Chemical characterization and antimicrobial activity against Paenibacillus larvae of propolis from Buenos Aires province, Argentina

Abstract

In this study, we examined the chemical composition and antimicrobial and radical scavenging activities of propolis from Buenos Aires province, Argentina. The polyphenol and flavonoids content of ethanol extracts of propolis (EEP) vary widely, ranging from 189 to 417 mg gallic acid equivalents (GAE)/g and from 46 to 191 mg equivalents of quercetin (QE)/g, respectively. High-performance liquid chromatography (HPLC) analyses indicate the presence of abscisic acid, p-coumaric acid, epicatechin, indoleacetic acid, and quercetin. All samples show antimicrobial activity against Paenibacillus larvae measured by the agar diffusion method and antioxidant activities, measured with both the ABTS and DPPH assays. In addition, EPR studies indicate that the scavenging activity of EEP towards hydroxyl radicals is high and reaches 71%. The antioxidant activity correlates positively with polyphenols and flavonoids content. Besides, the samples were analyzed by Fourier-transform infrared spectroscopy (FTIR) and UV–visible spectrophotometry. Principal component analysis (PCA) and hierarchical conglomerate analysis (HCA) were applied to the spectra data, clustering samples over the spectral ranges of 1700–1100 cm−1 and 410–240 nm. The results suggest a good predictive capability of FTIR and UV–vis spectroscopy for grouping propolis samples from related geographical origins.