The ethyl acetate extract of the leaves of Melicope vitiflora was separated by column chromatography and the resulting fractions tested for their bioactivity towards methicillin-resistant-Staphylococcus aureas (MRSA) and Micrococcus luteus (M L). The bioactive column chromatography fractions were further separated by preparative TLC and dereplication was carried out on them by first subjecting them to electrospray ionisation-ion trap mass spectrometry (ESI-MSn). The resulting molecular masses, their fragmentation patterns in addition to the chemnet database (www.chemnetbase.com) were used to aid in the structural elucidation of some of the compounds by permitting comparison with known structures of natural origin. Some molecular masses and the Corresponding fragmentations were found that did not correlate with any known compounds thus revealing potentially novel natural products that could be investigated on a larger scale and could ultimately find application as new drugs against MRSA and other multi drug resistant microorganisms. Structures are also proposed for known compounds that have not been previously reported for M. vitiflora. (C) 2008 Elsevier B.V. All rights reserved.