Unegbu, Immaculata Amarachi <br/><br/>
PHYTOCHEMICAL SCREENING AND SYNTHESIS OF  SILVER NANOPARTICLES AND INVESTIGATION OF  BIOLOGICAL ACTIVITIES OF Silybum marianum LEAF 
IMMACULATA AMARACHI UNEGBU; SUPERVISOR: ASST. PROF. DR. EMMANUEL MSHELIA HALILU 
 - xii, 84 sheets;  31 cm.  1 CD-ROM 
<br/><br/>Thesis (MSc) - Cyprus International University. Institute of Graduate Studies and Research Pharmacognosy Department 
<br/><br/>Includes bibliography (sheets 74-84) 
<br/><br/> ABSTRACT<br/>Silybum marianum is a therapeutic plant belonging to the family Asteraceae. It <br/>contains silymarin, as its principal component, and has been reported to demonstrate <br/>hepatoprotective activity. The study was aimed to investigate the phytochemical <br/>constituents, synthesis of nanoparticles, antioxidant activity and antimicrobial effects <br/>of the leaf extract. The physiochemical analysis revealed moisture content, total ash, <br/>acid insoluble, alcohol, water, and petroleum ether soluble extraction of 13.9 %, 1.35 <br/>%, 0.95 %, 5.8 %, 7.1 % and 0.8 % respectively. The chemical profile was evaluated <br/>by Gas Chromatography-Mass Spectrometry (GC-MS) assay and qualitative <br/>phytochemical. Extracts were synthesized from AgNO3 and characterized via FT-IR, <br/>U.V and XRD. The antioxidant activity was determined using DPPH, H2O2 and βcarotene assays. Similarly, all extracts expressed significant DPPH inhibition (IC50) of <br/>5.1, 5.0, 4.7, 2.3, 4.3 and 1.1 (ug/mL), H2O2 of 1.3, 2.2, 4.7, 5.6, 4.0 and 1.0 (ug/mL) <br/>from the methanol/water extract, nanoparticles, n-Hexane, ETOAC, n-Butanol and <br/>Ascorbic acid (standard) respectively. The extract exerted scavenging activity on βcarotene with a significant IC50 inhibition of 1.5, 0.8, 5.2, 0.8, 2.7, 4.8 at 0 hour and <br/>1.5, 0.8, 5.2, 0.8, 2.7 and 4.8 (ug/mL) after 2 hours water bath incubation at 50°C in <br/>the order of the extracts above. Additionally, nanoparticles and plant extracts <br/>significantly (p<0.0001) inhibited the growth of bacteria with mean zone of inhibition <br/>ranging 7-13 mm and 4-11 mm. This study demonstrated that extracts from different <br/>solvents of S. marianum possess significant antioxidant activity, as well as <br/>antimicrobial effects which are all concentration dependent. Thus, the result suggests <br/>that methanolic/water leaf extract of S. marianum could serve as a potential source of <br/>antioxidants and can be explored as a therapeutic agent in free radical induced <br/>diseases.<br/>Keywords: Antimicrobial, Antioxidant, Nanoparticles, Phytochemicals, Silybum <br/>marianum 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Antioxidants--Dissertations, Academic<br/> Nanoparticles--Dissertations, Academic<br/> Phytochemicals--Dissertations, Academic