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Highlights • First work using resveratrol as a photosensitizer in antimicrobial photodynamic therapy. • Photoactivated resveratrol has a modified structure to resveratrone and produces singlet oxygen. • Photoactivation of resveatrol in the air pocket model in mice led to an increase in the production of TNF-α and IL-17A, with in vivo bacterial clearance. Abstract Background Among the pathogens, Staphylococcus aureus is the main causative agent of bacterial diseases in the world. In this context, antimicrobial photodynamic therapy (aPDT) appears as a promising tool by means of microbial inactivation with the use of light. aPDT is applied in treatments involving photosensitizers capable of generating oxygen free radicals. Thus, this work proposes the use of resveratrol as a photosensitizer. Methods In vitro tests were performed to determine the antibacterial activity of photoactivated resveratrol with blue LED light, as well as uric acid experiments for verification of singlet oxygen formation. Possible resveratrol structural changes were evaluated by HPLC. In the in vivo assays, the air pouch model was performed in mice for antimicrobial activity and cytokine production. Results The photoactivated resveratrol exhibited an increase in its antibacterial action and it is possibly brought about by the singlet oxygen formation. In the air pouch model, TNF-α and IL-17A cytokines were produced, diminishing the bacterial load, and consequently, reducing inflammation after 24 h of infection. Cellular number decrease in the inflammatory environment was associated with resolution of inflammation along with greater IL-10 production. Conclusion It is the first time that resveratrol has been associated with aPDT. It was demonstrated in this work that resveratrol activated by blue LED light can be a promising photosensitizer. This compound, after the light stimulus, produces singlet oxygen, in addition to having effects on the immune system triggering TNF-α and IL-17A production, aiding in the clearance of several bacteria, including S. aureus. [ABSTRACT FROM AUTHOR]

Female individuals of Hyphessobrycon eques were exposed to Diflubenzuron (Dimilin ® ) in order to determine whether exposure to sublethal levels of this insecticide causes changes in gill morphology. Fish were exposed to 0.01, 0.1 and 1.0 mg L −1 for 96 h and 17 days and then submitted to pathological and histometric evaluation. Pathological lesions, such as hyperplasia, lamellar fusion, vascular congestion, secondary lamellar disarray, vasodilatation, hemorrhage and increased lamellar epithelium, were significantly more common in the gills of fish exposed to Dimilin ® than the control. Histometric analysis documented significant changes in blood vessel diameter, primary lamellae width and secondary lamellae length, and the appearance of hemorrhage foci in all concentrations tested. Even at low Dimilin ® concentrations, the histopathological alteration index was mild to moderate, thereby indicating that the function of this tissue was compromised. These findings indicate that indiscriminate use of Dimilin ® can adversely affect the structural integrity of the gills of H. eques , which can cause numerous problems for fish farming systems. [ABSTRACT FROM AUTHOR]