Melastoma malabathricum is a small shrub commonly found in cleared land, waste places, and roadside throughout the
Southeast Asian countries, including Malaysia. Local name for this plant is “senduduk merah”. The aim of the study was to
investigate the phytochemical compounds, antibacterial and antibiofilm activity of the ethanolic extract of M. malabathricum.
Phytochemical analysis of M. malabathricum leaves revealed the presence of tannins, alkaloids, saponins, phenols and
terpenoids. No alkaloid was detected. In the GC-MS analysis, 10 bioactive phytochemical compounds were identified in the
ethanolic extract of M. malabathricum. The main volatile compounds were squalene (25%), hexadecanoic acid, ethyl ester
(18.95%), linolenic acid ethyl ester (17.35%) and phytol (11.89%). Microbroth dilution method showed that of M.
malabathricum ethanolic extract against Pseudomonas aeruginosa strain ATCC 10145 was 6.25 mg/ml. From disc diffusion
assay, all test concentrations exhibited zone of inhibition against P. aeruginosa, which ranged from 9 to 11 mm. Furthermore, it
was also observed that M. malabathricum ethanolic extract inhibited formation of P. aeruginosa biofilm whereby numbers of
all the test concentrations (275-1650 x 103 CFU/ml) were found to be lower than that of control (2225 x 103 CFU/ml). To the
best of our knowledge, this is the first report on the antibiofilm activity of M. malabathricum. The result from this study reveals
the potential of this medicinal plant to inhibit the formation of P. aeruginosa biofilm.