Document Type : Original Article
The relationshipbetween secondary metabolites content and antioxidant activity was studied in aerial parts of Nasturtium officinale R. Br., at various altitudes and periods of growth in north of Iran. Total phenolics (TP), and total flavonoids (TF) contentsin aerial parts of the plantwere investigated spectrophotometrically and their antioxidant activitieswere obtained byTotal Antioxidant Capacity (TAC) method and then compared with standards such as butylatedhydroxyanisole, butylatedhydroxytoluene. Findings demonstrated that the TP content of aerial parts of Nasturtium officinalewere 8.03 to 9.35 mgGAE in vegetative period and 6.5 to 7.65 mgGAE in generative period. Also, TF contents were 26.5 to 31.11 mgQuE in vegetative period and 36.89 to 42.65 mgQuE in generative period. The highest secondary metabolitescontentsof TP were found in vegetative period. Aerial parts in high altitudes (1400 m) hadalso high amount of phenolic and flavonoid compounds. IC50 contents in aerial parts of the plant were 932 to 1494 µg/mlin TAC method.The highest antioxidant activity and radical scavenging effects were observed in vegetative period with the lowest IC50, 932 to 1227.5 µg/ml, whereas generative period with the highest amount of IC50 had the weakest antioxidant activity. Findings showeda positive correlation between antioxidant activity and the most important secondary metabolites,which explains why this plant is used by the rural healers in north of Iran for nutritionand anti-inflammation.