Radical Scavenging and Antibacterial Activity of Phenolic Compounds from Anacardium occidentale L. Stem Barks from South East Sulawesi-Indonesia

Three phenolic compounds, pinostrobin, pinocembrin and 4-hydroxybenzaldehide have been isolated and identified for the first time from methanol extract of Anacardium occidentale L. stem bark. The isolation was carried out using various techniques of chromatography such as thin layer chromatography, vacuum liquid chromatography and radial chromatography. Silica gel as adsorbent and a mixture of solvents as eluent were used during the separation process. Structures of the isolated compounds were determined by Fourier transforms infrared, mass and nuclear magnetic resonance (1- and 2-Dimensi) spectroscopies. Biological properties of the isolated compounds were evaluated against four strains of bacteria, Shigella dysenteriae ATCC 13313, Salmonella typhi YCTC, methicillin-resistant Staphylococcus aureus ATCC33591, and Escherichia coli ATCC 35219), as well as the radical scavenging potential in DPPH assay. Results indicated that pinocembrin was the most active isolated compound towards S. dysenteriae, S. typhi, methicillin-resistant S. aureus and E. coli, however in comparison to the MIC50 value of the standard, pinocembrin possessed low antibacterial activity. Meanwhile, 4-hydroxybenzaldehide showed the highest radical scavenger activity with IC50 value of 134.93±0.13 µM, but much lower compared to vitamin C with IC50 value of 63.32±0.22 µM.