Characterization and HPLC Quantification of Xylopic Acid in the Dried Fruits of Xylopia Aethiopica

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APRIL, 2010
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Xylopia aethiopica is an evergreen, aromatic tree growing up to 15cm high, bark slightly ridged, native to the West, Central and Southern Africa. Flowers appear in clusters of 2-4, fruits turn red when ripe and black when dried. The dried fruit is commonly called African pepper. The dried fruits of Xylopia aethiopica have been used in folklore medicine. The extracts of the fruit have been shown to have antibacterial and antifungal properties. Dried fruits of Xylopia aethiopica used for the project were obtained from the Kumasi Central Market and were authenticated by the Department of Pharmacognosy, KNUST. In order to obtain pure xylopic acid crystals for use as secondary reference xylopic acid was extracted from dried fruits of Xylopia aethiopica with petroleum ether (40-60oC) and recrystallised from ethanol. The melting point of the crystals was determined to be 261-262oC and the Rf value of xylopic acid using petroleum ether (40-60oC): ethylacetate (9:1) as the solvent system to be 0.53. NMR, infrared and mass spectroscopic analyses were carried out to characterise the isolated crystals. HPLC was used to quantify the xylopic acid in the dried fruits using methanol: water (9:1) as the mobile phase and a phenomenex hypersil 20 micron C 18 200 x 3.2 mm reverse column. The percentage content of xylopic acid in the whole fruit was estimated to be 1.15% ± 0.08 (n=8). The percentage content of xylopic acid in the seeds was determined to be 0.07% ± 0.02 (n=6) and the dried pericarp of the fruit was found to contain 0.87% ± 0.20 (n=6) xylopic acid. The purified xylopic acid crystals were subjected to stability studies for a period of three (3) months. The conditions employed for the stability studies were temperatures of 50oC, 60oC and 80oC. The crystals were assayed on the 20th, 50th and 70th days using the HPLC method developed for the assay of the crude fruit extract. The concentration at 50oC was 87.76%, 74.68% and 67.78% on the 20th, 50th and 70th days respectively. The concentration at 60oC was estimated to be 75.86%, 67.19% and 47.97% on the 20th, 50th and 70th days respectively. The concentration at 80oC was found to be 68.13%, 63.10% and 44.51% on the 20th, 50th and 70th days respectively.
Thesis Submitted In Partial Fulfilment of the Requirements for the Award of Degree of Master of Philosophy Pharmaceutical Chemistry,