Licania michauxii Prance root extract induces hsp 70 mRNA and necrotic cell death in cultured human hepatoma and colon carcinoma cell lines

Licania rigida leaf extract: Protective effect on oxidative stress, associated with cytotoxic, mutagenic and preclinical aspects

Brazilian plant biodiversity is a rich alternative source of bioactive compounds since plant-derived extracts and/or their secondary metabolites exhibit potential properties to treat several diseases. In this context, Licania rigida Benth (Chrysobalanaceae Family), a large evergreen tree distributed in Brazilian semi-arid regions, deserves attention for its widespread use in popular medicine, although its biological properties are still poorly studied. The aim of this study was to examine (1) acute and sub-chronic oral toxicity at 2000 mg/kg dose; (2) in vitro cytotoxicity at 0.1; 1; 10; 100 or 1000 µg/ml; (3) in vivo mutagenicity at 5, 10 or 20 mg/ml, and (4) potential antioxidant protective effect of L. rigida aqueous leaf extract of (AELr). No marked apparent toxic and genotoxic effects were observed using in vitro and in vivo assays after in vitro treatment of Chinese hamster ovary cell line (CHO-K1) with AELr or in vivo exposure of Wistar rats and Drosophila melanogaster to different extract concentrations. Concerning the antioxidant effect, the extract exhibited a protective effect by decreasing lipid peroxidation as determined by malondialdehyde levels. No significant changes were observed for glutathione (GSH) levels and activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Data demonstrate the beneficial potential of AELr to be employed for therapeutic purposes. However, further studies are required to validate the pharmacological application of this plant extract to develop as a phytotherapeutic formulation.

Phenolic Composition, Toxicity Potential, and Antimicrobial Activity of Licania rigida Benth (Chrysobalanaceae) Leaf Extracts

This study was conducted to evaluate the phenolic composition, toxicity, and antimicrobial activity of Licania rigida Benth, an underexploited wild Licania species. L. rigida leaf fractions (ethyl alcohol and ethyl acetate) were analyzed for their phenolic compound and flavonoid total, and high-performance liquid chromatography/ultraviolet spectra chromatographic profiles. Regarding the extract biological effects, toxicity was measured by acute oral toxicity in Wistar rats, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method, and apoptosis indicators with DAPI in VERO cells, whereas well-agar diffusion and broth microdilution assays were applied to evaluate the antimicrobial ability. The phytochemical analysis resulted in significant amounts of phenolic compounds and total flavonoids in the extract and fraction, with flavonol-3-O-glycosylates as the main constituent. Regarding the extract and fraction antimicrobial activity, the results showed a significant effect against gram-positive bacteria and fungi, among which Staphylococcus epidermidis and Candida krusei displayed more susceptibility. No toxicity effects were observed in animals. Concerning the cytotoxicity assay, only the highest dose tested exhibited a minimal toxic effect on the analyzed cell lines. These results are relevant considering the increase of multiresistant microorganisms to conventional treatments applied. Therefore, investigating the pharmacological properties of the genus Licania is promising in the search for new sources of antimicrobial compounds.

Therapeutic potency of heat-shock protein-70 in the pathogenesis of colorectal cancer: current status and perspectives

Heat-shock protein-70 (HSP70) is critical to the folding, stability, and activity of several client proteins including many responsible for cancer cell proliferation, apoptosis, drug toxicity, and metastasis. Up-regulation of HSP70 is positively associated with increased tumorigenicity as well as poor survival in colon cancer patients, supporting the diagnostic, prognostic, and therapeutic potencies of HSP70 in colorectal cancer. The administration of specific pharmacological inhibitors or gene knock-down for HSP70 suppresses tumor progression and enhances tumor cell chemosensitivity. This review summarizes the different tumorigenic properties of HSP70 and the potential therapeutic potency of HSP70 inhibitors in terms of a novel strategy for colorectal cancer therapy, for a better understanding, and hence better management of this disease.

Polyphenol Composition, Antioxidant Activity and Cytotoxicity of Seeds from Two Underexploited Wild Licania Species: L. rigida and L. tomentosa

Studies have shown the benefit of antioxidants in the prevention or treatment of human diseases and promoted a growing interest in new sources of plant antioxidants for pharmacological use. This study aimed to add value to two underexploited wild plant species (Licania rigida) and L. tomentosa) from Brazilian flora. Thus, the phenolic compounds profile of their seed ethanol extract and derived fractions were elucidated by HPLC, the antioxidant capacity was assessed by in vitro chemical tests and the cytotoxicity determined using the human carcinoma cell lines MCF-7 and Caco-2. Eleven phenolic compounds were identified in the extracts of each species. The extracts and fractions showed excellent antioxidant activity in the DPPH assay (SC₅₀, ranging from 9.15 to 248.8 µg/mL). The aqueous fraction of L. rigida seeds was most effective in preventing lipid peroxidation under basal conditions (IC₅₀ 60.80 µg/mL) whereas, in the presence of stress inducer, the methanolic fraction of L. tomentosa performed best (IC₅₀ 8.55 µg/mL). None of the samples showed iron chelating capacity. Ethanolic seed extracts of both species did not reveal any cytotoxicity against MCF-7 and Caco-2 cells. Both plant species showed a promising phenolic profile with potent antioxidant capacity and deserve attention to be sustainably explored.

Natural products with anti-Bredt and bridgehead double bonds

Well over a hundred years ago, Professor Julius Bredt embarked on a career pursuing and critiquing bridged bicyclic systems that contained ring strain induced by the presence of a bridgehead olefin. These endeavors founded what we now know as Bredt's rule (Bredtsche Regel). Physical, theoretical, and synthetic organic chemists have intensely studied this premise, pushing the boundaries of such systems to arrive at a better understood physical phenomenon. Mother nature has also seen fit to construct molecules containing bridgehead double bonds that encompass Bredt's rule. For the first time, this topic is reviewed in a natural product context.

Antitumor activity of kielmeyera coriacea leaf constituents in experimental melanoma, tested in vitro and in vivo in syngeneic mice

PURPOSE

The antitumor activity of Kielmeyera coriacea (Clusiaceae), a medicinal plant used in the treatment of parasitic, as well as fungal and bacterial infections by the Brazilian Cerrado population, was investigated.

METHODS

A chloroform extract (CE) of K. coriacea was tested in the murine melanoma cell line (B16F10-Nex2) and a panel of human tumor cell lines. Tumor cell migration was determined by the wound-healing assay and the in vivo antitumor activity of CE was investigated in a melanoma cell metastatic model. 1H NMR and GC/MS were used to determine CE chemical composition.

RESULTS

We found that CE exhibited strong cytotoxic activity against murine melanoma cells and a panel of human tumor cell lines in vitro. CE also inhibited growth of B16F10-Nex2 cells at sub lethal concentrations, inducing cell cycle arrest at S phase, and inhibition of tumor cell migration. Most importantly, administration of CE significantly reduced the number of melanoma metastatic nodules in vivo. Chemical analysis of CE indicated the presence of the long chain fatty compounds, 1-eicosanol, 1-docosanol, and 2-nonadecanone as main constituents.

CONCLUSION

These results indicate that K. coriacea is a promising medicinal plant in cancer therapy exhibiting antitumor activity both in vitro and in vivo against different tumor cell lines.

Effect of ascorbic acid and hydrogen peroxide on mouse neuroblastoma cells

Ascorbic acid is one of the antioxidant compounds widely used against free radical stress. The present study was undertaken to examine whether ascorbic acid and hydrogen peroxide (H2O2), alone or in combination, could influence cell viability. The murine neuroblastoma cell line, N2a, was used to perform a dose response curve for ascorbic acid. It was observed that ascorbic acid alone at physiological concentrations (0.1-0.4 mM) did not cause any cell death. However, at pharmacological concentrations (1-6 mM), ascorbic acid caused dose-dependent cell death. The lethal concentration at which 50% cells were killed (LC50) was determined to be approximately 3.141 mM ascorbic acid at 24 h. H2O2 up to 300 µM alone did not cause significant cell death. In the combined treatment, when the cells were treated with ascorbic acid at physiological concentrations (0.4 mM) and H2O2 at 400 µM, higher rates of cell death were observed compared to the cell death rates caused by either compound alone. Subsequent experiments revealed that cell death was partly mediated through the loss of total glutathione levels in the cells. These data suggest that the combination of ascorbic acid and H2O2 is disadvantageous for cancer cell survival. Further studies are required to ascertain the physiological significance of these observations.

On the structures of the diterpenes licamichauxiioic acids A and B

The structures of the diterpenes licamichauxiioic acids A and B, isolated from Licania michauxii, which had been reported as 15-oxo-ent-kaur-9(11),16-dien-19-oic acid (1) and 15-oxo-ent-kaur-13,16-dien-19-oic acid (3), respectively, are not correct. Starting from grandiflorenic acid (6) we had prepared a compound with the proposed structure for licamichauxiioic acid A, and its spectroscopic data are different from those given for this acid. In the case of licamichauxiioic acid B, its NMR data are not in accordance with the proposed structure 3, which also violates Bredt's rule. In addition, we described a useful method for the separation of grandiflorenic and grandiflorolic acids.

Biological autoimmunity screening in hepatitis C patients by anti-HepG2 lysate and anti-heat shock protein 70.1 autoantibodies

Viruses require viral and cellular chaperones during their life cycle and interactions of these molecules with the immune system are probable during the infection. Thus, an anti-chaperone antibody response has been firstly investigated in hepatitis C patients in this paper. A HepG2-lysate antigen (90, 79, 72, 70, 62, 54 and 48 kDa) was assayed in sera from 59 (19F/40M) chronic hepatitis C patients without cirrhosis before therapy. Forty of them were positive for anti-HepG2 lysate antigen antibodies and this test may evaluate biological autoimmunity. Hsp70.1, Hsp90 and calreticulin levels were significantly higher in this antigen than in a control HepG2 antigen. Secondly, Hsp70.1 was identified as Hsp 70 kDa protein-1 by proteomic analysis and studied as a possible antibody target. Fourteen out of 59 patients were positive for anti-Hsp70.1 antibodies that were inversely correlated with alanine aminotransferase levels, the Metavir activity index and viraemia. Finally, for comparative purposes, 50 sera from systemic lupus erythematosus (SLE) patients have been tested: eight and 41 of them were positive for anti-Hsp70.1 and anti-HepG2 lysate antigen antibodies, respectively. Therefore, anti-Hsp70.1 autoantibodies may be produced and can partially lead to biological autoimmunity in chronic hepatitis C patients.

Immunology of Apoptosis and Necrosis

A complex of reactions regulating the number of cells in organs and tissues under normal and pathologic conditions is one of the most important systems of multicellular organisms. In this system, which controls both cell proliferation and clearance, clearance has been given special attention during the last three decades. Some stages of the clearance are known (the choice of "unwanted" cells, their destruction not affecting the surrounding tissue, and, finally, removal of the corpses), and undeniable progress has been achieved in the understanding of the second stage mechanisms, whereas mechanisms of elimination per se of cells or their fragments still continue to be terra incognita. The clearance of such cells is mainly determined by different components of natural and adaptive immunity: phagocytes, complement, opsonins, antigen-presenting cells, etc. Recently specific "danger signals", such as hydrolases, DNA, heat shock proteins, and other potential immunogens released by cells during their elimination have been discovered. Entering the extracellular space, these signals induce inflammation and injury of the surrounding tissues, i.e., autoimmune reactions. Heat shock proteins, in addition to chaperon activity, act as signaling, costimulating, and antigen-carrying molecules in the interactions of dying cells and the immune system.

Chromones from Licania arianeae (Chrysobalanaceae)

The phytochemical studies of the leaves of Licania arianeae Prance (Crysobalanaceae) have led to the identification of ten new chromones, four 5,7-dihydroxy-2-alkylchromones, four 5,7-dihydroxy-6-chloro-2-alkylchromones and two 5,7-dihydroxy-6,8-dichloro-2-alkylchromones. The structures were established from IR, NMR and FAB-MS spectra data including 2D NMR experiments of natural substances and of the methyl derivatives.

Pharmacological activities of some Argyranthemum species growing in the Canary Islands

Methanolic extracts of eight subspecies of genus Argyranthemum were evaluated against brine shrimps, human cancer cell lines, malarial parasites and microorganisms under in vitro conditions. In the shrimp assay, samples of A. adauctum ssp. adauctum, A. adauctum ssp. erythrocarpon and A. frutetescens ssp. succulentum were active with ED50 values in the range of around 300 to 360 microg/ml. In the Caco-2, HepG2 and MCF-7 cell lines, the samples A. adauctum ssp. jacobaeifolium and A. adauctum ssp. palmensis were active with LC50 values ranging between 80-90 microg/ml. The secondary assay results of antimalarial activity of samples, A. adauctum ssp. adauctum, A. adauctum ssp. dugourii, A. adauctum ssp. erythrocarpon and A. adauctum ssp. jacobaeifolium have IC50 values <50 microg/ml. The samples demonstrated broad specific antimicrobial activity against five different microorganisms.

Cytotoxic activities of some Greek Labiatae herbs

Nineteen methanolic crude plant extracts of Labiatae family, collected in Greece from different locations, were evaluated for cytotoxic activity against brine shrimps and three human cancer cell lines along with a normal mouse cells as a control cell line. In the brine shrimp lethality test, Mentha pulegium was the only sample found to be active with an LC(50) value 347.3 micro g/ml, while all remaining samples had LC(50) values greater than 1000 micro g/ml. In case of Caco-2 and HepG2 cell lines, only one sample, namely Thymus parnassicus Halacsy, was active with LC(50) values 44.6 and 50.3 micro g/ml respectively, while against MCF-7 cell line, two samples, namely, Clinopodium vulgare L. (LC(50): 60.4 micro g/ml), and Thymus parnassicus Halacsy (LC(50): 54.7 micro g/ml), were found active.

Antioxidant and cytotoxic activities of Hypericum sp. on brine shrimps and human cancer cell lines

Ten different samples of five Hypericum sp. were tested on brine shrimps, human colon carcinoma and human hepatoma cell lines for their cytotoxic activities. H. triquetrifolium Turra. (Rafina) showed the highest activity (LC50 = 22 mg/mL) on brine shrimps, while the extracts of the other nine samples showed significant to moderate activities (LC50 from 37 to 107 mg/mL). H. empetrifolium Wild. (Parnon) showed the highest activity in human colon carcinoma and human hepatoma cell lines, with LC50 values 29 and 25.1 mg/mL, respectively, while the LC50 values of the other samples were more than 45 mg/mL. It is very interesting to observe that most Hypericum samples showed good antioxidant activity in vitro.