In vitro Studies of Antitumor Effect, Toxicity/Cytotoxicity and Skin Permeation/Retention of a Green Fluorescence Pyrene-based Dye for PDT Application.

Photosensitizers (PS) are compounds that can generate reactive oxygen species under irradiation of appropriate light and are widely used in photodynamic therapy (PDT). Currently, topical PDT is an effective treatment for several skin diseases, including bacterial infections, fungal mycoses and psoriasis. In addition, PDT is also used to treat nonmelanoma skin cancer and can be a potential tool for melanoma, associated with other treatments. In this work, we evaluated the antitumor photoactivity of a new pyrene-based PS (TPPy) by using the murine melanoma cell line (B16F10). The in vitro permeation/retention tests in porcine ear skin were also performed in order to evaluate the potential application of the PS for topical use in skin cancer. Moreover, to determine the toxicity in vivo, we used the Galleria mellonella as an alternative animal model of study. The results showed that TPPy is a promising PS for application in PDT, with potential antitumor photoactivity (IC50 6.5 µmol L-1 ), absence of toxicity in the G. mellonella model at higher concentration (70.0 mmol L-1 ) and the accumulation tendency in the epidermis plus dermis sites (165.20 ± 4.12 ng cm-2 ).

A Simple Isoniazid-Based N-Acylhydrazone Derivative as Potential Fluorogenic Probe for Zn2+ Ions.

This study evaluated three isoniazid-based N-acylhydrazone derivatives (HL1, HL2, and HL3) varying their substituting groups (-H, -N(CH3)2, and -NO2) as potential chemosensors for Zn2+ ions. To this end, the absorption and emission properties of these derivatives were investigated in the presence of Zn2+ ions. Results point to the derivative HL2 as the best chemosensor for Zn2+ ions because of its comparatively higher sensitivity. The color of this derivative changed from colorless to strong yellow with zinc addition, as indicated by the shift in UV-vis spectrum. Moreover, HL2 was the only derivative to emit fluorescence in the presence of Zn2+ ions, attributable to PET inhibition and bond isomerization promoted by coordination with this metal. LOD, LOQ, and binding constant values for HL2 + Zn2+ were 0.43 µmol.l-1, 0.93 µmol.l-1, and 5.04 × 1012 l.mol-1, respectively. The fluorescence of HL2 with other metal ions (Fe3+, Mg2+, Na+, Cd2+, Cu2+, Co2+, Ni2+, Ca2+, and K+) was also investigated. Zn2+ yielded the best result without Cd2+ interferences. Job's Plot showed that the stoichiometric ratio of the complex formed by HL2 and Zn2+ ions is 2:1 (ligand:metal). The strip test with adsorbed HL2 indicated fluorescence in the presence of zinc ions under 365 nm UV irradiation.