Efficacy ofEucalyptus cinereaas a Source of Bioactive Compounds for Curative Biocontrol of Crown Gall Caused byAgrobacterium tumefaciensStrain B6

Abstract

This research investigated the Eucalyptus cinerea leaves efficiency in the Agrobacterium tumefaciens biocontrol, the causative agent of crown gall. GC-MS analysis of the essential oil (EO) showed that the main components were 1,8-cineole (61%) and camphene (15.13%). Thanks to its polyphenols, flavonoids, quinones, terpenoids, alkaloids, and tannins richness, the EtOAc-F exhibited the most potent antibacterial activity in vitro. Indeed, compared to the other fractions, it has the lowest MIC and MBC values of 0.312 mg/mL and 2.5 mg/mL, respectively. The GC-MS analysis of EtOAc-F confirmed its richness in antibacterial compounds including gallic acid (7.18%), shikimic acid (5.07%), and catechin (3.12%). The time-kill curve assay of EtOAc-F (2.5 mg/mL) showed a potent bactericidal effect after 20 min of direct contact with A. tumefaciens. In planta experiments, gall weights were significantly reduced when EtOAc-F was applied at 0.625 and 2.5 mg/wounds. Besides, the disease reduction rates in gall weight were 95% and 97.5%, respectively. Interestingly, no phytotoxic effect was observed since tomato seeds germinated in the presence of the different concentrations of EtOAc-F. These results suggest that EtOAc-F has a good potential to be a curative biocontrol agent for crown gall disease.

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

“…In EOs from these four species, relative abundance of 1,8-cineole ranged between 83.80% and 88.66%, higher than the 80–85% indicated by the standard ISO as the minimum amount of 1,8-cineole for EO from E. globulus. Other papers in the literature reported the characterization of EOs from Eucalyptus cinereal [16,17,18] and Eucalyptus pulverulenta [16], while, to the authors’ knowledge, no reports on EO from Eucalyptus parvula have been published, to date. In such papers, the relative abundance of 1,8-cineole showed great variability ranging usually from 58.0 to 69.0% and sometimes reaching 87.8% in E. cinerea EOs and being approx.…”

“…Hill, Eucalyptus cinerea F. Muell, Eucalyptus pulverulenta Sims and Eucalyptus pulverulenta baby blue Sims. The characterization of EOs from Eucalyptus cinerea [16,17,18] and Eucalyptus pulverulenta [16] has been reported in the literature while, to the authors’ knowledge, no reports on EO from Eucalyptus parvula have been published, to date. Essential oil obtained from the leaves of these Eucalyptus species could potentially be employed for therapeutic ends and as natural additives for use in the food, cosmetics and perfume industries, extending the use of the plant beyond the predominantly ornamental one.…”

Eucalyptus species as a cause of airborne allergic contact dermatitis

“…Another possibility is that the allergen is not present in the essential oil of Eucalyptus species, but rather in other components of the leaves, such as phenolic compounds . In case 2, the allergen seemed to be more water‐soluble than lipid‐soluble (Table S2).…”

Pharmacokinetics of five phthalides in volatile oil of Ligusticum sinense Oliv.cv. Chaxiong, and comparison study on physicochemistry and pharmacokinetics after being formulated into solid dispersion and inclusion compound

“…The EtOAc fraction was separated by Pope Molecular Distillation after solvent was recovered, for the light component and heavy component. The light component was VOC (a brownish yellow oil, 0.93% of yield, w/w) [ 17 ].…”