In Vitro Photodynamic Inactivation of Plant-Pathogenic Fungi Colletotrichum acutatum and Colletotrichum gloeosporioides with Novel Phenothiazinium Photosensitizers

Photodynamic treatment with phenothiazinium photosensitizers kills both ungerminated and germinated microconidia of the pathogenic fungi Fusarium oxysporum, Fusarium moniliforme and Fusarium solani

“…Study using Sudan III and FM4-64 showed that NMBN has affinity for lipid bodies and small vesicles present in the cytoplasm of the conidia of Colletotrichum acutatum [31]. The PS entry and accumulation occurred only in the contact with the ungerminated and germinated microconidia and were independent of red light exposure.…”

“…Although the accumulation of S137 was not observed in any structure inside the germlings, APDT with S137 at 100 µM caused the formation of large vesicles in the cytoplasm of the F. oxysporum and F. solani (see Fig 4 and 6). It was previously observed that treatment with S137 caused cytoplasmic disorganization and formation of large vesicles in the cytoplasm of conidia of C. acutatum [31]. The disorganization of membranous cytoplasmic vesicles might be the reason for the higher dark toxicity of S137.…”

“…The integrated irradiance (570 to 670 nm) was 9.8 mW cm -2 . The determination of optimal conditions for the APDT with the phenothiazinium PS MB, TBO, NMBN and S137 were performed as previously described [31,33]. MIC-based experiments were performed in 96-well flat-bottomed microtiter plates (TPP, Switzerland).…”

“…Usually, the chosen PS accumulates preferentially in the target cell or has affinity for the microbial cell surface; the light should be at the appropriate wavelength to activate the photochemical process, which in the presence of molecular oxygen produces several reactive oxygen species (ROS), such as singlet oxygen [26,28,29]. ROS can cause oxidative damage to practically all biomolecules (proteins, lipids, nucleic acids and carbohydrates) leading to death of the fungal cell without causing significant damage to the host cell [26,30,31]. The multi-targeting feature of ROS reduces the chance of selecting resistant microorganisms.…”

In vitro susceptibilities of Neoscytalidium spp. sequence types to antifungal agents and antimicrobial photodynamic treatment with phenothiazinium photosensitizers

“…Three replicate dishes were prepared for each treatment in each experiment and three independent experiments were performed. The effect of the different treatments was calculated as previously described [53].…”