Linalool Research Articles

Diversity and morpho-chemo correlations of Cinnamon (Cinnamomum verum J. Presl) bark oil from Sri Lanka

The wide natural variation of Cinnamomum verum morphology in Sri Lanka suggests the chemo-diversity, which must be revealed for efficient utilization in a vast scope of industries. This study was carried out to determine the variation of essential oil constituents of cinnamon bark from major growing areas of Sri Lanka, morphological markers for oil constituents and genetic relationships for the correlations among major chemical constituents. E-Cinnamaldehyde (CM), (E)-Cinnamyl acetate (CA), Eugenol (EU), Benzyl benzoate (BB), linalool (LN) and β-caryophyllene (CR) were the highest abundant six out of 188 constituents reported through GC-MS analysis of bark essential oil. The mean values and 95% confidence intervals of CM, CA, EU, BB, LN and CR were 65.10±2.4 (60.15, 70.05), 15.93 ±2.14 (11.51, 20.34), 4.07±0.42 (3.19, 4.95), 3.21±0.52 (2.15, 4.28), 1.44 ± 0.16 (1.09,1.79) and 1.31±0.10 (1.11,1.53) respectively. CM was the highest abundant in 29/30 accessions, while CA was the highest abundant only in 1/30. CM varied with growing district. CM was negatively correlated with CA, (r=0.81) at the 0.01% level of significance irrespective of the growing district. The correlation between EU and BB was significant (r=0.49) at 0.01% level of significance. Chemical constituents were linked with the morphological characters: The leaf width (LW) was correlated with EU, (r=0.37) at 0.05% level of significance and the bark thickness (BT) was in a correlation with CR, (r=0.54) at 0.01% level of significance. Gene network model analysis identifying two pathways for CM, CA and BB biosynthesis, and two pathways for EU biosynthesis explained the correlations between major constituents.

Substance depletion of volatile monoterpenes – A confounding factor for toxicity testing in the Ames fluctuation test

In in vitro toxicology, reported test results are typically based on nominal concentrations, i.e., the calculated amounts of a substance added to a defined volume of the test system. Consequently, if a test system does not respond to a certain endpoint, the assay is interpreted as negative and the test substance is deemed to exert no toxicity at the tested nominal concentration. However, depending on the physicochemical properties of the test substance and assay setup, the actual exposure may differ widely from nominal concentrations due to different depletion processes. (R)-(+)-Limonene (RLIM), β-myrcene (βMYR) and linalool (LIN) are naturally occurring terpenes that are permitted as flavoring agents in the European Union without limitations based on their low toxicity. Nevertheless, their hydrophobicity and high volatility classifies them as difficult to test chemicals, which has not been considered in previous in vitro tests. To exclude possible false negative results, in the present study, we assessed the cytotoxic and mutagenic potential of the latter substances toward Salmonella Typhimurium in the Ames fluctuation test using different incubation setups to minimize possible substance losses due to sorption or volatilization. Actual substance concentrations during incubation were verified analytically at different time points via headspace gas-chromatography-mass spectrometry (hs-GC-MS). Possible substance depletion due to sorption to well-plate material or volatilization was minimized using a polystyrene-free and headspace-free incubation setup, respectively. The results showed complete volatilization of the monoterpenes RLIM and βMYR in the conventional Ames fluctuation test, which may confound mutagenicity testing. The headspace-free incubation setup greatly improved substance exposure and showed cytotoxicity in low micromolar concentrations, but no signs of mutagenicity were observed.

An Evaluation of the Autonomic Nervous Activity and Psychomotor Vigilance Level for Smells in the Work Booth

In this study, we investigated the effects of the smell environment in the work booth on autonomic nervous activity (ANS) and psychomotor vigilance levels (PVLs) using linalool (LNL) and trans-2-nonenal (T2N). The subjects were six healthy males (31 ± 6 years old) and six healthy females (24 ± 5 years old). They sat in the work booth filled with the smells of LNL and T2N for 10 min, and their electrocardiograms (ECGs), skin conductance levels, pulse wave variabilities, skin temperatures, and seat pressure distributions were measured. In addition, the orthostatic load test (OLT) and psychomotor vigilance test (PVT) were performed before and after entering the work booth, and a subjective evaluation of the smell was also performed after the experiment. This paper focused on ECG and PVT data and analyzed changes in heart rate variability indices and PVT scores. Males felt slightly comfortable with the LNL smell and showed promoted sympathetic nerve activity in the OLT after the smell presentation. Females felt slightly uncomfortable with the T2N smell and showed promoted sympathetic nerve activity and a decrease in PVT scores in the OLT after the smell presentation. Gender differences were observed in ANS and PVLs, and it is possible that the comfort of LNL increased sympathetic nervous activity in males, while the uncomfortableness of T2N may have reduced work performance in females.

Carboxymethyl chitosan coating infused with linalool-loaded molten globular β-Lactoglobulin nanoparticles for extended preservation of fresh-cut apples

This investigation employed molten globule state β-lactoglobulin nanoparticles (MG-BLGNPs) for encapsulating linalool (LN) combined with carboxymethyl chitosan (CMC) coating to enhance the shelf-life of fresh-cut apples. The effect of different MG structures on the encapsulation efficiency of BLGNPs and the properties of coating was studied. Structural characterization and molecular simulation showed structural differences between heat-induced MG state (70-BLGNPs, heated at 70 °C for 1 h) and sodium dodecyl sulfate-co-heat-induced MG state (SDS/70-BLGNPs, treated with 0.192 mg/mL SDS for 10 min, then heated at 70 °C for 1 h), with the latter being more unfolded. LN self-assembles into MG-BLGNPs, among the generated particles, SDS/70-BLG@LN exhibits stronger binding effect and higher LN loading capacity. Integration of MG-BLG@LN into CMC enhanced coating’s mechanical properties and adhesion to fresh-cut apples. The SDS/70-BLG@LN/CMC coating showed superior preservation on fresh-cut apples during storage, reducing enzymatic browning, membrane lipid oxidation, and microbial growth while maintaining hardness and overall quality.

Bioactive baicalin rhamno-nanocapsules as phytotherapeutic platform for treatment of acute myeloid leukemia

Leukemia, particularly acute myeloid leukemia (AML) is considered a serious health condition with high prevalence among adults. Accordingly, finding new therapeutic modalities for AML is urgently needed. This study aimed to develop a biocompatible nanoformulation for effective oral delivery of the phytomedicine; baicalin (BAC) for AML treatment. Lipid nanocapsules (LNCs) based on bioactive natural components; rhamnolipids (RL) as a biosurfactant and the essential oil linalool (LIN), were prepared using a simple phase-inversion method. The elaborated BAC-LNCs displayed 61.1 nm diameter and 0.2 PDI. Entrapment efficiency exceeded 98 % with slow drug release and high storage-stability over 3 months. Moreover, BAC-LNCs enhanced BAC oral bioavailability by 2.3-fold compared to BAC suspension in rats with higher half-life and mean residence-time. In vitro anticancer studies confirmed the prominent cytotoxicity of BAC-LNCs on the human leukemia monocytes (THP-1). BAC-LNCs exerted higher cellular association, apoptotic capability and antiproliferative activity with DNA synthesis-phase arrest. Finally, a mechanistic study performed through evaluation of various tumor biomarkers revealed that BAC-LNCs downregulated the angiogenic marker, vascular endothelial growth-factor (VEGF) and the anti-apoptotic marker (BCl-2) and upregulated the apoptotic markers (Caspase-3 and BAX). The improved efficacy of BAC bioactive-LNCs substantially recommends their pharmacotherapeutic potential as a promising nanoplatform for AML treatment.

Linalool exerts antioxidant activity in a rat model of diabetes by increasing catalase activity without antihyperglycemic effect.

Diabetes mellitus (DM) is a prevalent metabolic disorder often accompanied by oxidative stress, which contributes to various diabetic complications. Investigating the antioxidant activity of linalool (LIN) is crucial as it may offer a natural therapeutic approach to mitigate oxidative damage in DM. The aim of the present study was to investigate the antioxidant activity of LIN in a DM rat model. A total of 40 male Wistar albino rats (age, 8 weeks; weight, 250-300 g) were used. CONTROL and DM groups were administered physiological saline solution by oral gavage for 21 days. In rats in the DM + LIN and LIN groups, 100 mg/kg LIN was administered intragastrically after streptozotocin injection (n=10 per group). In the first (48 h after STZ injection), second (1 week later), third (2 weeks later), and fourth (3 weeks later) blood glucose measurements, a statistically significant increase was found in the blood glucose values of the DM and DM + LIN groups compared with those of the CONTROL group. During the 21-day experimental period, there was no reduction in blood glucose levels of the DM + LIN group. Consequently, no discernible anti-hyperglycemic effect of LIN was observed. Catalase enzyme activity, superoxide dismutase (SOD) enzyme activity, malondialdehyde (MDA) levels and glutathione (GSH) levels were measured spectrophotometrically. All assays were conducted according to the protocols provided in the respective kits. The results were analyzed to assess the oxidative status and antioxidant capacity in the experimental groups. Catalase (CAT) activity was decreased in the DM group compared with that in the CONTROL group in both the serum and liver. However, LIN administration restored CAT activity in the DM + LIN group to the level of the CONTROL group. In the liver, the DM + LIN-treated group showed a notable reduction in malondialdehyde (MDA) levels compared with those in the DM group. In conclusion, the present results suggest that the antioxidant properties of LIN may have a regulatory effect on the oxidative status in diabetes-affected systems, potentially offering therapeutic benefits in managing oxidative stress associated with diabetes.

Screening of Microorganisms Capable of Biotransforming Certain Monoterpenes Using Substrate Toxicity Test

Monoterpenes, such as Geraniol (G), Geranyl acetate (GA), Citral (CT), Limonene (LN), and Linalool (LL), are the most widely used phytochemicals in the aroma, food, and pharmaceutical industries. Here, we screened several bacteria and fungi to assess their potential to biotransform the selected monoterpenes (G, GA, CT, LN, and LL) through the substrate toxicity test. Three bacteria Pseudomonas fluorescens MTCC2421, Streptococcus mutans MTCC497, and Escherichia coli were found to be resistant to G, GA, and LN while two P. aeruginosa, and S. epidermidis MTTC 435 to GA and LN. In general, all fungal strains did not show resistance to any of the monoterpenes used, except Candida albicans and Fusarium oxysporum, which were slightly resistant to lower concentrations (0.05-0.1%) of GA. Interestingly, none of the bacteria and fungi showed any resistance to CT. The maximum concentrations of monoterpenes to which bacteria exhibited resistance ranged from 0.05-0.2%. The growth and biomass profiles of bacteria revealed that P. fluorescens and S. mutans grew well in the presence of monoterpenes GA and LN. Based on this, Pseudomonas fluorescens was capable of biotransforming GA and LN, while S. mutans only LN. The biotransformation of GA by P. fluorescens produced G and LL on the day 5th and 7th of the incubation. Hence, the study revealed the three potential bacteria, which may be useful in producing new aromatic derivatives from selected monoterpenes through biotransformation.

Hepatoprotective effects of linalool against liver ischemia-reperfusion: the role of Nrf2/HO-1/NQO1 and TLR4/RAGE/NFκB pathways.

Hepatic ischemia-reperfusion (H I/R) injury arises due to a temporary obstruction followed by the re-establishment of blood supply to the liver. Linalool (LIN), a main volatile constituent of essential oils in numerous aromatic plant species, exhibited various medicinal and pharmacological actions. This study investigated the protective effect of LIN on the status of H I/R, with the study of the possible mechanisms. In addition, linalool's antagonistic effects were tested against several metabolic targets using in silico molecular docking technique. Wistar rats were allocated into five groups. Sham and LIN + Sham groups in which animals were administered either vehicle (1% CMC) or LIN (200 mg/kg/day) orally for two weeks. H I/R group in which rats were administered 1% CMC for two weeks and then experienced hepatic ischemia for 60 min followed by 6 hours of reperfusion. LIN 100 + H I/R and LIN 200 + H I/R groups in which rats were pretreated with LIN (100, 200 mg/kg/day) respectively for two weeks, then subjected to H I/R. H I/R-induced injury resulted in impaired liver function and activated Keap1/Nrf2/HO-1/NQO1 and HMGB1/TLR4/RAGE/NFкB pathways with subsequent oxidative stress, inflammation, and apoptosis. LIN pretreatment alleviated I/R-induced impairment in liver function, promoted Keap1/Nrf2/HO-1/NQO1, and mitigated the HMGB1/TLR4/RAGE/NFкB pathway. LIN pre-administration deterred adhesion molecule, neutrophils infiltration, RAGE, IL-1β, IL-6, TNF-α, and apoptosis. LIN demonstrated hepato-protective effects against H I/R via instigation Keap1/Nrf2/HO-1/NQO1 and mitigating the HMGB1/TLR4/RAGE/NFкB pathways with subsequent deterring oxidative stress, inflammation, and apoptosis.

RİFAMPİSİN KAYNAKLI BEYİN DOKUSU HASARINDA LİNALOOL’UN İYİLEŞTİRİCİ RÖLÜ

Objective
 In this study linalool (LN), which has antihyperglycemic,
 hypolipidemic and antioxidant properties, is intended
 to be used in the treatment of neurodegenerations
 and neural disorders that may occur due to rifampicin
 (RF). For this reason, it was aimed to examine the
 effects of LN on the expression of genes, biochemical
 and histopathological parameters in these metabolic
 pathways against neurotoxicity that may occur due
 to RF, and to investigate the protective effects of LN,
 which has antioxidant properties.
 Material and Method
 Thirty healthy male Spraque-Dawley rats were divided
 into five groups (group 1; control, group 2; solvent
 control (DMSO); group 3, RF; group 4, LN; group 5;
 RF+LN). Brain tissues were taken for biochemical,
 histological and gene expressions analyses. Blood
 samples were taken to measure blood glucose levels.
 Results
 Rifampicin treatment significantly increased CYP1A1
 and CYP1A2 mRNA gene expression and blood
 glucose levels, while reducing brain weight according
 to findings. On the other hand, there was a significant
 decrease in CYP1A1 and CYP1A2 mRNA gene
 expression and blood glucose levels in the RF+LN
 group, while a significant improvement in brain weight
 was observed and as a result of histological analyzes,
 it was observed that the damage caused by RF
 decreased in the groups given LN.
 Conclusion
 LN was found to be highly effective in protecting the
 brain from the toxic effects of RF.

Quercetin Antagonizes the Sedative Effects of Linalool, Possibly through the GABAergic Interaction Pathway.

Sedatives promote calmness or sleepiness during surgery or severely stressful events. In addition, depression is a mental health issue that negatively affects emotional well-being. A group of drugs called anti-depressants is used to treat major depressive illnesses. The aim of the present work was to evaluate the effects of quercetin (QUR) and linalool (LIN) on thiopental sodium (TS)-induced sleeping mice and to investigate the combined effects of these compounds using a conventional co-treatment strategy and in silico studies. For this, the TS-induced sleeping mice were monitored to compare the occurrence, latency, and duration of the sleep-in response to QUR (10, 25, 50 mg/kg), LIN (10, 25, 50 mg/kg), and diazepam (DZP, 3 mg/kg, i.p.). Moreover, an in silico investigation was undertaken to assess this study's putative modulatory sedation mechanism. For this, we observed the ability of test and standard medications to interact with various gamma-aminobutyric acid A receptor (GABAA) subunits. Results revealed that QUR and LIN cause dose-dependent antidepressant-like and sedative-like effects in animals, respectively. In addition, QUR-50 mg/kg and LIN-50 mg/kg and/or DZP-3 mg/kg combined were associated with an increased latency period and reduced sleeping times in animals. Results of the in silico studies demonstrated that QUR has better binding interaction with GABAA α3, β1, and γ2 subunits when compared with DZP, whereas LIN showed moderate affinity with the GABAA receptor. Taken together, the sleep duration of LIN and DZP is opposed by QUR in TS-induced sleeping mice, suggesting that QUR may be responsible for providing sedation-antagonizing effects through the GABAergic interaction pathway.

Synergistic Interactions between Linalool and Some Antimycotic Agents against Candida spp. as a Basis for Developing New Antifungal Preparations

The incidence of superficial infections, including oral candidiasis, has recently increased significantly. Their treatment is quite difficult due to the growing resistance of Candida spp. to antifungal agents. Therefore, it is necessary to search for novel antimycotics or alternative antifungal therapies. The purpose of the study was to evaluate the antifungal activity of natural terpene—linalool (LIN)—against both reference fungi belonging to yeasts and Candida spp. isolates from the oral cavities of immunocompromised, hemato-oncology patients. Moreover, its mechanism of action and interactions with selected antifungal drugs or antiseptics were investigated. The broth microdilution technique, ergosterol or sorbitol tests, and a checkerboard method were used for individual studies. The LIN showed potential activity toward studied strains of fungi with a minimal inhibitory concentration (MIC) in the range of 0.5–8 mg/mL and fungicidal effect. This compound was also found to bind to ergosterol in the yeast cell membrane. Additionally, the interactions between LIN with antiseptics such as chlorhexidine, cetylpyridinium, and triclosan showed beneficial synergistic effect (with FIC = 0.3125–0.375), or an additive effect with silver nitrate and chlorquinaldol (FIC = 0.625–1). Moreover, statistically significant differences in MIC values were found for the synergistic combinations of LIN. No interaction was indicated for nystatin. These results confirm that the LIN seems to be a promising plant component used alone or in combination with other antimycotics in the prevention and treatment of superficial fungal infections. However, further clinical trials are required.

Linalool prevents kidney damage by inhibiting rifampicin-induced oxidative stress and apoptosis

Today, kidney diseases are increasing day by day and life quality is decreasing. In hospitalized patients of all ages, acute kidney injury (AKI) is commonly observed and associated with high rates of morbidity and mortality. Rifampicin (RF) or rifampin is an antibiotic drug from the rifamycin group with a bactericidal effect. RF causes acute kidney injury, often anemia, thrombocytopenia, liver damage and side effect such as cell death. RF causes tissue damage by means of oxidative stress and apoptosis. Thus, in this study, it was examined whether linalool (LN) which had antinociceptive, antimicrobial, antioxidant and anti-inflammatory effects, was beneficial for kidney damage in order to eliminate the side effects of RF. NGAL mRNA, creatinine (Cr), blood urea nitrogen (BUN), Caspase 9 (CAS-9) and nuclear factor-κB (NF-κB) levels increased in the group treated with RF compared to the control group, while the levels of albumin, uric acid and total protein were decreased in the RF-treated group. NGAL mRNA, BUN, Cr, CAS-9 and NF-κB levels decreased significantly in RF+LN administered rats, while it was observed that there was an increase in the levels of albumin, uric acid and total protein. From the results obtained, it was observed that LN was determined to be very effective in preventing tissue damage in kidneys caused by oxidative stress by RF.

Inhibitive effect and mechanism of cinnamaldehyde on growth and OTA production of Aspergillus niger in vitro and in dried red chilies

Mould and mycotoxin contamination is an ongoing issue in agriculture and food industry. Production by Aspergillus niger DTZ-12 in Guizhou dried red chilies was found, leading to significant economic losses. In this study, the inhibitive efficacy (Effective Concentration, EC) of cinnamaldehyde (CIN), eugenol (EUG), carvacrol (CAR), and linalool (LIN) against A. niger DTZ-12 were evaluated. CIN with the best antifungal capacity was then investigated for the comprehensive inhibitory activity against A. niger DTZ-12 including mycelia, spores, and physiological activities. Results showed that CIN can effectively retard mycelial growth, spore germination, and OTA production of A. niger DTZ-12 in vitro and in dried red chilies during storage. At physiological level, CIN can increase cell membrane permeability by reducing the ergosterol, decrease ATP content and ATPase activity, and promote the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in cell. These results suggested that CIN displayed a great potential to be employed as a natural and effective alternative preservative during dried red chili storage.

Neuro-protective effect of Linalool against spinal cord injury in rats and the mechanism involved

The current study was conducted to determine the neuroprotective role and mechanism of action of Linalool (LIN) in SCI. The SCI in Sprague-Dawley (SD) rats was induced by weight-drop contusion model. Results of the suggested that LIN showed improvement in the locomotor function of SCI rats in a BBB scoring analysis. It was found in agreement with histopathological analysis of spinal cord tissue where LIN improves the neuronal architecture of spinal cord tissues, and protect neurons from degeneration. It also reduces oxidative stress via modulating endogenous antioxidants (MDA, SOD, and GSH) and inhibits the generation of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). In western blot analysis, LIN showed dose-dependent reduction of expression of toll-like receptor (TLR-4) and nuclear factor-kappa B (NF-ĸB). Our study demonstrated that administration of Linalool alleviated spinal cord injury via anti-inflammatory and antioxidant activities in spinal cord tissues possibly due to inhibition of TLR4/NF-κB activation.

The uppermost monoterpenes improving Cinnamomum camphora thermotolerance by serving signaling functions.

Terpenes serve important functions in enhancing plant thermotolerance. Cinnamomum camphora mainly has eucalyptol (EuL), camphor (CmR), linalool (LnL) and borneol (BeL) chemotypes basing on the uppermost monoterpenes. To reveal the thermotolerance mechanisms of these uppermost monoterpenes (eucalyptol, camphor, linalool, and borneol) in C. camphora, we surveyed the ROS metabolism and photosynthesis in the 4 chemotypes fumigated with the corresponding uppermost monoterpene after fosmidomycin (Fos) inhibiting monoterpene synthesis under high temperature at 38°C (Fos+38°C+monoterpene), and investigated the related gene expression in EuL and CmR. Meanwhile, the thermotolerance differences among the 4 uppermost monoterpenes were analyzed. In contrast to normal temperature (28°C), ROS levels and antioxidant enzyme activities in the 4 chemotypes increased under 38°C, and further increased in the treatment with Fos inhibiting monoterpene synthesis at 38°C (Fos+38°C), which may be caused by the alterations in expression of the genes related with non-enzymatic and enzymatic antioxidant formation according to the analyses in EuL and CmR. Compared with Fos+38°C treatment, Fos+38°C+monoterpene treatments lowered ROS levels and antioxidant enzyme activities for the increased non-enzymatic antioxidant gene expression and decreased enzymatic antioxidant gene expression, respectively. High temperature at 38°C reduced the chlorophyll and carotenoid content as well as photosynthetic abilities, which may result from the declined expression of the genes associated with photosynthetic pigment biosynthesis, light reaction, and carbon fixation. Fos+38°C treatment aggravated the reduction. In contrast to Fos+38°C treatment, Fos+38°C+monoterpene treatments increased photosynthetic pigment content and improved photosynthetic abilities by up-regulating related gene expression. Among the 4 uppermost monoterpenes, camphor showed strong abilities in lowering ROS and maintaining photosynthesis, while eucalyptol showed weak abilities. This was consistent with the recovery effects of the gene expression in the treatments with camphor and eucalyptol fumigation. Therefore, the uppermost monoterpenes can enhance C. camphora thermotolerance as signaling molecules, and may have differences in the signaling functions.

Methyl Jasmonate Induces Genes Involved in Linalool Accumulation and Increases the Content of Phenolics in Two Iranian Coriander (Coriandrum sativum L.) Ecotypes.

The medicinal herb coriander (Coriandrum sativum L.), with a high linalool (LIN) content, is widely recognized for its therapeutic benefits. As a novel report, the goals of this study were to determine how methyl jasmonate (MeJA) affects total phenolic content (TPC), LIN content, flavonoid content (TFC), and changes in gene expression involved in the linalool biosynthesis pathway (CsγTRPS and CsLINS). Our findings showed that, in comparison to the control samples, MeJA treatment substantially enhanced the TPC, LIN, and TFC content in both ecotypes. Additionally, for both Iranian coriander ecotypes, treatment-induced increases in CsγTRPS and CsLINS expression were connected to LIN accumulation in all treatments. A 24 h treatment with 150 µM MeJA substantially increased the LIN content in the Mashhad and Zanjan ecotypes, which was between 1.48 and 1.69 times greater than that in untreated plants, according to gas chromatography–mass spectrometry (GC-MS) analysis. Our findings demonstrated that MeJA significantly affects the accumulation of LIN, TPC, and TFC in Iranian C. sativum treated with MeJA, which is likely the consequence of gene activation from the monoterpene biosynthesis pathway. Our discoveries have improved the understanding of the molecular mechanisms behind LIN synthesis in coriander plants.

Efficacy of pectin-based caproic acid, caprylic acid, linalool, and cuminaldehyde coatings in reducing Salmonella Heidelberg on chicken eggs

Among the animal derived food products, contamination of poultry eggs, and egg shell surface is one of the major causes for foodborne salmonellosis in the United States. As a means of reducing the pathogen transfer to the internal egg contents, polysaccharide-based coatings containing antimicrobial phytochemicals could potentially serve as a biocontrol strategy for shelled egg products. The current study investigated the efficacy of four GRAS (Generally Recognized as Safe)-status plant-derived compounds, namely, caproic acid (CAO), caprylic acid (CAY), linalool (LIN) and cuminaldehyde (CUM), as pectin-based coating treatments, individually or in combination, for reducing Salmonella Heidelberg (SH) on shell eggs. A three-strain mixture of SH (~8.0 log CFU in 50 μL inoculum) was spot-inoculated on surface sterilized white-shelled eggs. Eggs were evenly coated with either pectin-based treatments of CAO (1%), CAY (1%), LIN (1%) and CUM (1%), individually, or a combination of 4 phytochemicals (COMB- each phytochemical at 0.5% v/v level of inclusion). The treated eggs were stored at 4°C and SH counts were enumerated on days 0, 1, 3, 5, 7, 14, and 21 of storage. The study was replicated thrice, 3 eggs/treatment/day time point, and the data were analyzed using two-way ANOVA with significance tested at p < 0.05. On day 0, pectin-coated control eggs had ~7.6 log CFU of SH/egg. At the end of refrigerated storage (day 21), pectin-based coating of CAO and CAY at 1% level reduced SH by 2.0–2.5 log CFU/egg (P < 0.05) when compared to controls. In addition, the CUM and LIN based coatings produced 3.0 log and 3.9 log reduction, respectively, in SH counts on eggs by day 21 of storage. Among the treatments with phytochemical combinations, COMB1 [pectin (2%) + Caprylic acid, caproic acid and cuminaldehyde (each at 0.5% level)] was found to be most effective, reducing SH counts to 2.5–3.3 log CFU/egg from day 0 through day 14, and by the end of storage period (day 21), a 3.5 log CFU reduction/egg (p < 0.05) compared to untreated controls. Morphological studies of treated eggs using atomic force microscopy (AFM) have shown that the roughness of eggs can be influenced by a combination of various compounds. Results indicate the potential efficacy of the aforesaid phytochemicals in reducing SH on shell eggs; however, further studies investigating their industrial feasibility and effects on sensory attributes of eggs are warranted.

Anti-mosquito properties of Pelargonium roseum (Geraniaceae) and Juniperus virginiana (Cupressaceae) essential oils against dominant malaria vectors in Africa

BackgroundMore than 90% of malaria cases occur in Africa where the disease is transmitted by Anopheles gambiae and Anopheles arabiensis. This study evaluated the anti-mosquito properties of Juniperus virginiana (JVO) and Pelargonium roseum (PRO) essential oils (EOs) against larvae and adults of An. gambiae sensu lato (s.l.) from East Africa in laboratory and semi-field conditions.MethodsEOs was extracted from the aerial green parts of Asian herbs by hydrodistillation. Their constituents were characterized by gas chromatography-mass spectrometry (GC-MS). Larvicidal activities of JVO, PRO, and PRO components [citronellol (CO), linalool (LO), and geraniol (GO)] were investigated against An. gambiae sensu stricto (s.s.). The percentage of knockdown effects and mortality rates of all oils were also evaluated in the adults of susceptible An. gambiae s.s. and permethrin-resistant An. arabiensis.ResultsGC-MS analyses identified major constituents of JVO (sabinene, dl-limonene, β-myrcene, bornyl acetate, and terpinen-4-ol) and PRO (citronellol, citronellyl formate, L-menthone, linalool, and geraniol). Oils showed higher larvicidal activity in the laboratory than semi-field trials. The LC50 values for JVO/PRO were computed as 10.82–2.89/7.13–0.9 ppm and 10.75–9.06/13.63–8.98 ppm in laboratory and semi-field environments, respectively at exposure time of 24–72 h. The percentage of knockdown effects of the oils were also greater in An. gambiae s.s. than in An. arabiensis. Filter papers impregnated with JVO (100 ppm) and PRO (25 ppm) displayed 100% mortality rates for An. gambiae s.s. and 3.75% and 90% mortality rates, for An. arabiensis populations, respectively. Each component of CO, LO, and GO exhibited 98.13%, 97.81%, and 87.5%, respectively, and a mixture of the PRO components indicated 94.69% adult mortality to permethrin-resistant An. arabiensis.ConclusionsThe findings of this study show that PRO and its main constituents, compared to JVO, have higher anti-mosquito properties in terms of larvicidal, knockdown, and mortality when applied against susceptible laboratory and resistant wild populations of An. gambiae s.l. Consequently, these oils have the potential for the development of new, efficient, safe, and affordable agents for mosquito control.

Contrast Variation Small-Angle Neutron Scattering Study of Solubilization of Perfumes in Cationic Surfactant Micelles.

Perfume solubilization is an important process in the production of commercial products such as beverages, foods, and cosmetics. In the present study, small-angle neutron scattering (SANS) experiments were performed to investigate the solubilization behavior of perfumes in cetyltrimethylammonium bromide (CTAB) micelles. The solubilization of linalool (LL) and l-menthol (MT), which are relatively hydrophilic perfumes, did not change the size of the CTAB micelles although the perfumes were incorporated in the micelles, as indicated by a decrease in scattering length density. On the other hand, the solubilization of d-limonene (LN), a hydrophobic perfume, led to the swelling of CTAB micelles. An internal contrast variation SANS study was performed by the deuteration of CTAB molecules to directly observe the perfumes in the micelles. The radius of d-CTAB micelles solubilizing LL or MT corresponds to that of h-CTAB, which indicates that these perfumes are accommodated in the palisade layers of the micelles and are homogeneously distributed in the micelles. On the other hand, LN formed small droplets, as indicated by the SANS profile, which implies the solubilization of LN molecules in the core of the CTAB micelles. We found that the relatively hydrophilic perfumes (LL and MT) show less impact on the sizes of the cationic micelles in comparison to nonionic micelles. Thus, the internal contrast variation method of SANS allowed the direct observation of the solubilization sites of perfumes with different hydrophilicity-hydrophobicity balances. This method is a powerful tool to determine the solubilization states that affect the solubilization capacity, volatilization, or release speed of perfumes.

Morphological and metabolomics impact of sublethal doses of natural compounds and its nanoemulsions in Bacillus cereus

Microbiological safety in food industry are always a concern regarding sublethal tolerance in bacteria for common and natural sanitizers. Natural bacteriocins, such as nisin (NIS), may negatively interfere in the efficiency of major compounds of essential oils against foodborne pathogenic bacteria. However, nanoemulsioned forms increase the bactericidal potential of natural compounds acting synergistically. In this study, cinnamaldehyde (CIN), citral (CIT), and linalool (LIN) were evaluated independently, associated with NIS, and in nanoemulsions (NEs) against Bacillus cereus using untargeted-metabolomics. Results revealed morphological changes in the structure of B. cereus treated with NEs of CIN and CIT, both NIS-associated. In addition, sensibility tests and UHPLC-QTOF-MS analyses indicated that NIS might react together with CIT reducing the bactericidal efficiency, while the nanoemulsion of CIT effect was enhanced by NIS in nanoemulsioned forms. This study highlights the importance of prudent administration of natural compounds as antimicrobial agents to prevent sublethal tolerance in pathogenic bacteria.