ISOLATION OF A BIOACTIVE COMPOUND HYPERICIN FROM A MEDICINAL PLANT HYPERICUM PERFORATUM L. USING BASIC CHROMATOGRAPHY METHODS A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES OF THE MIDDLE EAST TECHNICAL UNIVERSITY BY BETÜL DURU IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN THE DEPARTMENT OF CHEMISTRY DECEMBER 2003