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Title: Steviol glycosides and polyphenolic contents of the honey leaf ‘Stevia rebaudiana’ (Bertoni) cultivated in Malta
Authors: Vella, Christian
Keywords: Stevia rebaudiana -- Malta
Issue Date: 2015
Abstract: The herb Stevia rebaudiana, belonging to the Compasitae family, contains sweet non-caloric diterpene glycosides which are responsible for conferring the leaves a particular sweet taste. These steviol glycosides occur at high concentrations in the leaves, with stevioside and rebaudioside A being the major representatives. Apart the special organoleptic properties conferred by these metabolites, these are also known to exert beneficial pharmacological activities including antihyperglycemic, antitumor, antihypertensive, antimicrobial, antiviral and anti-inflammatory actions. The safe nature and the presence of these glycosides, make leaf extracts a very popular application in the food industry. Furthermore, leaf extracts contain polyphenols which with their high antioxidative potential, are known to prevent degenerative diseases. The presence of polyphenols in stevia extracts enhances their beneficial properties. The contents of two steviol glycosides, stevioside and rebaudioside A and the total polyphenol content in the leaves of S. rebaudiana plants cultivated in Malta were analyzed. The growth performance of the crop was also assessed during the trial. The leaf extracts were prepared using alcoholic solvent extraction assisted with ultrasonication. The mean plant height, dry leaf mass and number of secondary branches was 80.71 cm, 47.6 g and 25 respectively. HPLC analysis revealed that the mean contents of the steviol glycosides stevioside and rebaudioside A in leaves were 3.87 % and 3.13 % respectively while the Folin Ciocalteu test revealed that the mean content of total polyphenols in leaves was 1.23 %. The results show that plants propagated by seeds, although subjected with the same environmental parameters, display a great variability in their morphology and their phytochemical contents. This variability is important since the contents of secondary metabolites in the plant are correlated with other morphological features such as number of leaves, hence making the selection of the best crops for our local climate possible.
Appears in Collections:Dissertations - InsESRSF - 2015

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