Comparison of Different Extraction Methods for Optimizing Antioxidant Compounds in Origanum Majorana L

Marjoram (Origanom majorana L)، a plant which belongs to lamiaceae family، is used in medicine and food industry for its high antioxidant compounds. Since antioxidant activity of plants is affected by extraction method، this study aimed to optimize the extraction method of these compounds from different tissues of majoram (leaf and flower) in vegetative and flowering stages. Methanolic extract was prepared from leaf dried powder before and after flowering. In fact، mixture of the flower and leaf was prepared by three methods including soaking، microwave and ultrasonic extraction. Then، antioxidant activities of the extracts were measured by two DPPH scavenging capacity of free radicals and linoleic acid peroxidation in β- carotene system. The microvawe extraction significantly extracted highest antioxidant compounds from different tissues of the majoram (p<0. 01)، whereas soaking and ultrasonic methods had lesser amount of these compounds. DPPH test obviously revealed the significant difference among antioxidant activity of the various extracts. Among the studied samples، leaf sample (before flowering stage) that was extracted by microvawe method had the highest antioxidant activity. The IC50 value of this sample was 0. 02 mg DW ml-1 in DPPH method and also inhibition percent of linoleic acid peroxidation was 110% compared to BHT. In contrast، extraction by ultrasonic method showed the lowest antioxidant activity (IC50 0. 28 mg DW ml-1 and 102% inhibition of lipid peroxidation). The study results indicated that microvawe extraction method can be introduced as the best technique for fast extraction of the antioxidant compounds from Origanum majorana L.