Avaliação in vitro da ação fotodinâmica antimicrobiana e antitumoral do complexo cis-[Ru(phen)2(pPDIp)]2+

Abstract

Photodynamic therapy (PDT) activates a photosensitizer by visible or infrared light to generate cytotoxic oxygen species that lead to cell death. PDT is generally used in applications in superficial lesions and can be used both in the treatment of skin cancer and in infections caused by microorganisms. Skin cancer can be distinguished into melanoma and non-melanoma, both of which affect several layers of the dermis, and melanoma cancer is more aggressive because it can metastasize and affect other organs. From infections caused by fungi, sporotrichosis and candidosis are considered a public health problem in Brazil. Sporotrichosis is caused by fungi of the pathogenic Sporothrix clade and is characterized by the formation of wounds on the skin, which is also a characteristic of infections caused by Candida species. This study investigates the photosensitizing efficiency of the Ru(phen)2(pPDIp)(PF6)2 complex, RupPDIp, against Sporothrix brasiliensis and Candida albicans. And also, against human melanoma cells (A375) and melanocytes (NGM). To assess the antimicrobial photodynamic action, the RupPDIp complex was tested with irradiation at 450 nm (blue light - 36 J/cm²) and 525 nm (green light - 25.2 J/cm²) in the concentration range of 0.05-20 µM. Control groups were performed in the absence/presence of RupPDIp and irradiation and compared by cell count. For tests on human melanocyte and melanoma cells, a light source at 415 nm (blue light) was used, delivering doses of 1.76 J/cm² and 2.12 J/cm². The viability of cells after PDT was revealed by the MTT method and compared with control groups containing the photosensitizer in the absence of irradiation. Under blue light irradiation (450 nm), the complex was able to completely inhibit the growth of S. brasiliensis with concentrations <5.0 μM. When irradiated in green light (525 nm) showed better results, completely inhibiting the growth of S. brasiliensis with concentrations <0.5 μM. For C. albicans, the concentration required for total fungal inhibition was 0.5 μM at 450 nm and 0.05 μM at 525 nm. It also proved to be a good photosensitizer against melanoma cells, presenting IC50 = 1.3 μM and for melanocyte cells it presents IC50 = 10 μM when a dose of 2.12 J/cm² was delivered. The RupPDIp complex has a good photodynamic action on melanoma cells, without showing excessive damage to healthy melanocyte cells. It is also a promising photosensitizer against microorganisms, completely eliminating colonies of S. brasiliensis and C. albicans at different wavelengths.