Effects of ecological factors on the antioxidant potential and total phenol content of Scrophularia striata Boiss

Scrophularia striata, commonly known as figwort, is one of the most important medicinal plants that mainly grows in cold regions of the Zagros Mountains (West of Iran). Although the chemical composition of this plant species has not yet been explored, people living in Ilam province (W Iran) have used it for many years to treat different illnesses. The present study aims to analyze the effect of some ecological factors on the antioxidant potential and the amount of phenol present in this plant species, using a random factorial design with two factors (elevation and region) and three replicates. The fruits of the plant were gathered from three different elevations. They were collected from three regions of the Ilam province (Badreh, Dareshahr, and Dehloran) in June 2016, when the fruits appear. Moreover, to analyze different soil chemical and physical features, soil samples were gathered from a depth of 0.5 m under the shrubs. The antioxidant action of the methanol extract from the plant samples and the total amount of phenol compounds were measured using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and the Folin-Ciocalteu method, respectively. The results showed that the effects of site and elevation, and the interaction between these factors, on the antioxidant potential and total phenol amount were significant with a probability of error of 1%. The maximum extract efficiency (19.37 ± 3.07%), antioxidant potential (126.5656 ± 0.96 µg/mL), and total amount of phenol (55.7689 ± 3.17 µg/mL) were obtained from Dareshahr at an elevation of 600 m above mean sea level. The minimum amount of total phenol (24.6544 ± 3.21 µg/ml) was recorded at the lowest elevation of Badreh, at which phosphorus, potassium, organic carbon, organic material, nitrogen, acidity, lime, and silt were present at the lowest amount. However, the antioxidant activity and total amount of phenol had a strong direct correlation in the two districts of Dareshahr and Badreh, but were reversely and strongly correlated in Dehloran. Therefore, it can be stated that Scrophularia striata has the potential for antioxidant activity, however, the complexity of the effect of ecological factors on one hand, and the emergence of different chemical processes in the plant under such effects on the other hand, has led to the synthesis of different compounds with antioxidant potential in the plant in different regions.