Antimicrobial resistance is a global health challenge. The involvement of bacterial biofilms and efflux pumps in the development of multidrug resistance (MDR) is well established. Medicinal plants have been proposed as alternatives for combating MDR focusing on their bioactive constituents with resistance modulatory activities. This study was aimed at investigating the stem bark of Aidia genipiflora for bioactive constituents with anti-biofilm, efflux pump inhibition and resistance modulatory activities. The crude methanol extract was purified by column chromatography and isolated compounds characterized by mass and nuclear magnetic resonance spectrometry. Antibacterial activity was determined by the High-throughput spot culture growth inhibition and the broth micro-dilution assay. The ethidium bromide accumulation assay was used to determine efflux pump inhibition property. Biofilm inhibition was determined in a microplate crystal violet retention assay. Purification of the ethyl acetate fraction led to the isolation of oleanonic acid (1), 4-hydroxy cinnamic acid docosyl ester (2), β-stigmasterol/β-sitosterol (mixture 3a/b) and D-mannitol (4). The minimum inhibitory concentrations (MICs) ranged from 250 to > 500 μg/mL for extracts and fractions and from 15 to 250 μg/mL for compounds. In the presence of sub-inhibitory concentrations of the compounds, the MIC of amoxicillin against E. coli (20 μg/mL) and P. aeruginosa (320 μg/mL) was reduced by 32 and 10 folds respectively. The whole extract demonstrated anti-biofilm formation and efflux pump inhibition in E. coli, S. aureus and P. aeruginosa. The sterol mixture (3a/b) at concentration of 100 μg/mL caused the highest inhibition (73%) of biofilm formation in S. aureus. Oleanonic acid (1) demonstrated remarkable efflux pump inhibition at MIC of 7.8 μg/mL in E. coli better than the standard drugs verapamil and chlorpromazine. This study confirms the prospects of A. genipiflora as a source of new antibacterial agents and adjuvants that could interact with some resistance mechanisms in bacteria to enhance the activity of hitherto ineffective antibiotics. “A small portion of the study has been presented in a conference in the form of poster”.

中文翻译：

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Aidia genipiflora茎皮具有抗菌，抗性调节，抗生物膜形成和外排泵抑制特性的生物活性成分

抗菌素耐药性是全球健康挑战。细菌生物膜和外排泵参与多药耐药性（MDR）的发展已得到充分证实。已经提出药用植物作为对抗MDR的替代物，其重点是具有抗性调节活性的生物活性成分。这项研究的目的是调查刺槐Aidia genipiflora的茎皮中具有抗生物膜，外排泵抑制和抗性调节活性的生物活性成分。通过柱色谱法纯化粗甲醇提取物，并通过质谱和核磁共振波谱表征分离出的化合物。通过高通量斑点培养物的生长抑制和肉汤微量稀释测定来确定抗菌活性。溴化乙锭积累测定法用于确定外排泵抑制性质。用微孔板结晶紫保留法测定生物膜抑制作用。乙酸乙酯馏分的纯化导致分离出齐墩果酸（1），4-羟基肉桂酸二十二烷基酯（2），β-豆甾醇/β-谷甾醇（混合物3a / b）和D-甘露糖醇（4）。提取物和馏分的最低抑菌浓度（MIC）为250至> 500μg/ mL，化合物的最低抑菌浓度为15至250μg/ mL。在亚抑制浓度的化合物存在下，阿莫西林对大肠杆菌（20μg/ mL）和铜绿假单胞菌（320μg/ mL）的MIC分别降低了32倍和10倍。整个提取物在大肠杆菌，金黄色葡萄球菌和铜绿假单胞菌中均显示出抗生物膜形成和外排泵抑制作用。浓度为100μg/ mL的固醇混合物（3a / b）在金黄色葡萄球菌中对生物膜形成的抑制作用最高（73％）。齐墩果酸（1）在大肠杆菌中的MIC表现出显着的外排泵抑制作用，比标准药物维拉帕米和氯丙嗪更好，抑制率为7.8μg/ mL。这项研究证实了gen草曲霉作为新型抗菌剂和佐剂的前景，可以与细菌中的某些耐药机制相互作用，以增强迄今无效的抗生素活性。“研究的一小部分已经在会议上以海报的形式展示了”。这项研究证实了gen草曲霉作为新型抗菌剂和佐剂的前景，可以与细菌中的某些耐药机制相互作用，以增强迄今无效的抗生素活性。“研究的一小部分已经在会议上以海报的形式展示了”。这项研究证实了gen草曲霉作为新型抗菌剂和佐剂的前景，可以与细菌中的某些耐药机制相互作用，以增强迄今无效的抗生素活性。“研究的一小部分已经在会议上以海报的形式展示了”。