Oxidative foliar photo-necrosis produced by the bacteria Pseudomonas cedrina

BACKGROUND: Although bioactive metabolites capable of causing oxidative photo-necrosis in plant tissues have been identified in fungi, little is known about this type of mechanism in bacteria. These metabolites act as photosensitizers that generate reactive oxygen species (ROS) capable of causing damage to cells. In addition, these metabolites can pass into an energetically excited state when they receive some luminous stimulus, a condition in which they interact with other molecules present in the environment, such as molecular oxygen (O2), also known as triplet oxygen (3 O2), generating ROS. RESULTS: The suspension of the bacterial culture of Pseudomonas cedrina was shown to produce foliar necrosis in papaya leaves (Carica papaya L.) only in the presence of sunlight, which is evidence of photosensitizing mechanisms that generate singlet oxygen (1 O2). From the chemical study of extracts obtained from this bacteria, 3-(4-(2-carboxipropyl) phenyl) but-2-enoic acid (1) was isolated. This compound, in the presence of light and triplet oxygen (3 O2), was able to oxidize ergosterol to its peroxide, since it acted as a photosensitizer producing 1 O2, with which it was corroborated that a photosensitization reaction occurs, mechanism by which this bacterium could prove to cause oxidative foliar photo-necrosis. CONCLUSIONS: P. cedrina was able to induce oxidative foliar photo-necrosis because of its potential ability to produce photosensitizing metabolites that generate singlet oxygen in the plants it colonizes. Based on the above, it can be proposed that some bacteria can cause oxidative foliar photo-necrosis as an important mechanism in the pathogenesis of host species.

Effects of Blending Oil of Lavender and Thyme on Oxidative Stress, Immunity, and Skin Condition in Atopic Dermatitis Induced Mice

PURPOSE: The purpose of this study was to evaluate the effects of essential oil on oxidative stress, immunity, and skin condition in atopic dermatitis (AD) induced mice. METHODS: This study was a 3x3 factorial design. Factors were oil type (Lavender, Thyme, and 2:1 mixture of lavender and thyme oil [blending oil]) and treatment period (0 day, 7 days, and 21 days). The samples were 45 mice with AD and randomly assigned to nine groups of five mice per group. The dependent variables such as superoxide radical, IgE, degranulated mast cells, and epidermal thickness were measured. Data were collected from February to April in 2014. Descriptive statistics, One-way ANOVA, Two-way ANOVA, and Tukey's HSD test were performed using the SPSS WIN 20.0 program. RESULTS: Dependent variables were not statistically significantly different by the three oil types (p >.05). Essential oils such as lavender, thyme, and blending oil were all effective in reducing AD symptoms and especially 2:1 blending oil were most effective. There were statistically significant differences by the three treatment periods in all dependent variables (p <.001). There were statistically significant interactions between oil types and treatment periods in all dependent variables (p <.01). For decreasing superoxide radical, degranulated mast cells, and epidermal thickness, 2:1 mixed oil should be applied for at least 21 days. Otherwise to reduce IgE, 2:1 mixed oil should be used for at least 7 days. CONCLUSION: These findings provide bases for developing effective interventions for AD patients to manage their AD symptoms.