Characterisation and evaluation of antibacterial potential of guava extract loaded poly‐3‐hydroxybutyrate‐co‐3‐hydroxyvalerate nanoparticles against multidrug‐resistant bacteria

In this work, the antibacterial potential of different plant's leaves, i.e. Psidium guajava (guava) , Raphanus sativus (radish), Solanum pseudocapsicum (winter cherry), Mentha royaleana (mint) and Calotropis procera (rubber tree) was evaluated against the multidrug‐resistant (MDR) bacteria. Methicillin‐resistant Staphylococcus aureus (MRSA) , Vibrio cholerae O1 El Tor (VC O1 ET), V. cholerae Non‐O1/Non‐O139 (VC N‐O1/N‐O139), enteroaggregative Escherichia coli (EAEC) and enteropathogenic Escherichia coli (EPEC) were included among the MDR bacterial strains. The significantly high ( P < 0.001) antibacterial activities were observed against the MDR bacteria in case of the methanol extract of the P. guajava (GUV) leaves. The characterisation studies of GUV extract were done by thin layer chromatography, wide angle X‐diffraction and Fourier transform infrared techniques. The GUV extract was encapsulated in poly‐3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) nanoparticles using the nanoprecipitation method. Blank PHBV nanoparticles demonstrated no antibacterial activity against the selected MDR strains. The GUV extract loaded PHBV nanoparticles produced significantly large ( P < 0.001) zones of inhibition, i.e. MRSA (24 mm), EPEC (23 mm), EAEC (23 mm), VC O1 ET (21 mm) and VC N‐O1/N‐O139 (20 mm) against the MDR bacterial strains as compared with the GUV extract alone. The results have demonstrated a great potential of PHBV nanoparticles to become an efficient carrier for delivery of the potent bioactive molecules.