Green Synthesis of Silver Nanoparticles from Parinari curatellifolia Methanol Stem Bark Extract and Evaluation of Antioxidant and Antimicrobial Activities

Abstract

Parinari curatellifolia Planch ex. Benth (Chrysobalanaceae) has been used traditionally for the treatment of cancer, pneumonia, fever, dressing of wounds and fractures. The green synthesized nanoparticles from phytochemicals have been utilized as effective antimicrobial and anticancer agents. The research was designed to synthesize nanoparticles from methanol stem bark extract of P. curatellifolia and to investigate its antioxidant and antibacterial activities. The stem bark was powdered and then extracted by maceration. Silver nanoparticles were synthesised using 5 mM AgNO3 solution. DPPH free radical and hydrogen peroxide scavenging assays were employed to determine the antioxidant activity. The antibacterial activity was determined using agar disk diffusion method on Staphylococcus aureus, Bacillus subtilis, Salmonella typhi and Escherichia coli. The phytochemical screening of the extract revealed the presence of saponins, flavonoids and tannins. XRD analysis of the synthesized silver nanoparticles revealed a crystalline structure with face cantered cubic orientation. The SEM revealed particle size of 1 nm and consisted of highly agglomerated particles which formed large aggregates. The IC50 of DPPH free scavenging activity of the extract, silver nanoparticles and ascorbic acid (standard) were 2.804 mg/mL, 2.367 mg/mL and 2.065 mg/mL respectively. Also, that of H2O2 against the extract, silver nanoparticles and ascorbic acid (standard) were 4.986 mg/mL, 36.56 mg/mL and 6.414 mg/mL respectively. The nanoparticles inhibited the growth of the organisms with zone of inhibition between 8-12 mm whereas that of standard antibiotic (gentamicin) ranged from18-26 mm. This therefore implies that PC extract can be used in the synthesis of nanoparticles for its use against bacteria strains and as antioxidants.