Monoterpenes In Essential Oils Research Articles

Study of essential oil extraction from Moroccan Rosmarinus officinalis L. by distillation based on quantum chemical calculation and molecular dynamics simulation

In this work, essential oils were extracted from rosemary leaves (Rosmarinus officinalis L.) from the eastern region of Morocco using hydrodistillation (Hd) and steam distillation (Sd). The yield, chemical composition, thermal stability, and antioxidant activity of the essential oils obtained by the two methods were compared. Determining the chemical composition of rosemary essential oil, with GC-MS, showed a significant qualitative and quantitative difference in certain components. The Sd method improved the extraction of sesquiterpene compounds with high molecular weight and low vapour pressure. The findings reveal that sesquiterpene and oxygenated monoterpenes in essential oils improved the antioxidant activity and thermal stability. Determining antioxidant activity using DPPH and the β-carotene bleaching assay showed that the Sd and Hd oils presented good radical scavenging activity (IC50 = 4960 μg/mL for Hd oil and 4570 μg/mL for Sd oil), capable of delaying β-carotene discolouration with 16.3 and 9.71% inhibition for Sd and Hd respectively. Thermal stability analysis of the oil products was performed using TGA/DTG analysis, and the results showed that the decomposition points of Hd oil and Sd oil were 362 and 368 K respectively. Furthermore, to identify intermolecular interactions and develop better knowledge of phenomena occurring during the extraction of the family of sesquiterpene compounds by water, quantum chemical calculation and molecular simulation by molecular dynamics (MD) were performed. The results suggested the relative stability of caryophyllene-water and the development of intermolecular bonding interactions of van der Walls and steric effect, improving extraction of the substance studied under steam distillation conditions.

Exploring the Anticancer Potential of Origanum majorana Essential Oil Monoterpenes Alone and in Combination against Non-Small Cell Lung Cancer

Lung cancer is the second most commonly diagnosed cancer and has the highest mortality rate worldwide despite the remarkable advances in its treatment. Origanum majorana Essential Oil (OMEO) has been shown to be effective against non-small cell lung cancer (NSCLC) cells, decreasing their viability and colony growth in vitro, as well as inhibiting tumor growth in chick embryo chorioallantoic membranes (CAM) and nude mice in vivo. OMEO is mainly composed of four monoterpenes, namely terpinen-4-ol, sabinene hydrate, α-terpinene, and γ-terpinene. In this study, we aimed to investigate the potential anticancer effects of these monoterpenes, either alone or in combination, on NSCLC. Our findings indicate that these four monoterpenes significantly decreased NSCLC cell viability in a concentration-dependent manner, reduced their colony growth in vitro, and also downregulated survivin expression in these cells. Moreover, different combined mixtures of these monoterpenes further enhanced their anticancer effects on cellular viability, with a terpinen-4-ol and sabinene hydrate combination being the most potent. We also found that terpinen-4-ol, in combination with sabinene hydrate, markedly enhanced the anticancer effect of the individual monoterpenes on NSCLC viability within a shorter treatment duration through, at least in part, survivin downregulation. Furthermore, this combination enhanced the inhibition of colony growth in vitro and the tumor growth of NSCLC cells xenografted onto chick embryo CAM in vivo. Altogether, our study highlights the potential of these monoterpenes for use in further pre-clinical investigations against various cancer hallmarks.

Protective effect of citronellol in rhabdomyolysis-induced acute kidney injury in mice.

Acute kidney injury (AKI) is a serious pathophysiological event consequent to rhabdomyolysis. Inflammatory mechanisms play a role in the development of rhabdomyolysis-induced AKI. Citronellol (CT) is a naturally occurring monoterpene in essential oils of aromatic plant species. In this study, we explored the protective effects of citronellol on AKI resulting from glycerol-induced rhabdomyolysis. Rhabdomyolysis was induced by a single intramuscular injection of glycerol 50% (10mg/kg) in the thigh caudal muscle. Four groups of mice were assigned, including a control group, a group administered with glycerol to induce AKI as a model, a group treated with glycerol plus 50mg/kg CT, and a group treated with glycerol plus 100mg/kg CT. The renal function of mice from all groups was evaluated using kidney histopathological changes and kidney injury molecule-1 (KIM-1). Myoglobin levels were measured to detect rhabdomyolysis. Apoptosis was evaluated by renal cleaved caspase-3 and BAX levels. Both doses of citronellol (50mg/kg and 100mg/kg) significantly reduced KIM-1 mRNA expression and myoglobin levels compared to the glycerol group. In addition, citronellol resulted in lower cleaved caspase-3 and BAX in the renal tissue, indicating that citronellol exerted an anti-apoptotic effect in AKI. Citronellol showed a reno-protective effect against rhabdomyolysis-induced AKI, which may be attributed to its anti-apoptotic effects.

Phytochemical and physiological reactions of feverfew (Tanacetum parthenium (L.) Schultz Bip) to TiO2 nanoparticles

Nanomaterials can be used as elicitors for improving the biosynthesis of secondary metabolites in medicinal plants. The present study was conducted to assay the titanium dioxide-nanoparticles (TiO2-NPs) effects on feverfew (Tanacetum parthenium) as an anti-cancer plant. The study showed that TiO2-NPs application increased the amounts of the main compounds and oxygenated monoterpene in essential oils, thereby causing an improvement in the quantity and quality of the essential oils compared to control. The highest effect was related to 1500 ppm TiO2-NPs concentration. Regarding parthenolide, TiO2-NPs had no positive effect on parthenolide content and the highest content was observed in control. Increasing the concentrations over 1500 ppm resulted in a decrease in chlorophyll content, capitule diameter, flower yield, and harvest index compared to other concentrations and control. Additionally, the results indicated that TiO2-NPs foliar spray reduced flower number, biological yield, fresh weight, and dry weights compared with untreated plants. The increase in quality and content of essential oil and lack of increase in parthenolide content, and reproductive and vegetative characteristics showed that TiO2-NPs mainly affected the content and composition of essential oil. Totally, the application of TiO2-NPs in terms of positive effect on the yield and metabolites (without damaging biological effects) can be recommended and followed up to the concentration of 1000 ppm. Overall, the results indicated that improving the synthesis of valuable medicinal metabolites using TiO2-NPs has promising results depending on the type of species, concentration used and target metabolites.

The toxicity of the monoterpenes from lemongrass is mitigated by the detoxifying symbiosis of bacteria and fungi in the tick Haemaphysalis longicornis

The entry mode of terpenes into the atmosphere is via volatilization of hydrocarbons from foliage over heavily forested areas besides entering the environment through surface water runoff. Some monoterpenes in essential oils are phytotoxins, acting as plant chemical defenses against bacteria or fungi infections and plant-eating insects. For organisms to survive, their enzymatic systems are activated in response to an assault by potentially harmful compounds. Certain bacterial and fungal genera have developed special abilities to transform toxic terpenes into less toxic derivatives. Here, we investigated the response of the bacterial and fungal community in Haemaphysalis longicornis exposed to Cymbopogon citratus (lemongrass) essential oil (EO) and citronellal. Sequencing of bacterial 16S rRNA and fungal ITS1 regions on an Illumina NovaSeq PE250 sequencing platform was performed for H. longicornis tick samples treated with 15 and 20 mg/mL of lemongrass essential oil and citronellal. The diversity recorded in samples treated with C. citratus EO was higher in comparison to those treated with citronellal but significantly lower in the control samples as reflected by the Shannon diversity index. All major H. longicornis bacterial phyla, including Proteobacteria (93.81 %), Firmicutes (2.58 %), and Bacteroidota (0.99 %) were detected. A switch of dominance from Coxiella to Pseudomonas, which has high biotransformation capacity, was observed in the bacterial community, whereas the phylum Ascomycota (Genera: Aspergillus, Archaeorhizomyces, Alternaria, and Candida) dominated in the fungal community indicating detoxifying symbiosis. Other significantly abundant bacterial genera include Ralstonia, Acinetobacter, Vibrio, and Pseudoalteromonas, while Ganoderma and Trichosporon (yeasts) spp. represented the fungi Basidiomycota. This study expanded the understanding of enzymatic modification of phytotoxic substances by microorganisms, which could provide deeper insights into the mitigation of harmful phytotoxins and the synthesis of eco-friendly derivatives for the control of ticks.

Chromosome-level genome assembly of Mentha longifolia L. reveals gene organization underlying disease resistance and essential oil traits

Mentha longifolia (L.) Huds., a wild, diploid mint species, has been developed as a model for mint genetic and genomic research to aid breeding efforts that target Verticillium wilt disease resistance and essential oil monoterpene composition. Here, we present a near-complete, chromosome-scale mint genome assembly for M. longifolia USDA accession CMEN 585. This new assembly is an update of a previously published genome draft, with dramatic improvements. A total of 42,107 protein-coding genes were annotated and placed on 12 chromosomal scaffolds. One hundred fifty-three genes contained conserved sequence domains consistent with nucleotide binding site-leucine-rich-repeat plant disease resistance genes. Homologs of genes implicated in Verticillium wilt resistance in other plant species were also identified. Multiple paralogs of genes putatively involved in p-menthane monoterpenoid biosynthesis were identified and several cases of gene clustering documented. Heterologous expression of candidate genes, purification of recombinant target proteins, and subsequent enzyme assays allowed us to identify the genes underlying the pathway that leads to the most abundant monoterpenoid volatiles. The bioinformatic and functional analyses presented here are laying the groundwork for using marker-assisted selection in improving disease resistance and essential oil traits in mints.

PRISMA Based Systematic Review: Pharmacognostic Study of Zanthoxylum armatum DC.

Herb, Zanthoxylum armatum DC., commonly called Indian prickly ash, and Nepal pepper (family Rutaceae), is widely utilized in the traditional medicinal system. The current review provides requisite data for collecting descriptive information on the organoleptic, microscopical, ethnobotanical use, and phytochemicals and pharmacological properties of Z. armatum; therefore, it may help in forming a bridge between research gaps and the upcoming future findings for most of the researches. The systematic literature survey was conducted using the PRISMA methodology. The collective information was gathered from books, renowned journals, and electronic databases including Science Direct, Web of Science, Scopus and PubMed from 1966 to 2020. Most of the bioactive metabolites are isolated and characterized till date, such as monoterpenes in essential oil and lignan components are reported to be present in the herbs. Several in vitro and in vivo pharmacological bioassays revealed the potential of Z. armatum having as possessing antimicrobial, antifungal, antibacterial, and hepatoprotective effects and so on. Therefore, the current review summarizes the organoleptic, microscopy, phytochemistry and biological activities of Z. armatum, providing more emphasis on in vitro as well as in-vivo studies along with clinical research, helpful in exploring the potential efficacy of the plant.

Carvacrol inhibits the neuronal voltage-gated sodium channels Nav1.2, Nav1.6, Nav1.3, Nav1.7, and Nav1.8 expressed in Xenopus oocytes with different potencies

Carvacrol is the predominant monoterpene in essential oils from many aromatic plants. Several animal studies showing analgesic effects of carvacrol indicate potential of carvacrol as a new medication for patients with refractory pain. Voltage-gated sodium channels (Nav) are thought to have crucial roles in the development of inflammatory and neuropathic pain, but there is limited information about whether the analgesic mechanism of carvacrol involves Nav. We used whole-cell, two-electrode, voltage-clamp techniques to examine the effects of carvacrol on sodium currents in Xenopus oocytes expressing α subunits of Nav1.2, Nav1.3, Nav1.6, Nav1.7, and Nav1.8. Carvacrol dose-dependently suppressed sodium currents at a holding potential that induced half-maximal current. The half-maximal inhibitory concentration values for Nav1.2, Nav1.3, Nav1.6, Nav1.7, and Nav1.8 were 233, 526, 215, 367, and 824 μmol/L, respectively, indicating that carvacrol had more potent inhibitory effects towards Nav1.2 and Nav1.6 than Nav1.3, Nav1.7, and Nav1.8. Gating analysis showed a depolarizing shift of the activation curve and a hyperpolarizing shift of the inactivation curve in all five α subunits following carvacrol treatment. Furthermore, carvacrol exhibits a use-dependent block for all five α Nav subunits. These findings provide a better understanding of the mechanisms associated with the analgesic effect of carvacrol.

Зміни вмісту монотерпенів живиці сосни у звʼязку з ураженням кореневою губкою (Heterobasidion annosum (Fr.) Bref.)

За допомогою газорідинної хроматографії виявлено тенденції змін вмісту монотерпенів у складі живиці дерев сосни IV класу віку, уражених кореневою губкою у різному ступені. Виявлено, що з розвитком хвороби вміст α-пінену і камфену знижується. Найменший їхній уміст, якщо порівняти зі здоровими деревами, виявлено у дерев, що знаходяться в активній зоні осередку всихання, ступінь ураження коріння яких становить 11–30 %. Уміст ∆3-карену в складі живиці цих дерев проти неуражених є, навпаки, вищим на 15–16 %. Уміст β-пінену в уражених кореневою губкою дерев був в 1,8–2,0 разу вищим, ніж у неуражених. Відзначено, що зміни в складі ефірних олій дерев в активній зоні осередку хвороби є сигналом щодо ослаблення дерева та можливості його заселення лубоїдами. Зміни в складі ефірних олій живиці в осередках кореневої губки провокують як патологічні процеси, так і зміни екології дерев унаслідок розвитку хвороби.

RNAi targeting the gene for 1,8-cineole synthase induces recomposition of leaf essential oil in lavandin (Lavandula × intermedia Emeric)

Recomposition of volatile compounds is an effective way to alter the fragrance of an essential oil. Using RNA interference (RNAi), we attempted to reduce the production of 1,8-cineole, a major monoterpene in essential oils, to alter the composition of the essential oil in lavandin. We obtained 12 transgenic regenerants via inoculation with Agrobacterium tumefaciens, including an RNAi inducing vector targeting five regions of the gene for 1,8-cineole synthase (CINS). Of these, two regenerants, targeting a coding region about 250 nt upstream with 5′-UTR and a coding region about 300 nt downstream of CINS mRNA (CINS I and V), respectively, showed a significant decrease of 1,8-cineole production in leaf essential oil, although the overall composition was barely altered because the production of other compounds decreased concurrently. By contrast, in two other regenerants, targeting a coding region about 1000 nt in the middle and a coding region about 300 nt downstream of CINS mRNA (CINS IV and V), respectively, 1,8-cineole production could be barely observed, without any decrease in production of other compounds. Expression of CINS in these transgenic regenerants was extremely suppressed to 0.02 and 0.08 of that of a nontransgenic regenerant control. The composition of leaf essential oil in the transgenic regenerants was changed by the RNAi. Specifically, the major compounds changed from 1,8-cineole, camphor, and borneol, to linalool, camphor, and borneol. Consequently, the fragrance of essential oils of these plants was perceived as more citrusy than the fragrance of the nontransgenic regenerant. These results suggest that the knockdown strategy was a useful tool for altering the fragrance in lavandin.

Development of an electrochemical method to determine phenolic monoterpenes in essential oils

A simple, rapid and non-expensive method is proposed to determine phenolic monoterpenes such as thymol and carvacrol in essential oils of thyme and oregano. The linear sweep voltammetry based on glassy carbon electrodes was the electrochemical technique used. Thymol and carvacrol have one main oxidation peak in non-aqueous media centered at about 1.3 V vs. Ag/AgCl. The electron transfer process is mainly diffusion controlled.The calibration plots generated using the commercial standards of thymol and carvacrol were used to estimate the total content in real samples. The calibration plots were linear in the concentration range from 8.5 × 10−5 to 1.3 × 10−3 mol L−1 and 7.9 × 10−5 to 1.2 × 10−3 mol L−1 for thymol and carvacrol, respectively.Results obtained with the electrochemical method are in good agreement with those of the official method (gas chromatography). In addition, the analytical procedure does not require previous preparation of the sample or modification of the electrode surface. The electrochemical technique used is very simple to apply. Under these conditions, the methodology proposed is a good, simple and fast option to perform a quality control of essential oils.

Alpha pinene modulates UVA-induced oxidative stress, DNA damage and apoptosis in human skin epidermal keratinocytes

AimsThis study aims to evaluate the protective effect of alpha pinene (AP), an essential oil monoterpene, against ultraviolet-A (UVA; 320–400 nm) induced cellular damages in human skin epidermal keratinocytes (HaCaT cells). Materials and methodsIn this study, HaCaT cells were subjected to single UVA-irradiation (10 J/cm2) in the presence and absence of AP (30 μM) then different cellular end points were analyzed. The protective effect of AP against UVA-induced cytotoxicity was evaluated by MTT-based metabolic assay. Generation of reactive oxygen species (ROS), alteration of mitochondrial membrane potential (MMP), DNA single- and double strand breaks (SSBs and DSBs) and apoptotic morphological changes during different treatment conditions were measured by fluorescence microscopy and spectrofluorometry. Modulatory role of AP against UVA-mediated inflammatory markers expression, nucleotide excision repair (NER) proteins and apoptotic markers expression during AP and/or UVA treatment were studied by western blot. Key findingsPretreatment with AP prevented UVA-induced cytotoxicity, generation of ROS, lipid peroxidation and DNA stand breaks probably through its antioxidant property. AP also inhibited UVA-induced inflammatory mediators such as NF-κB, TNF-α and IL-6 expression in HaCaT cells. Further, AP modulates NER proteins via activation of p53 and p21 thereby subsequently prevent the formation of UVA-induced cyclobutane pyrimidine dimers (CPDs). We also noticed that AP inhibits apoptotic cell death by preventing UVA-induced loss of mitochondrial membrane potential through modulating Bax/Bcl-2 expression in HaCaT cells. SignificanceThe present findings suggest that AP prevent UVA-induced oxidative stress, inflammation, DNA damages and apoptosis in human skin cells.

Novel polymeric micelles for insect pest control: encapsulation of essential oil monoterpenes inside a triblock copolymer shell for head lice control.

BackgroundEssential oil components (EOCs) are molecules with interesting application in pest control, these have been evaluated against different insect pest from more than 100 years, but their practical use is rather limited. Thus, the enhancement of their bioavailability and manageability due to their dispersion in water can open new perspective for the preparation of formulations for the control of insect pest. In this work, we studied the encapsulation of different monoterpenes in a poloxamer shell in order to prepare aqueous formulations that can be used for the development of platforms used in pest control.MethodsMicellar systems containing a 5 wt% of poloxamer 407 and 1.25 wt% of the different monoterpenes were prepared. Dynamic Light Scattering (DLS) experiments were carried out to characterize the dispersion of the EOCs in water. The pediculicidal activity of these micellar systems was tested on head lice using an ex vivo immersion test.ResultsThe poloxamers allowed the dispersion of EOCs in water due to their encapsulation inside the hydrophobic core of the copolymer micelles. From this study, we concluded that it is possible to make stable micellar systems containing water (>90 wt%), 1.25 wt% of different monoterpenes and a highly safe polymer (5wt% Poloxamer 407). These formulations were effective against head lice with mortality ranging from 30 to 60%, being the most effective emulsions those containing linalool, 1,8-cineole, α-terpineol, thymol, eugenol, geraniol and nonyl alcohol which lead to mortalities above 50%.DiscussionSince these systems showed good pediculicidal activity and high physicochemical stability, they could be a new route for the green fabrication of biocompatible and biosustainable insecticide formulations.

Involvement of transient receptor potential A1 channel in algesic and analgesic actions of the organic compound limonene.

TRPA1 is a Ca-permeable nonselective cation channel expressed in sensory neurons and acts as a nocisensor. Recent reports show that some monoterpenes, a group of naturally occurring organic compounds, modulate TRP channel activity. Here, we report that limonene, being contained in citrus fruits and mushrooms, shows a unique bimodal action on TRPA1 channel. We examine the effects of limonene on sensory neurons from wild-type, TRPV1- and TRPA1-gene-deficient mice and on heterologously expressed channels invitro. Molecular determinants were identified with using mutated channels. Cellular excitability is monitored with ratiometric Ca imaging. Nociceptive and analgesic actions of limonene are also examined invivo. In wild-type mouse sensory neurons, limonene increased the intracellular Ca(2+) concentration ([Ca(2+) ]i ), which was inhibited by selective inhibitors of TRPA1 but not TRPV1. Limonene-responsive neurons highly corresponded to TRPA1 agonist-sensitive ones. Limonene failed to stimulate sensory neurons from the TRPA1 (-/-) mouse. Heterologously expressed mouse TRPA1 was activated by limonene. Intraplantar injection of limonene elicited acute pain, which was significantly less in TRPA1 (-/-) mice. Systemic administration of limonene reduced nociceptive behaviours evoked by H2 O2 . In both heterologously and endogenously expressed TRPA1, a low concentration of limonene significantly inhibited H2 O2 -induced TRPA1 activation. TRPA1 activation by limonene was abolished in H2 O2 -insensitive cysteine-mutated channels. Topically applied limonene stimulates TRPA1, resulting in elicitation of acute pain, but its systemic application inhibits nociception induced by oxidative stress. Because limonene is a safe compound, it may be utilized for pain control due to its inhibition of TRPA1 channels. What does this study add: Limonene, a monoterpene in essential oils of various plants, has been known for its antitumor and anti-inflammatory properties. However, molecular basis of their actions has not been identified. This study shows that limonene activates nociceptive TRPA1 and elicits acute pain, when it is topically applied. In addition, systemic application of limonene exerts inhibitory effects on nociception induced by an oxidative stress-induced TRPA1 activation.

Biocontrol potential of essential oil monoterpenes against housefly, Musca domestica (Diptera: Muscidae)

Housefly (Musca domestica L.), one of the most common insects in human settlements, has been associated as vectors for various food-borne pathogens, causing food spoilage and disease transmission. The control of housefly was attempted using plant monoterpenes; menthone, menthol, menthyl acetate, limonene, citral and 1,8-cineole, against different life stages of housefly. Bioefficacy against housefly adults revealed highest repellent activity by menthol (95.6 percent) and menthone (83.3 percent). Against housefly larvae, menthol with an LC90 of 0.02µl/cm2 in contact toxicity assay and menthone with a LC90 value of 5.4µl/L in fumigation assay were found to be most effective control agent. With respect to pupicidal activity, superior performance was shown by menthol, citral and 1,8-cineole in contact toxicity assay and citral and 1,8-cineole in fumigation assay. Limonene was found to be the poorest performer in all the assays. Overall, highest efficacy observed for menthol and menthone in various bioassays was in agreement with the results of essential oil activity obtained previously. Significant activity of monoterpenes against various life stages of housefly demonstrates their potential as excellent insecticides with prospects of monoterpenes being developed into eco-friendly and acceptable products for housefly control.

Analysis of genetic variability and relationships among Mentha L. using the limonene synthase gene, LS

The genus Mentha comprises a group of aromatic plants with worldwide distribution. Because of frequent interspecific hybridization, the genetic relationships within the genus are not clearly understood. Limonene synthase, which catalyses the first committed step in the essential oil monoterpene biosynthetic pathway, is considered to be a possible rate limiting enzyme. With the homology-based cloning method, primers were designed according to cDNA sequence to amplify full-length DNA sequences in 13 Mentha samples from five species, using Perilla as an outgroup. Analyses of gene structure, length variation, GC-content, Ts/Tv ratio and evolutionary diversity were carried out. Consensus phylogenetic trees were obtained using maximum likelihood, neighbor-joining, and maximum parsimony, respectively, based on the full-length genomic DNA sequences, complete ORF coding sequences and predicted amino acid sequences. The results presented here based on the sequence of MhLS provide the first credibly supported genetic relationships for Mentha, which enables a basis for further mint taxonomy, cultivation and breeding.

Effect of Methanolic Leaf Extract ofOcimum basilicumL. on Benzene-Induced Hematotoxicity in Mice

The aim of the present study was to investigate the protective role of methanolic leaf extract of Ocimum basilicum L. against benzene-induced hematotoxicity in Swiss albino mice. GC analysis and subacute toxicity level of the extract were tested. Mice were randomly divided into three groups among which II and III were exposed to benzene vapour at a dose 300 ppm × 6 hr/day × 5 days/week for 2 weeks and group I was control. Group III of this experiment was treated with the leaf methanolic extract at a dose of 100 mg/kg body weight, a dose in nontoxic range. Hematological parameters (Hb%, RBC and WBC counts), cell cycle regulatory proteins expression and DNA fragmentation analysis of bone marrow cells was performed. There was an upregulation of p53 and p21 and downregulation of levels of CDK2, CDK4, CDK6, and cyclins D1 and E in leaf extract-treated group. DNA was less fragmented in group III compared to group II (P < 0.05). The present study indicates that the secondary metabolites of O. basilicum L. methanolic leaf extract, comprising essential oil monoterpene geraniol and its oxidized form citral as major constituents, have modulatory effect in cell cycle deregulation and hematological abnormalities induced by benzene in mice.

Identification of Secondary Metabolites in Citrus Fruit Using Gas Chromatography and Mass Spectroscopy

This experiment targets undergraduate students in an analytical or organic instructional context. Using a simple extraction, this protocol allows students to quantify and qualify monoterpenes in essential oils from citrus fruit peels. The procedures involve cooling down the peels by immersing them into icy water. After a few minutes, the chilled peels are pulped in a simple kitchen blender using acidic brine to hydrolyze the undesired fatty acids. Essential oils are extracted from the emulsion using methylene chloride and are then injected in a gas chromatograph coupled with a mass spectrometer. Among the fruit tested—limes, grapefruits, and oranges—all showed a high concentration of (R)-limonene, a monoterpenoid commonly found in these fruits. Students are invited to quantify (R)-limonene in the extracts following an accurate 5-point standard calibration curve. For students, this experiment may be a first contact with the analysis of plant extracts as well as an introduction to the biochemistry of monote...

Low concentration of 3‐carene stimulates the differentiation of mouse osteoblastic MC3T3‐E1 subclone 4 cells

Recently, natural products have gained more interest as alternative treatments for metabolic bone disorders and for the maintenance of bone health. In this study, the anabolic activities of 89 natural compounds were evaluated by measuring the amount of newly synthesized calcium in the differentiation process of mouse osteoblastic MC3T3-E1 subclone 4 cells. Of these compounds, a low concentration (up to 5 microm) of 3-carene, which is a bicyclic monoterpene in essential oils extracted from pine trees, was shown to stimulate significantly the activity and expression of alkaline phosphatase, an early phase marker of osteoblastic differentiation, on differentiation day 9. On day 15, it dramatically promoted the induction of calcium in a dose-dependent manner. The stimulatory effect of 3-carene on mineralization might be associated with its potential to induce the protein expression/activation of the mitogen-activated protein kinases and the transcript levels of osteoblast mineralization-related genes such as osteopontin and type I collagen. Further studies are needed to determine the precise mechanism, but the anabolic activity of 3-carene in bone metabolism suggested that the use of natural additives to the diet including essential oils could have a beneficial effect on bone health.

Essential oil composition and variability of Hypericum perforatum L. growing in Lithuania

The composition of essential oils obtained from flowers and leaves in 11 accessions of Hypericum perforatum L. was analysed by GC and GC–MS. All the analysed oils were dominated by their oxygenated sesquiterpene fraction. Differences were attributed to the main components: caryophyllene oxide, spathulenol and viridiflorol. There were only a few monoterpenes in essential oil of all accessions. The data indicated some differences in sesquiterpene and aliphatic hydrocarbons, as well as in oxygenated aliphatics biosynthesis in flowers and leaves. The concentrations of β-caryophyllene and caryophyllene oxide in essential oils from leaves were higher than those from flowers, whereas dodecanol, spathulenol, viridiflorol, carotol and tetradecanol were present in higher quantities in flowers. Cluster analysis of all identified components grouped oils from flowers and from leaves into three clusters that corresponded with their major components: caryophyllene oxide, tetradecanal, tetradecanol and manool. Chemical variability of the analysed accessions seems likely to result from the genetic variability, since the influence of different environmental factors has been eliminated.