Department of Biology and Microbiology, Faculty of Science, King Saud University, P.O. Box 22452, Riyadh, 11495, Saudi Arabia.
Department of Biology, College of Science, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh, 11671, Saudi Arabia.
Sci Rep. 2020 Oct 8;10(1):16781. doi: 10.1038/s41598-020-73683-z.
Recently, increase bacterial resistance to antimicrobial compounds issue constitutes a real threat to human health. One of the useful materials for bacterial control is Silver nanoparticles (AgNPs). Researchers tend to use biogenic agents to synthesize stable and safe AgNPs. The principal aim of this study was to investigate the ability of lichen in AgNPs formation and to find out their suppression ability to MDR bacteria as well as their cytotoxic activity. In the current study, lichens (Xanthoria parietina, Flavopunctelia flaventior) were collected from the south of the Kingdom of Saudi Arabia. Lichens methanolic extracts were used for conversion of Ag ions to AgNPs. Prepared biogenic AgNPs were characterized by Ultraviolet-Visible (UV-Vis) Spectroscopy, Transmission electron microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential and Energy-Dispersive X-ray Spectroscopy (EDS). Lichens Secondary metabolites were determined by Fourier-Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS). The antibacterial activity and synergistic effect of AgNPs were evaluated against pathogenic bacteria, including gram-positive; Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), and gram-negative; (Pseudomonas aeruginosa, Escherichia coli) as well as the reference strains (ATCC) using the agar disk diffusion method. Cytotoxic effect of biogenic AgNPs was tested against HCT 116 (Human Colorectal Cancer cell), MDA-MB-231 (Breast cancer cell), and FaDu (Pharynx cancer cell) by MTT test. TEM imaging showed well-dispersed spherical particles of 1-40 nm size as well as zeta size showed 69-145 nm. Furthermore, FTIR and GC-MS identified various lichen chemical molecules. On the other hand, the highest antibacterial activity of AgNPs was noticed against P. aeruginosa, followed by MRSA, VRE, and E. coli. AgNPs influence on gram-negative bacteria was greater than that on gram-positive bacteria and their synergistic effect with some antibiotics was noted against examined microbes. Moreover, higher cytotoxicity for biogenic AgNPs against FaDu and HCT 116 cell line in relation to MDA-MB-231 was noted. Given the current findings, the biogenic AgNPs mediated by lichens had positive antibacterial, synergistic and cytotoxic powers. Therefore, they might be considered as a promising candidate to combat the multi-drug resistance organisms and some cancer cells.
最近，抗菌化合物的细菌耐药性增加问题对人类健康构成了真正的威胁。银纳米粒子 (AgNPs) 是控制细菌的有用材料之一。研究人员倾向于使用生物制剂来合成稳定和安全的 AgNPs。本研究的主要目的是研究地衣在 AgNPs 形成中的能力，并找出它们对 MDR 细菌的抑制能力以及它们的细胞毒性活性。在本研究中，地衣 (Xanthoria parietina、Flavopunctelia flaventior) 从沙特阿拉伯南部采集。地衣甲醇提取物用于将 Ag 离子转化为 AgNPs。制备的生物合成 AgNPs 采用紫外可见分光光度法 (UV-Vis)、透射电子显微镜 (TEM)、动态光散射 (DLS) 和 Zeta 电位以及能谱 (EDS) 进行表征。地衣次生代谢物通过傅里叶变换红外光谱 (FTIR) 和气相色谱-质谱 (GC-MS) 确定。采用琼脂平板扩散法评价 AgNPs 对致病性细菌（包括革兰氏阳性菌：耐甲氧西林金黄色葡萄球菌 (MRSA)、万古霉素耐药肠球菌 (VRE) 和革兰氏阴性菌：铜绿假单胞菌、大肠杆菌）以及参考菌株（ATCC）的抗菌活性和协同作用。通过 MTT 试验测试生物合成 AgNPs 对 HCT 116（人结肠癌细胞）、MDA-MB-231（乳腺癌细胞）和 FaDu（咽癌细胞）的细胞毒性作用。TEM 成像显示粒径为 1-40nm 的分散良好的球形颗粒，Zeta 粒径为 69-145nm。此外，FTIR 和 GC-MS 鉴定了地衣的各种化学分子。另一方面，AgNPs 对铜绿假单胞菌的抗菌活性最高，其次是 MRSA、VRE 和大肠杆菌。AgNPs 对革兰氏阴性菌的影响大于革兰氏阳性菌，并且在检查的微生物中注意到它们与某些抗生素的协同作用。此外，与 MDA-MB-231 相比，生物合成 AgNPs 对 FaDu 和 HCT 116 细胞系的细胞毒性更高。鉴于目前的研究结果，地衣介导的生物合成 AgNPs 具有积极的抗菌、协同和细胞毒性作用。因此，它们可能被认为是对抗多药耐药菌和一些癌细胞的有前途的候选物。
