The redox couple avarol/avarone in the fight with malignant gliomas: the case study of U-251 MG cells

<p>This study aimed to screen <i>in vitro</i> antitumour activity of the redox couple avarol/avarone against the human malignant glioma cell line U-251 MG for the first time. Compared both with avarol and positive controls used (temozolomide and doxorubicin), avarone was found to be the most active compound with IC₅₀ value below 1 μM (IC₅₀ 0.68 ± 0.04 μM, 96 h). Considerable less DNA damage in the cells treated with avarol and avarone vs. doxorubicin (105 & 123% vs. 299%, respectively; untreated U-251 MG cells were used as a control, 100%), coupled with no sign of cytotoxicity against the normal human foetal lung fibroblast MRC-5 cells (IC₅₀ > 100 μM), has actually pointed out the importance of this marine sesquiterpenoid quinone structure as a promising lead compound in development of novel brain chemotherapeutics.</p

<i>In vitro</i> avarol does affect the growth of <i>Candida</i> sp.

<p>This work extends <i>in vitro</i> screening of antimicrobial activity of avarol, the marine natural product firstly isolated from the Mediterranean sponge <i>Dysidea avara</i>. Its anticandidial activity was evaluated by microdilution method against eight <i>Candida</i> strains, two ATCC and six clinical ones. At a different extent this compound was proven to be active against all the strains tested (MIC 0.8–6.0 μg/mL and MFC 1.6–12.0 μg/mL, respectively). According to the best of our knowledge, this is the first report on avarol activity towards any yeast strain which may be of relevance for Alzheimer’s disease. Indeed, avarol derivatives showing moderate AChE activity should be screened for anticandidial activity both <i>in vitro</i> and <i>in vivo</i>.</p

<i>In vitro</i> evaluation of cytotoxic and mutagenic activity of avarol

<p>The cytotoxicity of avarol, a main secondary metabolite of the Mediterranean sponge <i>Dysidea avara</i>, was <i>in vitro</i> screened by MTT assay against four human tumour cell lines. The colon HT-29 tumour cells practically showed to be the only sensitive ones towards this organic compound. No toxicity was found against the fetal lung fibroblast MRC-5 cells at the concentrations tested. In comparison with doxorubicin, used as a positive control, avarol actually exhibited at least 588-fold less toxicity towards normal MRC-5 cells. Finally, comet assay indicated that DNA fragmentation was almost fivefold higher upon the treatment with doxorubicin, compared to avarol. The obtained results have actually confirmed that avarol scaffold may contribute to development of new cytostatics inspired by nature.</p

Effect of SC and CSP on DNA fragmentation.

<p>The T47D cells were treated with SC (10 µg/ml), CSP (10 µg/ml) or Dauno (100 µM) for 24 h, thereafter DNA fragmentation was analyzed by comet assay (A), agarose gel electrophoresis (B) and diphenylamine assay (C). Basal DNA damage from untreated cells, DNA damage from SC or CSP cells (A). Data are from a single experiment and representative of 50 randomly selected cells stained with ethidium bromide (EtBr). Data illustrated in (B) are from a single experiment and representative of three separate experiments, while data in (C) are expressed as mean ± S.E.M. of three separate experiments. ***p<0.001 <i>vs.</i> control (untreated cells).</p

Effect of SC and CSP on p50 and p65 nuclear translocation.

<p>Representative Western blot of p50 and p65 as well as the densitometric analysis shows p50 and p65 nuclear translocation in T47D cells incubated with CSP (10 µg/ml) or SC (10 µg/ml) for 24 h. The results are from a single experiment and are representative of three separate experiments. Densitometric data are expressed as mean ± S.E.M. of three separate experiments. ***p<0.001 <i>vs</i>. untreated cells. The expression of GAPDH is shown as an equal loading control.</p

Effect of SC and CSP on apoptosis induction.

<p>Detection of dead and dying cells by FACS (A). Cells treated overnight with SC, CSP and cisPt were stained with ΔΨ_m-sensitive dye DiOC₆(3) and the vital dye propidium iodide (PI). The white portions of the columns refer to the DiOC₆(3)^low/PI⁺ population (dead) and the remaining part of the column corresponds to the DiOC₆(3)^low/PI^- (dying) population. Results are means ± S.E.M. of three independent experiments. Expression profile of apoptosis-related proteins (B). Cell lysates from HeLa cells, treated with SC (10 µM) and CSP (10 µM) overnight, were analyzed by human apoptosis profiler. Data are expressed as means ± S.D. of two independent experiments.</p

Cacospongionolide and Scalaradial: structures and original sponges.

<p>Chemical structures of cacospongionolide and scalaradial isolated from marine sponges <i>Fasciospongia cavernosa</i> and <i>Cacospongia scalaris</i>, respectively.</p

Antioxidant and cytotoxic activities investigation of tomato seed extracts

<div><p>Biological activities of different varieties of tomato seed extracts were evaluated to verify the potential antioxidant and/or antiproliferative activity of the bioactive metabolites present in them. Findings demonstrated that among all the varieties investigated (San Marzano Rosso, San Marzano Giallo, Corbarino, Black Tomato and San Marzano/Black Tomato hybrid) San Marzano Rosso seed extract exhibited the highest free radical-scavenging activity with 68% of 2,2-Diphenyl-1-picrylhydrazyl radical inhibition, and the best cytotoxic activity evaluated by using the brine shrimp test (LD₅₀: 23,198 ppm) and 3-(4,5-dimethylthiazol-2-yl)-2,5-phenyl-2H-tetrazolium bromide assay on A375 cell line (IC₅₀: 137.7 μg/mL).</p></div