Ecotoxicology of human pharmaceuticals.

Complementary and alternative medicines such as tea tree (melaleuca) oil have become increasingly popular in recent decades. This essential oil has been used for almost 100 years in Australia but is now available worldwide both as neat oil and as an active component in an array of products. The primary uses of tea tree oil have historically capitalized on the antiseptic and anti-inflammatory actions of the oil. This review summarizes recent developments in our understanding of the antimicrobial and anti-inflammatory activities of the oil and its components, as well as clinical efficacy. Specific mechanisms of antimicrobial and anti-inflammatory action are reviewed, and the toxicity of the oil is briefly discussed.

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Melaleuca alternifolia (Tea Tree) Oil: a Review of Antimicrobial and Other Medicinal Properties

Antioxidant activity of selected essential oil components in two lipid model systems

Improvement in shelf-life and safety of perishable foods by plant essential oils and smoke antimicrobials

VOLUME I Introduction The Incentive Physical-Chemical Properties Experimental Methods Quantitative Structure-Property Relationships (QSPRs) Mass Balance Models of Chemical Fate Data Sources and Presentation Illustrative QSPR Plots and Fate Calculations References Aliphatic and Cyclic Hydrocarbons Lists of Chemicals and Data Compilations Summary Tables and QSPR plots References Mononuclear Aromatic Hydrocarbons Lists of Chemicals and Data Compilations Summary Tables and QSPR plots References Polynuclear Aromatic Hydrocarbons (PAHs) and Related Aromatic Hydrocarbons Lists of Chemicals and Data Compilations Summary Tables and QSPR plots References VOLUME II * Halogenated Aliphatic Hydrocarbons Chlorobenzenes and Other Halogenated Mononuclear Aromatics Polychlorinated Biphenyls (PCBs) Chlorinated Dibenzop-dioxins Chlorinated Dibenzofurans VOLUME III * Ethers Alcohols Aldehydes and Ketones Carboxylic Acids Phenolic Compounds Esters VOLUME IV Nitrogen and Sulfur Compounds Lists of Chemicals and Data Compilations Summary Tables References Herbicides Lists of Chemicals and Data Compilations Summary Tables References Insecticides Lists of Chemicals and Data Compilations Summary Tables References Fungicides Lists of Chemicals and Data Compilations Summary Tables References APPENDICES List of Symbols and Abbreviations Alphabetical Index CAS Registry Index Molecular Formula Index * Each chapter contains lists of chemicals and data compilations, summary tables, QSPR plots, and references

Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals

The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans have been determined. Hierarchical cluster analysis was used to group the compounds into five groups according to their activity patterns against the four microorganisms. K-Means cluster analysis was then used to confirm these groupings and to show the differences in the activity patterns of the groups. Ten molecular properties of the terpenoids, either calculated via molecular modelling or determined by direct measurement, were then used as variables in a forward stepwise discriminant analysis to identify which variables discriminated between groups. Low water solubility of Group IV compounds, mainly hydrocarbons and acetates, was found to be associated with their relative inactivity. The remaining groups, all containing oxygenated terpenoids, showed characteristic but distinct activity patterns towards the four test organisms. Hydrogen bonding parameters were found to be associated with antimicrobial activity in all cases. Activity against Gram-negative E. coli and P. aeruginosa was associated with a combination of a hydrogen bonding and size parameters. This was not found to be the case for the Gram-positive S. aureus or the yeast C. albicans. Copyright © 1999 John Wiley & Sons, Ltd.

The role of structure and molecular properties of terpenoids in determining their antimicrobial activity.

Determination of octanol-water partition coefficient for terpenoids using reversed-phase high-performance liquid chromatography.

Methods for the measurement of the minimum inhibitory concentration (MIC) of antibacterial agents have been developed for water-soluble substances and require adaptation for use with water-insoluble essential oils. This paper reports a standardized agar dilution MIC method, using 0.5% v/v Tween 20 as a dispersant, which provides a reliable and reproducible technique. The method was tested using two Melaleuca alternifolia oil samples with two different levels of terpinen-4-ol (37% and 45% v/v). The MIC values of die tea tree oil samples against a wide selection of bacteria, moulds and yeast are reported.

An Agar Dilution Method for the Determination of the Minimum Inhibitory Concentration of Essential Oils

Essential oils, extracted from species of the genus Zieria using cold methanol extraction, were used to divide the Zieria species into eight groups based on the chemical compositions of their oils using hierarchical cluster analysis. The major components of most Zieria oils were oxygenated terpenes or other related compounds including car-3-en-2-one, chrysanthenone, eucarvone, methyl eugenol, elemicin and safrole. In several of the Zieria oils the major oxygenated monoterpene made up between 50–60% of the oil composition. Measurements of minimum inhibitory concentration, using an agar dilution method and E. coli, Staph, aureus, Ps. aeruginosa and C. albicans as test organisms, have demonstrated that essential oils from Zieria exhibit antimicrobial activity. Several of the major oxygenated compounds were tested individually and found, in most cases, to be comparable in bioactivity to the oils in which they occurred.

Antimicrobial activity of essential oils from Zieria

Four pairs of oxygenated terpenes, with closely related chemical structures but considerably different minimum inhibitory concentration values (1) against P. aeruginosa or E. coli, showed differences in rate of cells killed over 2 h. Addition of polymyxin B nonapeptide (PMBN) as an outer membrane permeabilising agent was found to significantly increase the initial rates and overall numbers of cells killed for all compounds. The hydrocarbon limonene and the ester geranyl acetate, normally inactive, were also investigated. Both compounds had little killing effect when added alone to the cells but did show an enhanced killing capacity upon the addition of PBMN.

Role of the Outer Membrane of Eschericia coli AG100 and Pseudomonas aeruginosa NCTC 6749 and Resistance/Susceptibility to Monoterpenes of Similar Chemical Structure

Shane G. Griffin

Papers

The role of structure and molecular properties of terpenoids in determining their antimicrobial activity.

Determination of octanol-water partition coefficient for terpenoids using reversed-phase high-performance liquid chromatography.

An Agar Dilution Method for the Determination of the Minimum Inhibitory Concentration of Essential Oils

Antimicrobial activity of essential oils from Zieria

Role of the Outer Membrane of Eschericia coli AG100 and Pseudomonas aeruginosa NCTC 6749 and Resistance/Susceptibility to Monoterpenes of Similar Chemical Structure