CHARALAMPOS PROESTOS¹*, KHALED RASHED², ROIDAKI ANNA¹, VASSILIA J. SINANOGLOU³

*Corresponding author

1. Laboratory of food Chemistry, department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, GR-15771, Athens, Greece
2. Pharmacognosy Department, National Research Centre, 33 El-bohouth st., Dokki, Giza, Egypt. P.o.12622
3. Instrumental Food Analysis Laboratory, Department of Food Technology, Technological Educational Institution of Athens, Greece

Abstract

Selected plants of interest in traditional diets were examined in order to determine their phenolic composition, their antioxidant capacity and their antimicrobial activity. The antioxidant capacity of the extracts and of the isolated polyphenols compounds were determined with the Rancimat test using sunflower oil as substrate (the PF factor was determined), the FRAP assay and the DPPH assay (IC50 was determined). The antimicrobial activity of the extracts against selected microorganisms was also investigated using the disc diffusion method. The plants, Acalypha wilkesiana, Cassia nodosa and Ficus benjamina exhibit the most potent antimicrobial activity against all selected pathogenic microorganisms such as E. coli and L. monocytogenes. These results suggest that the plants selected for this study have properties that require attention for their potential health effect and for possible applications in food products, nutraceuticals and dietary supplements.

INTRODUCTION

Lipid oxidation occurring in food products is one of the major concerns in food technology. It is responsible for rancid odors and flavors of the products, with a consequent decrease in nutritional quality and safety, caused by the formation of secondary, potentially toxic compounds. In order to limit these undesirable effects various methods have been proposed. Besides physical processes, such as oxygen removal and refrigeration, the use of substances that decrease the rate of these oxidation processes plays an important role. Antioxidants, especially those naturally found in plants have been largely viewed as effective tools in the fight against oxidation, whereas in the search for naturally occurring ones, herbs and spices are considered of being one of the most important targets from the point of view of safety (1).

This report regards the antioxidant activities of plant extracts by means of the DPPH and FRAP assay (1), Rancimat test and their total phenolic content determined spectrometrically by applying the Folin-Ciocalteau assay. The antimicrobial activity of the extracts against selected microorga ...