Lippia javanica: a cheap natural source for the synthesis of antibacterial silver nanocolloid

Application of Plant-Derived Nanoparticles (PDNP) in Food-Producing Animals as a Bio-Control Agent against Antimicrobial-Resistant Pathogens

Antibiotics are regularly used in animal husbandry to treat diseases. This practice is beneficial to animals' health and helps ensure food security. However, the misuse of antibiotics, especially in food-producing animals, has resulted in the advent of antimicrobial resistance (AMR) and its dissemination among foodborne pathogens. The occurrence of AMR in bacteria pathogens that cause infections in animals and those associated with food spoilage is now considered a global health concern affecting humans, animals and the environment. The search for alternative antimicrobial agents has kindled the interest of many researchers. Among the alternatives, using plant-derived nanoparticles (PDNPs) for treating microbial dysfunctions in food-producing animals has gained significant attention. In traditional medicine, plant extracts are considered as safe, efficient and natural antibacterial agents for various animal diseases. Given the complexity of the AMR and concerns about issues at the interface of human health, animal health and the environment, it is important to emphasize the role of a One Health approach in addressing this problem. This review examines the potential of PDNPs as bio-control agents in food-producing animals, intending to provide consumers with microbiologically safe food while ensuring food safety and security, better health for animals and humans and a safe environment.

Green synthesis of silver nanoparticles and evaluation of their anti-bacterial activities: use of Aloe barbadensis miller and Ocimum tenuiflorum leaf extracts

The presence of various phytochemicals makes the leaf extract-based green synthesis advantageous to other conventional methods, as it facilitates the production of non-toxic by-product. In the present study, leaf extracts from two different plants: Aloe barbadensis miller and Ocimum tenuiflorum, were used to synthesise Ag nanoparticles. The absorbance at 419-432 nm from UV-visible spectroscopy indicates the formation of Ag in the synthesised samples. The effect of precursors’ concentration on the stability, size and shape of the synthesised samples has also been investigated at constant heating temperature, stirring time, and the pH of the solution. The TEM results showed that all the synthesised samples of nanoparticles demonstrated stability with a size range of 7-70 and 9-48 nm with Aloe barbadensis miller and Ocimum tenuiflorum leaf extracts, respectively. The formation of smaller Ag nanoparticles due to utilisation of different precursor concentration and leaf extracts was also explained. The synthesised samples’ anti-bacterial activity was examined against the pathogens, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. In general, the green synthesis approach established a prospective for developing highly stable Ag nanoparticles with rigid particle shape/size distribution from different leaf extracts for the development of better anti-bacterial agents.

Bionanocomposite films of agar incorporated with ZnO nanoparticles as an active packaging material for shelf life extension of green grape

Zinc oxide nanoparticles (ZnONPs) were synthesized by green protocol using Mimusops elengi fruit extract as a novel natural resource. The synthesized particles were polyhedral (mostly hexagonal) in shape between 14 - 48 nm with an average size of 24.75 ± 0.78 nm. Nano zinc oxide (ZnO) at concentrations of 2% (w/w) and 4% (w/w), were incorporated into agar matrix. Solution casting method was used to fabricate the bionanocomposite films with ZnONPs in agar. Surface morphology, particle size, crystallinity, thermal stability and functional groups were determined using SEM, TEM, XRD, TGA and FTIR, respectively. Loading of ZnONPs in composite films improved thermal stability, elongation and film thickness, whereas tensile strength and transparency decreased. The films were used for packaging of green grapes, and appearance of the fruit was observed during ambient storage. Grapes packaged in composite films showed fresh appearance up to 14 and 21 days in ambient conditions for 2% (w/w) and 4% (w/w) ZnONPs in films, respectively. The results showed the potential of the fabricated agar-ZnO nanocomposite film as a promising packaging material to enhance postharvest shelf-life of fresh fruits like green grapes.

Phytochemicals, antioxidant, and anthelmintic activity of selected traditional wild edible plants of lower Assam

Objective:

Clerodendrum viscosum, Eryngium foetidum, Lippia javanica, and Murraya koenigii are one among the common wild edible plants in Northeast India which are also used as antidiabetic, stomach-ache relieving drugs, etc., The present study was aimed to reveal the phytochemical, antioxidant, and anthelmintic activity of the plants.

Materials and Methods:

The antioxidant capacity of methanolic extract of plants was studied by 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power, TBARS, and total antioxidant activity (TAA). Total phenolics, flavonoids, Vitamin C, carbohydrate, and protein are also estimated following standard protocols. Anthelmintic activity of the extracts has also been studied in vitro against trematode parasites.

Results:

The result showed that the methanolic extracts of plants possess a substantial quantity of alkaloids, phenolics, flavonoids, proteins, carbohydrates, and Vitamin C. Phenolics, flavonoids, and Vitamin C contents were found higher in C. viscosum followed by M. koenigii, L. javanica, and E. foetidum. The in vitro antioxidant assays revealed substantial free radical scavenging property in all the plants. TAA increased in the order C. viscosum > M. koenigii > L. javanica > E. foetidum. Similarly, C. viscosum displayed a better antioxidant capacity with IC₅₀ values 29.74 ± 3.63 μg and 148.77 ± 18.38 μg for DPPH and thiobarbituric acid reactive species, respectively. In addition, the plant extracts also showed good anthelmintic activity against Paramphistomum sp. Time taken for paralysis and death were 0:56 ± 0:09 h and 1:35 ± 0:07 h for L. javanica at 50 mg/mL concentration.

Conclusion:

The study therefore suggests the importance of tested plants as a natural source of free radical scavenger and plausible veterinary uses.