Nano-Conversion of Ineffective Cephalosporins into Potent One against Resistant Clinical Uro-Pathogens via Gold Nanoparticles.

Infections caused by resistant bacterial pathogens have increased the complications of clinicians worldwide. The quest for effective antibacterial agents against resistant pathogens has prompted researchers to develop new classes of antibiotics. Unfortunately, pathogens have acted more smartly by developing resistance to even the newest class of antibiotics with time. The culture sensitivity analysis of the clinical samples revealed that pathogens are gaining resistance toward the new generations of cephalosporins at a very fast rate globally. The current study developed gold nanoparticles (AuNPs) that could efficiently deliver the 2nd (cefotetan-CT) and 3rd (cefixime-CX) generation cephalosporins to resistant clinical pathogens. In fact, both CT and CX were used to reduce and stabilize AuNPs by applying a one-pot synthesis approach, and their characterization was performed via spectrophotometry, dynamic light scattering and electron microscopy. Moreover, the synthesized AuNPs were tested against uro-pathogenic resistant clinical strains of Escherichia coli and Klebsiella pneumoniae. CT-AuNPs characteristic SPR peak was observed at 542 nm, and CX-AuNPs showed the same at 522 nm. The stability measurement showed ζ potential as -24.9 mV and -25.2 mV for CT-AuNPs and CX-AuNPs, respectively. Scanning electron microscopy revealed the spherical shape of both the AuNPs, whereas, the size by transmission electron microscopy for CT-AuNPs and CX-AuNPs were estimated to be 45 ± 19 nm and 35 ± 17 nm, respectively. Importantly, once loaded onto AuNPs, both the cephalosporin antibiotics become extremely potent against the resistant strains of E. coli and K. pneumoniae with MIC50 in the range of 0.5 to 0.8 µg/mL. The findings propose that old-generation unresponsive antibiotics could be revived into potent nano-antibiotics via AuNPs. Thus, investing efforts, intellect, time and funds for a nano-antibiotic strategy might be a better approach to overcome resistance than investing the same in the development of newer antibiotic molecule(s).

3-Methoxy Carbazole Impedes the Growth of Human Breast Cancer Cells by Suppressing NF-κB Signaling Pathway.

Breast cancer represents the most frequently occurring cancer globally among women. As per the recent report of the World Health Organization (WHO), it was documented that by the end of the year 2020, approximately 7.8 million females were positively diagnosed with breast cancer and in 2020 alone, 685,000 casualties were documented due to breast cancer. The use of standard chemotherapeutics includes the frontline treatment option for patients; however, the concomitant side effects represent a major obstacle for their usage. Carbazole alkaloids are one such group of naturally-occurring bioactive compounds belonging to the Rutaceae family. Among the various carbazole alkaloids, 3-Methoxy carbazole or C13H11NO (MHC) is obtained from Clausena heptaphylla as well as from Clausena indica. In this study, MHC was investigated for its anti-breast cancer activity based on molecular interactions with specific proteins related to breast cancer, where the MHC had predicted binding affinities for NF-κB with −8.3 kcal/mol. Furthermore, to evaluate the biological activity of MHC, we studied its in vitro cytotoxic effects on MCF-7 cells. This alkaloid showed significant inhibitory effects and induced apoptosis, as evidenced by enhanced caspase activities and the cellular generation of ROS. It was observed that a treatment with MHC inhibited the gene expression of NF-kB in MCF-7 breast cancer cells. These results suggest that MHC could be a promising medical plant for breast cancer treatment. Further studies are needed to understand the molecular mechanisms behind the anticancer action of MHC.

Gold Nanoparticle-Based Resuscitation of Cefoxitin against Clinical Pathogens: A Nano-Antibiotic Strategy to Overcome Resistance.

Gold nanoparticles have gained popularity as an effective drug delivery vehicle due to their unique features. In fact, antibiotics transported via gold nanoparticles have significantly enhanced their potency in the recent past. The present study used an approach to synthesize gold nanoparticles in one step with the help of cefoxitin antibiotic as a reducing and stabilizing agent. Cefoxitin is a second-generation cephalosporin that loses its potential due to modification in the porins (ompK35 and ompK36) of Gram-negative pathogens. Thus, the present study has developed an idea to revive the potential of cefoxitin against clinical Gram-negative pathogens, i.e., Escherichia coli and Klebsiella pneumoniae, via applying gold nanoparticles as a delivery tool. Prior to antibacterial activity, characterization of cefoxitin-gold nanoparticles was performed via UV-visible spectrophotometry, dynamic light scattering, and electron microscopy. A characteristic UV-visible scan peak for gold nanoparticles was observed at 518 nm, ζ potential was estimated as -23.6 ± 1.6, and TEM estimated the size in the range of 2-12 nm. Moreover, cefoxitin loading efficiency on gold nanoparticles was calculated to be 71.92%. The antibacterial assay revealed that cefoxitin, after loading onto the gold nanoparticles, become potent against cefoxitin-resistant E. coli and K. pneumoniae, and their MIC50 values were estimated as 1.5 µg/mL and 2.5 µg/mL, respectively. Here, gold nanoparticles effectively deliver cefoxitin to the resistant pathogens, and convert it from unresponsive to a potent antibiotic. However, to obtain some convincing conclusions on the human relevance, their fate and toxicity need to be evaluated.