Chemical composition, antifungal, antioxidant and hemolytic activities of Moroccan Thymus capitatus essential oil.

This study aimed to define the chemical composition of Moroccan Thymus capitatus essential oil, and to investigate its in vitro antioxidant and antifungal activities against human pathogenic fungi. Chemical analysis using GC-FID and GC-MS system revealed 28 constituents, representing 99% of total compounds. Oxygenated monoterpenes represented the highest proportion (79.79%), among which carvacrol (75.73%) was the predominant compound, followed by linalol (2.26%). Monoterpene hydrocarbons represented the second major fraction (16.29%): within them, the predominant constituents were γ-terpinene (5,55%), ρ-cymene (5,50%), and ß-caryophyllene (2.73%). Antioxidant activity was performed by DPPH scavenging, ß-carotene bleaching inhibition, and ferric reducing power. T. capitatus revealed pronounced DPPH radical scavenging activity (IC50=110.53µg.mL-1), strong ferric reducing ability (EC50=644.4µg.mL-1), and a remarkable degree of protection against lipid peroxidation during ß-carotene bleaching inhibition (IC50=251.76µg.mL-1). Antifungal activity was carried out against Candida, Aspergillus, and Rhizopus species by microdilution method.  T. capitatus   exhibited potent anticandidal activity (MIC=125-500µg.mL-1) and strong inhibition against filamentous fungi (MIC=250-500µg.mL-1). Its hemolytic activity against human erythrocytes had a low toxic effect at concentrations lower than 1250µg.mL-1. The useful antioxidant properties and broad antifungal effect of T. capitatus EO confirm its considerable potential for the food industry and for phytopharmaceutical production.

Caveolin-1 is essential for metformin inhibitory effect on IGF1 action in non-small-cell lung cancer cells.

Metformin causes an AMP/ATP ratio increase and AMP-activated protein kinase (AMPK) activation. Since caveolin-1 (Cav-1) plays a role in AMPK activation and energy balance, we investigated whether Cav-1 could participate in metformin's inhibitory effect on IGF1 signaling. The effect of metformin was studied in two non-small-cell lung cancer (NSCLC) cell lines, Calu-1 and Calu-6, expressing higher and lower amounts of Cav-1, respectively. In Calu-1, but not in Calu-6 cells, metformin reduced phosphorylation of type 1 insulin-like growth factor receptor (IGF-IR) substrates Akt and Forkhead transcription factor 3a (FOXO3a), inhibited IGF1-dependent FOXO3a nuclear exit, and decreased IGF1-dependent cell proliferation. Here, we show that sensitivity of NSCLC cells to metformin was dependent on Cav-1 expression and that metformin required Cav-1 to induce AMPK phosphorylation and AMP/ATP ratio increase. Cav-1 silencing in Calu-1 and overexpression in Calu-6 reduced and improved, respectively, the inhibitory effect of metformin on IGF1-dependent Akt phosphorylation. Prolonged metformin treatment in Calu-6 cells induced a dose-dependent expression increase of Cav-1 and OCT1, a metformin transporter. Cav-1 and OCT1 expression was associated with the antiproliferative effect of metformin in Calu-6 cells (IC(50)=18 mM). In summary, these data suggest that Cav-1 is required for metformin action in NSCLC cells.

IGF-IR internalizes with Caveolin-1 and PTRF/Cavin in HaCat cells.

BACKGROUND: Insulin-like growth factor-I receptor (IGF-IR) is a tyrosine kinase receptor (RTK) associated with caveolae, invaginations of the plasma membrane that regulate vesicular transport, endocytosis and intracellular signaling. IGF-IR internalization represents a key mechanism of down-modulation of receptors number on plasma membrane. IGF-IR interacts directly with Caveolin-1 (Cav-1), the most relevant protein of caveolae. Recently it has been demonstrated that the Polymerase I and Transcript Release Factor I (PTRF/Cavin) is required for caveolae biogenesis and function. The role of Cav-1 and PTRF/Cavin in IGF-IR internalization is still to be clarified. METHODOLOGY/PRINCIPAL FINDINGS: We have investigated the interaction of IGF-IR with Cav-1 and PTRF/Cavin in the presence of IGF1in human Hacat cells. We show that IGF-IR internalization triggers Cav-1 and PTRF/Cavin translocation from plasma membrane to cytosol and increases IGF-IR interaction with these proteins. In fact, Cav-1 and PTRF/Cavin co-immunoprecipitate with IGF-IR during receptor internalization. We found a different time course of co-immunoprecipitation between IGF-IR and Cav-1 compared to IGF-IR and PTRF/Cavin. Cav-1 and PTRF/Cavin silencing by siRNA differently affect surface IGF-IR levels following IGF1 treatment: Cav-1 and PTRF/Cavin silencing significantly affect IGF-IR rate of internalization, while PTRF/Cavin silencing also decreases IGF-IR plasma membrane recovery. Since Cav-1 phosphorylation could have a role in IGF-IR internalization, the mutant Cav-1Y14F lacking Tyr14 was transfected. Cav-1Y14F transfected cells showed a reduced internalization of IGF-IR compared with cells expressing wild type Cav-1. Receptor internalization was not impaired by Clathrin silencing. These findings support a critical role of caveolae in IGF-IR intracellular traveling. CONCLUSIONS/SIGNIFICANCE: These data indicate that Caveolae play a role in IGF-IR internalization. Based on these findings, Cav-1 and PTRF/Cavin could represent two relevant and distinct targets to modulate IGF-IR function.