a significant increase in the frequencies of chromosomal aberrations. When eremanthine was tested on BALB/c mice following gavage at doses of 100, 200, and 300 mg/kg bw, it did not induce structural or numerical chromosomal aberrations. In the in vitro treatment of human lymphocyte cultures, eremanthine also did not cause any increase in chromosomal aberrations or sister chromatid exchanges at the following concentrations in culture medium: 1.25, 2.50, and 5.00 micrograms/ml. From these results, under our experimental conditions, neither "sucupira" oil nor eremanthine showed clastogenic effects on mammalian cells in vivo or in vitro.

Evaluation of the genotoxic potential of the alkaloid boldine in mammalian cell systems in vitro and in vivo.

Boldine is an alkaloid present in Peumus boldus (popularly called "boldo-do-chile" in Brazil) which has healing properties and is used for the treatment of gastrointestinal disorders. The possible clastogenic effect of the drug was tested in vitro on human peripheral blood lymphocytes by evaluating the induction of chromosome aberrations and sister-chromatid exchanges (SCEs). Cultures from different individuals were treated with boldine at concentrations of 10, 20 and 40 micrograms/ml of culture medium. The effect of the alkaloid was also tested in an in vivo assay using BALB/c mouse bone marrow cells. Boldine was administered to the animals by gavage at the concentrations of 225, 450 and 900 mg/kg body weight. Under the conditions used, boldine did not induce a statistically significant increase in the frequency of chromosome aberrations or SCEs in either test system.