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    •   BracU IR
    • School of Data and Sciences (SDS)
    • Department of Mathematics and Natural Sciences (MNS)
    • Bachelor of Science in Biotechnology
    • Thesis (Bachelor of Science in Biotechnology)
    • View Item
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    Extraction of secondary metabolites, phytochemical screening and the analysis of antibacterial activity in stevia rebaudiana

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    Date
    2015-09
    Publisher
    BRAC University
    Author
    Zohra, Fatima Tuz
    Metadata
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    URI
    http://hdl.handle.net/10361/4549
    Abstract
    Stevia rebaudiana is a plant of the Asteraceae family and native to Paraguay. Its sweetness and calorie free property has increased its demand commercially all over the world as a sugar substitute in food beverages and medicines. Stevia has many pharmacological and therapeutic properties including antimicrobial, antifungal, antioxidant and anticarcinogenic activity. Due to this importance the leaf was analyzed for preliminary phytochemical studies to find the presence of phytoconstituents such as alkaloids, flavonoids, steroidal compounds, sponins, tannins, phenols, and cardiac glycosides. In this study, the crude plant extract from three different extractions (ethanol, methanol, and water) were collected and tested for the presence of phytochemicals. Comparative analysis of the antimicrobial activity of the extracts was investigated against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Streptococus peneumoniae and Shigella flexnari). This was done using agar diffusion method and as controls kanamycin, tetracycline and chloramphenicol were used. The diameter of the clear zone of inhibition surrounding the disc was measured in millimeters. The results showed that methanolic and ethanolic extracts of Stevia rebaudiana contained the highest amounts of phytochemicals. Antibacterial activity results showed there is no inhibitory effect of stevia against S.aureus and S.flexnari. The highest amount inhibition was formed against B.subtilis and S.pneumoniae. It can be concluded from the results that methanolic, ethanolic and aqueous extracts of Stevia rebaudiana may be considered as an antibacterial agent against S.pneumoniae and B.subtilis and be used to source antibiotic substances.
    Keywords
    Mathematics and Natural Sciences; Biotechnology; Stevia rebaudiana
     
    Description
    This thesis report is submitted in partial fulfillment of the requirement for the degree of Bachelor of Science in Biotechnology, 2015.
     
    Cataloged from PDF version of thesis.
     
    Includes bibliographical references (page 52-53).
    Department
    Department of Mathematical and Natural Science, BRAC University
    Collections
    • Thesis (Bachelor of Science in Biotechnology)

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