Antioxidant and anti-browning activities of Mentha suaveolens extracts

The inhibition of enzymatic browning and oxidation is still an important challenge in food processing. This study was designed to examine in vitro the inhibition of enzymatic browning in apple and the antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferrous ion chelating activity by Mentha suaveolens phenol, methanol and aqueous extracts. The use of various extracts in the prevention of the enzymatic browning, catalysed by polyphenol oxidases (PPO) and peroxidases (POD) showed that the phenol extract had a high effect on PPO more than synthetic inhibitor (potassium sorbate), whereas all extracts of M. suaveolens presented only a minor effect on POD of apple. The radical scavenging activity of various extracts of M. suaveolens using DPPH showed that the phenol extract had same activity as butyl hydroxyl toluene (BHT) which is a known inhibitor for its antioxidant activity. The highest ferrous ion chelating activity was found in phenol and methanol extracts. The chemical analysis of the phenol extract using the high performance liquid chromatography (HPLC) suggests that the rosmarinic acid could explain the observed inhibition. In conclusion, these data suggest that the M. suaveolens compounds can act as preservatives of food against oxidation and enzymatic browning.Keywords: Mentha suaveolens, phenolic compounds, enzymatic browning, antioxidant activit

Effects of Virgin Olive Oil Phenolic Compounds on LDL Oxidation and Vasorelaxation Activity

This study examined the efficacy of virgin olive oil phenolic extract and other phenolic compounds (oleuropein, caffeic acid) in preventing oxidative modifications of human low density lipoprotein oxidised by CuCl2. The vasorelaxant effect of these compounds on rat aortic ring with and without functional endothelium is also discussed. Olive oil phenolic extract, caffeic acid and oleuropein increased the lag time of conjugated diene formation in a concentration-dependent manner. Moreover, phenolic extract produced a vasorelaxant effect that persisted in denuded aorta and after inhibition of nitric oxide synthase by N$^{\rm{G}}$-methyl-L-arginine (L-NMMA) or methylene blue. Oleuropein did not produce a relaxant effect, whereas caffeic acid produced partial relaxation at concentration 0.5 g/L