Chemical Components of the Essential Oils from Three Species of Malaysian Plumeria L. and Their Effects on the Growth of Selected Microorganisms

The chemical components of the essential oils obtained from the flowers of three Malaysian species of Plumeria, namely P. rubra L. (red flower variety), P. acutifolia Poir. (yellow flower variety) and P. obtusa L. (white flower variety) were analyzed by GC/MS and 27 components were identified. Seven components were separated and identified from P. rubra, 14 components from P. obtusa and 19 components from P. acutifolia. The major component that is found in all three species is 2-hydroxybenzoic acid phenylmethyl ester. Those three species also shared two alkane hydrocarbons, that is nanodecane and heneicosane. The antimicrobial properties of the essential oils (at 2 i per disk) were determined using agar diffusion method. Eight different microorganisms were used in this study, that are Escherichia coli (Gram negative bacteria), Staphylococcus aureus and Bacillus cereus (Gram positive bacteria), Candida albicans and C. humicola (yeast), and Trichophyton mentagrophytes, T. rubrum and Microsporum canis (furigi). The broad spectrum of inhibition was exhibited by the essential oil of P. obtusa. The extract inhibited all tested microorganisms except for E. coli. The largest inhibition zone was shown by the P. obtusa essential oil against C. humicola.