Multi-targets of antimicrobial photodynamic therapy mediated by erythrosine against Staphylococcus aureus identified by proteomic approach.

Staphylococcus aureus is a global challenge to the clinical field and food industry. Therefore, the development of antimicrobial photodynamic therapy (aPDT) has become one of the valuable methods to control this pathogen. The antibacterial activity of photoinactivation by erythrosine (Ery) against S. aureus has been reported, but its modes of action are unclear. This study aimed to employ a proteomic approach to analyze modes of action of Ery-aPDT against S. aureus. We determined the antibacterial effect by Ery-aPDT assays, quantified reactive oxygen species (ROS) and injury to the cell membrane, and determined protein expression using a proteomic approach combined with bioinformatic tools. Ery-aPDT was effective in reducing S. aureus to undetectable levels. In addition, the increment of ROS accompanied the increase in the reduction of cell viability, and damage to cellular membranes was shown by sublethal injury. In proteomic analysis, we found 17 differentially expressed proteins. These proteins revealed changes mainly associated with defense to oxidative stress, energy metabolism, translation, and protein biosynthesis. Thus, these results suggest that the effectiveness of Ery-aPDT is due to multi-targets in the bacterial cell that cause the death of S. aureus.

"Antibacterial effect and possible mechanism of action of 1,3,4-oxadiazole in Staphylococcus aureus".

Staphylococcus aureus is one of the main etiological agents causing foodborne diseases, and the development of new antibacterial agents is urgent. This study evaluated the antibacterial activity and the possible mechanism of action of the 1,3,4-oxadiazole LMM6 against S. aureus. The minimum inhibitory concentration (MIC) of LMM6 ranged from 1.95 to 7.81 µg ml-1. The time-kill assay showed that 48-h treatment at 1× to 8× MIC reduced S. aureus by 4 log colony forming unit (CFU), indicating a bacteriostatic effect. Regarding the possible mechanism of action of LMM6, there was accumulation of reactive oxygen species (ROS) and an increase in the absorption of crystal violet (∼50%) by the cells treated with LMM6 at 1× and 2× MIC for 6-12 h. In addition, there was increased propidium iodide uptake (∼84%) after exposure to LMM6 for 12 h at 2× MIC. After 48 h of treatment, 100% of bacteria had been injured. Scanning electron microscopy observations demonstrated that LMM6-treated cells were smaller compared with the untreated group. LMM6 exhibited bacteriostatic activity and its mechanism of action involves increase of intracellular ROS and disturbance of the cell membrane, which can be considered a key target for controlling the growth of S. aureus.

Proteomic Investigation over the Antimicrobial Photodynamic Therapy Mediated by Rose Bengal Against Staphylococcus aureus.

In order, understanding the antimicrobial action of photodynamic therapy and how this technique can contribute to its application in the control of pathogens. The objective of the study was to employ a proteomic approach to investigate the protein profile of Staphylococcus aureus after antimicrobial photodynamic therapy mediated by rose bengal (RB-aPDT). S. aureus was treated with RB (10 nmoL L-1 ) and illuminated with green LED (0.17 J cm-2 ) for cell viability evaluation. Afterward, proteomic analysis was employed for protein identification and bioinformatic tools to classify the differentially expressed proteins. The reduction in S. aureus after photoinactivation was ~2.5 log CFU mL-1 . A total of 12 proteins (four up-regulated and eight down-regulated) correspond exclusively to alteration by RB-aPDT. Functionally, these proteins are distributed in protein binding, structural constituent of ribosome, proton transmembrane transporter activity and ATPase activity. The effects of photodamage include alterations of levels of several proteins resulting in an activated stress response, altered membrane potential and effects on energy metabolism. These 12 proteins required the presence of both light and RB suggesting a unique response to photodynamic effects. The information about this technique contributes valuable insights into bacterial mechanisms and the mode of action of photodynamic therapy.

Antidepressive and antinociceptive effects of ethanolic extract and fruticuline A from Salvia lachnostachys Benth leaves on rodents.

OBJECTIVES: This study investigated the antidepressant and antinociceptive effects of ethanolic extract (SLEE) and pure fruticuline A obtained from Salvia lachnostachys leaves on rats and mice. METHODS: In this study, SLEE (100 mg/kg, p.o. route) was evaluated for its effects on spared nerve injury (SNI) in rats. The animals were submitted to mechanical sensitivity, forced swim (FST) and cold sensitivity tests 10 and 15 days after surgery. SLEE (100 mg/kg, p.o.) and fruticuline A (3 mg/kg, p.o.) were also evaluated with respect to nociceptive behavior induced by formalin. In addition, clonidine-induced depressive-like behavior was also analyzed. RESULTS: The oral administration of SLEE for up to 15 days and the subcutaneous injection of 10 mg/kg of ketamine (positive control) significantly inhibited SNI-induced mechanical hyperalgesia and decreased immobility in the FST. On the 15th day of oral treatment, SLEE prevented the SNI-induced increase in cold sensitivity. In the formalin test, SLEE and fruticuline A significantly reduced the frequency of paw licking during the first and second phases and decreased the formation of edema. In locomotor analysis (open field test without clonidine treatment), SLEE and fruticuline A did not alter the response. SLEE and fruticuline A significantly attenuated clonidine-induced suppression of spontaneous locomotor activity (squares invaded and licking) and emotionality (grooming and freezing) compared with controls, similar to the naive group. CONCLUSION: SLEE exhibits antihyperalgesic, antidepressant, and antinociceptive effects, and fruticuline A appears to be at least partly responsible for the effects of SLEE. Together, these results demonstrate the antidepressive effects of SLEE and fruticuline A and indicate that both derivatives obtained from S. lachnostachys act against spontaneous neuropathic pain.