Azzurra Sargenti | AICCON - Associazione Italiana per la Promozione della Cultura della Cooperazione e del Non Profit (original) (raw)

Uploads

Papers by Azzurra Sargenti

Research paper thumbnail of Effects of supplementation with different Mg salts in cells: is there a clue?

Magnesium research : official organ of the International Society for the Development of Research on Magnesium

The differing bioavailability of magnesium salts remains an open question, both at the cellular a... more The differing bioavailability of magnesium salts remains an open question, both at the cellular and systemic level. However, this issue is relevant for identifying the most effective magnesium supplement. We compared the effects of three widely used magnesium salts: MgSO4, MgCl2 and Mg pidolate, on the proliferation of four human cell types: promyelocytic leukaemia HL60, osteoblast-like Saos-2 and U-2 OS, and endothelial cells from the umbilical vein. The three magnesium salts had no effect on endothelial and leukemic cell growth, but magnesium pidolate impaired cell growth in osteoblast-like cells. In particular, in Saos-2 cells, 1 mM pidolate induced a slight accumulation of cells in the G0/G1 phase of the cell cycle and, in parallel, an early rise in intracellular calcium and a late decrease in intracellular magnesium content. Interestingly, when cultured in 5 mM magnesium pidolate, Saos-2 cells grew as fast as the controls. Moreover, intracellular magnesium and calcium concentra...

Research paper thumbnail of Intracellular magnesium content decreases during mitochondria-mediated apoptosis induced by a new indole-derivative in human colon cancer cells

Magnesium research : official organ of the International Society for the Development of Research on Magnesium

A newly synthesized indole-derivative is able to induce cytostatic and cytotoxic effects in the c... more A newly synthesized indole-derivative is able to induce cytostatic and cytotoxic effects in the colon cancer cells HT29, effecting apoptosis by activation of an intrinsic pathway. Magnesium is involved in both cell growth and apoptosis even though its role in the latter process is not well defined. The aims of this work were: firstly, to verify if magnesium content is related to the proliferative rate in HT29 cells; secondly, to assess the involvement of the cation in mitochondria-mediated apoptosis triggered by the new antiproliferative molecule. The effects of the indole-derivative in treated cells included cell-cycle arrest in the G2/M phase, and apoptotic death confirmed by release of cytochrome c from the mitochondrial compartment. Moreover, we demonstrated that the basal content of magnesium in HT29 cells inversely correlates with cell saturation density. In addition, a decrease in both free and intracellular total magnesium concentration was observed along with the induced ap...

Research paper thumbnail of Intracellular magnesium content changes during mitochondria-mediated apoptosis: in depth study of early events on mitochondrial membrane potential

Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2014

A recent study showed the antitumor activity of a new indole-derivative -MM-67 -inducing mitochon... more A recent study showed the antitumor activity of a new indole-derivative -MM-67 -inducing mitochondria-mediated apoptosis and a decrease of intracellular magnesium (Mg) concentration in HT29 colon cancer cells. Aim of this work was to assess cellular Mg levels throughout MM-67-induced apoptosis from the early to the final stage of the process and to evaluate the correlation with mitochondrial membrane potential (ΔΨm) variations. All analysis were performed by flow cytometry: ΔΨm was assessed by using mitochondrial potential sensitive dye DiOC6, while free and total intracellular cation concentrations were assessed by using the commercial probe MagFluo4-AM (Kd=4.7 mM), and the new synthesized DCHQ5 (Kd=8.3 mM), respectively. Our results evidenced that the MM67 induced apoptosis is characterized by a direct correlation between ΔΨ and free intracellular Mg content variations.

Research paper thumbnail of Magnesium intracellular content and distribution map in drug-resistant and -sensitive whole cells

Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2014

Research paper thumbnail of A novel fluorescent chemosensor allows the assessment of intracellular total magnesium in small samples

The Analyst, 2014

The present study investigated the analytical capabilities of a new fluorescent chemosensor, name... more The present study investigated the analytical capabilities of a new fluorescent chemosensor, named DCHQ5, a phenyl derivative belonging to the family of diaza-crown-hydroxyquinolines, for the quantitative assessment of total intracellular Mg content. The results obtained were compared to the analytical performances of DCHQ1 - the parent probe of the series which so far was the only suitable species for the quantitative assessment of the intracellular total magnesium and showed comparable results to atomic absorption spectroscopy. Different protocols were tested in several cell lines both by flow cytometry and by steady state fluorescence spectroscopy assays. The results obtained support the possibility to use DCHQ5 to accurately quantify the intracellular total Mg in much smaller samples than DCHQ1, also displaying an increased stable intracellular staining. These features, combined with the high fluorescence enhancement upon cation binding, and the possibility to be excited both in the UV and visible region, make DCHQ5 a valuable and versatile analytical tool for Mg assessment in biological samples.

Research paper thumbnail of Expanding the targets of the diaza-18-crown-6 hydroxyquinoline derivatives family to Zn(II) ions for intracellular sensing

Supramolecular Chemistry, 2013

ABSTRACT We have recently developed an optimised synthetic strategy for the preparation of chemos... more ABSTRACT We have recently developed an optimised synthetic strategy for the preparation of chemosensors based on the diaza-18-crown-6 hydroxyquinoline structure. This flexible approach allows to obtain a variety of substituted derivatives with improved fluorescence, metal ion binding, uptake and localisation properties. In this context, we have focused our attention on the design of specific chemosensors for intracellular Zn2+ ions, because of their important role in many biological processes. Interestingly, among them one in particular shows the properties of making it a promising candidate for effective Zn(II) ions detection in biological environments. It presents, in fact, a very low toxicity, Zn2+/Mg2+ selectivity and a very large fluorescence enhancement on complexation.

Research paper thumbnail of Quantitative Chemical Imaging of the intracellular spatial distribution of fundamental elements and light metals in single cells

Analytical Chemistry, 2014

We report a method that allows a complete quantitative characterization of whole single cells, as... more We report a method that allows a complete quantitative characterization of whole single cells, assessing the total amount of carbon, nitrogen, oxygen, sodium, and magnesium and providing submicrometer maps of element molar concentration, cell density, mass, and volume. This approach allows quantifying elements down to 10(6) atoms/μm(3). This result was obtained by applying a multimodal fusion approach that combines synchrotron radiation microscopy techniques with off-line atomic force microscopy. The method proposed permits us to find the element concentration in addition to the mass fraction and provides a deeper and more complete knowledge of cell composition. We performed measurements on LoVo human colon cancer cells sensitive (LoVo-S) and resistant (LoVo-R) to doxorubicin. The comparison of LoVo-S and LoVo-R revealed different patterns in the maps of Mg concentration with higher values within the nucleus in LoVo-R and in the perinuclear region in LoVo-S cells. This feature was not so evident for the other elements, suggesting that Mg compartmentalization could be a significant trait of the drug-resistant cells.

Research paper thumbnail of Monitoring magnesium efflux cyclic AMP-induced in HL60 cells by using a new hydroxyquinoline fluorescent chemosensor

Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2014

Cellular homeostasis of magnesium is still unclear. Several studies documented the occurrence of ... more Cellular homeostasis of magnesium is still unclear. Several studies documented the occurrence of fluxes of magnesium across the plasmamembrane within minutes from the application of metabolic or hormonal stimuli. These fluxes, however, result in limited variation of free Mg 2+ intracellular concentration and large changes in total Mg content. It has been reported that a stimulation with cyclic AMP caused a movement of total magnesium within 10 min after treatment in cardiomyocytes. In this study we tested this hypothesis in HL60 leukemic cells, not excitable but highly proliferating cell model. We evaluated Mg flux by DCHQ5, the phenyl-derivative of hydroxyquinoline fluorescent probe family. We observed a drastic decrease of intracellular total magnesium in the first 3 min. We also verified that at least 10% of the total intracellular amount of magnesium moved in the supernatant of stimulated cells.

Research paper thumbnail of Effects of supplementation with different Mg salts in cells: is there a clue?

Magnesium research : official organ of the International Society for the Development of Research on Magnesium

The differing bioavailability of magnesium salts remains an open question, both at the cellular a... more The differing bioavailability of magnesium salts remains an open question, both at the cellular and systemic level. However, this issue is relevant for identifying the most effective magnesium supplement. We compared the effects of three widely used magnesium salts: MgSO4, MgCl2 and Mg pidolate, on the proliferation of four human cell types: promyelocytic leukaemia HL60, osteoblast-like Saos-2 and U-2 OS, and endothelial cells from the umbilical vein. The three magnesium salts had no effect on endothelial and leukemic cell growth, but magnesium pidolate impaired cell growth in osteoblast-like cells. In particular, in Saos-2 cells, 1 mM pidolate induced a slight accumulation of cells in the G0/G1 phase of the cell cycle and, in parallel, an early rise in intracellular calcium and a late decrease in intracellular magnesium content. Interestingly, when cultured in 5 mM magnesium pidolate, Saos-2 cells grew as fast as the controls. Moreover, intracellular magnesium and calcium concentra...

Research paper thumbnail of Intracellular magnesium content decreases during mitochondria-mediated apoptosis induced by a new indole-derivative in human colon cancer cells

Magnesium research : official organ of the International Society for the Development of Research on Magnesium

A newly synthesized indole-derivative is able to induce cytostatic and cytotoxic effects in the c... more A newly synthesized indole-derivative is able to induce cytostatic and cytotoxic effects in the colon cancer cells HT29, effecting apoptosis by activation of an intrinsic pathway. Magnesium is involved in both cell growth and apoptosis even though its role in the latter process is not well defined. The aims of this work were: firstly, to verify if magnesium content is related to the proliferative rate in HT29 cells; secondly, to assess the involvement of the cation in mitochondria-mediated apoptosis triggered by the new antiproliferative molecule. The effects of the indole-derivative in treated cells included cell-cycle arrest in the G2/M phase, and apoptotic death confirmed by release of cytochrome c from the mitochondrial compartment. Moreover, we demonstrated that the basal content of magnesium in HT29 cells inversely correlates with cell saturation density. In addition, a decrease in both free and intracellular total magnesium concentration was observed along with the induced ap...

Research paper thumbnail of Intracellular magnesium content changes during mitochondria-mediated apoptosis: in depth study of early events on mitochondrial membrane potential

Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2014

A recent study showed the antitumor activity of a new indole-derivative -MM-67 -inducing mitochon... more A recent study showed the antitumor activity of a new indole-derivative -MM-67 -inducing mitochondria-mediated apoptosis and a decrease of intracellular magnesium (Mg) concentration in HT29 colon cancer cells. Aim of this work was to assess cellular Mg levels throughout MM-67-induced apoptosis from the early to the final stage of the process and to evaluate the correlation with mitochondrial membrane potential (ΔΨm) variations. All analysis were performed by flow cytometry: ΔΨm was assessed by using mitochondrial potential sensitive dye DiOC6, while free and total intracellular cation concentrations were assessed by using the commercial probe MagFluo4-AM (Kd=4.7 mM), and the new synthesized DCHQ5 (Kd=8.3 mM), respectively. Our results evidenced that the MM67 induced apoptosis is characterized by a direct correlation between ΔΨ and free intracellular Mg content variations.

Research paper thumbnail of Magnesium intracellular content and distribution map in drug-resistant and -sensitive whole cells

Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2014

Research paper thumbnail of A novel fluorescent chemosensor allows the assessment of intracellular total magnesium in small samples

The Analyst, 2014

The present study investigated the analytical capabilities of a new fluorescent chemosensor, name... more The present study investigated the analytical capabilities of a new fluorescent chemosensor, named DCHQ5, a phenyl derivative belonging to the family of diaza-crown-hydroxyquinolines, for the quantitative assessment of total intracellular Mg content. The results obtained were compared to the analytical performances of DCHQ1 - the parent probe of the series which so far was the only suitable species for the quantitative assessment of the intracellular total magnesium and showed comparable results to atomic absorption spectroscopy. Different protocols were tested in several cell lines both by flow cytometry and by steady state fluorescence spectroscopy assays. The results obtained support the possibility to use DCHQ5 to accurately quantify the intracellular total Mg in much smaller samples than DCHQ1, also displaying an increased stable intracellular staining. These features, combined with the high fluorescence enhancement upon cation binding, and the possibility to be excited both in the UV and visible region, make DCHQ5 a valuable and versatile analytical tool for Mg assessment in biological samples.

Research paper thumbnail of Expanding the targets of the diaza-18-crown-6 hydroxyquinoline derivatives family to Zn(II) ions for intracellular sensing

Supramolecular Chemistry, 2013

ABSTRACT We have recently developed an optimised synthetic strategy for the preparation of chemos... more ABSTRACT We have recently developed an optimised synthetic strategy for the preparation of chemosensors based on the diaza-18-crown-6 hydroxyquinoline structure. This flexible approach allows to obtain a variety of substituted derivatives with improved fluorescence, metal ion binding, uptake and localisation properties. In this context, we have focused our attention on the design of specific chemosensors for intracellular Zn2+ ions, because of their important role in many biological processes. Interestingly, among them one in particular shows the properties of making it a promising candidate for effective Zn(II) ions detection in biological environments. It presents, in fact, a very low toxicity, Zn2+/Mg2+ selectivity and a very large fluorescence enhancement on complexation.

Research paper thumbnail of Quantitative Chemical Imaging of the intracellular spatial distribution of fundamental elements and light metals in single cells

Analytical Chemistry, 2014

We report a method that allows a complete quantitative characterization of whole single cells, as... more We report a method that allows a complete quantitative characterization of whole single cells, assessing the total amount of carbon, nitrogen, oxygen, sodium, and magnesium and providing submicrometer maps of element molar concentration, cell density, mass, and volume. This approach allows quantifying elements down to 10(6) atoms/μm(3). This result was obtained by applying a multimodal fusion approach that combines synchrotron radiation microscopy techniques with off-line atomic force microscopy. The method proposed permits us to find the element concentration in addition to the mass fraction and provides a deeper and more complete knowledge of cell composition. We performed measurements on LoVo human colon cancer cells sensitive (LoVo-S) and resistant (LoVo-R) to doxorubicin. The comparison of LoVo-S and LoVo-R revealed different patterns in the maps of Mg concentration with higher values within the nucleus in LoVo-R and in the perinuclear region in LoVo-S cells. This feature was not so evident for the other elements, suggesting that Mg compartmentalization could be a significant trait of the drug-resistant cells.

Research paper thumbnail of Monitoring magnesium efflux cyclic AMP-induced in HL60 cells by using a new hydroxyquinoline fluorescent chemosensor

Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2014

Cellular homeostasis of magnesium is still unclear. Several studies documented the occurrence of ... more Cellular homeostasis of magnesium is still unclear. Several studies documented the occurrence of fluxes of magnesium across the plasmamembrane within minutes from the application of metabolic or hormonal stimuli. These fluxes, however, result in limited variation of free Mg 2+ intracellular concentration and large changes in total Mg content. It has been reported that a stimulation with cyclic AMP caused a movement of total magnesium within 10 min after treatment in cardiomyocytes. In this study we tested this hypothesis in HL60 leukemic cells, not excitable but highly proliferating cell model. We evaluated Mg flux by DCHQ5, the phenyl-derivative of hydroxyquinoline fluorescent probe family. We observed a drastic decrease of intracellular total magnesium in the first 3 min. We also verified that at least 10% of the total intracellular amount of magnesium moved in the supernatant of stimulated cells.