Department of Botany and Microbiology, Faculty of Science (Boys), Al-Azhar University, Nasr City, Cairo, 11884, Egypt.
Department of Pharmacognosy, Faculty of Pharmacy, Cairo University, Kasr el-Aini street, Cairo, 11562, Egypt.
J Ethnopharmacol. 2020 May 23;254:112669. doi: 10.1016/j.jep.2020.112669. Epub 2020 Feb 20.
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.
To evaluate the effect of C. citrinus crude extract and isolated compounds on methicillin-resistant and sensitive Staphylococcus aureus.
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.
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.
最近，从天然来源开发新的细菌毒力因子抑制剂受到了广泛关注。金蒲桃（Callistemon citrinus Skeels）是一种具有重要药用价值的重要植物。其抗菌活性已有相关记载。尽管从这种植物中分离出了几种化合物，但负责其抗菌活性的实际生物活性化合物仍未被揭示。
评估金蒲桃粗提取物和分离化合物对耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）的影响。
通过索氏提取器从金蒲桃叶中制备二氯甲烷-甲醇提取物（MME）。使用几种正相和反相硅胶柱对 MME 进行生物导向分离。评估 MME 及其分离化合物对耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）的效力。此外，还通过三种毒力因子（抗生物膜活性、抑制金葡素生物合成和耐酸能力的影响）研究了耐药机制。通过 TEM 观察 MRSA 和 MSSA 的超微结构变化，以了解这些化合物的作用方式。
从 MME 最具生物活性的部分分离出了 pulverulentone A（C1）、8-去甲桉叶素（C2）和桉叶素（C3）。共聚焦扫描激光显微镜图像显示，金蒲桃分离化合物破坏了生物膜的完整结构、厚度并减少了其生物量。 pulverulentone A（C1）对 MRSA 和 MSSA 的抗生物膜活性最强，分别达到 71%和 62.3%。它对 MRSA 和 MSSA 的金葡素生物合成的抑制作用也最高，分别为 55.6%和 54.5%。当暴露于 C1-C3 时，细菌细胞膜受损，完整性丧失，释放出重要的细胞成分。
金蒲桃酚类和酰基间苯三酚可能是植物类抗菌剂的潜在来源，因此可用于控制 MRSA 生物膜的形成。
