20 Ximenia americana: Chemistry, Pharmacology and Biological Properties, a Review Francisco José Queiroz Monte 1 , Telma Leda Gomes de Lemos 1 , Mônica Regina Silva de Araújo 2 and Edilane de Sousa Gomes 1 Programa de Pós-Graduação em Química Universidade Federal do Ceará, Fortaleza - Ceará Depatamento de Química, Universidade Federal do Piauí, Teresina - Piauí, Brasil 1. Introduction The use of plants as medicinal agents to the treat of many diseases has been investigated for a long time since the antique civilizations. Several plants are used in traditional medicine against inflammatory diseases as well as various types of tumors on the base the potential of their chemical constituents. Although many compounds are extremely toxic, when we have the relation between the toxicity of a compound and its chemical pattern of substitution that can result in a more in-depth understanding of these compounds (Atta-ur-Rahman, 2005). Today, even after more than 200 years, the chemistry of natural products remains a challenge and an important field of research in several science areas (chemistry, biology, medicine, agronomy, botany and pharmacy). The reasons for it’s large use are the considerable pharmacological potential observed in natural products, in the great development in the process of detection, isolation, purification and, especially, the advances in spectrometric techniques [infrared (IR), mass spectrometry (MS) and nuclear magnetic resonance (NMR 1 H and 13 C) for structural elucidation of new and complex compounds. These advances were outstanding in both NMR and MS spectrometry. The NMR allows the complete 1 H and 13 C NMR spectral assignments (chemical shifts and coupling constants) which serve to build a data base to support computer assisted structure elucidation. These data are also useful in the fuller understanding of the correlations between molecular conformation and biological activity of natural substances with biological importance (Loganathan et al., 1990). Mass spectrometry has a huge application in chemistry, biochemistry, medicine, pharmacology, agriculture and food science. Although the mass spectrometric ionization techniques EI (electron impact) and CI (chemical ionization) required the analyte molecules to be present in the gas phase and were thus suitable only for volatile compounds, the development of several desorption ionization methods [FD (field desorption), FABMS (fast atom bombardment), ESIMS (electrospray), MALDI-MS (matrix assisted laser desorption ionization)] allowed the hight-precision mass spectrometric analysis of different classes of biomolecules. The genus Ximenia belongs to the Olacaceae and comprises about 8 species (Brasileiro et al., 2008): Ximenia roiigi, Ximenia aegyptiaca, Ximenia parviflora, Ximenia coriaceae, Ximenia aculeata, Ximenia caffra, Ximenia americana and Ximenia aegyptica. X. caffra stands out for