The antioxidative and antimicrobial properties of the blue honeysuckle (Lonicera caerulea L.), Siberian rhubarb (Rheum rhaponticum L.) and some other plants, compared to ascorbic acid and sodium nitrite

Abstract

The aim of the present study was to evaluate the antioxidative and antimicrobial effects of the ethanol and buffered water infusions of six different plants grown in Estonia, namely Siberian rhubarb (Rheum rhaponticum L.), blue honeysuckle (Lonicera caerulea L.), tomato (Lycopersicon esculentum Mill.), bilberry (Vaccinium myrtillus L.), sea-buckthorn (Hippophae rhamnoides L.) and black currant (Ribes nigrum L.), compared to the food additives ascorbic acid (E300) and sodium nitrite (NaNO2, E250). Additionally, the content of vitamin C and the content of anthocyanins, flavonols and total polyphenols in the studied samples were estimated using High performance liquid chromatography (HPLC) method.Of the bacterial species used in present study, gram-positive bacteria were represented by Listeria monocytogenes, Kocuria rhizophila and Bacillus subtilis. Gram-negative foodborne pathogenic bacteria were represented by Escherichia coli and Campylobacter jejuni. Probiotic bacterial species, often used in dairy products, were represented by Bifidobacterium bifidum and Lactobacillus acidophilus.The studied plant infusions had both antioxidant and antimicrobial properties. The highest antioxidative effect in the buffered water infusion was found with the berries of blue honeysuckle. However, in the 30% ethanol infusions the antioxidative effect was the highest with the petioles of the Siberian rhubarb, exceeded only by the ascorbic acid solution with the concentration of 10 mg/ml. Among tested plant infusions, the roots of the Siberian rhubarb exhibited the highest antibacterial effect against all bacterial species assayed.