Background: Rumex turcomanicus Czerep. Locally named Sagh-Torshak, is one of native green vegetable medicinally valuable plant belongs to family Polygonaceae, growing spontaneously in Northeast Iran, where its leaves are highly appreciated and consumed. Despite the high consumption, its knowledge is inconsiderable.

Objective: The aim of this study was to evaluate the changes of main phytochemical compound in leaf and root parts of R. turcomanicus Czerep. in different phenological stages.

Methods: The wild-growing plants were harvested at vegetative, floral budding, full floweringand mature seed stages and dissected into root and shoot tissues, which were dried separately and subsequently assayed for total phenolics, flavonoid, ascorbic acid, oxalic acid content and antioxidant activity, by spectrophotometric method.

Results: The results showed considerable contents of phenol, flavonoid and antioxidant activity in roots and shoots of plant, with the higher contents in roots as compared to shoots. Among different phonological stages the highest total phenol, flavonoid, oxalic acid content and antioxidant activity of shoots was obtained in mature seed stage. Ascorbic acid of shoot was highest in floral budding stage. The greatest total phenol and flavonoid content of root was observed in floral budding stage, while the highest antioxidant activity was obtained in mature seed stage. A high negatively correlation was obtained between ascorbic acid and Oxalic acid.

Conclusion: The concentrations of secondary metabolites in Rumex turcomanicus Czerep. depend on the phenological stage and tissue of the plant. As plant aged, oxalic acid and ascorbic acid of shoots were increased and decreased, respectively.