Abstract

Abstract:Medicinalplants, also called medicinal herbs, have been discovered and used intraditional medicine practices since prehistoric times. This research work hasaimed at achieving the synthesis of metal nanoparticles by using the leafextract of the Plectranthusamboinicus(Oma valli). Phytochemical screening of aqueous extract of theplant revealed the various bioactive compounds like Saponins, Polyuronidesreducing compounds; alkaloids, flavonoids, terpenoids and glycosides.  Leaf extracts of P.A. and variousconcentration of Cobalt chloride hexahydrate (0.02M, 0.04M, 0.06M, and 0.08M)were prepared. 25 mL of the Plectranthusamboinicus was added to each concentration of cobalt (II) chloridehexahydrate in 1:1 ratio. The mixture was then subjected to heating processwhich leads to the formation of nanoparticles in various extractconcentrations. The nanoparticles formed were subjected to IR and UV studies.Antibacterial activity was carried out on well diffusion method for Pseudomonas and Streptococcus bacteria atdifferent concentrations.  Minimuminhibitory zone was found only in Pseudomonasat the concentrations 0.04M and 0.08M (at 50μL both shows zone of inhibition0.8mm, but at 100μL 0.04M shows slightly higher inhibition of 1mm 0.9mm).Cobalt nanoparticle showed good antibacterial and antifungal properties. Themetal and metal oxide nanoparticles have high surface area and high fraction ofatoms which was responsible for their fascinating property of antimicrobialactivity.

Keywords: Metalnanoparticles cobalt (II) chloride hexahydrat Plectranthus amboinicus(Omavalli) Leaf extracts Antibacterial activity