Affiliations: Department of Chemistry, The University of the West Indies, Mona, Kingston 7, Jamaica
Corresponding author: Andrea M. Goldson Barnaby, The University of the West Indies, 2 Plymouth Crescent, Mona, Kingston 7, Jamaica. Tel.: +1 876 977 9891; Fax: +1 876 977 1835; E-mail: email@example.com.
Abstract: BACKGROUND: Cissus sicyoides berries are currently underutilized and may be a potentially novel source of antioxidants. Extracts from the leaves of this vine are utilized in traditional medicine. The chemical composition and functional properties of C. sicyoides berries were investigated. OBJECTIVE: Phenylalanine ammonia lyase (PAL) an essential enzyme in the phenylpropanoid pathway was characterized and the antioxidant properties, fatty acid profile and mineral content of the berries evaluated. METHODS: The PAL, free radical scavenging activity and total phenolic content of C. sicyoides berries were determined by use of a spectrophotometric assay. Lipids were extracted, methylated and the fatty acid methyl esters identified by gas chromatography mass spectrometry. The chemical composition of the berries was also evaluated by infra red spectroscopy. RESULTS: The PAL enzyme from C. sicyoides exhibits Michaelis Menten kinetics with the substrate phenylalanine (Km, 1.21±0.28 mM) and has a Vmax of 6.24±0.28 μM/min. The enzyme has a temperature optimum of 25°C and a pH optimum of 7.5. C. sicyoides berries possess high free radical scavenging activity (84.4±4.4%) and contain a phenolic content of 3.2±0.4 mg gallic acid/g dry weight. Berry extracts had an ascorbic acid concentration of 2.8±0.1 mg/mL. The major fatty acids identified in extracts of the fruit include palmitic acid (43.6±1.8%), oleic acid (13.8±1.7%) and linoleic acid (13.9±2.0%). The oil has a predicted iodine value of 35. Berry extracts had a refractive index of 17 °Brix. A positive Fehlings test confirmed the presence of reducing sugars. The fruit is low acid with a pH of 6, and a titratable acidity of 0.165 g of tartaric acid per 100 mL of juice. FTIR analysis of ashed samples indicated the presence of the minerals potassium and phosphorus. CONCLUSION: C. sicyoides berries possess high levels of free radical scavenging activity and may be a novel source of antioxidants.