School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Durban, 4001 KwaZulu-Natal, South Africa.
Sensors (Basel). 2013 Feb 27;13(3):2802-17. doi: 10.3390/s130302802.
The increasing incidence of multidrug-resistant pathogens has stimulated the search for novel anti-virulence compounds. Although many phytochemicals show promising antimicrobial activity, their power lies in their anti-virulence properties. Thus the quorum sensing (QS) inhibitory activity of four crude Kigelia africana fruit extracts was assessed qualitatively and quantitatively using the Chromobacterium violaceum and Agrobacterium tumefaciens biosensor systems. Inhibition of QS-controlled violacein production in C. violaceum was assayed using the qualitative agar diffusion assay as well as by quantifying violacein inhibition using K. africana extracts ranging from 0.31-8.2 mg/mL. Qualitative modulation of QS activity was investigated using the agar diffusion double ring assay. All four extracts showed varying levels of anti-QS activity with zones of violacein inhibition ranging from 9-10 mm. The effect on violacein inhibition was significant in the following order: hexane > dichloromethane > ethyl acetate > methanol. Inhibition was concentration-dependent, with the ≥90% inhibition being obtained with ≥1.3 mg/mL of the hexane extract. Both LuxI and LuxR activity were affected by crude extracts suggesting that the phytochemicals target both QS signal and receptor. K. africana extracts with their anti-QS activity, have the potential to be novel therapeutic agents, which might be important in reducing virulence and pathogenicity of drug-resistant bacteria in vivo.
耐药性病原体的发病率不断上升，促使人们寻找新型的抗毒化合物。虽然许多植物化学物质表现出有希望的抗菌活性，但它们的力量在于它们的抗毒特性。因此，使用 Chromobacterium violaceum 和 Agrobacterium tumefaciens 生物传感器系统，定性和定量评估了四种非洲吊灯果果实粗提物的群体感应（QS）抑制活性。使用定性琼脂扩散测定法以及使用 0.31-8.2 mg/mL 范围的非洲吊灯果提取物定量测定抑制物来测定 QS 控制的紫色素产生的抑制作用。使用琼脂扩散双环测定法研究了 QS 活性的定性调节。四种提取物均显示出不同程度的抗 QS 活性，紫色素抑制带的范围为 9-10mm。抑制作用按以下顺序显著：正己烷>二氯甲烷>乙酸乙酯>甲醇。抑制作用呈浓度依赖性，用≥1.3 mg/mL 的正己烷提取物即可获得≥90%的抑制。LuxI 和 LuxR 活性均受粗提取物的影响，表明植物化学物质同时靶向 QS 信号和受体。具有抗 QS 活性的非洲吊灯果提取物有可能成为新型治疗剂，这可能对减少体内耐药菌的毒力和致病性非常重要。
