VOLUME 64 : 2016

Recent studies showed that the Rubiaceae family, the 4th largest family among dicotyledonous flowering plants, contains compounds that exhibit antimicrobial properties. This study aims to characterize the antimicrobial activity of the extracts and determine the chemical constituents of the hexane extract from endemic Philippine Rubiaceae species Uncaria cordata var. circa, Psychotria luzoniensis, and Psydrax puberula. The crude leaves extract of each plant species were subjected to solvent-solvent extraction to obtain the hexane, chloroform, and butanol extracts. The sub-extracts of each plant were subjected to antimicrobial micro-plate dilution assay. Extracts from the three plants exhibited promising MIC and MBC activities against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923. Characterization of the hexane extracts using GC-MS showed that these plants contained compounds that exhibited biological activities. The results provided in this study have shown that the three endemic plants are new sources of biologically-active secondary metabolites.

Keywords: Rubiaceae, Psychotria, Uncaria, Psydrax, MIC, MBC, GC-MS