The rise of antibiotic resistance has necessitated a search for new antimicrobials with potent activity against multidrug-resistant gram-negative pathogens, such as carbapenem-resistant Acinetobacter baumannii (CRAB). In this study, a library of botanical extracts generated from plants used to treat infections in traditional medicine was screened for growth inhibition of CRAB. A crude extract of Schinus terebinthifolia leaves exhibited 80% inhibition at 256 µg/mL and underwent bioassay-guided fractionation, leading to the isolation of pentagalloyl glucose (PGG), a bioactive gallotannin. PGG inhibited growth of both CRAB and susceptible A. baumannii (MIC 64–256 µg/mL), and also exhibited activity against Pseudomonas aeruginosa (MIC 16 µg/mL) and Staphylococcus aureus (MIC 64 µg/mL). A mammalian cytotoxicity assay with human keratinocytes (HaCaTs) yielded an IC₅₀ for PGG of 256 µg/mL. Mechanistic experiments revealed iron chelation as a possible mode of action for PGG’s activity against CRAB. Passaging assays for resistance did not produce any resistant mutants over a period of 21 days. In conclusion, PGG exhibits antimicrobial activity against CRAB, but due to known pharmacological restrictions in delivery, translation as a therapeutic may be limited to topical applications such as wound rinses and dressings.

抗生素耐药性的上升使得人们需要寻找对多重耐药革兰氏阴性病原体（例如耐碳青霉烯鲍曼不动杆菌(CRAB)）具有有效活性的新型抗菌药物。在这项研究中，筛选了传统医学中用于治疗感染的植物中产生的植物提取物库，以检测 CRAB 的生长抑制作用。 Schinus terebinthifolia叶子的粗提物在 256 µg/mL 时表现出 80% 的抑制作用，并经过生物测定引导的分级分离，从而分离出五没食子酰葡萄糖 (PGG)，一种具有生物活性的没食子单宁。 PGG 抑制 CRAB 和敏感鲍曼不动杆菌(MIC 64–256 µg/mL) 的生长，并且还表现出对抗铜绿假单胞菌(MIC 16 µg/mL) 和金黄色葡萄球菌(MIC 64 µg/mL) 的活性。使用人角质形成细胞 (HaCaTs) 进行的哺乳动物细胞毒性测定得出 PGG 的 IC ₅₀为 256 µg/mL。机理实验表明，铁螯合是 PGG 对抗 CRAB 活性的一种可能的作用方式。抗性传代测定在 21 天的时间内没有产生任何抗性突变体。总之，PGG 对 CRAB 表现出抗菌活性，但由于已知的递送药理学限制，作为治疗剂的转化可能仅限于局部应用，例如伤口冲洗和敷料。