黄芪、穿心莲单独或与抗菌肽LL-37联合应用对铜绿假单胞菌生物膜的影响

Effects of Radix Astragali,Herba Andrographis Alone or Combined with Antimicrobial Peptide LL-37 on Pseudomonas aeruginosa Biofilms

【目的】探讨黄芪、穿心莲对铜绿假单胞菌(PA)生物膜的抑制作用及与抗菌肽LL-37联合应用是否有协同作用。【方法】培养铜绿假单胞菌野生菌株PAO1生物膜,并采用紫外分光光度法进行鉴定。采用微量肉汤稀释法分别检测黄芪、穿心莲和抗菌肽LL-37对铜绿假单胞菌的最小抑菌浓度(MIC)。采用紫外分光光度法检测20、50、100 g/L黄芪,20、50、100 g/L穿心莲单独用药或分别与32、64μg/mL抗菌肽LL-37联合应用对PAO1生物膜的作用。【结果】成功构建体外PAO1生物膜模型。黄芪、穿心莲在3.125～200 g/L浓度范围内对PAO1无抑制作用。抗菌肽LL-37对PAO1的MIC为256μg/mL。黄芪、穿心莲单独用药对PAO1生物膜早期形成均具有抑制作用(P<0.05),呈现浓度依赖性。黄芪/穿心莲与抗菌肽LL-37联合用药对PAO1生物膜的形成及对成熟生物膜的清除作用不明显,不具有协同作用。【结论】黄芪、穿心莲均能够早期抑制PAO1生物膜的形成并且在一定程度上对成熟生物膜结构有一定的破坏作用;与抗菌肽LL-37联合应用时,不具有协同作用。

Objective To explore the inhibitory effect of Radix Astragali and Herba Andrographis on the biofilm formation of Pseudomonas aeruginosa(PA),and to investigate their possible synergistic effect used together with antimicrobial peptide LL-37.Methods Biofilms of PA strain PAO1 were cultured,and then were identified by ultraviolet spectrophotometry.The minimal inhibitory concentration(MIC)of Radix Astragali,Herba Andrographis,and antimicrobial peptide LL-37 on PA was determined by broth microdilution assay.Ultraviolet spectrophotometry was used to identify the effects of 20,50,100 g/L of Radix Astragali,20,50,100 g/L of Herba Andrographis alone and the combination of Radix Astragali or Herba Andrographis with 32,64μg/mL of antimicrobial peptide LL-37 on the biofilm of PAO1.Results The model of PAO1 biofilm formation in vitro was successfully established.Radix Astragali and Herba Andrographis alone in the range of 3.125-200 g/L had no inhibitory effects on PAO1,and MIC of antimicrobial peptide LL-37 was 256μg/mL.Radix Astragali and Herba Andrographis alone had inhibitory effects on the early formation of PAO1 biofilms(P<0.05),in a concentration-dependent manner.The combination of Radix Astragali or Herba Andrographis with antimicrobial peptide LL-37 had no obvious effects on the formation of PAO1 biofilms and the clearance of mature PAO1 biofilm,showing no synergistic effects.Conclusion Radix Astragali and Herba Andrographis alone can inhibit the early formation of PAO1 biofilms,and to some extent have certain destructive effect on the structure of mature biofilms.But the combination of Radix Astragali or Herba Andrographis with antimicrobial peptide LL-37 has no synergistic effects.