In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized using leaf extract of Catharanthus roseus (C. roseus) under different physical parameters. Biosynthesis of ZnO NPs was confirmed by UV-Visible spectrophotometer and further, characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray spectroscopy (EDX), Atomic Force Microscopy (AFM), Photoluminescence study and Dynamic Light Scattering (DLS). We have also confirmed that several physical parameters such as pH, temperature, concentration of metal ions and reaction time were able to regulate shape and size of synthesized ZnO NPs. XRD and TEM analysis provided the information about the average size and hexagonal morphology of ZnO NPs. FTIR spectra analysis suggested that phenolic compounds played crucial role in the biosynthesis of ZnO NPs. The significant antibacterial activity of ZnO NPs was observed against Staphylococcus aureus MTCC 9760 (S. aureus), Streptococcus pyogenes MTCC 1926 (S. pyogenes), Bacillus cereus MTCC 430 (B. cereus), Pseudomonas aeruginosa MTCC 424 (P. aeruginosa), Proteus mirabilis MTCC 3310 (P. mirabilis) and Escherichia coli MTCC 40 (E. coli). The synthesized ZnO NPs have shown antibacterial efficacy against both Gram-positive and Gram-negative pathogens. Synergistic effects of ZnO NPs and streptomycin showed increased efficacy as indicated by the increased zone of clearance in comparison to their individual effects (either ZnO NPs or streptomycin). Overall, the results elucidated a rapid, cost-effective, environmentally friendly and convenient method for ZnO NPs synthesis, which could be used as a potential antimicrobial agent against drug resistant microbes.

The fact that the population is getting older has greatly increased the occurrence of cognitive decline and neurodegenerative diseases, underlining the importance of having reliable biomarkers that can measure biological aging before irreversible neurological damage takes place. New evidence shows that brain aging is not just the result of changes within neurons themselves but is also greatly affected by the gut microbiota via immune, metabolic, endocrine, and neurovascular signaling. This review brings together the existing knowledge about biomarkers of biological aging-such as telomere shortening, epigenetic clocks, oxidative stress, inflammation, cellular senescence, and metabolic dysfunction-as well as established cognitive biomarkers obtained from neuroimaging, cerebrospinal fluid, blood, genetic evaluations, and neuropsychological tests. We also point out that changes associated with age in the composition of the gut microbiota and the metabolites it produces are becoming more and more involved in the mechanisms connecting intestinal dysbiosis, dysfunction of the blood-brain barrier (BBB), neuroinflammation, and age-related cognitive decline. Through this approach of combined and complementary biomarker systems, we hypothesize that the gut microbiota has emerged as a central regulator of biological and cognitive aging and may provide a useful source for development of biomarkers of cognitive resilience and risk of neurodegenerative diseases. Lastly, we consider microbiome-based interventions, including probiotics, prebiotics, dietary changes, fecal microbial transplant, and new treatment modalities derived from molecular studies, as possible approaches to the prevention and management of age-related cognitive decline. Collectively, this review provides a comprehensive framework linking aging biology, microbiome science, and cognitive biomarkers to advance biomarker-driven precision medicine for healthy brain aging.

The Asian Journal of Pharmaceutics is a peer-reviewed open-access medical journal published by Medknow Publications on behalf of the B.R. Nahata Smriti Sansthan (Memorial Trust) (Mandsaur, India). Articles address topics in pharmaceutics, biopharmaceutics, pharmaceutical chemistry, pharmacognosy, pharmacology, pharmaceutical analysis, pharmacy practice, and clinical and hospital pharmacy.