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Objectives: This study was designed to investigate the potential protective effect of a methanolic extract of Peumus boldus leaves on UV light and nitric oxide (NO)-mediated DNA damage. In addition, we investigated the growth inhibitory activity of this natural product against human melanoma cells (M14)., Methods: Boldine, catechin, quercetin and rutin were identified using a HPLC method. The extract was incubated with plasmid DNA and, before irradiating the samples with UV-R, H(2) O(2) was added. For analysis of DNA single-strand breaks induced by NO, the experiments were performed by incubating the extract with Angeli's salt. In the study on M14 cell line, cell viability was measured using MTT assay. Release of lactate dehydrogenase, a marker of membrane breakdown, was also measured. For the detection of apoptosis, the evaluation of DNA fragmentation (COMET assay) and caspase-3 activity assay were employed. The expression of heat shock protein 70 (Hsp70) was detected by Western blot analysis. Generation of reactive oxygen species was measured by using a fluorescent probe., Key Findings: The extract (demonstrating the synergistic effect of the constituents boldine and flavonoids), showed a protective effect on plasmid DNA and selectively inhibited the growth of melanoma cells. But a novel finding was that apoptosis evoked by this natural product in M14 cells, appears to be mediated, at least in part, via the inhibition of Hsp70 expression, which may be correlated with a modulation of redox-sensitive mechanisms., Conclusions: These results confirm the promising biological properties of Peumus boldus and encourage in-vivo investigations into its potential anti-cancer activity., (© 2011 The Authors. JPP © 2011 Royal Pharmaceutical Society.)

Rosmarinus officinalis L. is receiving increasing attention due to its anti-inflammatory and antioxidative constituents. Our recent studies showed that R. officinalis extract, containing 31.7% of carnosic acid, was able to counteract the deleterious effects of UV-R, by protecting plasmid DNA from hydroxyl radicals generated by UV-A. In this work, we evaluated the effects of this extract on pBR322 DNA cleavage induced by nitric oxide, and the growth inhibitory activity against two human melanoma cell lines, M14 and A375. The extract showed a protective effect on plasmid DNA damage, and at concentrations of 10-80 microg/mL was able to reduce significantly (p<0.001) the growth (MTT assay) of both melanoma cell lines. In addition, our results indicate that apoptotic cell demise is induced in M14 and A375 cells. No statistically significant increase in LDH release was observed in melanoma cells, correlated to a fragmentation of genomic DNA, determined by COMET assay.

Members of the family Anacardiaceae are known to contain a number of biologically active substances, such as phenolic lipids, alkyl-catechols and alkyl-resorcinols. In the present study, human cancer cell lines, DU-145 cells (androgen-insensitive prostate cancer cells), KB cells (human epidermoid cells), and human melanoma cell line, M14, were treated for 72 h with 0.59-9.5 microM litreol (3-[pentadecyl-10-enyl-catechol]), a alkyl-catechol isolated from Lithraea caustica (Molina) Hook. & Arn. The results showed, for the first time, that litreol inhibited cancer cell viability in a dose-dependent manner. In addition, the treatment with this compound at 0.59-1.18 microM concentrations induced apoptotic cell death, demonstrated by the fragmentation of genomic DNA and by a significant increase of caspase-3 activity. The significant production of reactive oxygen species (ROS) evidenced in these experimental conditions could trigger the apoptosis cascades. Taken together, these results demonstrate that litreol attenuate the growth of human cancer cells, at least in part, triggering an apoptotic process, and they may offer a further impulse to the development of its analogues with more potent efficacy against human cancer cells.

In humans both UV-A and UV-B can cause gene mutations and suppress immunity, which leads to skin cancer, including melanoma. Inhibition of reactive oxygen species (ROS) and reactive nitrogen species (RNS) appears particularly promising as ROS and RNS production by both UV-A and UV-B contributes to inflammation, immunosuppression, gene mutation and carcinogenesis. We evaluated the effect of two lichen compounds, sphaerophorin (depside) and pannarin (depsidone) on pBR322 DNA cleavage induced by hydroxyl radicals (()OH), and by nitric oxide (NO), and their superoxide anion (O(2)(-)) scavenging capacity. In addition, we investigated the growth inhibitory activity of these compounds against human melanoma cells (M14 cell line). Sphaerophorin and pannarin showed a protective effect on plasmid DNA and exhibited a superoxide dismutase like effect. The data obtained in cell culture show that these lichen metabolites inhibit the growth of melanoma cells, inducing an apoptotic cell death, demonstrated by the fragmentation of genomic DNA (COMET and TUNEL Assays) and by a significant increase of caspase-3 activity, and correlated, at least in part, to the increase of ROS generation, These results confirm the promising biological properties of sphaerophorin and pannarin and encourage further investigations on their molecular mechanisms.

Previously, it was isolated from the fruiting bodies of the gilled mushroom Pholiota spumosa (Basidiomycetes, Strophariaceae), putrescine-1,4-dicinnamide, a phenylpropanoid derivative conjugated with polyamine putrescine never isolated before as a natural compound. Recently, polyamine analogs that are similar in structure to the natural polyamines but that cannot mimic their functions that are essential for cellular growth and differentiation, have shown antitumor activity in several types of human cancer cells. Therefore, we have now investigated the response of DU-145 cells, a well characterized androgen-independent human prostate cancer (PCA) cell line, to this phenylpropanoid derivative. The results presented here demonstrate that putrescine-1,4-dicinnamide, as suggested for polyamine analogs synthesized artificially, inhibits the cell growth of cancer cells inducing apoptosis cell death, mediated, at least in part, by the activation of caspase cascades, that at higher doses shift to necrosis, through the increase of reactive oxygen species (ROS) generation.

The naphthoquinones 2-hydroxy-3-(1,1-dimethylallyl)-1,4-naphthoquinone (CS-1), (-)-2,3,3-trimethyl-2-3-dihydronaphtho[2,3-b]furan-4,9-quinone (CS-3), and 2-acetoxy-3-(1,1-dimethylallyl)-1,4-naphthoquinone (CS-5) isolated from Calceolaria sessilis were tested against Trypanosoma cruzi epimastigotes, the TA3 tumor cell line and the methotrexate-resistant subline TA3-MTX-R. Naphthoquinone CS-3 was the most active; the 50% culture growth inhibition (I50) on T. cruzi (Tulahuén and LQ strain and DM28c clone) was at concentrations ranging from 2.1 to 5.2 mumolar. Also CS-3 inhibited TA3 and TA3-MTX-R culture growth with an I50 of 2.1 and 3.8 mumolar, respectively. Naphthoquinone CS-3 inhibited the respiration of the tumor cells by interfering with the electron transport at some point between NADH and ubiquinone. The respiration of T. cruzi was not inhibited by naphthoquinone CS-3. Naphthoquinone CS-3 produced a temporary increase of oxygen consumption in T. cruzi and tumor cells, suggesting the generation and participation of free radicals.