<em>In-Vitro</em> antioxidant activity of essential oils and oleoresins of cinnamon, clove bud, ginger and their synergistic interactions

Abstract

Essential oils (EOs) and oleoresins (ORs) are well distinguished for their antioxidant properties and they can be widely used in the food industry as preservatives. The present study was executed for evaluating the synergistic interactions on antioxidant efficacy of EOs and ORs of cinnamon, clove bud and ginger and their combinations. EOs and ORs were obtained by hydro-distillation and solvent extraction. In-vitro antioxidant properties were investigated by DPPH free radical scavenging assay, phosphomolybdenum method (Total Antioxidant Capacity, TAC) and ABTS radical scavenging activity assay. EOs and ORs which consisted with different chemical constituents and different Total Phenolic Content (TPC) and Total Flavanoid Content (TFC) exhibited a range of variation in the inhibition percentage of DPPH and IC50 values (0.1645-6.5181 mg/mL). The TAC of EOs and ORs was within the range of 0.27-3.94 mg AAE/mg. The ORs showed higher inhibition percentages and TAC compared to EOs of the same spice. This study revealed that clove buds contains higher antioxidant properties than cinnamon and ginger. Significant reductions in IC50 values were shown in EO blends compared to the ORs blends. The combination of cinnamon EO/clove bud EO and combination cinnamon EO/ginger EO showed strong synergy in tested samples. Therefore, both EOs and ORs of Cinnamomum zeylanicum, Syzygium aromaticum, Zingiber officinale and their blends are excellent sources for natural and effective natural antioxidant agents in the food industry.