EFFECT OF DIFFERENT SOLVENTS ON POLYPHENOLIC CONTENT, ANTIOXIDANT CAPACITY AND ANTIBACTERIAL ACTIVITY OF IRISH YORK CABBAGE

Abstract

Cabbage is a rich source of a number of bioactive compounds such as flavonoids, glucosinolates and their breakdown products, which may have antibacterial, antioxidant and anticancer properties. This investigation was undertaken to estimate the effect of using water and different organic solvents such as ethanol, acetone and methanol at various concentrations on the total polyphenols, antibacterial activity and antioxidant capacity of Irish York cabbage. Water has the highest extraction yield of 3.85%, whereas 60% methanolic extract has the highest content of total polyphenols (33.5 mg gallic acid equivalents per gram [dried weight, dw] of extract) and flavonoid (21.9 mg quercetin equivalents per gram [dw] of extract). A concentration-dependent antioxidative capacity was confirmed for different reactive oxygen species, including hydrogen peroxide, metal chelating capacity, reducing power and lipid peroxidation. The crude extracts showed a broad spectrum of antibacterial activity for the different extraction solvents applied; however, 60% methanolic extract (1.4%) exhibited higher antibacterial activity against Listeria monocytogenes (100%). PRACTICAL APPLICATIONS The problem of oxidation and microbial contamination are most common aspects of food preservation, especially when the products develop undesirable flavors, unpleasant taste, rancid odors, discoloration and other forms of spoilage often responsible for the loss of quality, and safety and shortening of shelf life. Over the last decade, interest in using extracts from plant origin with antibacterial and antioxidant properties to control oxidative deterioration and microbial spoilage has been increasing. Present work demonstrates that conventional organic-solvent extracts of Irish York cabbage are rich in polyphenols and are potential sources for this phytochemical, and have appreciable amount of antioxidant and antimicrobial activity. This extract may be exploited as bio-preservatives in food applications in order to enhance safety and quality of food or neutraceuticals for possible application in food and dietary supplemental products for health promotion.