Anti-MME monoclonal antibody, clone 67D7

Ethnopharmacological relevance: The development of new inhibitors of bacterial virulence factors from natural origin has recently received significant attention. Callistemon citrinus Skeels is an important plant of great medicinal value. Its antimicrobial activity is well documented. Although several compounds were isolated from this plant, the actual bioactive compounds responsible for its antimicrobial activity are still unrevealed. Aim of the study: To evaluate the effect of C. citrinus crude extract and isolated compounds on methicillin-resistant and sensitive Staphylococcus aureus. Materials and methods: The methylene chloride-methanol extract (MME) of C. citrinus leaves was prepared by Soxhlet apparatus. Biologically guided fractionation of MME was accomplished using several normal and reversed phase silica gel columns. The potency of MME and its isolated compounds against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) was evaluated. In addition, the mechanism of resistance was studied using three virulence factors; antibiofilm activity, inhibition of staphyloxanthin biosynthesis and effect on acid tolerance. Ultrastructural changes in MRSA and MSSA were observed by TEM to understand mode of action of these compounds. Results: Pulverulentone A (C1), 8- desmethyl eucalyptin (C2) and eucalyptin (C3) were isolated from the most bioactive fraction of MME. Confocal scanning laser microscopy images revealed that C. citrinus isolated compounds destroyed the intact architecture of biofilm, thickness and reduced its biomass. Pulverulentone A (C1) showed the most potent anti-biofilm activity up to 71% and 62.3% against MRSA and MSSA, respectively. It also exhibited the highest inhibition of staphyloxanthin biosynthesis of MRSA and MSSA by 55.6% and 54.5%, respectively. The bacterial cell membrane was compromised, losing its integrity and releasing important cellular constituents when exposed to C1-C3 Conclusions: C. citrinus phenolics and acylphloroglucinols may serve as potential source of plant-based antibacterials and thus could be implicated to control MRSA biofilm formation.

Accumulating evidence suggests that epigenetic mechanisms play an essential role in the formation and maintenance of memory as well as addiction. In this study, we examined the role of D1-like dopamine receptor (D1 DR) on spatial memory in the offspring of morphine-abstinent rats. Adult male and female rats received morphine orally for 21 days and were drug-free for ten days. The rats were prepared to mate and the offspring were divided into four groups: offspring of drug-naive parents, offspring of maternal morphine-exposed, offspring of paternal morphine-exposed, and PME + MME group. Saline or SCH23390 was injected into the hippocampus and prefrontal (PFC), and the Morris Water Maze task was performed. Afterward, the rats were sacrificed, and phosphorylated-CREB (p-CREB) was assessed using Western blotting. The data obtained from saline-treated offspring indicated that spatial memory was deteriorated in the offspring of morphine-abstinent parents compared with the control which improved when they received SCH23390. The level of p-CREB also decreased in the hippocampus, while it increased in the PFC and hippocampus after SCH23390 administration. Our results suggested that morphine exposure before conception could induce impairment in spatial memory in the offspring. Since D1 DR was up-regulated in the PFC of the offspring, blocking D1 DR led to improved memory deficit in the offspring of morphine-abstinent rats. Improvement of memory is correlated to p-CREB level in the hippocampus and PFC. (C) 2019 Elsevier B.V. and Japan Neuroscience Society. All rights reserved.