Detecting the presence of rebaudioside a in two varieties of stevia rebaudiana (morita & paraguay) in various parts of plant via thin layer chromatography (TLC) / Najwa Baharom

Stevia rebaudiana is a species which is characterized by high level of steviol glycosides in its tissues, especially in leaves. These glycosides are a source of natural zero-calorie sweetener which is considered sweeter than sugar (sucrose). There are two popular varieties in this species, namely Morita and Paraguay. In this study, it is suggested that Morita variety leaves contain higher level of rebaudioside A compared to Paraguay variety. Apart from leaves, there are other potential parts of plant that contain steviol glycosides such as stem and root. This allows optimizing usage of other parts of plant in order to maximize the production of rebaudioside A. Thus, extraction was made with water, methanol and ethanol as the extraction solvents. After extraction has completed, Thin-Layer Chromatography (TLC) analysis was performed to detect the compound that exists in the crude extract plant. With some modification of mobile phase, ethyl acetate: ethanol: methanol with ratio 20: 10: 2 was used to both varieties. For Morita variety, the Rr values of roots, leaves and stems with water extraction were 0.42, 0.53 and 0.51 respectively. While, the Rr values for ethanol extraction were 0.26, 0.64 and 0.60 and the Rr values for methanol extraction were 0.61, 0.67 and 0.50. For Paraguay variety, the Rr values of roots, leaves and stems with water extraction were 0.36, 0.51 and 0.56 respectively. While, the Rf values for ethanol extraction were 0. 73, 0.64 and 0.57 respectively and lastly, the Rf values for methanol extraction were 0.70, 0.53 and 0.52 respectively. From the results, it showed that methanol extracts gave distinctive spots with better colour intensity whereas other solvents (water and ethanol) exhibited smear lines with fade colour on TLC plate. This can be suggested that methanol extract interacted compatibly with the mobile phase mixture through the chromatography process. The comparison of colour between these two varieties was made and it can be suggested that most of Morita's extracts in every parts of plant showed higher intensity than Paraguay's extracts. Among the parts of plant, leaves extract of Morita showed the best intensity spots. This can be initially indicated that leaves of Morita contained more rebaudioside A compared to other parts of plant.