Variation in biochemical profile and health beneficial compounds and biological activities of Brassica oleraceavar gongylodesL. morphological parts

Brassica oleraceavar. gongylodes, commonly used as food, is loaded with biochemicals that fend diabetes, cancer, high cholesterol and it improves the general human health. The present study aimed at evaluating the antioxidant and antibacterial activities of leaves, flesh and peel extracts of B. oleraceavar. gongylodescultivated in Tunisia. Besides, biochemical, phenolic and nutritional composition was investigated. Phenolics and ascorbic acid were detected and quantified by high performance liquid chromatography (HPLC) method, while fatty acids and sugars were identified by gas chromatography flame ionization detector (GC-FID). Nutritional composition was determined for each plant part. Antioxidant activities were estimated by DPPH, ABTS and reducing power assays. Agar disk diffusion and micro-dilution methods were adopted to determine antibacterial activity. Leaves showed significantly high antiradical (EC50= 0.26–0.32 mg/mL), antioxidant (EC50= 0.46 mg/mL) and antibacterial (MIC = 0.625 mg/mL) activities. Chlorogenic acid, catechol, epigallocatechin and epicatechin 3-O-gallate were present in leaves. Isorhamnetin-3-O-glucoside was detected in peel and flesh. Gallic acid was present only in flesh. Peel showed higher ascorbic acid content (223.2 mg/100 g DW) than flesh and leaves. Hemicellulose, chlorophylls, proteins, Na, P and microelements amounts were significantly elevated in leaves. Sucrose is the main sugar in stem tissues. Linoleic, palmitic and oleic acids were the major fatty acids in this species. The present study provides important data on phytochemical, nutritional composition, bioactivities and emphasizes B. oleraceavar. gongylodesas a potential nutraceutical and functional food. Moreover, this species can be employed as an alternative and complementary therapy for the running of related diseases of oxidative stress.