Bioproducts from forest biomass: Essential oils and hydrolates from wastes of Cupressus lusitanica Mill. and Cistus ladanifer L.

摘要

Unattended forest wastes are, among others, a potential source of wildfires, as well as a growth media for forest pests. As a way of lowering the detrimental effect of these wastes, it is important to convert these under-valued resources into a value-generating market forest wastes use. Essential oils (EOs) and hydrolates (Hs) from Cupressus lusitanica and Cistus ladanifer waste products, resulting from forest landscaping in Portugal, were evaluated for chemical composition and biological activity. Essential oils and Hs were obtained by steam-distillation (SD) and hydrodistillation (HD). Essential oils and Hs volatiles were analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC MS). The antimicrobial activity of EOs was studied by disk agar diffusion method against Escherichia coli, Staphylococcus aureus and Candida albicans. Antioxidant activity of EOs and Hs was evaluated by 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical, superoxide anion radical formation, xanthine oxidase and chelating metal ions assays. Antiinflammatory activity of Hs was assessed by albumin denaturation assay. Monoterpene hydrocarbons and oxygen-containing monoterpenes dominated C. lusitanica EO (SD, 82-86 %, HD, 80-85 %) and Hs volatiles (SD, 93-94 %; HD 64-81 %), respectively. alpha-Pinene (14-36 %), limonene (8-21 %), delta-3-carene (8-19 %) and sabinene (6-18 %) were the main EO constituents. Hydrolates volatiles were dominated by cis-3-hexen-1-ol (0.1-13 %), camphor (1-11 %), umbellulone (t-48 %), p-cymene-8-ol (11-16 %) and terpinen-4-ol (21-31 %). C. ladanifer EOs were dominated by monoterpene hydrocarbons (SD, 48-80 % and HD, 29 %) and Hs by oxygen containing monoterpenes (SD, 38-43 %, HD, 39 %). The EO major constituents were alpha-pinene (13-28 %) and camphene (5-25 %), whereas 2,6,6-trimethyl cyclohexanone (2-12 %) and trans-pinocarveol (5-13 %) dominated the Hs volatiles. This study reports for the first time the chemical composition of the hydrolate volatiles of these two species and their anti-inflammatory properties. Among the studied biological activities, the EOs showed the best antioxidant properties while Hs demonstrated higher anti-inflammatory activity.