Comparative study on the antimicrobial activities of different sandalwood essential oils of various origin

In total, eight samples of different sandalwoods [Amyris balsamifera L., Santalum album L. and Santalum spicatum (R.Br.) A.DC.] and a mixture of α‐ and β‐santalols, as well as eugenol as reference compound, were tested by an agar dilution and agar diffusion method for their antimicrobial activities against the yeast Candida albicans, the Gram‐positive bacterium Staphylococcus aureus and the Gram‐negative bacteria Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. The main compounds of each essential oil were investigated by gas chromatographic–spectroscopic (GC‐FID and GC–MS) and –olfactory methods to obtain information about the inßuence of these volatiles on the observed antimicrobial effects. For the santalol mixture, as well as for one S. album and one S. spicatum sample with moderate concentrations of santalols, antimicrobial activity was found against all the strains used. The A. balsamifera sample, containing only a small quantity of α‐santalol and nearly no β‐santalol, showed high effects only against Klebsiella pneumoniae, while against the other strains weak or no activity was observed. Therefore, santalols in medium and/or high concentrations in sandalwood oils show a significant inßuence on antimicrobial potential in such natural products.