Chemical and Bio-analytical Studies on Pergularia tomentosa and Species from the Mentha Genus

In this study samples of plant species Pergularia tomentosa; family Asclepiadaceae were collected from the Sultanate of Oman and extracted with organic solvents. These extracts were screened for their relative total phenol content, total antioxidant and anti-microbial properties. This species of plants has been traditionally used in Oman and much of the Middle East for the treatment of skin diseases, as abortive agents and as a laxative. The ethanolic extract of the plant was shown to possess anti-oxidant activity (inhibition of DPPH• radical), which is related to their phenolic content and also anti-bacterial and anti-viral properties. Partial purification of these extracts (and associated anti-oxidant activity) has also been achieved by a combination of column chromatography and HPLC. Although complete structural elucidation of the compounds present within the extracts has not been possible, NMR analysis has indicated the presence of certain functional groups. Antioxidant activities of the extracts have been determined by using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) assay and phospho-molybdate method. Folin-Ciocalteu method was used to determine total phenolic contents. In order to detect anti-bacterial activities of extracts a preliminary screening study was performed by using Varioskan spectrophotometer (Transgalactic Ltd). The second objective of this thesis describes the overall phenotypic relationships of the mint species and their interspecific hybrids and to provide some additional vision as to the development of the cultivated mint plants. Protocols for the extraction (microwave) and analysis (GC-MS) of the essential oil content within fresh and historical (dried) mint leave samples have been developed. By applying these methods to samples from both parental and hybrid mint species and carrying out a Principal coordinate analysis (PCoA) analysis we have been able to determine the relationship between essential oil composition and parental genus.