Nutraceutical Potential and Health Benefits of Different Polyphenol-Rich Vegetables Stalk Extracts by Exploring Antioxidant Activities

Abstract

Edible stalk portion of vegetable is essential constituents of well-balanced diet enriched with minerals, dietary fiber, vitamins and phytochemicals. The main aim of the present research work was to determine the antioxidant of different polyphenol-rich vegetables stalk extracts (Cauliflower Stalk (CS), Broccoli Stalk (BC), Garlic Stalk (GC), Onion Stalk (OS), Parsley Stalk (ps), Young Bamboo Shoot (YBSS), Sarson Stalk (SS) and Sugar Cane SCS). The methanol crude extracts of all the stalks were prepared by orbital shaker. Quantification of phenolic acids and flavonoids was evaluated by RP-HPLC. In-vitro antioxidant activity was carried out by measuring the total phenolic contents, total flavonoid contents, DPPH radical scavenging activity, reducing potential and inhibition of linoleic acid peroxidation. HPLC analysis showed the presence of gallic acid, p-coumaric acid, chlorogenic acid and benzoic acid was found as major phenolic acids, while catechin was found as a major flavonoid in many stalk extracts. TPC was ranged from (0.41 to 1.26 and 0.05 to 0.18 mg/g of dry weight of stalk). Highest TPC and TFC were found in garlic stalk (1.26 g/100 g of dry stalk measured as gallic acid) and broccoli stalk (0.19 g/100 g of dry weight of stalk measured as catechin equivalent). Garlic stalk (17.23 mg/mL) showed the excellent radical scavenging activity. Among these vegetables’ stalks, Garlic stalk showed the promising DPPH radical scavenging activity, reducing potential and inhibition of linoleic acid peroxidation. HPLC analysis showed four phenolic acids were detected: gallic acid, p-hydroxyl benzoic acid, caffeic acid and ferulic acid. Gallic acid and p-hydroxy benzoic acid were the major phenolic acids present in abundance in extracts of all the stalks. Two flavonoids—catechin and quercetin—are being reported as the major flavonoids in edible stalk extract, analyzed.