The study of phytochemical properties and antioxidant activity of different genotypes Rheum ribes L. collected from different regions of Iran

The genus Rheum L. is one of the most important members of the Polygonaceae family. Rhubarb stems are as rich sources phenolic compounds and antioxidants that have beneficial effects on human health. The aim of this study was to investigate the phytochemical characteristics and antioxidant activity of sixteen genotypes of Rheum collected from different places in Iran. The results showed that location has significant effect (P<0.01) on phytochemical characteristics (including total phenol content, flavonoid content, vitamin C, total tannin, soluble carbohydrate, carotenoid, chlorophyll a and b, TA, pH and TSS). The highest total phenolic content (16.33 mg GAE/g DW) and total flavonoid content (0.37 mg QUE/g DW) were in G3 and G13 genotypes, respectively. Vitamin C was in its highest values in the stems of G13 genotype (28.18mg/g DW). The results showed that location has significant effect (P<0.01) on antioxidant activity of Rhubarb genotypes. Antioxidant capacity (by DPPH) was in its highest values in G13 (91.24%), whereas the lowest capacity was found in G10 (10.80%). In the FRAP method, antioxidant capacity was in its highest values in G8 (15.98 μmol Fe2+/g DW), whereas the lowest capacity was found in G10 (0.14 μmol Fe2+/g DW). Multivariate analysis and clustering revealed three distinct categories of genotypes based on their antioxidant activity and phytochemical traits. These results showed that different genotypes of Rheume specially G1 (Oshnavieh), G8 (Lavasan) and G13 (Saqqez) are promising sources of natural antioxidants and other bioactive compounds beneficial to be used in the food or the pharmaceutical industries.