Enzymatic Properties of Red Beet (Beta vulgaris L.) Leaf, Root Pulp, and Peel

Abstract

Background: Beetroot (Beta vulgaris L.) is botanically classified as a herbaceous biennial belonging to the Chenopodiaceae family and has several varieties with bulb colors ranging from yellow to red. Peroxidases are widely occurring in organisms including microorganisms, plants, and animals, and have been involved in various physiological and biochemical functions. Objective: The study was conducted to investigate the characteristics of enzyme extracts from red beet leaves, root pulp, and peel. Methods: The enzyme extraction involved the homogenization of the sample and filtrate in cold acetone and then the filtrate was homogenized in 0.1M sodium acetate buffer, pH 7. The protein content was determined using the Lowry assay using bovine serum albumin (BSA) as a standard protein. Then, enzymatic activity was determined by peroxidase, polyphenol oxidase, and catalase assays. The patent for biological activity of enzymes was obtained from the Office of Career Development, Haramaya University. The antioxidant activities of the enzyme extract were conducted by using DPPH and hydrogen peroxide free radical scavenging activities. Results: The result indicated that the Enzymatic activity of crude enzyme extract of red beet leaf, root pulp and peel indicated that significantly the highest total soluble protein (16.68 mg/ml), peroxidase activity (PODA, 111.50 U/ml), polyphenol oxidase activity (PPOA, 170.90 U/ml), polyphenol oxidase specific activity (PPOspa, 10.25 U/mg), catalase activity (CATA, 180.50 U/ml) and catalase specific activity (CATspa, 10.82 U/mg), were recorded for red beet leaf enzyme extract. The antioxidant activity of the enzyme extracts demonstrated that significantly higher DPPH radical scavenging activity of leaf extract (59.16) and peel extract (61.92) were recorded. The Pearson correlation coefficient of enzyme activity parameters and free radical scavenging activities presented that protein content was significantly and positively correlated with CATA, PPOA, and PPOspa. Catalase- specific activity (CATspa) was significant and positively correlated only with HPSA. Peroxidase-specific activity (PODspa) was significant and positively correlated with PODA and DPPH. Based on the plot for principal component PC2 vs. PC1 for D statistics DPPH, PODA, and PODspa have close PC1 and PC2 scores (with vector angle < 90°showing similar/correlated effects. Conclusion: In this study, B. vulgaris has shown promising peroxidase enzyme activity. Beetroot peel contained higher antioxidant compounds thus promising a more intense utilization of the peels in food and nutraceuticals.