Juçara Fruit (Euterpe Edulis Martius) Valorization Combining Emergent Extraction Technologies and Aqueous Solutions of Alkanediols.

Anthocyanins from juçara fruits were extracted by pressurized liquid extraction (PLE) or ultrasound-assisted extraction (UAE), using aqueous solutions of 1,2-alkanediols and glycerol ethers as biobased solvents. The PLE (100 bar, 13 min, 1 mL/min flow rate) in the optimal extraction conditions originated 23.1 mganthocyanins·gdry biomass-1. On the other hand, the UAE was 10 min long, and the optimal conditions using 1,2-propanediol were 42.6 wt%, 160 W, and pH 7.0, leading to 50 mganthocyanins·gdry biomass-1. Extractions at the UAE optimized conditions, with aqueous solutions of five different 1,2-alkanediols and three glycerol ethers were performed, and compared to water and ethanolic extracts. The biobased solvent solutions presented anthocyanin yields up to 33% higher than water, and were shown to be as efficient as ethanol/water, but generated extracts with higher antioxidant capacity. The anthocyanin-rich extract of juçara, obtained with 1,2-propanediol, was used in the production of a natural soap and incorporated into a cream, showing that the addition of the juçara extract resulted in an antioxidant capacity in both products.

Sustainable extraction of antioxidants from out-of-caliber kiwifruits.

Valorisation of discarded kiwifruits is proposed by extracting bioactive compounds using sustainable solvents namely deep eutectic solvents (DES). A screening of fifteen DES and several hydrogen bonding donor solvents was carried out. Extraction efficiency was measured in terms of antioxidant activity using DPPH and FRAP tests. The influence of solvents characteristics in particular DES structure, presence of ethanol or water, and pH of DES/water mixture on the antioxidant properties of the extracts was studied. Results show that kiwi peels extracts obtained with DES based on carboxylic acids exhibit enhanced antioxidant activity compared to conventional solvents and alcohol-based DES with a maximum DPPH scavenging activity of 42.0 mg TE/g DW. Glycerol or ethylene glycol are also efficient at extracting antioxidant compounds with DPPH scavenging activity of 33.1 and 36.7 mg TE/g DW. Finally, a chemical analysis of extracts using HPTLC revealed that most active compounds extracted are polyphenolic compounds, presumably tannins.

Heterobinuclear copper(II)­platinum(II) complexes with oxindolimine ligands: Interactions with DNA, and inhibition of kinase and alkaline phosphatase proteins.

Two mononuclear copper(II) compounds, [Cu(isad)(H2O)Cl]Cl 1 and [Cu(isah)(H2O)Cl]Cl 2, and its corresponding heterobinuclear species containing also platinum(II), [CuCl(isad)Pt(NH3)Cl2] 3 and [CuCl(isah)Pt(NH3)Cl2] 4 (where isad and isah are oxindolimine ligands, (E)-3-(2-(3-aminopropylamino)ethylimino)indolin-2-one, and (E)-3-(3-amino-2-hydroxypropylimino)indolin-2-one, respectively), have been previously synthesized and characterized by different spectroscopic techniques in our laboratory. Cytotoxicity assays performed with B16F10 murine cancer cells, and MES-SA human uterine sarcoma cells, showed IC50 values lower or in the same order of cisplatin. Herein, in order to better elucidate their probable modes of action, possible interaction and damage to DNA, as well as their effect on the activity of crucial proteins were verified. Both mononuclear complexes and the binuclear compound 4 displayed a significant cleavage activity toward plasmid DNA, while compound 3 tends to protect DNA from oxidative damage, avoiding degradation. Complementary experiments indicated a significant inhibition activity toward cyclin-dependent kinase (CDK1/cyclinB) activity in the phosphorylation of histone H1, and only moderate inhibition concerning alkaline phosphatase. Results also revealed that the reactivity is reliant on the ligand structure and on the nature of the metal present, in a synergistic effect. Simulation studies complemented and supported our results, indicating different bindings of the binuclear compounds to DNA. Therefore, the verified cytotoxicity of these complexes comprises multiple modes of action, including modification of DNA conformation, scission of DNA strands by reactive oxygen species, and inhibition of selected proteins that are crucial to the cellular cycle.

Reactivity of dinuclear copper(II) complexes towards melanoma cells: Correlation with its stability, tyrosinase mimicking and nuclease activity.

In this work, the influence of two new dinuclear copper(II) complexes in the viability of melanoma cells (B16F10 and TM1MNG3) was investigated, with the aim of verifying possible correlations between their cytotoxicity and their structure. One of the complexes had a polydentate dinucleating amine-imine ligand (complex 2), and the other a tridentate imine and a diamine-bridging ligand (complex 4). The analogous mononuclear copper(II) species (complexes 1 and 3, respectively) were also prepared for comparative studies. Crystal structure determination of complex 2 indicated a square-based pyramidal geometry around each copper, coordinated to three N atoms from the ligand and the remaining sites being occupied by either solvent molecules or counter-ions. Complex 4 has a tetragonal geometry. Interactions of these complexes with human albumin protein (HSA) allowed an estimation of their relative stabilities. Complementary studies of their reactivity towards DNA indicated that all of them are able of causing significant oxidative damage, with single and double strand cleavages, in the presence of hydrogen peroxide. However, nuclease activity of the dinuclear species was very similar and much higher than that of the corresponding mononuclear compounds. Although complex 2, with a more flexible structure, exhibits a much higher tyrosinase activity than complex 4, having a more rigid environment around the metal ion, both complexes showed comparable cytotoxicity towards melanoma cells. Corresponding mononuclear complexes showed to be remarkably less reactive as tyrosinase mimics as well as cytotoxic agents. Moreover, the dinuclear complexes showed higher cytotoxicity towards more melanogenic cells. The obtained results indicated that the structure of these species is decisive for its activity towards the malignant tumor cells tested.

The isatin-Schiff base copper(II) complex Cu(isaepy)2 acts as delocalized lipophilic cation, yields widespread mitochondrial oxidative damage and induces AMP-activated protein kinase-dependent apoptosis.

We previously demonstrated that Bis[(2-oxindol-3-ylimino)-2-(2-aminoethyl)pyridine-N,N']copper(II) [Cu(isaepy)(2)] was an efficient inducer of the apoptotic mitochondrial pathway. Here, we deeply dissect the mechanisms underlying the ability of Cu(isaepy)(2) to cause mitochondriotoxicity. In particular, we demonstrate that Cu(isaepy)(2) increases NADH-dependent oxygen consumption of isolated mitochondria and that this phenomenon is associated with oxy-radical production and insensitive to adenosine diphosphate. These data indicate that Cu(isaepy)(2) behaves as an uncoupler and this property is also confirmed in cell systems. Particularly, SH-SY5Y cells show: (i) an early loss of mitochondrial transmembrane potential; (ii) a decrease in the expression levels of respiratory complex components and (iii) a significant adenosine triphosphate (ATP) decrement. The causative energetic impairment mediated by Cu(isaepy)(2) in apoptosis is confirmed by experiments carried out with rho(0) cells, or by glucose supplementation, where cell death is significantly inhibited. Moreover, gastric and cervix carcinoma AGS and HeLa cells, which rely most of their ATP production on oxidative phosphorylation, show a marked sensitivity toward Cu(isaepy)(2). Adenosine monophosphate-activated protein kinase (AMPK), which is activated by events increasing the adenosine monophosphate:ATP ratio, is deeply involved in the apoptotic process because the overexpression of its dominant/negative form completely abolishes cell death. Upon glucose supplementation, AMPK is not activated, confirming its role as fuel-sensing enzyme that positively responds to Cu(isaepy)(2)-mediated energetic impairment by committing cells to apoptosis. Overall, data obtained indicate that Cu(isaepy)(2) behaves as delocalized lipophilic cation and induces mitochondrial-sited reactive oxygen species production. This event results in mitochondrial dysfunction and ATP decrease, which in turn triggers AMPK-dependent apoptosis.