Synthesis of silver nanoparticles using extract of Ocimum kilimandscharicum and its antimicrobial activity against plant pathogens

Abstract

Biological synthesis of silver nanoparticles using plants is gaining importance as an economically viable and ecofriendly approach. The present study reports synthesis of silver nanoparticles using an important Himalayan medicinal herbal plant Ocimum kilimandscharicum and the potential of biosynthesized silver nanoparticles for control of plant pathogens. The reducing effect of the aqueous plant extract for synthesis of silver nanoparticles was investigated at different concentrations and temperatures. UV-visible absorption spectrum recorded for samples prepared with different concentrations (20, 30, 40 and 50% v/v) of plant extract and treated at different temperatures (40, 60, 80 °C and room temperature) confirmed the formation of silver nanoparticles. Antimicrobial activity of the silver nanoparticles was tested against Fusarium oxysporum, Colletotrichum gloeosporioides, Bacillus sp. and Enterobacter cloacae. Complete inhibition of F. oxysporum was observed at 75 ppm concentration of silver nanoparticles as compared to 67.75 ± 1.15 mm radial growth without silver nanoparticles after 7 days of incubation. No growth of C. gloeosporioides was observed in vitro at 100 ppm silver nanoparticles as compared to 44.50 ± 1.14 mm radial growth in the absence of the silver nanoparticles. Inhibitory effect of biosynthesized silver nanoparticles was also observed against bacterial pathogens. The highest inhibition zone of 14.5 ± 1.11 mm was observed against E. cloacae with 100 ppm silver nanoparticles. The obtained results confirm strong antimicrobial activity of the silver nanoparticles synthesized using O. kilimandscharicum against plant pathogens.

Phytochemical Screening and GC-MS Analysis of Methanolic and Aqueous Extracts of Ocimum kilimandscharicum Leaves

“…kilimandscharicum. These results are consistent with prior findings reported in others ocimum species by Singh et al except for the presence of saponins and alkaloids. However, the presence of these bioactive compounds has been reported in other Ocimum species. , On the other hand, our findings suggest the absence of tannins in aqueous leaf extract, which is not surprising given that the content of tannins are optimal in hydro-alcoholic extracts .…”

A Comprehensive Review of the Pharmacological Activities of Ocimum kilimandscharicum: Camphor Basil

“…[76] Responsive oxygen species are likewise created by silver particles through their response with oxygen which makes harm proteins, lipids, and nucleic acids. [77,78]…”

There is plenty of room at the plant science: A review of nanoparticles applied to plant cultures

“…The particles are classified according to their size: the coarse particles have a size between 2,500 to 10,000 nm, the fine ones have sizes between 100 and 2,500 nm and, the ultrafine or NPs are particles from 1 to 100 nm in size. In nanotechnology, a particle is defined as a small object that behaves as an entire unit in terms of its transport and properties (R. Singh et al, 2019; P. Singh, et al, 2016). Thus, the particles are classified according to the diameter.…”

“…The synthesis of NPs from metals or metal oxides (precursors) is based on their reduction and simultaneous attachment to an organic structure (ligand or stabiliser), with the separation of the reduced precursors in the solution. This bonding occurs because the orbital ligands of the reduced metals are available, and, consequently, the ligands have unsaturation in the conformational structures or electron pairs available for bonding to happen (Dimkpa et al, 2017; R. Singh et al, 2019).…”

“…Biological syntheses of noble metals NPs using microorganisms and plants are being widely developed (Al‐Dhabi, Mohammed Ghilan, & Arasu, 2018; Grasso, Zane, & Dragone, 2020; R. Singh et al, 2019; Stozhko et al, 2019). Their antioxidant and reducing properties are responsible for the reduction of metallic compounds into their respective NPs.…”