henol analysis by HPLC-DAD, and antimicrobial and antioxidant activities of two species extracts of Pelargonium: P. graveolens and P. zonale

Abstract

Introduction. Pelargonium graveolens is a well-known ethno-medicinal plant used in traditional medicine, whereas Pelargonium zonale has not been investigated thoroughly. Objective. This study was designed to quantify phenolic compounds in extracts of Pelargonium graveolens and Pelargonium zonale, evaluate their antioxidant activities, establish a method for assaying phenolic compounds by HPLC-DAD, and determine the antimicrobial activity of these extracts. Material and methods. Aerial parts polyphenols were extracted with solvents of different polarities. Total content of polyphenols, flavonoids, and condensed tannins were determined. Antioxidant activity was assessed by measuring free radical scavenging activity of 2,2-diphenyl-2-picrylhydrazyl (DPPH). Agilent C18 with a linear gradient elution program was performed for chromatographic separation, and disk diffusion method was used to determine antimicrobial activity. Results. Total polyphenols content ranged from 159.4 to 164.2 mg GAE/g, and that of total flavonoids from 26.92 to 63.68 mg QE/g. DPPH values of ethanol extracts reached IC50 = 91.84±0.1 μg/mL. HPLC method permitted to analyze and separate twelve phenolic compounds (Acacetin, apigenin, myrecitin, quercetin, catechin, naringin, hesperetin, galengine, flavone, tannic acid, vanillic acid, and α-tocopherol). Extracts showed moderate to strong antimicrobial activity against five strains withminimum inhibitory concentration (MIC) ranging from 0.46 to 3.9 mg/mL. Conclusion. These results confirm richness of extracts by phenolic compounds, and are strongly correlated with DPPH values. In addition, the applied method is precise, and allows simultaneous determination of 12 phenolic compounds.