The fabrication of metal nanoparticles through green synthetic pathways using plant extracts has increased attention due to low cost, benevolent methods, fewer hazardous byproducts, and applications. Silver nanoparticles (AgNPs) were synthesized by reacting to aqueous root extracts of Rubus ellipticus Sm. (RERE) with AgNO3 solution (1 mM) at an ambient condition. The visual change of color from light yellow to reddish brown and the absorption peak at 416-420 nm in the UV-visible spectra indicated the formation of AgNPs in the solution. The shifting of the positions in the FTIR spectra indicated the potential role of the functional groups as capping and stabilizing agents. The powder XRD diffractogram exposed the crystalline nature of the nanoparticles. The surface morphology and the elemental composition of the AgNPs were established by the FESEM and EDX analysis. The TEM images revealed the spherical and monodispersed nanoparticles of size ranging from 13.85 to 34.30 nm with an average of 25.20 ± 7.01   nm ( n = 10 ). The biogenic AgNPs showed a better 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with lower IC50 ( 13.83 ± 0.33   μ g / mL ) as compared to that of the RERE with IC50 ( 15.86 ± 4.14   μ g / mL ). The synthesized AgNPs showed higher zones of inhibition (ZOI) on the agar well diffusion method against Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), and Klebsiella pneumoniae (ATCC 700603). The result of this study highlights the potential benefits of R. ellipticus root extract-based AgNPs for biomedical practices.

Plants have long been considered as a basis of medicines for different indigenous cultures around the globe. They continue as a prominent source of important phytoconstituents which exhibit significant biological activities. In this study, we performed the phytochemical screening, estimation of total phenolic and flavonoids, antioxidants, and antimicrobial activities of the stem bark of Beilschmiedia roxburghiana Nees using different solvents. The total phenolic and total flavonoid contents ranged from 106.73 ± 1.62 mg GAE/g and 99.32 ± 0.66 mg QE/g (methanol extract) to 65.59 ± 1.79 mg GAE/g and 29.98 ± 0.90 mg QE/g (n-hexane extract), respectively. The maximum 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity with a half-maximal inhibitory concentration (IC50) of 39.86 ± 3.69 μg/mL was observed for methanol extract followed by aqueous (IC50 = 43.55 ± 6.16 μg/mL), ethyl acetate (IC50 = 44.30 ± 5.88 μg/mL), dichloromethane (IC50 = 71.50 ± 4.70 μg/mL), and the lowest activity was observed for n-hexane extract. The disc diffusion method revealed that the ethyl acetate extract exhibited relatively higher activity against Salmonella typhi (ZOI = 13 mm), and moderate activities against Shigella sonnei, Acinetobacter baumannii, Klebsiella pneumoniae, and Staphylococcus aureus (ZOI = 12 mm). The methanol and aqueous extracts showed nearly parallel and the n-hexane and dichloromethane extracts exhibited mild antibacterial activities. The results indicated that the polarity index of the extracting solvents amplified the biological activities of the extract. The study is helpful to support the validity of the traditional application of the plant as natural medicine.

Medicinal plants have been known to treat simple to life-threatening diseases in different communities of Nepal for many years. This study aims to analyze the phytochemicals as plant secondary metabolites, evaluate the antioxidant and antibacterial activities of Rubus ellipticus, Ziziphus mauritiana, Pyrus pashia, and Drynaria coronans extracts that are commonly being used as traditional medicine. Phytochemical analysis was performed to investigate the plant's secondary metabolites such as polyphenols, alkaloids, flavonoids, terpenoids, reducing sugar, glycosides, tannins, carotene, phytosterols, coumarins, saponins, and anthracenes. The methanol extracts of the plants were used to evaluate the in vitro antioxidant activity by using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical and the antibacterial activity against Staphylococcus aureus (ATCC 25923), Klebsiella pneumoniae (ATCC 700603), Escherichia coli (ATCC 25922) and Salmonella typhi (ATCC 14028) by the agar well diffusion method. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined by the Resazurin Microtiter Assay (REMA) method. Root extract of R. ellipticus was observed to have the highest antioxidant activity with IC 50 of 42.40 ± 1.5 μg/ml followed by the root extract of Z. mauritiana (IC 50 55.67 ± 7.41 μg/ml), leaf and bark extract of P. pashia (IC 50 58.33 ± 2.9 μg/ml) and tuber extract of D. coronans (IC 50 93.30 ± 5.19 μg/ml) as compared to the standard ascorbic acid with IC 50 of 28.44 ± 0.97 μg/ml. The plants were found active against Gram-positive Staphylococcus aureus with Zone of Inhibition (ZOI) for R. ellipicus 17 mm, P. pashia 12 mm, Z. mauritiana 9 mm and D. coronans 8 mm. The extracts exhibited no effect on all of the tested Gram-negative bacteria. The MIC and MBC of R. ellipticus and P. pashia were 3.125 mg/ml, 12.5 mg/ml, and 12.5 mg/ml, 25 mg/ml respectively.

The northern areas of Nepal are rich in biodiversity and contain a large number of medicinal plant species including the Genus Ephedra of evergreen gymnosperm, belonging to the family Ephedraceae. The plants have been used by the peoples of the Himalayan region for the treatment of asthma, blood pressure, and gastritis for many years. This study was aimed for the evaluation of phytochemical, antioxidant, and antimicrobial activities of methanol, ethyl acetate, dichloromethane, and n-hexane extracts, and gas chromatography-mass spectrometry (GCMS) profiling of the essential oil of the aerial parts of Ephedra pachyclada Boiss from Mustang district of Nepal. Antioxidant activity was evaluated by 2,2-dipheny-1-picrylhydrazyl (DPPH) free radical scavenging assay and antimicrobial activity by the agar well diffusion method. Total phenolics and total flavonoid content were determined by Folin-Ciocalteu and aluminum chloride colorimetric method, respectively. The methanol extract contained the highest total phenolic content of 54.42 ± 1.40 mg GAE/g followed by the ethyl acetate (46.84 ± 0.62 mg GAE/g), DCM extract (19.58 ± 0.24 mg GAE/g), and the lowest TPC was shown for n-hexane extract (5.21 ± 1.40 mg GAE/g) of the dry weight. The methanol extract showed the maximum TFC of 33.28 ± 0.48 mg QE/g, followed by ethyl acetate extract (31.73 ± 0.52 mg QE/g), DCM extract (31.64 ± 0.56 mg QE/g), and the least value was obtained for the n-hexane extract (21.44 ± 2.91 mg QE/g). The methanol extract showed the highest antioxidant activity with a half-maximal inhibitory concentration (IC50) of 37.81 ± 2.24 μg/mL. The methanol extract showed potent activity against Escherichia coli (ATCC 25922), and Staphylococcus aureus (ATCC 25923) with zones of inhibition of 13 mm and 12 mm respectively. Ethyl acetate extract showed a slight potency against Staphylococcus aureus (ATCC 25923) with a zone of inhibition of 9 mm. The essential oil contained diisooctyl phthalate (46.90%), dodecane, 2,6,11-trimethyl-(16.35%), dodecane, 4,6-dimethyl- (11.59%), tetrapentacontane (11.56%), and myrtenol (4.37) as the major compounds. The plant exhibited significant antioxidant and antimicrobial activities which could be used as the source to isolate the active natural antioxidant and antimicrobial agent as the drug candidate in the future drug discovery process.

The management of municipal solid always poses serious environmental problems on land, air, and groundwater, especially in the case of developing countries. The characterization and assessment of leachates are necessary to understand the water quality in the urban region as well as has enormous importance in sustaining the livelihoods of people in the riverine environment maintaining the ecological balance. Landfill leachate contains thousands of complex components, which contaminate the nearby water bodies, and communities with several hazardous ingredients. The present study was conducted to assess the influence of landfill leachates on the quality of Seti River water. The samples were collected from four stations (Tatopani, Ramghat, Landfill, Below landfill, and Kotre). The samples were analyzed for pH, total hardness, dissolved oxygen, biochemical oxygen demand, turbidity, total dissolved solids, electrical conductivity (EC), Cl-, NH3, and PO43- by standard methods. The pH and EC were measured in situ whereas other parameters were analyzed in the laboratory adopting standard protocols. The physicochemical parameters of river water and that of leachates were compared to monitor the level of contamination. The research reveals the landfill to have insignificant pollution of water on matching the parameters with World Health Organization (WHO) guideline values. Regular monitoring of the quality of river water and sustainable management of solid waste is essential for the ecological quality and integrity of the environment in the region. Scientific information obtained by this study could contribute to policymakers for the sustainable management of water quality and landfill in the downstream and urban segments of the river basins.