GC-MS and HS-SPME-GC×GC-TOFMS Determination of the Volatile Composition of Essential Oils and Hydrosols (By-Products) from Four Eucalyptus Species Cultivated in Tuscany

Abstract

Essential oils are widely used as functional ingredients for potential multi-purpose functional uses. Hydrosols, co-products of the distillation of plant material, are used in food and cosmetic industries and in biological agriculture, but their volatile composition is poorly investigated. The volatile fractions of essential oils and hydrosols from four less-studied 1,8-cineol-rich Eucalyptus species (E. parvula L.A.S. Johnson & K.D. Hill, E. cinerea F. Muell, E. pulverulenta Sims and E. pulverulenta baby blue Sims), cultivated in Tuscany in a system of organic farming, were characterized by solvent dilution (essential oils) or extraction (hydrosols) followed by GC-MS and by HS-SPME-GC×GC-TOFMS analysis. GC-MS analysis showed that essential oils were mainly constituted by oxygenated monoterpenes, particularly 1,8-cineole, with monoterpenes hydrocarbons up to 10.8%. Relative differences in the abundance of minor terpenes as limonene, α-pinene, γ-terpinene, p-cymene, terpinen-4-ol, α-terpineol, and alloaromandrene were pointed out and seem to be suitable for differentiation among EOs of the four different Eucalyptus species. Hydrosols of these species were characterized for the first time: they were mainly constituted by oxygenated monoterpenes (97.6–98.9%), with 1,8-cineole up to 1.6 g/L, while monoterpene and sesquiterpene hydrocarbons were detected only in traces. HS-SPME-GC×GC-TOFMS analysis also allowed providing metabolic profiling of hydrosols for the direct comparison and visualization of volatile components, pointing out the potentially different uses of these products as functional ingredients in food, beverage, and cosmetic industries.

Hydrolates: By-products of essential oil distillation: Chemical composition, biological activity and potential uses

“…Leaves from different Eucalyptus sp. mainly contain 1,8-cineole as the dominant compound, both in essential oil and hydrolate [22,23], while E. citrodora contain citronellal and citronellol in the essential oil, as well as in the hydrolate [1].…”

Evaluating the Antimicrobial Potential of Eucalyptus baileyana F. Muell. and Eucalyptus major (Maiden) Blakely against the Fish Spoilage-causing Bacterium Shewanella putrefaciens

“…22,23 Of note, numerous Eucalyptus spp. have been reported to contain high levels of 1,8-cineol, a terpenoid well-documented as an antibacterial agent 24,25 and it is likely that this compound contributes to the activity reported herein. This compound has also been reported to be toxic 26,27 and may account for the toxicity reported in our study.…”

…Fell Upas Sits, the Hydra-Tree of Death †, or the Phytotoxicity of Trees

“…These fractions also showed strong phytotoxicity against Solanum elaeagnifolium Cav. The analysis of water soluble volatile fractions from other four eucalypt species also proved that they contained mostly 1,8-cineole (about 90%) [249].…”