The use of natural products together with standard antimicrobial drugs has recently received more attention as a strategy to combat infectious diseases caused by multidrug-resistant (MDR) microorganisms. This study aimed to evaluate the capacity of a galactose-binding lectin from Vatairea macrocarpa seeds (VML) to modulate antibiotic activity against standard and MDR Staphylococcus aureus and Escherichia coli bacterial strains. The minimum inhibitory concentration (MIC) obtained for VML against all strains was not clinically relevant (MIC ≥ 1024 μg/mL). However, when VML was combined with the antibacterial drugs gentamicin, norfloxacin and penicillin, a significant increase in antibiotic activity was observed against S. aureus, whereas the combination of VML and norfloxacin presented decreased and, hence, antagonistic antibiotic activity against E. coli. By its inhibition of hemagglutinating activity, gentamicin (MIC = 50 mM) revealed its interaction with the carbohydrate-binding site (CBS) of VML. Using molecular docking, it was found that gentamicin interacts with residues that constitute the CBS of VML with a score of − 120.79 MDS. It is this interaction between the antibiotic and the lectin’s CBS that may be responsible for the enhanced activity of gentamicin in S. aureus. Thus, our results suggest that the VML can be an effective modulating agent against S. aureus. This is the first study to report the effect of lectins as modulators of bacterial sensitivity, and as such, the outcome of this study could lay the groundwork for future research involving the use of lectins and conventional antibiotics against such infectious diseases such as community-acquired methicillin-resistant S. aureus (MRSA).

中文翻译：

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从Vatairea macrocarpa种子分离的半乳糖结合凝集素增强了抗金黄色葡萄球菌抗性菌株的抗生素作用。

天然产物与标准抗微生物药物的结合作为对抗由多重耐药性（MDR）微生物引起的传染病的策略，近来受到越来越多的关注。这项研究旨在评估来自Vatairea macrocarpa种子（VML）的半乳糖结合凝集素调节针对标准和MDR金黄色葡萄球菌以及大肠杆菌菌株的抗生素活性的能力。VML对所有菌株获得的最低抑菌浓度（MIC）与临床无关（MIC≥1024μg/ mL）。但是，当VML与抗菌药庆大霉素，诺氟沙星和青霉素联用时，发现针对金黄色葡萄球菌的抗生素活性显着增加。，而VML和诺氟沙星的组合出现减少，因此对大肠杆菌具有拮抗抗生素活性。通过抑制血凝活性，庆大霉素（MIC = 50 mM）揭示了其与VML的碳水化合物结合位点（CBS）的相互作用。使用分子对接，发现庆大霉素与构成VML CBS的残基相互作用，得分为-120.79 MDS。抗生素和凝集素的CBS之间的这种相互作用可能是金黄色葡萄球菌中庆大霉素活性增强的原因。因此，我们的结果表明VML可以是针对金黄色葡萄球菌的有效调节剂。这是第一项报道凝集素作为细菌敏感性调节剂的作用的研究，因此，这项研究的结果可能为今后使用凝集素和常规抗生素治疗诸如社区获得性感染等传染病奠定基础耐甲氧西林的金黄色葡萄球菌（MRSA）。