Evaluation of diversity in some phytochemical characteristics among flower extract of wild-growing populations of Rheum ribes L. in Iran

Medicinal plants uses and their active ingredients as natural antioxidant agents are interested recently. Rheum ribes L. with high flavonoid and proanthocyanin antioxidants get a great importance in the food and drug industries. In the present study the flowers of 13 wild-growing genotypes of Rheum ribes L. were evaluated phytochemically. Plant extract was obtained by ultrasonic technique. Total phenol and flavonoid content were measured by Folin-Ciocalteu reagent and Aluminium chloride method, respectively. The vitamin C content by titration with potassium iodide , soluble carbohydrate by anthrone reagent and spectrophotometer method, tannin by vanillin reagent and spectrophotometer method, total carotenoid, chlorophyll a and b content by Lichtenthaler method and antioxidant activity by DPPH and FRAP methods .The highest amount of total phenols and flavonoids (110.53 GAE/g DW and 1.49 mg Qu. g-1 DW) were recorded in G8 and G9, respectively. Also the lowest content of flower phenols (9.80 GAE/g DW) and flavonoids (0.33 mg Qu. g-1 DW) were obtained in G13 sample. Highest antioxidant activity based on DPPH and FRAP bioassays were recorded in G1 (94.75 %) and G8 (59.86 µmol Fe /g DW) and lowest were obtained in G13 and G4 with the 68.17 % and 7.42µ mol Fe /gDW, respectively. The conclusion based on the different genotypes of Rheum ribes L. are natural sources of antioxidant, among the studied genotypes, G1, G8 and G9 with high levels of active compounds and antioxidants advisable to use in food and pharmaceutical industries.