Composition, Antioxidant, Antibacterial Activities and Mode of Action of Clove (Syzygium aromaticum L.) Buds Essential Oil

Abstract

The use of natural antimicrobial compounds, especially extracted from plants, as food preservatives is nowadays widely used, since plant matrices possesses antimicrobial and antioxidant natural products to protect themselves from microbial infection and deterioration as well as for human health benefit properties. The present work was undertaken to examine the antioxidant and antimicrobial activities of clove (Syzygium aromaticum L.) buds essential oil. Clove essential oil (CEO) exhibited high amount of total phenolic compounds (TPC) with high radical scavenging activity toward DPPH, ABTS and linoleic acid radicals as well as iron chelating activity. The TPC of CEO was 845 mg GAE g-1 demonstrated 509 µmol of TE g-1DPPH radicals scavenging activity and 713 µmol of TE g-1 ABTS radicals scavenging activity. The antioxidant capacity of CEO exhibited 94% reduction when evaluated by β-carotene bleaching assay. The Reducing power activity related to iron chelating was 314 µmol of AAE g-1. The composition of CEO exhibit high eugenol content (80.19%) over 16 identified components by GC-MS analysis. Furthermore, CEO exhibited antibacterial activity in vitro at low concentrations against tested food borne pathogens applying disc diffusion and microdilutions assays. The minimum inhibitory concentration values (MICs) for tested bacteria which were sensitive to CEO were in the range of 1400–3600µg ml-1. The phenolic components of CEO are most active and appear to act principally as membrane permeabilizers which established using staining-DNA fluorescence dye assay. Quantification of membrane permeabilization exudes a positive relationship between the cell membrane damaging and concentrations. Therefore, the CEO can be reliably used in commercial applications as antioxidant, antibacterial and flavoring agent in individual or in combination with common preservatives for controlling the undesirable organoleptic and microbial deteriorations in foodstuffs.