Chemical composition and antioxidant properties of γ-irradiated Iranian Zataria multiflora extracts

Irradiation is the process of exposing food such as herbal plant to ionizing radiation to destroy microorganisms. Zataria multiflora Boiss (Lamiaceae), known as Avishan-e-Shirazi in Persian, is a thyme-like plant that grows naturally in central and southern parts of Iran and is used in traditional folk medicine.

In this study, the effects of γ-radiation on chemical composition and antioxidant properties of Z. multiflora were investigated.

The plants were first irradiated with Co60 source (0, 10, and 25 kGy) and then subjected to Clevenger extraction to obtain essential oils. The composition of the oil was analyzed by a gas chromatography and compared with samples pretreated under different conditions. In parallel, the hydroalcoholic extract was prepared and used for measuring flavonoid content. Thereafter, the free-radical scavenging and antioxidant properties of essential oils and hydroalcoholic extract were examined.

Despite the minor change in the individual oil constituents, the total percentage of the main components remained unaffected before and after irradiation (~95%). In addition, the total flavonoid content of hydroalcoholic extract was also unchanged due to irradiation (~32 mg QE/g extract). The high radical scavenging activity of the oil (~67%) and hydroalcoholic extract (~71%), in addition, the antioxidant properties of the oil (~91%) and hydroalcoholic extract (~95%), were unaffected after irradiation.

These findings may suggest the sustainability of Z. multiflora extract properties pretreated with γ-radiation. With a view to its antioxidant applications, resistance of Z. multiflora and its properties against radiation effects are promising findings.