Evaluation of Biological Activities of Quinone-4-oxoquinoline Derivatives against Pathogens of Clinical Importance.

BACKGROUND: Microbial resistance has become a worldwide public health problem and may lead to morbidity and mortality in affected patients. OBJECTIVES: Therefore, this work aimed to evaluate the antibacterial activity of quinone-4- oxoquinoline derivatives. METHODS: These derivatives were evaluated against Gram-positive and Gram-negative bacteria by their antibacterial activity, anti-biofilm, and hemolytic activities and in silico assays. RESULTS: The quinone-4-oxoquinoline derivatives presented broad-spectrum antibacterial activities and, in some cases, were more active than commercially available reference drugs. These compounds also inhibited bacterial adhesion, and the assays revealed seven non-hemolytic derivatives. The derivatives seem to cause damage to the bacterial cell membrane, and those containing the carboxyl group at the C-3 position of the 4-quinolonic nucleus were more active than those containing a carboxyethyl group. CONCLUSION: The isoquinoline-5,8-dione nucleus also favored antimicrobial activity. The study showed that the target of the derivatives must be a non-conventional hydrophobic allosteric binding pocket on the DNA gyrase enzyme.

Molecular modeling as a design tool for sunscreen candidates: a case study of bemotrizinol.

Sunscreen-based photoprotection is an important strategy to prevent photoaging and skin cancer. Among the effective and modern sunscreens, triazine compounds are known as an important class based on their physical-chemical properties, such as photostability and UV broad-spectrum absorption (UVA and UVB). Molecular modeling and quantum mechanical calculations approaches can be helpful to orientate the design of sunscreens. Herein, a case study is presented to demonstrate the importance of the molecular modeling as a design tool for promising sunscreen candidates based on the synthesis research previously described of bemotrizinol, a broad-spectrum photostable organic UV filter present in many sunscreens products. Time-dependent density functional theory (TD-DFT) calculations performed in gas phase on the isolated organic UV filters proved to reproduce the experimental UV absorption, guiding the choice of the most efficient candidate as sunscreen. The present work highlights the importance of molecular modeling as an effective tool to support synthesis research, increasing the possibility of obtaining promising compounds with reduced costs and effluent production. Graphical abstractA case study to demonstrate the importance of the molecular modeling as a design tool for promising sunscreen candidates is presented. The method proved to be a valuable tool to reproduce the experimental UV absorption and to determinate the most efficient molecule as sunscreen among the candidates.