Antimicrobial Activity of Essential Oils and Solvent Extracts from Zieria species (Rutaceae)

Essential oils were hydrodistilled from six Zieria species, including two previously not investigated: Z. floydii and Z. odorifera subsp. williamsii, and characterized using GC-MS. Additionally, solvent extracts of leaf material from five of these species were prepared using n-hexane, acetone and methanol as solvents, respectively. These solvent extracts were examined, along with essential oils, for antibacterial activity using micro titer plate broth dilution assays. Antifungal activity against pathogenic Trichophyton species responsible for dermal infections such as Tinea and Kangaroo Pox (uncommon), was examined using a similar method. Results of essential oil characterizations are relatively consistent with those previously reported. Interestingly, the essential oil composition of Z. floydii showed car-3-en-2-one at a concentration of 71%, similar to that observed in a previous study for Z. furfuracea and Z. granulata, thus complementing the observations of A.G. Floyd that Z. floydii is morphologically allied with these two species (CANB 598758). Antimicrobial assays demonstrated relatively high antibacterial and antifungal activity, using both essential oils and solvent extracts. This is particularly true for the n-hexane extract from Z. smithii. We therefore conclude that Zieria species may be a useful source for the development of antiseptic, cosmaceutical and/or topical nutraceutical products. In addition, they may well serve as a source of further novel, purified compounds providing scaffolds for pharmaceutical development in the future.