Prasastha Ram Vemula, Yasur Jyothsna, Abishad Padikkamannil, Unni Varsha, Purushottam Gourkhede Diksha, Nishanth Maria Anto Dani, Niveditha Pollumahanti, Vergis Jess, Singh Malik Satya Veer, Kullaiah Byrappa, Kurkure Nitin Vasantrao, Ramesh Chatragadda, Dufossé Laurent, Rawool Deepak B, Barbuddhe Sukhadeo B
Division of Veterinary Public Health, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly 243122, India.
ICAR-National Research Centre on Meat, Hyderabad 500092, India.
Pharmaceutics. 2022 Sep 12;14(9):1924. doi: 10.3390/pharmaceutics14091924.
The global emergence of antimicrobial resistance (AMR) needs no emphasis. In this study, the in vitro stability, safety, and antimicrobial efficacy of nanosilver-entrapped cinnamaldehyde (AgC) against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli (EAEC) were investigated. Further, the in vivo antibacterial efficacy of AgC against MDR-EAEC was also assessed in Galleria mellonella larval model. In brief, UV-Vis and Fourier transform infrared (FTIR) spectroscopy confirmed effective entrapment of cinnamaldehyde with nanosilver, and the loading efficiency was estimated to be 29.50 ± 0.56%. The AgC was of crystalline form as determined by the X-ray diffractogram with a mono-dispersed spherical morphology of 9.243 ± 1.83 nm in electron microscopy. AgC exhibited a minimum inhibitory concentration (MIC) of 0.008−0.016 mg/mL and a minimum bactericidal concentration (MBC) of 0.008−0.032 mg/mL against MDR- EAEC strains. Furthermore, AgC was stable (high-end temperatures, proteases, cationic salts, pH, and host sera) and tested safe for sheep erythrocytes as well as secondary cell lines (RAW 264.7 and HEp-2) with no negative effects on the commensal gut lactobacilli. in vitro, time-kill assays revealed that MBC levels of AgC could eliminate MDR-EAEC infection in 120 min. In G. mellonella larvae, AgC (MBC values) increased survival, decreased MDR-EAEC counts (p < 0.001), had an enhanced immunomodulatory effect, and was tested safe to the host. These findings infer that entrapment enhanced the efficacy of cinnamaldehyde and AgNPs, overcoming their limitations when used individually, indicating AgC as a promising alternative antimicrobial candidate. However, further investigation in appropriate animal models is required to declare its application against MDR pathogens.
抗菌药物耐药性（AMR）在全球的出现已无需强调。在本研究中，研究了纳米银包裹肉桂醛（AgC）对多重耐药（MDR）聚集性大肠杆菌（EAEC）菌株的体外稳定性、安全性和抗菌效果。此外，还在大蜡螟幼虫模型中评估了AgC对MDR-EAEC的体内抗菌效果。简而言之，紫外可见光谱和傅里叶变换红外（FTIR）光谱证实肉桂醛与纳米银有效包裹，负载效率估计为29.50±0.56%。通过X射线衍射图确定AgC为晶体形式，在电子显微镜下呈单分散球形形态，直径为9.243±1.83nm。AgC对MDR-EAEC菌株的最低抑菌浓度（MIC）为0.008−0.016mg/mL，最低杀菌浓度（MBC）为0.008−0.032mg/mL。此外，AgC具有稳定性（在高温、蛋白酶、阳离子盐、pH值和宿主血清中），对绵羊红细胞以及二级细胞系（RAW 264.7和HEp-2）测试安全，对共生肠道乳酸杆菌无负面影响。体外时间杀菌试验表明，AgC的MBC水平可在120分钟内消除MDR-EAEC感染。在大蜡螟幼虫中，AgC（MBC值）提高了存活率，降低了MDR-EAEC数量（p<0.001），具有增强的免疫调节作用，并且对宿主测试安全。这些发现表明，包裹增强了肉桂醛和AgNPs的功效，克服了它们单独使用时的局限性，表明AgC是一种有前途的替代抗菌候选物。然而，需要在合适的动物模型中进行进一步研究，以宣布其对MDR病原体的应用。
