A pH-Sensitive Fluorescent Chemosensor Turn-On Based in a Salen Iron (III) Complex: Synthesis, Photophysical Properties, and Live-Cell Imaging Application.

pH regulation is essential to allow normal cell function, and their imbalance is associated with different pathologic situations, including cancer. In this study, we present the synthesis of 2-(((2-aminoethyl)imino)methyl)phenol (HL1) and the iron (III) complex (Fe(L1)2Br, (C1)), confirmed by X-ray diffraction analysis. The absorption and emission properties of complex C1 were assessed in the presence and absence of different physiologically relevant analytes, finding a fluorescent turn-on when OH- was added. So, we determined the limit of detection (LOD = 3.97 × 10-9 M), stoichiometry (1:1), and association constant (Kas = 5.86 × 103 M-1). Using DFT calculations, we proposed a spontaneous decomposition mechanism for C1. After characterization, complex C1 was evaluated as an intracellular pH chemosensor on the human primary gastric adenocarcinoma (AGS) and non-tumoral gastric epithelia (GES-1) cell lines, finding fluorescent signal activation in the latter when compared to AGS cells due to the lower intracellular pH of AGS cells caused by the increased metabolic rate. However, when complex C1 was used on metastatic cancer cell lines (MKN-45 and MKN-74), a fluorescent turn-on was observed in both cell lines because the intracellular lactate amount increased. Our results could provide insights about the application of complex C1 as a metabolic probe to be used in cancer cell imaging.

Synthesis, characterisation, crystal structure and antimicrobial evaluation of novel 6-alkoxyergosta-4,6,8(14),22-tetraen-3-one derived from natural ergosta-5,7,22-trien-3ß-ol.

In this study, we report a facile transformation starting from 5α-hydroxyergosta-7,22-dien-3,6-dione (1) to afford two novel compounds: 6-methoxyergosta-4,6,8(14),22-tetraen-3-one (2) and 6-ethoxyergosta-4,6,8(14),22-tetraen-3-one (3) using alcoholic acid catalysis. Their structures were elucidated using NMR experiments, FT-IR, MS and X-ray analysis. These compounds were evaluated for antibacterial activity using the disk and broth diffusion test. In those tests, compound 3 was found to be the most significant antibacterial agent. In general, compounds 1-3 showed inhibition zone in the range of 7.00-12.3 mm for S. aureus and S. mutans, meanwhile for Gram-negative bacteria E. coli and Pseudomonas sp. was found to be in the range of 7.00-8.00 mm. For the most active, compound 3, MIC was significantly lower than that reported for ergosterol, in a value of 160 µg/mL. Overall, these compounds were more active than their natural precursor.

A novel type of organometallic 2-R-2,4-dihydro-1H-3,1-benzoxazine with R = [M(η5-C5H4)(CO)3] (M = Re or Mn) units. Experimental and computational studies of the effect of substituent R on ring-chain tautomerism.

The syntheses, characterization, X-ray crystal structures, electrochemical properties and anticancer and antichagasic activities of the first examples of 2-substituted 2,4-dihydro-1H-3,1-benzoxazines with half-sandwich organometallic arrays, [M(η5-C5H4)(CO)3] (M = Re or Mn), at position-2 are described. Experimental and computational studies based on DFT calculations on the open forms [Schiff bases of general formulae R-CH[double bond, length as m-dash]N-C6H4-2-CH2OH] (5), with R = ferrocenyl (a), phenyl (b), cyrhetrenyl (c) or cymantrenyl (d), and their tautomeric forms (2-substituted 2,4-dihydro-1H-3,1 benzoxazines) have allowed us to establish the influence of substituents a-d and solvents on: (a) the extent of tautomeric equilibria (5a-5d) ↔ (6a-6d) and (b) their electrochemical properties and the electronic distribution on the open and closed forms. Despite the formal similarity between 6c and 6d, their anticancer and antiparasitic activities are markedly different. Compound 6d is inactive in the HCT116, MDA-MB231 and MCF7 cancer cell lines, but 6c shows moderate activity in the latter cell line, while the Mn(i) complex (6d) is a more potent anti-Trypanosoma cruzi agent than its Re(i) analogue (6c).