RESULTS: Phenolics were extracted from mangosteen bark, leaf and fruit pericarp in methanol and in water using response
surfacemethodology to optimize recovery. Initial examination of antimicrobial effects revealed a lack of antimicrobial activity
against fungi and weak activity against the Gram-negative bacteria Escherichia coli and Salmonella typhimurium. In contrast,
extracts prepared from bark or fruit pericarp exhibited strong pH-dependent bacteriostatic and bactericidal effects against
Listeria monocytogenes and Staphylococcus aureus.Activitywas slightly weaker in aqueous extracts due to lower concentrations
of tartaric acid esters and flavonols than in methanolic extracts. Measurement of propidium iodide uptake and ATP leakage
indicated that the extracts induced damage to themembrane of Gram-positive bacteria.