Phytochemistry and Antioxidant Activity of Citrullus colocynthis (L.) Fruit Tissues: Correlation to Soil Macronutrients

Sultan Alsharari

Background and Objective: Citrullus colocynthis is a wild plant that grows in many places in the world and the antioxidant activity varies by geographic origin. Profiling of the antioxidant activity, total phenolic content (TP) and total flavonoid content (TF) of the peel, pulp and seed tissues of the dry fruit were investigated using various in vitro assays. Materials and Methods: Fruit samples grown in clayey and sandy soils were collected from five places. The ferric reducing antioxidant power (FRAP) and the 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) assays were used to measure antioxidant activity. In all sites, the peel tissue exhibited the highest total antioxidant activity followed by the seeds and finally the pulp. Results: The scavenging activity for clayey and sandy soils ranged from 52.0 to 88.0% and from 39.0 to 82.6%, respectively. The clayey fruits showed higher DPPH activity than the sandy ones with a difference in the range of 2.0-14.0%. The Folin-Ciocalteu and aluminum chloride spectrophotometry assays, respectively, were employed to determine the TP and TF. The clayey and sandy soils showed TP in the range 3.38-4.07 and 2.48-3.67 mg gallic acid equivalent g^–1 of dry weight of the whole fruit. Also, the TF was 0.72-0.95 and 0.56-0.77 mg quercetin equivalent g^–1, respectively. The correlation matrix (CM) showed a significant correlation between the DPPH, TP and TF with nitrogen content in the soil. Cluster analysis was also applied for fruit discrimination. Conclusion: The ecological discrimination of the fruit origin was affected by the contents of the macronutrients and the type of the soil.

View Fulltext Back