Citronellal

Modulatory-antibiotic activity of the essential oil from Eucalyptus citriodora against MDR bacterial strains.[Pubmed:32583772]

Cell Mol Biol (Noisy-le-grand). 2020 Jun 25;66(4):60-64.

The growing number of bacterial strains resistant to therapeutic agents has been surpassing the various antibiotics developed by the chemical and pharmaceutical industries. This problem has driven the development of research using agents with antimicrobial potential, with an emphasis on plant-derived natural products. This study evaluated the chemical compounds present in Eucalyptus citriodora essential oil (EOEc) cultivated in northeastern Brazil and its properties as an antibacterial agent and resistance modifier against methicillin-resistant Staphylococcus aureus (MRSA) and beta-lactamase-producing strains. The EOEc was obtained using the hydrodistillation method, later analyzed by GC/MS, presenting a total of twelve compounds, with Citronellal (65.45%); citronellol (14.87%); isopulegol (11.80%) and citronellyl acetate (2.51%) as its main constituents. The microdilution test was used to determine the minimum inhibitory concentration (MIC) and the bacterial resistance modulation of the essential oil. The EOEc did not present significant activity against the tested strains (MIC > 1000 microg mL-1). However, when evaluating the capacity of the EOEc to modify the resistance of S. aureus and E. coli strains to different antimicrobials, synergistic effects were obtained with reduced MIC values for all tested antibiotics being obtained. The EOEc showed antimicrobial and beta-lactam optimizing potential against resistant strains, presenting itself as a possible alternative for the use of these drugs at concentrations lower than those indicated against resistant strains.

Antinociceptive Activity of Chemical Components of Essential Oils That Involves Docking Studies: A Review.[Pubmed:32547391]

Front Pharmacol. 2020 May 29;11:777.

Introduction: Pain is considered an unpleasant sensory and emotional experience, being considered as one of the most important causes of human suffering. Computational chemistry associated with bioinformatics has stood out in the process of developing new drugs, through natural products, to manage this condition. Objective: To analyze, through literature data, recent molecular coupling studies on the antinociceptive activity of essential oils and monoterpenes. Data source: Systematic search of the literature considering the years of publications between 2005 and December 2019, in the electronic databases PubMed and Science Direct. Eligibility Criteria: Were considered as criteria of 1) Biological activity: non-clinical effects of an OE and/or monoterpenes on antinociceptive activity based on animal models and in silico analysis, 2) studies with plant material: chemically characterized essential oils and/or their constituents isolated, 3) clinical and non-clinical studies with in silico analysis to assess antinociceptive activity, 4) articles published in English. Exclusion criteria were literature review, report or case series, meta-analysis, theses, dissertations, and book chapter. Results: Of 16,006 articles, 16 articles fulfilled all the criteria. All selected studies were non-clinical. The most prominent plant families used were Asteraceae, Euphorbiaceae, Verbenaceae, Lamiaceae, and Lauraceae. Among the phytochemicals studied were alpha-Terpineol, 3-(5-substituted-1,3,4-oxadiazol-2-yl)-N'-[2-oxo-1,2-dihydro-3H-indol-3-ylidene] propane hydrazide, beta-cyclodextrin complexed with Citronellal, (-)-alpha-bisabolol, beta-cyclodextrin complexed with farnesol, and p-Cymene. The softwares used for docking studies were Molegro Virtual Docker, Sybyl((R))X, Vlife MDS, AutoDock Vina, Hex Protein Docking, and AutoDock 4.2 in PyRx 0.9. The molecular targets/complexes used were Nitric Oxide Synthase, COX-2, GluR2-S1S2, TRPV1, beta-CD complex, CaV1, CaV2.1, CaV2.2, and CaV2.3, 5-HT receptor, delta receptor, kappa receptor, and MU (mu) receptor, alpha adrenergic, opioid, and serotonergic receptors, muscarinic receptors and GABAA opioid and serotonin receptors, 5-HT3 and M2 receptors. Many of the covered studies used molecular coupling to investigate the mechanism of action of various compounds, as well as molecular dynamics to investigate the stability of protein-ligand complexes. Conclusions: The studies revealed that through the advancement of more robust computational techniques that complement the experimental studies, they may allow some notes on the identification of a new candidate molecule for therapeutic use.

The Mosquito Repellent Activity of the Active Component of Air Freshener Gel from Java Citronella Oil (Cymbopogon winterianus).[Pubmed:32411423]

J Parasitol Res. 2020 Jan 29;2020:9053741.

This study examines the active component of Cymbopogon winterianus (Java citronella) oil, as a green mosquito repellent, obtained through a steam distillation method. Java citronella oil, which contains citronellol, Citronellal, and geraniol, was isolated by batch vacuum fractional distillation, and their effect was tested against the dengue fever (DF) vector, known as Aedes aegypti. Furthermore, air freshener gels were formulated with Java citronella oil, carrageenan, gum, sodium benzoate, ethylene glycol, polysorbate 20, sodium chloride, and distilled water, at varying concentrations. The results show that formula I has the best controlled release evaporation for Citronellal, citronellol, and geraniol, as well as the best storage time of 16.82 days and 12.77 days for geraniol and citronellol, respectively. The most significant specific gravity (0.0136) was recorded in formula V, while gel formula I exhibited the highest level of instability at 35 degrees C, with a syneresis value of 77.11% in t = 72 h and pH 5.33. In addition, formula IV at 5 degrees C demonstrated the highest syneresis (75.34%) in t = 72 h, with pH 7.04, while a peak viscosity of 100,958 cP was recorded in formula IV. The repellent activity of each active component was measured based on the period of protection conferred against the bites of Aedes aegypti within one hour, and the results showed geraniol and citronellol, with respective activity of 78.00% +/- 4.83 and 77.34% +/- 3.57, as the most effective.

Chemical composition, antioxidant, anti-inflammatory and antiproliferative activities of the essential oil of Cymbopogon nardus, a plant used in traditional medicine.[Pubmed:32304294]

Biomol Concepts. 2020 Apr 15;11(1):86-96.

Objectives Natural products commonly used in traditional medicine, such as essential oils (EOs), are attractive sources for the development of molecules with anti-proliferative activities for future treatment of human cancers, e.g., prostate and cervical cancer. In this study, the chemical composition of the EO from Cymbopogon nardus was characterized, as well as its antioxidativeproperties and anti-inflammatory and antiproliferative activities on LNCaP cells derived from prostate cancer. Methods The chemical composition of the EO was determined by GC/FID and GC/MS analyses. The antioxidative properties were assessed using DPPH radical scavenging assay and ABTS+* radical cation decolorization assay, and the anti-inflammatory capacity was determined by the inhibition of the lipoxygenase activity. Antiproliferative activity was evaluated by MTT assay. Results Collectively, our data show that the major constituents of C. nardus EO are Citronellal (33.06 %), geraniol (28.40 %), nerol (10.94 %), elemol (5.25 %) and delta-elemene (4.09 %). C. nardus EO shows modest antioxidant and anti-inflammatory activity compared to the standard galic acid. C. nardus EO exhibits the best antiproliferative activity on the prostate cancer cell line LNCaP with an IC50 of 58.0 +/- 7.9 mug/mL, acting through the induction of the cell cycle arrest. Conclusions This study has determined that C. nardus EO efficiently triggers cytotoxicity and pens a new field of investigation regarding the putative use of this EO in vivo.

Quantitative Structure-Activity Relationship Modeling and Docking of Monoterpenes with Insecticidal Activity Against Reticulitermes chinensis Snyder and Drosophila melanogaster.[Pubmed:32251592]

J Agric Food Chem. 2020 Apr 22;68(16):4687-4698.

The goal of this study was to perform in silico identification of bioinsecticidal potential of 42 monoterpenes against Drosophila melanogaster and Reticulitermes chinensis Snyder. Quantitative structure-activity relationship (QSAR) modeling was performed for both organisms, while docking and molecular dynamics were used only for Drosophila melanogaster. Neryl acetate has the lowest interaction energy (-87 kcal/mol) against active site of acetylcholinesterase, which is comparable to the ones of methiocarb and pirimicarb (-90 kcal/mol) and reported PDB binder 9-(3-iodobenzylamino)-1,2,3,4-tetrahydroacridine (-112.67 kcal/mol). Interaction stability was verified by molecular dynamics simulations and showed that the stability of ACHE active site complexes with three selected terpenes is comparable to the one of the pirimicarb and methiocarb. Overall, our results suggest that pulegone, Citronellal, carvacrol, linalyl acetate, neryl acetate, citronellyl acetate, and geranyl acetate may be considered as a potential pesticide candidates.

[Deodorants and antiperspirants].[Pubmed:32248967]

Ann Dermatol Venereol. 2020 May;147(5):387-395.

The terms deodorants and antiperspirants very frequently used interchangeably despite the fact that they employ completely different active substances and mechanisms of action. Antiperspirants are necessarily deodorants due to the lack of substrate to decompose. They nevertheless represent a group of very specific substances that create particular problems due to the presence of aluminium chlorohydrate, or ACH, (Al2(OH)5Cl, 2H2O), aluminium sesquichlorohydrate and aluminium-zirconium complex, which, after hydrolysis, causes intense acidification of the skin, hence the importance of inclusion of emollients and pH regulators in formulations. Moreover, systemic aluminium is thought to be genotoxic and to promote breast cancer, and it is thus at the centre of numerous scientific controversies. Nevertheless, its potential toxicity following topical application is related to its ability to penetrate skin, which is as yet poorly understood but considered very low, a fact that may provide some degree of reassurance regarding its use in cosmetic products. Its role in Alzheimer's disease has not been proven. On the other hand, zirconium salts are considered toxic and are partly regulated in Europe. The problems associated with deodorants are those arising from the presence of antiseptics (triclosan, usnic acid) capable of inducing bacterial resistance, but more particularly, the presence of axillary dermatitis due to the allergenic potential of the fragrances and essential oils used (e.g. isoeugenol, Citronellal, lyral, cinnamic aldehyde, etc.).

Do rainfall and tick burden affect the efficacy of pour-on formulations against Rhipicephalus (Boophilus) microplus?[Pubmed:32203813]

Prev Vet Med. 2020 Apr;177:104950.

Rhipicephalus (Boophilus) microplus is the most important livestock tick, causing economical losses especially in tropical and subtropical regions. Pour-on formulations using synthetic chemicals, remain the most farmer friendly conventional form of tick control method. Misuse of acaricides can lead to the emergence of resistance, residual chemicals in animal products, the poisoning of vertebrates and environment contamination. Despite the increase in the use of pour-on formulations, little is known regarding the therapeutic and residual efficacy of these products after the treated animals are exposed to rainfall. Moreover, information is scanty on whether efficacy is modulated by different levels of tick burden. Three studies were conducted. In the two first experiments, we evaluated the therapeutic and residual efficacies of commercial pour-on products (fluazuron 2.5 mg/kg and fipronil 1.0 mg/kg, respectively) on cattle naturally infested with R. (B.) microplus under the condition of simulated rainfall. In the third study, we investigated whether tick burden affects the efficacy of the drugs used a chemical control method involving three different formulations (Day 0: cypermethrin 5.0 mg/kg + chlorpyrifos 7.0 mg/kg + Citronellal 0.5 mg/kg; Day 7: fluazuron 3.0 mg/kg + abamectin 0.5 mg/kg and Day 56: fipronil 1.0 mg/kg + fluazuron 3.0 mg/kg). Tick counts were performed on different days to assess efficacy. It was observed that the residual efficacy of the commercial formulations was lower on animals that received simulated rain. In addition, therapeutic and residual efficacies of the products were reduced in the group of animals with a high tick burden of R. (B.) microplus. In conclusion, rainfall decreases the efficacy of acaricides. Also, the tick burden must be considered when selecting a pour-on formulation.

An approach to natural insect repellent formulations: from basic research to technological development.[Pubmed:32119826]

Acta Trop. 2020 Feb 28:105419.

The incidence of dengue, Zika, chikungunya, yellow fever and malaria cases has increased significantly in the world. To avoid mosquito bites, one of the best strategies is the use of repellents. The interest in using plants as mosquito repellents has increased significantly. In this review, has been performed a bibliographic survey of the plants with repellent activity, evaluate the trends of natural repellent formulations in the scientific literature, those described in patents and commercially available products. Limonene, 1,8-cineole, geraniol, eugenol and Citronellal are the active compounds that mostly appear in the essential oils of plants with repellent activity. The type of natural repellent formulation mostly widely marketed is the spray and lotion, respectively. In patents, classic formulation as emulsion was most frequently used, followed by lotions and sprays. Data collected from scientific articles and patents show that microparticles are the most widely used extended release systems nowadays for natural repellents. The citronella essential oil was the one mostly used among the classic commercially available formulations, as well as in the extended release systems described in the literature and patents. Future research must be conducted to the use of nanotechnology in the development of extended release systems containing essential oils with repellent activity produced from natural and biodegradable materials.

TRPA1 modulates noxious odor responses in Lygus hesperus.[Pubmed:32113955]

J Insect Physiol. 2020 Apr;122:104038.

Lygus hesperus isa key pest of many economically important crops across western North America. Central to many aspects of the lives of these insects is chemical signalling, with identified roles in host plant selection, aggregation and passive mate guarding. The development of novel monitoring and control approaches for this insect will rely on a sound understanding of how these cues are perceived and processed, and their impact on behavior. Towards this end, we investigated allyl isothiocyanate, cinnamaldehyde and Citronellal, compounds that are noxious repellents to other insects. We found that L. hesperus avoided areas containing the three compounds and that exposure induced increases in movement velocity and duration in both nymphs and adults. This suggests these compounds may work as repellents. To better understand the underlying physiology of this response, RNA interference by dsRNA injection was used to inhibit the expression of two chemosensory-associated proteins, the odorant receptor co-receptor (Orco) and the transient receptor potential A (TRPA1) channel. While knockdown of Orco did not change the reaction of adult females to Citronellal, TRPA1 silencing effectively eliminated the induced increase to movement, suggesting a chemoperceptory role in Citronellal detection.

Age-dependent release of and response to alarm pheromone in a ponerine ant.[Pubmed:32098887]

J Exp Biol. 2020 Mar 16;223(Pt 6). pii: jeb.218040.

Social insect societies are characterized by division of labour and communication within the colony. The most frequent mode of communication is by chemical signals. In general, pheromones elicit specific responses in the receiver, although reactions may vary depending on the receiving individual's physiological or motivational state. For example, it has been shown that pheromones can elicit different responses in morphological worker castes. However, comparably little is known about such effects in worker castes of monomorphic species. Here, we comprehensively studied a monomorphic species showing age polyethism, the thelytokous ant Platythyrea punctata Our analyses revealed that the species' alarm pheromone consists of (S)-(-)-Citronellal and (S)-(-)-actinidine, and is produced in the mandibular glands. Ants responded with increased movement activity and increasing ant density towards the pheromone source in whole-colony bioassays, confirming the alarming effect of these compounds. We found age classes to differ in their absolute pheromone content, in the propensity to release alarm pheromone upon disturbance and in their reaction towards the pheromone. Absolute amounts of pheromone content may differ simply because the biosynthesis of the pheromone begins only after adult eclosion. Nonetheless, our results indicate that this clonal species exhibits age-related polyethism in the emission of as well as in the response to its alarm pheromone.

A combination extract of kaffir lime, galangal, and lemongrass maintains blood lipid profiles, hepatocytes, and liver mitochondria in rats with nonalcoholic steatohepatitis.[Pubmed:31978768]

Biomed Pharmacother. 2020 Apr;124:109843.

Kaffir lime leaves and the rhizomes of galangal and lemongrass are the main ingredients in several Thai foods with desirable medicinal effects. Based on their beneficial activities, this study aimed to indicate the chemical properties and in vivo efficacy of a combination of the herbs at a 1:2:1 ratio in a water extract form. Its volatile constituents were analyzed by gas chromatography coupled with mass spectrometer, which mainly consists of eucalyptol, Citronellal, and citral. Clinicohistopathological and electron microscopic studies demonstrated that the extract corrected blood cholesterol, LDL, HDL, and triglyceride levels similarly as simvastatin treatment in association with its antioxidative properties, as indicated by the levels of superoxide dismutase and malondialdehyde in serum and the increment of nuclear factor erythroid 2-related factor 2 levels in hepatocytes. Hepatitis was significantly less severe in rats fed the extract for 14 days than in simvastatin-treated rats. Regarding its immunomodulatory properties, the extract also accelerated hepatic resolution from steatohepatitis during hypercholesterolemia as indicated by the upregulation of vimentin, cytokeratin, and CD206(+). Interestingly, liver mitochondria were also preserved in hypercholesterolemic rats treated with the extract in relation to their architecture and the expression of haloacid dehalogenase-like hydrolase domain-containing protein 3 as well as metabolic and energy regulators. Therefore, the study concluded that the water extract of kaffir lime leaves and the rhizomes of galangal and lemongrass has beneficial effects on blood cholesterol, the severity of steatohepatitis, and the maintenance of mitochondrial architecture via its antioxidative and immunomodulatory activities.

Gamma rays induced acquisition of structural modification in chitosan boosts photosynthetic machinery, enzymatic activities and essential oil production in citronella grass (Cymbopogon winterianus Jowitt).[Pubmed:31862372]

Int J Biol Macromol. 2020 Feb 15;145:372-389.

Oligomers derived through irradiation of marine polysaccharides have generated a lot of interest of plant biologists as the application of these molecules has yielded positive results regarding various plant processes. To comprehend the previously established growth-promoting activity of irradiated chitosan (ICH) and to gain insight of the structure-property relationship, gamma rays induced structural changes were analyzed using techniques such as Fourier Transform Infrared (FT-IR) spectroscopy, Ultraviolet-visible (UV-Vis) spectroscopy, (13)C-Nuclear Magnetic Resonance (NMR) spectroscopy and Scanning Electron Microscopy (SEM). Moreover, to study the bioactivity of ICH samples a pot experiment was conducted on citronella grass (Cymbopogon winterianus) to access its response to foliar application of various levels (40, 60, 80 and 100 mg L(-1)) of ICH in terms of growth, physiological attributes and essential oil (EO) production. The application of ICH at 80 mg L(-1)(ICH-80) resulted in the maximum values of most of the attributes studied. Due to this treatment, the maximum improvement in the content (29.58%) and yield (90.81%) of EO in Cymbopogon winterianus were achieved. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that ICH-80 also increased the content of Citronellal (14.81%) and geraniol (18.15%) of the EO as compared to the control.

Prediction of Terpenoid Toxicity Based on a Quantitative Structure-Activity Relationship Model.[Pubmed:31805724]

Foods. 2019 Dec 1;8(12). pii: foods8120628.

Terpenoids, including monoterpenoids (C10), norisoprenoids (C13), and sesquiterpenoids (C15), constitute a large group of plant-derived naturally occurring secondary metabolites with highly diverse chemical structures. A quantitative structure-activity relationship (QSAR) model to predict terpenoid toxicity and to evaluate the influence of their chemical structures was developed in this study by assessing in real time the toxicity of 27 terpenoid standards using the Gram-negative bioluminescent Vibrio fischeri. Under the test conditions, at a concentration of 1 microM, the terpenoids showed a toxicity level lower than 5%, with the exception of geraniol, citral, (S)-Citronellal, geranic acid, (+/-)-alpha-terpinyl acetate, and geranyl acetone. Moreover, the standards tested displayed a toxicity level higher than 30% at concentrations of 50-100 microM, with the exception of (+)-valencene, eucalyptol, (+)-borneol, guaiazulene, beta-caryophellene, and linalool oxide. Regarding the functional group, terpenoid toxicity was observed in the following order: alcohol > aldehyde ~ ketone > ester > hydrocarbons. The CODESSA software was employed to develop QSAR models based on the correlation of terpenoid toxicity and a pool of descriptors related to each chemical structure. The QSAR models, based on t-test values, showed that terpenoid toxicity was mainly attributed to geometric (e.g., asphericity) and electronic (e.g., maximum partial charge for a carbon (C) atom (Zefirov's partial charge (PC)) descriptors. Statistically, the most significant overall correlation was the four-parameter equation with a training coefficient and test coefficient correlation higher than 0.810 and 0.535, respectively, and a square coefficient of cross-validation (Q(2)) higher than 0.689. According to the obtained data, the QSAR models are suitable and rapid tools to predict terpenoid toxicity in a diversity of food products.

Anthelmintic activity of Eucalyptus citriodora essential oil and its major component, citronellal, on sheep gastrointestinal nematodes.[Pubmed:31800886]

Rev Bras Parasitol Vet. 2019 Oct-Dec;28(4):644-651.

This study aimed to evaluate the anthelmintic activity of Eucalyptus citriodora essential oil and Citronellal on sheep gastrointestinal nematodes. Essential oil composition was determined by gas chromatography mass spectrometry. The substances were evaluated in vitro using adult worm motility test (AWMT) and transmission electron microscopy (TEM). The acute toxicity test in mice and the fecal egg count reduction test (FECRT) in sheep were performed. Citronellal was confirmed as the essential oil major constituent (63.9%). According to the AWMT, 2 mg/mL of essential oil and Citronellal completely inhibited Haemonchus contortus motility at 6 h post exposure. H. contortus exposed to essential oil and Citronellal exhibited internal ultrastructural modifications. The lethal dose 50 values in mice were 5,000 and 2,609 mg/kg for essential oil and Citronellal, respectively. E. citriodora essential oil reduced sheep epg at 14 days post treatment by 69.5% (P<0.05). No significant differences were observed in epg between the Citronellal and negative control groups (P>0.05). The interaction between Citronellal and other constituents in the essential oil may be relevant for its in vivo anthelmintic activity. Thus, E. citriodora essential oil and Citronellal pharmacokinetic studies may help elucidate the anthelmintic activity of these compounds.

Characterization of Volatile Compounds in Four Different Rhododendron Flowers by GCxGC-QTOFMS.[Pubmed:31547401]

Molecules. 2019 Sep 12;24(18). pii: molecules24183327.

Volatile compounds in flowers of Rhododendron delavayi, R. agastum, R. annae, and R. irroratum were analyzed using comprehensive two-dimensional gas chromatography-mass spectrometry (GCxGC) coupled with high-resolution quadrupole time-of-flight mass spectrometry (QTOFMS). A significantly increased number of compounds was separated by GCxGC compared to conventional one-dimensional GC (1DGC), allowing more comprehensive understanding of the volatile composition of Rhododendron flowers. In total, 129 volatile compounds were detected and quantified. Among them, hexanal, limonene, benzeneacetaldehyde, 2-nonen-1-ol, phenylethyl alcohol, Citronellal, isopulegol, 3,5-dimethoxytoluene, and pyridine are the main compounds with different content levels in all flower samples. 1,2,3-trimethoxy-5-methyl-benzene exhibits significantly higher content in R. irroratum compared to in the other three species, while isopulegol is only found in R. irroratum and R. agastum.