Green Synthesis of Ag Nanoparticles with Anti-bacterial Activity Using the Leaf Extract of an African Medicinal Plant, Ipomoea asarifolia (Convolvulaceae)

Abstract

Herbal drugs prepared with the plant Ipomoea asarifolia has many medicinal uses throughout West Africa, including its employ as diuretic, emmenagogue and purgative. This species is a good source of acylated anthocyanins, and the methanol and ethyl acetate extracts of I. asarifolia are known for their strong acetylcholinesterase inhibitory effects. Here, green synthesis of Ag nanoparticles (Ag NPs) was performed at room temperature using the I. asarifolia leaf extract. The Ag NPs were characterized by UV–visible spectroscopy, FT-IR, XRD, AFM, SEM with EDX and TEM. AFM and SEM analyses showed that spherical morphology of I. asarifolia-synthesized Ag NPs with a size range of 20 to 60 nm. TEM revealed that I. asarifolia-synthesized Ag NPs had a mean particle size of 40 nm. The I. asarifolia-synthesized Ag NPs was tested against four bacterial pathogens using the disk diffusion method. The zone of inhibition varied  significantly in a dose-dependent manner. Overall, our results underlined the potential of cheap aqueous extracts from this African medicinal plant species for the synthesis of silver nanocomplexes with wide efficacy against human pathogenic bacteria.