Abstract
The impact of soil macronutrients on the antioxidant activity of the Haloxylon Salicornicum plant collected from Al-Muzahmiyah, Al-Quwaiyiyaih, Ath Thumamah and Huraymilah in the Riyadh region was investigated. Liquid chromatography and the antioxidant activity profiling including the 2,2-dipheny1-1-picrylhydrazyl, ferric reducing antioxidant power, Folin-Ciocalteu total phenolic content, and aluminum chloride total flavonoid content assays were studied. Chromatographic analysis showed a descending order in the total phenolic content from Al-Quwaiyiyaih, Al-Muzahmiyah, Huraymilah and Ath Thumamah sites. The 2,2-diphenyl-1-picrylhydrazyl activity ranged from 67.5 to 79.0%. The corresponding 50% activity at extract concentration is 0.18-0.25 mg mL(-1) dry extract. The ferric reducing power ranged from 30.2 to 45.4% and the 50% activity extract concentration was from 0.14 to 0.20 mg mL(-1). The total phenolic content was 15.5 to 24.7 mg gallic acid equivalent g(-1) dry weight and total flavonoid content was 4.2 to 6.7 mg quercetin equivalent g'. The correlation matrix is significant and highly positive for nitrogen and potassium with the measured antioxidant activity properties (Pearson correlation=0.952-0.993, at p<0.05). Cluster analysis showed a grouping of the sample sites Ath Thumamah and Al-Muzahmiyah. The principal component analysis showed the strong and essential correlation between all studied factors, except for phosphorus, on the antioxidant activity.