Effects of clary sage oil and its main components, linalool and linalyl acetate, on the plasma membrane of Candida albicans: an in vivo EPR study

Abstract

The effects of clary sage (Salvia sclarea L.) oil (CS-oil), and its two main components, linalool (Lol) and linalyl acetate (LA), on cells of the eukaryotic human pathogen yeast Candida albicans were studied. Dynamic and thermodynamic properties of the plasma membrane were investigated by electron paramagnetic resonance (EPR) spectroscopy, with 5-doxylstearic acid (5-SASL) and 16-SASL as spin labels. The monitoring of the head group regions with 5-SASL revealed break-point frequency decrease in a temperature dependent manner of the plasma membrane between 9.55 and 13.15 °C in untreated, in CS-oil-, Lol- and LA-treated membranes. The results suggest a significant increase in fluidity of the treated plasma membranes close to the head groups. Comparison of the results observed with the two spin labels demonstrated that CS-oil and LA induced an increased level of fluidization at both depths of the plasma membrane. Whereas Lol treatment induced a less (1 %) ordered bilayer organization in the superficial regions and an increased (10 %) order of the membrane leaflet in deeper layers. Acute toxicity tests and EPR results indicated that both the apoptotic and the effects exerted on the plasma membrane fluidity depended on the composition and chemical structure of the examined materials. In comparison with the control, treatment with CS-oil, Lol or LA induced 13.0, 12.3 and 26.4 % loss respectively, of the metabolites absorbing at 260 nm, as a biological consequence of the plasma membrane fluidizing effects. Our results confirmed that clary sage oil causes plasma membrane perturbations which leads to cell apoptosis process.

Linalool-induced oxidative stress processes in the human pathogen Candida albicans

“…Our results clearly indicate the existence of oxidative stress intensity-dependent regulation of the antioxidant system. To summarize the findings related to the adverse acute toxicity effects of Lol at high (70-80%) survival rate (in the present study), these can be explained in terms of the following processes at the molecular level: (i) Lol induces damage in the plasma membrane structure, parallel with increase in membrane fluidity [5,22], (ii) Lol depresses the respiratory rate through interference with mitochondrial complexes I and II, resulting in a decrease in ATP level and cell viability [43; this study], (iii) Lol induces the accumulation of peroxides through mitochondrial-dependent O 2 •generation and membrane-dependent lipid peroxidation [12, 43; this study), which (iv) alters the concentration of the crucial antioxidant GSH and results increased GSSG content [43; this study] and (v) up-or down-regulates the activities of certain antioxidant enzymes (GR, GPx and CAT) in a concentration-dependent manner (the present study).…”

“…In chronic and long-term acute tests, (i) Lol inhibits one of the key enzymes of sterol biosynthesis [10,22,24], (ii) leading to disorganization of the plasma membrane through changes in the composition of the plasma membrane and loss of essential cell components [5,8], and (iii) the ROS-induced unbalanced redox state may contribute to a cell cycle arrest and DNA damage, resulting in apoptosis or necrosis [19,46].…”

“…A well-characterized adenine auxotroph C. albicans strain 33erg + (ATCC 44829, American Type Culture Collection Maryland, USA) was selected for the experiments [33]. This strain was the same as we applied earlier to investigate the modes of action of clary sage oil, and its main components Lol and linalyl acetate [5]. Mid-exponential phase cultures were obtained on a shaker operating at a shaking frequency of 33.3 Hz in liquid minimal medium (MM) containing 1% dextrose, 0.5% (NH 4 ) 2 SO 4 , 0.1% KH 2 PO 4 , 0.05% MgSO 4 (w/v) and 50 μg ml −1 adenine, 2 μg ml -1 biotin, 4 μg ml -1 thiamine, pH 4.1, at 30 °C.…”

Prediction of Terpenoid Toxicity Based on a Quantitative Structure–Activity Relationship Model

“…Terpenoids can function as antimicrobial agents to protect their natural hosts, with antibacterial activity occurring via disruption of the lipid membrane, resulting in the alteration of membrane organization and function [1,6]. As a result of lipophilic compounds partitioning into the lipid bilayer, damage occurs in the cell membrane by impairing vital functions (e.g., loss of ions, metabolites, lipids, and proteins; and dissipation of the pH gradient and electrical potential) [6][7][8]. Enzymes and DNA have also been mentioned as possible targets, as lipophilic compounds tend to associate with the hydrophobic core of several proteins leading to conformational changes, and consequently protein inactivation [6].…”

Prediction of Terpenoids Toxicity Based on Quantitative Structure-Activity Relationships Model

“…Terpenoids can function as antimicrobial agents to protect their natural hosts, with antibacterial activity occurring via disruption of the lipid membrane, resulting in alteration of membrane organization and functions [1,6]. As a result of lipophilic compounds partitioning into the lipid bilayer damage occurs in the cell membrane by impairing vital functions (e.g., ions, metabolites, lipids, and proteins loss; dissipation of the pH gradient and electrical potential) [6][7][8]. However, enzymes and DNA have also been mentioned as possible targets, as lipophilic compounds tend to associate with the hydrophobic core of several proteins leading to conformational changes, and consequently protein inactivation [6].…”