Gemiarto Adrian Tandhyka, Ninyio Nathaniel Nyakaat, Lee Siew Wei, Logis Joko, Fatima Ayesha, Chan Eric Wei Chiang, Lim Crystale Siew Ying
Department of Biotechnology, Faculty of Applied Sciences, UCSI University, No 1, Jalan Menara Gading, UCSI Heights, 56000, Cheras, Kuala Lumpur, Malaysia.
Antonie Van Leeuwenhoek. 2015 Aug;108(2):491-504. doi: 10.1007/s10482-015-0503-6. Epub 2015 Jun 10.
The emergence of antibiotic-resistant bacterial pathogens, especially Gram-negative bacteria, has driven investigations into suppressing bacterial virulence via quorum sensing (QS) inhibition strategies instead of bactericidal and bacteriostatic approaches. Here, we investigated several bee products for potential compound(s) that exhibit significant QS inhibitory (QSI) properties at the phenotypic and molecular levels in Chromobacterium violaceum ATCC 12472 as a model organism. Manuka propolis produced the strongest violacein inhibition on C. violaceum lawn agar, while bee pollen had no detectable QSI activity and honey had bactericidal activity. Fractionated manuka propolis (pooled fraction 5 or PF5) exhibited the largest violacein inhibition zone (24.5 ± 2.5 mm) at 1 mg dry weight per disc. In C. violaceum liquid cultures, at least 450 µg/ml of manuka propolis PF5 completely inhibited violacein production. Gene expression studies of the vioABCDE operon, involved in violacein biosynthesis, showed significant (≥two-fold) down-regulation of vioA, vioD and vioE in response to manuka propolis PF5. A potential QSI compound identified in manuka propolis PF5 is a hydroxycinnamic acid-derivative, isoprenyl caffeate, with a [M-H] of 247. Complete violacein inhibition in C. violaceum liquid cultures was achieved with at least 50 µg/ml of commercial isoprenyl caffeate. In silico docking experiments suggest that isoprenyl caffeate may act as an inhibitor of the violacein biosynthetic pathway by acting as a competitor for the FAD-binding pockets of VioD and VioA. Further studies on these compounds are warranted toward the development of anti-pathogenic drugs as adjuvants to conventional antibiotic treatments, especially in antibiotic-resistant bacterial infections.
抗生素耐药性细菌病原体的出现，尤其是革兰氏阴性菌，促使人们通过群体感应（QS）抑制策略而非杀菌和抑菌方法来研究抑制细菌毒力。在此，我们以紫色色杆菌ATCC 12472作为模式生物，在表型和分子水平上研究了几种蜂产品中具有显著群体感应抑制（QSI）特性的潜在化合物。麦卢卡蜂胶对紫色色杆菌平板琼脂上的紫色菌素产生的抑制作用最强，而蜂花粉未检测到QSI活性，蜂蜜具有杀菌活性。分级后的麦卢卡蜂胶（合并组分5或PF5）在每片干重1 mg时表现出最大的紫色菌素抑制圈（24.5±2.5 mm）。在紫色色杆菌液体培养物中，至少450 µg/ml的麦卢卡蜂胶PF5完全抑制了紫色菌素的产生。参与紫色菌素生物合成的vioABCDE操纵子的基因表达研究表明，响应麦卢卡蜂胶PF5，vioA、vioD和vioE显著下调（≥两倍）。在麦卢卡蜂胶PF5中鉴定出的一种潜在QSI化合物是一种羟基肉桂酸衍生物，异戊烯基咖啡酸，[M-H]为247。在紫色色杆菌液体培养物中，至少50 µg/ml的商业异戊烯基咖啡酸可实现对紫色菌素的完全抑制。计算机对接实验表明，异戊烯基咖啡酸可能通过作为VioD和VioA的FAD结合口袋的竞争者，充当紫色菌素生物合成途径的抑制剂。有必要对这些化合物进行进一步研究，以开发作为传统抗生素治疗辅助剂的抗病原体药物，尤其是在抗生素耐药性细菌感染中。
