Phytochemical evaluation and antioxidant activity of essential oil byproducts of ‎German iris hybrids and parents (Iris germanica L.) ‎

Iris species are known to be a rich source of isoflavonoids. Iris germanica L. is one of the most important species of bearded irises which is known as Irsa in traditional medicine. In this study, the amount of phenolic compounds and antioxidant activity of the waste obtained during the essential oil extraction process of 34 samples of German iris rhizomes (6 parent samples, 27 hybrid samples and 1 commercial sample) were evaluated. Iris samples were collected from the Ornamental Plants Research Center (OPRC) in Mahallat city and commercial sample were purchased from the market. After extracting the EO, samplings were carried out using the extract in balloon. The phenol content was measured by Folin-Ciocalteu method, flavonoid by Aluminum-chloride method and antioxidant activity with DPPH and FRAP assay. The results of variance analysis showed that all measured factors were affected by the type of hybrid, which was significant in all factors (P<0.01). The results of mean comparison showed that samples with purple and violet flower colors had the highest amount of phenol and flavonoid, followed by the highest level of antioxidant activity. In other words, the highest amount of flavonoid (113.22 mg QUE/g DW plant) and antioxidant activity (DPPH) (817.73 mg TBHQ/gDW plant) was observed in sample P6 (purple parent) and the highest amount of phenol content (261.31 mg GAE/g DW plant) was observed in sample P3 (violet parent). In general, the water residues from the Iris EO extraction can be used as a suitable and cheap source for obtaining natural antioxidants.