Showing papers on "Citral published in 2019"

Utilizing Lemon Balm extract as an effective green corrosion inhibitor for mild steel in 1M HCl solution: A detailed experimental, molecular dynamics, Monte Carlo and quantum mechanics study

Abstract: This study concerns with mild steel corrosion inhibition in 1M HCl solution protected with different concentrations of Lemon Balm extract. Electrochemical and theoretical approaches are utilized for approaching this goal. The type of functional groups in the active components present in the Lemon Balm extract (LB.E) was examined through UV–visible analysis, Fourier Transform Infrared (spectroscopy) (FT-IR) and Raman spectroscopy. According to the electrochemical impedance spectroscopy (EIS) test results the maximum inhibition efficiency of about 95% was obtained in the solution containing 800 ppm LB.E. Potentiodynamic polarization test results revealed that in the presence of LB.E the rates of anodic steel dissolution and cathodic hydrogen evolution reactions significantly decreased and a mixed inhibition effect was obtained. Surface studies were done by contact angle test, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results revealed that the steel surface damage as a result of HCl solution attack significantly decreased by addition of 800 ppm LB.E. In addition, deposition of a highly hydrophobic film composed of organic compounds of inhibitors on mild steel surface was demonstrated by contact angle test results. The excellent corrosion inhibition effect of LB.E on mild steel in HCl solution is related to the adsorption of active inhibitive compounds such as caryophyllene, germacrene, citral, luteolin, chlorogenic acid and rosmarinic acid on the anodic/cathodic places of mild steel surface. Furthermore, the theoretical results derived from Monte Carlo, molecular dynamics and quantum mechanics techniques evidenced the inhibitors adsorption onto steel substrate through donor-acceptor interactions.

Antifungal activity and mechanism of citral, limonene and eugenol against Zygosaccharomyces rouxii

Abstract: The aim of this study was to investigate the antifungal activity and mechanisms of citral, limonene and eugenol against Zygosaccharomyces rouxii. All the three essential oil ingredients presented strong antifungal activities against Z. rouxii. Minimum inhibitory concentrations of citral, limonene and eugenol were 0.188, 0.75 and 0.4 μL/mL, and the minimum fungicidal concentrations were 0.375, 3 and 0.8 μL/mL, respectively. Scanning electron microscopy showed that the tested essential oil compounds had destructive effects on the yeast cell surface. After treated by citral, limonene and eugenol, the relative electric conductivity and leakage of nucleic acid were increased significantly. SDS-PAGE analysis indicated that the essential oil components could result in the loss of soluble proteins and might also destroy the yeast protein or inhibit their expression. These results demonstrated that citral, limonene and eugenol exerted their antifungal action against Z. rouxii through cell membrane damage and destruction of cellular proteins. This study provided a theoretical possibility that citral, limonene and eugenol could be used as natural food preservatives for the control of Z. rouxii-related spoilage in the fruit juice industry.

Bioactivity of the Cymbopogon citratus (Poaceae) essential oil and its terpenoid constituents on the predatory bug, Podisus nigrispinus (Heteroptera: Pentatomidae).

Abstract: Podisus nigrispinus Dallas (Heteroptera: Pentatomidae), released in biological control programs, is a predator of Lepidopteran and Coleopteran species. Lemongrass essential oil and its constituents can be toxic to this natural enemy. The major constituents of lemongrass essential oil are neral (31.5%), citral (26.1%), and geranyl acetate (2.27%). Six concentrations of lemongrass essential oil and of its citral and geranyl acetate constituents were applied to the thorax of P. nigrispinus nymphs and adults. The walking and respiratory behavior of the P. nigrispinus third-instar nymphs, treated with citral and geranyl acetate at the LD50 and LD90 doses, were analyzed with video and respirometer. The lemongrass essential oil toxicity increased from first- to fifth-instar P. nigrispinus nymphs. The P. nigrispinus respiration rates (μL de CO2 h-1/insect) with citral and geranyl acetate in the LD50 and LD90 differed. Nymphs exposed to the lemongrass essential oil and its constituents on treated surfaces presented irritability or were repelled. Podisus nigrispinus adults were tolerant to the lemongrass essential oil and its constituents, geranyl acetate and citral. The altered respiratory activity with geranyl acetate and the fact that they were irritated and repelled by citral suggest caution with regard to the use of the lemongrass essential oil and its constituents in integrated pest management incorporating this predator, in order to avoid diminishing its efficiency against the pests.

In vitro cytotoxicity and anticancer effects of citral nanostructured lipid carrier on MDA MBA-231 human breast cancer cells.

Abstract: Very recently, we postulated that the incorporation of citral into nanostructured lipid carrier (NLC-Citral) improves solubility and delivery of the citral without toxic effects in vivo. Thus, the objective of this study is to evaluate anti-cancer effects of NLC-Citral in MDA MB-231 cells in vitro through the Annexin V, cell cycle, JC-1 and fluorometric assays. Additionally, this study is aimed to effects of NLC-Citral in reducing the tumor weight and size in 4T1 induced murine breast cancer model. Results showed that NLC-Citral induced apoptosis and G2/M arrest in MDA MB-231 cells. Furthermore, a prominent anti-metastatic ability of NLC-Citral was demonstrated in vitro using scratch, migration and invasion assays. A significant reduction of migrated and invaded cells was observed in the NLC-Citral treated MDA MB-231 cells. To further evaluate the apoptotic and anti-metastatic mechanism of NLC-Citral at the molecular level, microarray-based gene expression and proteomic profiling were conducted. Based on the result obtained, NLC-Citral was found to regulate several important signaling pathways related to cancer development such as apoptosis, cell cycle, and metastasis signaling pathways. Additionally, gene expression analysis was validated through the targeted RNA sequencing and real-time polymerase chain reaction. In conclusion, the NLC-Citral inhibited the proliferation of breast cancer cells in vitro, majorly through the induction of apoptosis, anti-metastasis, anti-angiogenesis potentials, and reducing the tumor weight and size without altering the therapeutic effects of citral.

Preparation and Characterization of Self Nano-Emulsifying Drug Delivery System Loaded with Citraland Its Antiproliferative Effect on Colorectal Cells In Vitro

Abstract: Citral is an active compound naturally found in lemongrass, lemon, and lime. Although this pale-yellow liquid confers low water solubility, the compound has been reported to possess good therapeutic features including antiproliferative and anticancer modalities. The self nano-emulsifying drug delivery system (SNEDDS) is a type of liquid-lipid nanocarrier that is suitable for the loading of insolubilized oil-based compound such as Citral. This study reports the design and optimization of a SNEDDS formulation, synthesis and characterization as well as loading with Citral (CIT-SNEDDS). Further assessment of theantiproliferative effects of CIT-SNEDDS towards colorectal cancer cells was also conducted. SNEDDS composed of coconut oil, dimethyl sulfoxide (DMSO) and Tween 80. CIT-SNEDDS was prepared via gentle agitation of SNEDDS with 0.5% Citral for 72 h at room temperature. Physicochemical characterization was performed using several physicochemical analyses. The average particle size of CIT-SNEDDS was16.86 ± 0.15 nm, zeta potential of 0.58 ± 0.19 mV, and polydispersity index (PDI) of 0.23 ± 0.01. In vitro drug release of Citral from CIT-SNEDDS was 79.25% of release, and for Citral the release percentage was 93.56% over 72 h. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was done to determine the cytotoxicity effect of CIT-SNEDDS in human colorectal cancer cell lines HT29 and SW620. The half maximal inhibitory concentrations (IC50) for 72 hof CIT-SNEDDS and Citral on SW620 were 16.50 ± 0.87 µg/mL and 22.50 ± 2.50 µg/mL, respectively. The IC50 values of CIT-SNEDDS and Citral after 72 h of treatment on HT29 were 34.10 ± 0.30 µg/mL and 21.77 ± 0.23 µg/mL, respectively. This study strongly suggests that CIT-SNEDDS has permitted the sustained release of Citral and that CIT-SNEDDS constitutes a potential soluble drug nanocarrier that is effective against colorectal cancer cells.

Review on the chemical composition of Litsea cubeba essential oils and the bioactivity of its major constituents citral and limonene

Abstract: There are two chemotypes of Litsea cubeba (Lour.) Pers. (fam. Lauraceae) essential oils (EOs), either dominated by citral and limonene or by citronellal. L. cubeba EOs exhibits broad antimicrobial ...

Attenuation of Multiple Vibrio parahaemolyticus Virulence Factors by Citral.

Abstract: Citral was known as a widely used food additive with antimicrobial activity; however, whether it can be a potential therapy for controlling bacterial virulence with less risk of antimicrobial resistance remains to be investigated. Herein, we demonstrated that Vibrio parahaemolyticus virulence factors that contribute to infection were effectively inhibited to different degrees by sub-inhibitory concentrations (3.125, 6.25, and 12.5 μg/ml) of citral. Citral exerted strong inhibition of autoinducer-2 production and adhesion to Caco-2 cells. Biofilm formation of V. parahaemolyticus was effectively decreased by citral at 30°C and 20°C. Moreover, citral repressed the transcription of genes related to flagella biosynthesis, biofilm formation, type III secretion effectors, and antibiotic resistance, as well as genes contributing to the regulation of quorum sensing and toxin production. Therefore, citral could effectively attenuate multiple virulence properties of V. parahaemolyticus, and its effect on in vivo infection by V. parahaemolyticus needs further investigation.

Effects of Essential Oil Citral on the Growth, Mycotoxin Biosynthesis and Transcriptomic Profile of Alternaria alternata.

Abstract: Alternaria alternata is a critical phytopathogen that causes foodborne spoilage and produces a polyketide mycotoxin, alternariol (AOH), and its derivative, alternariol monomethyl ether (AME). In this study, the inhibitory effects of the essential oil citral on the fungal growth and mycotoxin production of A. alternata were evaluated. Our findings indicated that 0.25 μL/mL (222.5 μg/mL) of citral completely suppressed mycelial growth as the minimum inhibitory concentration (MIC). Moreover, the 1/2MIC of citral could inhibit more than 97% of the mycotoxin amount. Transcriptomic profiling was performed by comparative RNA-Seq analysis of A. alternata with or without citral treatment. Out of a total of 1334 differentially expressed genes (DEGs), 621 up-regulated and 713 down-regulated genes were identified under citral stress conditions. Numerous DEGs for cell survival, involved in ribosome and nucleolus biogenesis, RNA processing and metabolic processes, and protein processing, were highly expressed in response to citral. However, a number of DEGs responsible for the metabolism of several carbohydrates and amino acids, sulfate and glutathione metabolism, the metabolism of xenobiotics and transporter activity were significantly more likely to be down-regulated. Citral induced the disturbance of cell integrity through the disorder of gene expression, which was further confirmed by the fact that exposure to citral caused irreversibly deleterious disruption of fungal spores and the inhibition of ergosterol biosynthesis. Citral perturbed the balance of oxidative stress, which was likewise verified by a reduction of total antioxidative capacity. In addition, citral was able to modulate the down-regulation of mycotoxin biosynthetic genes, including pksI and omtI. The results provide new insights for exploring inhibitory mechanisms and indicate citral as a potential antifungal and antimytoxigenic alternative for cereal storage.

Sustainable Recovery of Volatile Fatty Acids fromAqueous Solutions Using Terpenoids and Eutectic Solvents

Abstract: Volatile fatty acids (VFAs) are produced in the anaerobic digestion of urban or food wastes and sewage sludge. The interest in these compounds has increased because of their use as platform chemicals. In this paper, the application of natural terpenoids and eutectic solvents to sustainably recover VFAs from aqueous solutions by extraction has been evaluated. First, a screening of solvents has been done using COSMO-RS, selecting three terpenoids: geraniol, citral, and eugenol, and two hydrophobic eutectic solvents formed by octanoic acid and menthol or thymol. These solvents have been tested in the extraction of acetic, propionic, butyric, and valeric acids. The highest yields were obtained using geraniol and the (octanoic acid + thymol) eutectic solvent, being comparable or higher than those for organic solvents from the literature. The back-extraction of the VFAs from both solvents has been studied using NaOH and Na2CO3 solutions, concluding that the eutectic solvent is not chemically stable to be reused...

Effects of orange essential oil on intestinal microflora in mice.

Abstract: BACKGROUND The intestinal microbiota has a wide variety of functions in the host. A positive effect of plant extract on intestinal microbiota in animals has been reported. However, the effect of orange essential oil and its components limonene, linalool and citral on intestinal microflora in mice has seldom been reported. The effects of intragastric administration of orange essential oil and limonene, linalool and citral on intestinal microflora and biochemical indexes in mice were studied. RESULTS The effect of essential oil, linalool and citral on immune organ index (spleen and thymus index), IgM and IL-2 was not significant (P > 0.05). A significant increase (P < 0.05) of H+ K+ -ATPase activity, IgA, IgG, and IL-2 in the limonene group was observed when compared with the control group. Orange essential oil, limonene, linalool and citral could significantly reduce the content of short-chain fatty acids in the cecum and colon of mice. Principal coordinates analysis showed that intestinal bacterial structure of limonene group cecum and colon was apparently separated from other groups. The relative abundance of Lactobacillus in cecum and colon in essential oil, limonene, linalool and citral groups was higher than that in the control group. CONCLUSIONS Orange essential oil and limonene, linalool and citral could affect the intestinal microflora of mice, and enhance the relative abundance of Lactobacillus. The intestinal bacterial structure of cecum and colon in the limonene group was quite different from other groups. This indicated a more obvious effect of limonene on intestinal bacteria, also resulting in significant changes in blood immune index and short-chain fatty acids in mice. © 2019 Society of Chemical Industry.

In Vivo Anti-Tumor Effects of Citral on 4T1 Breast Cancer Cells via Induction of Apoptosis and Downregulation of Aldehyde Dehydrogenase Activity

Abstract: Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death among females globally. The tumorigenic activities of cancer cells such as aldehyde dehydrogenase (ALDH) activity and differentiation have contributed to relapse and eventual mortality in breast cancer. Thus, current drug discovery research is focused on targeting breast cancer cells with ALDH activity and their capacity to form secondary tumors. Citral (3,7-dimethyl-2,6-octadienal), from lemon grass (Cymbopogon citrates), has been previously reported to have a cytotoxic effect on breast cancer cells. Hence, this study was conducted to evaluate the in vivo effect of citral in targeting ALDH activity of breast cancer cells. BALB/c mice were challenged with 4T1 breast cancer cells followed by daily oral feeding of 50 mg/kg citral or distilled water for two weeks. The population of ALDH+ tumor cells and their capacity to form secondary tumors in both untreated and citral treated 4T1 challenged mice were assessed by Aldefluor assay and tumor growth upon cell reimplantation in normal mice, respectively. Citral treatment reduced the size and number of cells with ALDH+ activity of the tumors in 4T1-challenged BALB/c mice. Moreover, citral-treated mice were also observed with smaller tumor size and delayed tumorigenicity after reimplantation of the primary tumor cells into normal mice. These findings support the antitumor effect of citral in targeting ALDH+ cells and tumor recurrence in breast cancer cells.

Synthesis, characterization, and antimicrobial efficacy of composite films from guar gum/sago starch/whey protein isolate loaded with carvacrol, citral and carvacrol-citral mixture

Abstract: The aim of this research was to formulate antimicrobial, composite films of guar gum, sago starch, and whey protein isolate for the prophylaxis of the bacterial gastroenteritis. The model antibacterial agents incorporated were essential oils, namely, carvacrol, citral and their combination. The films became darker and brownish in color due to the entrapment of the oils. The surface of the oil-entrapped films was more rough and coarse compared to the control film. Confocal micrographs affirmed the uniform distribution of the oil droplets within the biopolymeric network. The highest crystallite size and lowest lattice strain were estimated in the citral-containing film. FTIR analysis demonstrated that the incorporation of citral increased the proportion of the β-sheet structures of the whey protein isolate within the film matrix. However, the film formulation containing combination of carvacrol and citral demonstrated the lowest water vapor transmission rate (WVTR), highest tensile strength, Young's modulus and work to failure. All the oil-containing films demonstrated good antibacterial potency against the model bacterial gastroenteritis causing bacteria, namely, Bacillus cereus and Escherichia coli. In gist, it can be concluded that the prepared antimicrobial films could be used for the prophylaxis of the bacterial gastroenteritis.

Characterization of Tri-Phasic Edible Films from Chitosan, Guar Gum, and Whey Protein Isolate Loaded with Plant-Based Antimicrobial Compounds

Abstract: Essential oil containing tri-phasic films of chitosan, guar gum, and whey protein isolate were prepared. Eugenol, carvacrol, and citral were used as the oil phase, either alone or in combination. T...

Combination Effect of High-Pressure Processing and Essential Oil (Melissa officinalis Extracts) or Their Constituents for the Inactivation of Escherichia coli in Ground Beef

Abstract: The inactivation of a five-strain cocktail of Escherichia coli by high-pressure processing (HPP) and Melissa officinalis leaf extracts (MoEOs) or their similar chemical constituents (CCs; citral, geraniol, β-caryophyllene or a mixture) in fresh ground beef was investigated. The pathogenic bacteria post-process growth and survival were further determined at 4 °C, 7 days storage. Ground beef pressurized at 300, 350, and 400 MPa for 15 min in combination with 0.5 and 1.0% of MoEOs or CCs was investigated. A 5-log CFU/g reduction was achieved with properly selected pressure and MoEOs, CCs, or MIX [a reconstituted mixture of 1/3 citral, 1/3 geraniol, and 1/3 β-caryophyllene (weight basis)] concentration. Without the HPP, the inactivation potential of citral, geraniol, MoEOs, or MIX was similar and negligible, while under pressure, the inactivation potential increased significantly as the pressure and concentration increased. The Escherichia coli strains tested include Shiga toxin-producing E. coli (STEC) O157, O111, O121, O128, and O145, which are involved in many food-borne pathogen outbreaks worldwide. For 24 h under refrigeration, 1.0% citral, 1.0% geraniol, 1.0% MIX, and 1.0% MoEOs with 350 and 400 MPa could reduce ca. 3–6 log CFU/g of E. coli. The inactivation potential continued to show effectiveness during the low-temperature storage test (e.g., 4 °C, 7 days). In conclusion, the combination treatment of HPP and M. officinalis extracts was found to be significantly effective in the inactivation of E. coli. Transmission electron microscope (TEM) images further demonstrated the cell structure damaged under HPP and antimicrobial compound stresses.

Peel oils from three Citrus species: volatile constituents, antioxidant activities and related contributions of individual components

Abstract: In the present study, peel oils were extracted through hydrodistillation and cold pressing from three Citrus species (Valencia orange, Ponkan and Eureka lemon) to investigate their volatile constituents and antioxidant activities. A total of 47 volatile components were identified by GC–MS, and then grouped by principal component analysis. The extraction methods were found to have an obvious effect on the proportion of terpenes and oxygenated compounds in the six Citrus oils, especially for Eureka lemon oils. The major fractions in the Citrus oils were found to be monoterpenes (78.65–96.57%), with limonene occupying a dominant percentage (51.22–86.65%). Furthermore, γ-terpinene and terpinolene displayed strong DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging abilities and efficient inhibition of lipid peroxidation, while oxygenated compounds of α-terpineol and terpinen-4-ol showed poor DPPH radical-scavenging abilities. Therefore, hydrodistillated Eureka lemon oil with high levels of α-terpineol (9.11%) and terpinen-4-ol (4.69%) presented low radical scavenging capability. Citral displayed a high pro-oxidant ability against thiobarbituric acid reactive species formation, which might lead to the decreased ability of the Eureka lemon oils in inhibition of lipid peroxidation, since citral was significantly high in Eureka lemon oils. This study facilitated the understanding of volatile constituents and antioxidant activities in different Citrus peel oils.

Effect of cold plasma on essential oil content and composition of lemon verbena.

Abstract: Cold plasma is known as a novel nonthermal processing method for decontamination of medicinal and aromatic plants (MAPs); however, there are little research studies about its effects on active ingredients of these plants. The aim of this research was to investigate the influence of low-pressure cold plasma (LPCP) treatments (1, 3, and 5 min) on the essential oil (EO) content and composition of lemon verbena leaves. The EO content was determined using hydro-distillation, and the composition of the extracted EOs was quantified using gas chromatography and gas chromatography-mass spectrometry techniques. The results showed that by increasing the LPCP treatment duration, the EO content was reduced from 1.2 to 0.9 (% v/w). The highest content of monoterpene hydrocarbons (e.g., limonene) and oxygenated sesquiterpenes (e.g., spathulenol and globulol) was also observed in LPCP-treated ones, whereas the oxygenated monoterpenes (e.g., citral) content of control was measurably higher than those treated with LCPC.

Effect and mechanism of citral against methicillin-resistant Staphylococcus aureus in vivo.

Abstract: BACKGROUND Citral is an active component of many plant extracts, and it is a safe additive used in food and cosmetics. A previous study showed that citral has a good antibacterial effect against methicillin-resistant Staphylococcus aureus (MRSA) in vitro, but its in vivo anti-infective activity has not been studied. Anti-MRSA activity and the preliminary mechanism of citral against MRSA were investigated in MRSA-infected KM mice. The ED50 was calculated using Karber's method. Groups were selected for inflammatory and oxidative stress level tests, and lung and liver tissues were counterstained with HE for detection of pathological changes. Cytokines and oxidative factors were evaluated using the ELISA method (one-way ANOVA computed using SPSS 19.0.). RESULTS With the increase in the concentration of citral, the survival rate of MRSA-infected mice increased accordingly. The ED50 values of citral for intramuscular injection and intragastric administration were 0.09 and 0.26 g kg-1 respectively. Citral significantly reduced cytokines (IL-1β, IL-6, TNF-α) and oxidative factors (malondialdehyde and hydroxyl radicals) of MRSA-infected mice, whereas it increased gluthtione and superoxide dismutase levels. Citral can reduce the lung inflammatory infiltrates infected by MRSA. CONCLUSIONS Citral exerted a dose-dependent anti-MRSA effect and ameliorated MRSA-induced abnormal changes in inflammation and oxidative stress. This indicates that citral has the potential for development as a new anti-MRSA drug. © 2019 Society of Chemical Industry.

Citral prevents UVB-induced skin carcinogenesis in hairless mice.

Abstract: The incidence of skin cancers has increased worldwide, requiring more prevention of this type of cancer. The use of sunscreen and the control of the time of exposure to sunlight are the recognized forms of prevention. However, new substances have been researched in order to develop formulations with more efficient protective activity. Citral is a natural compound with lemon scent that is used in food and cosmetic industries. The present work evaluated the chemoprotective effect of citral during UVB-induced skin carcinogenesis. Male hairless mice HRS/J, 8–12 weeks old, were exposed to UVB irradiation for 24 weeks, with a cumulative radiation dose of 13.875 J/cm2. Citral (0.1, 0.5 and 1%) was applied to the skin at a dosage of 0.1 g/animal, 5 min after UVB exposure. At the end of the experiment, the number of lesion/animal, and size of lesions were measured. The histological sections of the skin were evaluated for the presence and intensity of actinic keratosis and squamous cell carcinoma. TUNEL assay was performed for apoptosis evaluation. Skin samples were used for the measurement of oxidative stress parameters (total radical-trapping antioxidant parameter of skin, glutathione, catalase activity and malondialdehyde), and cytokines levels (IL-1β, IL-4, IL-10, IL-23, TNF-α, and IFNγ). Citral 1% completely inhibited UVB-induced skin carcinogenesis by reducing levels of oxidative stress and pro-inflammatory cytokines, increasing apoptotic rate in the skin.

Oil in water nanoemulsion formulations of botanical active substances

Abstract: Water-based nanoemulsions of insecticidal botanical oils and extracts have advantages over emulsifiable concentrates and macroscopic emulsions, particularly due to the small droplet size ( Pyrethrum extract gave a reduction in RD50 from 0.131%–0.025% if a nanoemulsion was applied instead of a macroscopic emulsion in the choice laboratory bioassay with M. persicae. However, in greenhouse experiments, the number of aphids on pepper plants was not different between both treatments. Obviously, spraying pyrethrum had insecticidal effects in comparison with a control. On the other hand, the preventive application of citral or anise in pepper plants showed some repellence but only if the binary mixture at doses of 0.1%–0.2% was sprayed. A reduction in the number of aphids per plant was observed. Pyrethrum nano was less toxic to Aphidius colemani (LC90 = 0.064%) than the macroscopic pyrethrum emulsion (LC90 = 0.038%). Citral or anise was much safer for natural enemies (parasitoids) and had no residual contact toxicity up to 0.1%.

In Vitro Anti-Biofilm Activities of Citral and Thymol Against Candida Tropicalis.

Abstract: Candida tropicalis is an emerging non-albicans Candida species which is pathogenic to the immune-compromised humans, especially in tropical countries, including India. The acquired resistance of Candida species towards antifungal therapies is of major concern. Moreover, limited efficacy and dosage constraint of synthetic drugs have indicated the prerequisite of finding new and natural drugs for treatment. In the present study, we have compared the influence of citral and thymol on C. tropicalis and its biofilm along with expression levels of certain antifungal tolerance genes. The antifungal and anti-biofilm activities of the both were studied using 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide sodium salt (XTT) reduction assay, field emission scanning electron microscope (FE-SEM) and confocal laser scanning microscope (CLSM) and real-time reverse transcription polymerase chain reaction (RT-PCR) analysis. Citral and thymol have damaged the cells with distorted surface and less viability. Quantitative real-time PCR analysis showed augmented expression of the cell membrane biosynthesis genes including ERG11/CYT450 against citral and the cell wall related tolerance genes involving CNB1 against thymol thus, depicting their differential mode of actions.

Impact of Citral and Phloretin, Alone and in Combination, on Major Virulence Traits of Streptococcus pyogenes.

Abstract: Streptococcus pyogenes is well documented as a multi-virulent and exclusively human pathogen. The LuxS-based signaling in these bacteria has a crucial role in causing several infections through pathways that are pathogenic. This study evaluated the individual and synergistic effects of citral and phloretin against S. pyogenes in relation to major virulence traits. The in vitro synergy of citral and phloretin was evaluated by the checkerboard method. The fractional inhibitory concentration (FIC) values were calculated to determine the interactions between the inhibitors. The bacteria's virulence properties were tested in the presence of the molecules, individually as well as in combination. Molecules' cytotoxicity was tested using human tonsil epithelial cells. The synergistic effects of the molecules on the expression of biofilm and quorum sensing genes were tested using quantitative real-time polymerase chain reaction (qRT-PCR). The molecules were also tested for their impact on LuxS protein by molecular docking, modeling, and free-energy calculations. When the two molecules were assessed in combination (synergistic effect, FIC Index of 0.5), a stronger growth inhibitory activity was exhibited than the individual molecules. The cell surface hydrophobicity, as well as genes involved in quorum sensing and biofilm formation, showed greater suppression when the molecules were tested in combination. The in silico findings also suggest the inhibitory potential of the two molecules against LuxS protein. The binding orientation and the binding affinity of citral and phloretin well support the notion that there is a synergistic effect of citral and phloretin. The data reveal the combination of citral and phloretin as a potent antibacterial agent to combat the virulence of S. pyogenes.

Effects of citral on oxidative stress and hepatic key enzymes of glucose metabolism in streptozotocin/high-fat-diet induced diabetic dyslipidemic rats.

Abstract: Objective(s): Phytochemicals such as polyphenols, alkaloids, and terpenoids, protect against the development of early stages and complications of diabetes mellitus according to various reports. The aim of this study was to measure the anti-dyslipidemic and anti-diabetic effects of Citral on high-fat-diet (HFD) and streptozotocin (STZ) induced diabetic dyslipidemic rats and to see also its effect on carbohydrate metabolic regulatory enzymes in the liver. Materials and Methods: Rats were kept on a high-fat diet for 2 weeks, then diabetes was induced by a single dose of STZ (35 mg/kg/BW, intraperitoneally), Citral was administered orally at a dose of 45 mg/kg/BW for 28 days to diabetic rats. Blood glucose, plasma insulin, and lipid profile in blood were studied. Antioxidant activities were assayed in the liver, pancreas, and adipose tissues. Carbohydrate metabolic enzymes of the liver were also studied in diabetic dyslipidemic rats.Results: The results of this study confirmed that administration of Citral significantly (P<0.05) decreased the blood glucose level and increased plasma insulin in diabetic rats. Citral also improved oxidative markers along with anti-oxidative enzymes of the liver, adipose tissue, and pancreas in the HFD/STZ group. Citral also regulated the activity of the glucose-metabolic enzymes in the liver. The results of the present study were compared to Glibenclamide, which is a standard oral drug for lowering the blood sugar. Conclusion: Results may show that Citral possesses anti-dyslipidemic activity as well as anti-diabetic activity and also regulates the enzyme activity of glycolytic and gluconeogenic processes in the liver.

Heat-Assisted Pulsed Electric Field Treatment for the Inactivation of Saccharomyces cerevisiae: Effects of the Presence of Citral.

Abstract: Pulsed electric field (PEF) treatment is a non-thermal technology that has shown good potential for microbial inactivation. However, in many cases, it cannot be sufficient to avoid microbial proliferation and the combination with other stabilizing technologies is needed. In the framework of the hurdle concept, several researches have been focused on the use of PEF in combination with heat and/or antimicrobials to increase its efficacy. This study investigated the inactivation effect of PEF on a strain of Saccharomyces cerevisiae (isolated from spoiled beverages) in a model system (growth medium). The efficacy of PEF treatment was evaluated in relation to different variables, such as electric field strength (25 and 50 kV/cm), treatment time (from 1 to 5 seconds), initial inoculum level (4 or 6 log cfu/ml), pre-heating at 50°C, medium pH (4 or 6) and addition of citral at sub lethal concentration (i.e. half of minimum inhibiting concentration). The data from plate counting, modelled with the Weibull equation, showed that one of the main factors affecting yeast inactivation was the pre-heating of the suspension at 50°C. Indeed, higher cell load reductions were obtained with heat-assisted PEF, especially in the presence of citral. The effect of initial cell load was negligible, while pH affected yeast inactivation only without pre-heating, with higher death kinetics at pH 6. Flow cytometry (FCM) analysis confirmed higher mortality under these conditions. However, the occurrence of injured cells, especially in samples treated at pH 4, was observed. The ability of these cells to recover from the damages induced by treatments was affected by both citral and pre-heating. The synergic effects of PEF, pre-heating and citral were likely due to the increase of membrane permeability (especially at pH 6), as the primary target of electroporation, which favoured the solubilization of citral in the cell membrane, enhancing the efficacy of the whole process. The multi-analytical approach (traditional plate counting and FCM) allowed defining parameters to increase PEF efficacy against S. cerevisiae. Moreover, FCM, able to discriminate different physiological states of the yeast population, was helpful to better clarify the action mechanism and the potential recovery of cells after treatment.

Supported Co–Re Bimetallic Catalysts with Different Structures as Efficient Catalysts for Hydrogenation of Citral

Abstract: Bimetallic Co-Re/TiO2 catalysts were developed for efficient citral hydrogenation. Bimetallic catalysts were prepared by co-impregnation (CI), successive-impregnation (SI), and surface redox method (SR). The arrangement between the Co and Re species on these systems was fully characterized using several techniques (TEM-energy-dispersive X-ray spectroscopy, H2 temperature-programmed reduction, temperature-programmed desorption, XRD, CO FTIR spectroscopy, model reaction of cyclohexane dehydrogenation), and their catalytic performances were evaluated for the selective hydrogenation of citral towards unsaturated alcohols. The Re and Co species are completely isolated in the CI sample, presenting a very limited Co-Re interaction. In SI samples, the metals coexist in a Janus-type structure with a concentration of Re around Co. Decoration/core-shell structures are observed for SR samples resulting from the redox exchange between the metallic surface of the parent Co/TiO2 catalyst and the Re7+ species of the modifier precursor salt. The contact degree between the two metals gradually increases as follows: Isolated structure (CI)