Effects of Taiwanese indigenous cinnamon (Cinnamomum osmophloeum) leaf hot-water extract on nonspecific immune responses, resistance against Vibrio parahaemolyticus, nonviable cells, and haemocyte subpopulations in white shrimp (Penaeusvannamei).

This study investigated the effects of Cinnamomum osmophloeum leaf hot-water extract (CLWE) on nonspecific immune responses and resistance to Vibrio parahaemolyticus in white shrimp (Penaeus vannamei). Firstly, a cell viability assay demonstrated that the CLWE is safe to white shrimp heamocytes in the concentration of 0-500 mg L-1. Haemocytes incubated in vitro with 10 and 50 mg L-1 of CLWE showed significantly higher response in superoxide anion production, PO activity, and phagocytic activity. In the in vivo trials, white shrimp were fed with 0, 0.5, 1, 5, and 10 g kg-1 CLWE supplemented feeds (designated as CLWE 0, CLWE 0.5, CLWE 1, CLWE 5, and CLWE 10, respectively) over a period of 28 days. In vivo experiments demonstrated that CLWE 0.5 feeding group resulted in the highest total haemocyte count, superoxide anion production, phenoloxidase activity, and phagocytic activity. Moreover, CLWE 0.5 supplemented feed significantly upregulated the clotting system, antimicrobial peptides, pattern recognition receptors, pattern recognition proteins, and antioxidant defences in white shrimp. Furthermore, the shrimp were infected with V. parahaemolyticus injections after 14 days of feeding as challenge test. Based on the challenge test result, both CLWE 0.5 and CLWE 5 demonstrated a strong resistance to V. parahaemolyticus. These two dosages effectively reduced the number of nonviable cells and activated different haemocyte subpopulations. These findings indicated that treatment with CLWE 0.5 could promote nonspecific immune responses, immune-related gene expression, and resistance to V. parahaemolyticus in white shrimp.

The crude extract obtained from Cinnamomum macrostemon Hayata regulates oxidative stress and mitophagy in keratinocytes.

Four ethanol fractionated crude extracts (EFCEs [A-D]) purified from the leaves of Cinnamomum macrostemon Hayata were screened for antioxidative effects and mitochondrial function in HaCaT cells. The higher cell viability indicated that EFCE C was mildly toxic. Under the treatment of 50 ng/mL EFCE C, the hydrogen peroxide (H2O2)-induced cytosolic and mitochondrial reactive oxygen species levels were reduced as well as the H2O2-impaired cell viability, mitochondrial membrane potential (MMP), ATP production, and mitochondrial mass. The conversion of globular mitochondria to tubular mitochondria is coincident with EFCE C-restored mitochondrial function. The mitophagy activator rapamycin showed similar effects to EFCE C in recovering the H2O2-impaired cell viability, MMP, ATP production, mitochondrial mass, and also mitophagic proteins such as PINK1, Parkin, LC3 II, and biogenesis protein PGC-1α. We thereby propose the application of EFCE C in the prevention of oxidative stress in skin cells.

Identification of Fatty Acids, Amides and Cinnamic Acid Derivatives in Supercritical-CO2 Extracts of Cinnamomum tamala Leaves Using UPLC-Q-TOF-MSE Combined with Chemometrics.

Cinnamomum tamala leaf (CTL), also known as Indian bay leaf, is used all over the world for seasoning, flavoring, and medicinal purposes. These characteristics could be explained by the presence of several essential bioactive substances and lipid derivatives. In this work, rapid screening and identification of the chemical compounds in supercritical (SC)-CO2 extracts of CTL by use of UPLC-Q-TOF-MSE with a multivariate statistical analysis approach was established in both negative and positive mode. A total of 166 metabolites, including 66 monocarboxylic fatty acids, 52 dicarboxylic fatty acids, 27 fatty acid amides, and 21 cinnamic acid derivatives, were tentatively identified based on accurate mass and the mass spectrometric fragmentation pattern, out of which 142 compounds were common in all SC-CO2 extracts of CTL. Further, PCA and cluster hierarchical analysis clearly discriminated the chemical profile of analyzed extracts and allowed the selection of SC-CO2 extract rich in fatty acids, fatty acid amides, and other bioactive constituents. The result showed that the higher number of compounds was detected in CTL4 (300 bar/55 °C) extract than the other CTL extracts. The mono- and di-carboxylic fatty acids, fatty acid amides, and cinnamic acid derivatives were identified in CTL for the first time. UPLC-Q-TOF-MSE combined with chemometric analysis is a powerful method to rapidly screen the metabolite profiling to justify the quality of CTL as a flavoring agent and in functional foods.

Application of Cinnamomum burmannii Essential Oil in Promoting Wound Healing.

Skin wounds, leading to infections and death, have a huge negative impact on healthcare systems around the world. Antibacterial therapy and the suppression of excessive inflammation help wounds heal. To date, the application of wound dressings, biologics and biomaterials (hydrogels, epidermal growth factor, stem cells, etc.) is limited due to their difficult and expensive preparation process. Cinnamomum burmannii (Nees & T. Nees) Blume is an herb in traditional medicine, and its essential oil is rich in D-borneol, with antibacterial and anti-inflammatory effects. However, it is not clear whether Cinnamomum burmannii essential oil has the function of promoting wound healing. This study analyzed 32 main components and their relative contents of essential oil using GC-MS. Then, network pharmacology was used to predict the possible targets of this essential oil in wound healing. We first proved this essential oil's effects in vitro and in vivo. Cinnamomum burmannii essential oil could not only promote the proliferation and migration of skin stromal cells, but also promote M2-type polarization of macrophages while inhibiting the expression of pro-inflammatory cytokines. This study explored the possible mechanism by which Cinnamomum burmannii essential oil promotes wound healing, providing a cheap and effective strategy for promoting wound healing.

[Quality evaluation and grading standard discussion on Cinnamomi Ramulus].

This study explored the relationship between the appearance traits and internal components of Cinnamomi Ramulus pieces, so as to provide a reference for the quality evaluation and the formulation of grade standards. This study determined the appearance traits and index component contents of 41 batches of Cinnamomi Ramulus pieces in the core producing areas of Guangxi and Guangdongand established the HPLC characteristic map method. The weight of the pieces, the narrowest diameter, and the widest diameter of the tr ansverse section were used as the indices of appearance traits. The content of index components(cinnamic acid and cinnamalde hyde)was determined by the established content determination method. The chromatographic characteristics were determinedon a Waters XBridge C_(18)(4. 6 mm×250 mm, 5 µm) column with a mobile phase consisting of 0. 1% phosphoric acidacetonitrile and gradient elution at the flow rate of 1 mL ·min~(-1). The column temperature was 30 ℃, and the detection wavelength was 254 nm. Cluster analysis, principal component analysis, and other stoichiometric methods were used to analyze the correlation between theap pearance traits and the index/characteristic components of Cinnamomi Ramulus pieces and compare the qu ality differences of the piecesfrom different batches and plac es. The results showed that the larger weight, the narrowest diameter, andthe widest diameter of the tra nsverse section indicated lowercontent of main indexes/characteristic components, and there was a synergistic decreasing trend amongd ifferent components. The overall quality of Cinnamomi Ramulus pieces in Guangdong Province and Guangxi Province was similar, but there were still differences between different origins and different batches of the same origin. It is scientific and feasible to evaluatethe quality of Cinnamomi Ramulus pieces and establish grading standards based on the appearance traits and index/character istic components. The research provides a more scientific and comprehensive basis for the quality control evaluation and standardformulation of Cinnamomi Ramulus.

[Chemical constituents from Cinnamomi Ramulus decoction].

Six compounds were isolated from the ethyl acetate extracts of Cinnamomi Ramulus decoction by RP-18, silica gel, Sephadex LH-20 column chromatography, together with prep-HPLC methods. Based on HR-ESI-MS, MS, 1D and 2D NMR spectral analyses, the structures of the six compounds were identified as 4,5,10,11-tetrahydroxybisabol-7-ene(1), 4,5,10,11-tetrahydroxybisabolin(2), 1-phenyl-1,2,3-glycerol(3),(+)-lyoniresinol(4), benzoic acid(5), and decumbic acid(6). Compound 1 was a new bisabolene-type sesquiterpene, and compounds 2 and 3 were isolated from the Cinnamomi Ramulus for the first time. Moreover, the bisabolene-type sesquiterpene(2) was assayed for its anti-inflammatory activity and cytotoxicity to human pancreatic cancer cells(PANC-1 cells). RESULTS:: showed that compound 2 exhibited an inhibitory rate of 32.9% on nitric oxide(NO) at a dose of 40 µmol·L~(-1) and a proliferation inhibition rate of 14.5% against PANC-1 cells at a dose of 20 µmol·L~(-1). It did not demonstrate significant activity.

Comparative Chemical Composition and Acetylcholinesterase (AChE) Inhibitory Potential of Cinnamomum camphora and Cinnamomum tamala.

Cinnamomum species have applications in the pharmaceutical and fragrance industry for wide biological and pharmaceutical activities. The present study investigates the chemical composition of the essential oils extracted from two species of Cinnamomum namely C. tamala and C. camphora. Chemical analysis showed E-cinnamyl acetate (56.14 %), E-cinnamaldehyde (20.15 %), and linalool (11.77 %) contributed as the major compounds of the 95.22 % of C. tamala leaves essential oil found rich in phenylpropanoids (76.96 %). C. camphora essential oil accounting for 93.57 % of the total oil composition was rich in 1,8-cineole (55.84 %), sabinene (14.37 %), and α-terpineol (10.49 %) making the oil abundant in oxygenated monoterpenes (70.63 %). Furthermore, the acetylcholinesterase inhibitory activity for both the essential oils was carried out using Ellman's colorimetric method. The acetylcholinesterase inhibitory potential at highest studied concentration of 1 mg/mL was observed to be 46.12±1.52 % for C. tamala and 53.61±2.66 % for C. camphora compared to the standard drug physostigmine (97.53±0.63 %) at 100 ng/ml. These multiple natural aromatic and fragrant characteristics with distinct chemical compositions offered by Cinnamon species provide varied benefits in the development of formulations that could be advantageous for the flavor and fragrance industry.

Variations in Essential Oils from the Leaves of Cinnamomum bodinieri in China.

Cinnamomum plants are rich in natural essential oils, which are widely used as materials in the fragrance, insecticidal, antibacterial agent, pharmaceutical, and food industries; however, few studies have investigated the essential oil components of Cinnamomum bodinieri. Therefore, this study investigated the diversity of essential oils from the leaves of 885 individual C. bodinieri plants across 32 populations in five provinces. Essential oils were extracted by hydrodistillation, and then qualitative and quantitative analyses of the compounds were performed by GC-MS and GC-FID. A total of 87 chemical constituents were identified in the essential oils, including 33 monoterpenes, 48 sesquiterpenes, and six other compounds. The average oil yield was 0.75%, and individual oil yields ranged from 0.01% to 4.28%. A total of 16 chemotypes were classified according to variations in the essential oil chemical constituents of C. bodinieri, among which the camphor-type, citral-type, and eucalyptol-type were dominant. Moreover, the borneol-type, cymol-type, elemol-type, methylisoeugenol-type, and selina-6-en-4-ol-type were reported in C. bodinieri for the first time. The yield and principal components of the essential oils were mainly affected by altitude, temperature, and sunshine duration, among which altitude had the most significant effect; thus, low-altitude areas are more suitable for the synthesis and accumulation of essential oils. Based on the different characteristics of the essential oils in the leaves of C. bodinieri, several excellent populations and individuals were identified in this study. Moreover, the findings provide a foundation for breeding superior varieties and studying essential oil biosynthesis mechanisms in the future.

Cinnamomum sp. and Pelargonium odoratissimum as the Main Contributors to the Antibacterial Activity of the Medicinal Drink Horchata: A Study Based on the Antibacterial and Chemical Analysis of 21 Plants.

Horchata, a herbal infusion drink from Ecuador containing a mixture of medicinal plants, has been reported to exhibit anti-inflammatory, analgesic, diuretic, and antioxidant activity. The antibacterial activity of each of the plants contained in the horchata mixture has not been fully evaluated. Thus, in this study, we analysed the antibacterial activity of 21 plants used in horchata, collected from the Ecuadorian Andes region, against bacterial strains of clinical importance. The methanolic extract of Cinnamomum sp. showed minimal inhibitory concentration (MIC) values of 250 µg/mL against Staphylococcus aureus ATCC25923 and Methicillin-resistant S. aureus (MRSA), while Pelargonium odoratissimum exhibited a MIC value of 500 µg/mL towards S. aureus ATCC25923. The high-performance liquid chromatography-diode array detector-tandem mass spectrometry (HPLC-DAD-MS/MS) analyses identified in Cinnamomum sp. epicatechin tannins, cinnamaldehyde, and prehelminthosporol molecules, whereas in P. odoratissimum, gallocatechin and epigallocatechin tannins, some flavonoids, and gallic acid and derivatives were identified. Finally, Cinnamomum sp. and P. odoratissimum showed partial inhibition of biofilm formation of S. aureus ATCC25923 and MRSA. Overall, our findings revealed which of the plants used in horchata are responsible for the antibacterial activity attributed to this herbal drink and exhibit the potential for Cinnamomum sp. and P. odoratissimum secondary metabolites to be explored as scaffolds in drug development.

Cinnamomum japonicum Siebold Branch Extracts Attenuate NO and ROS Production via the Inhibition of p38 and JNK Phosphorylation.

Cinnamomum japonicum (CJ) is widely distributed in Asian countries like Korea, China, and Japan. Modern pharmacological studies have demonstrated that it exhibits various biological activities, including antioxidant and anti-inflammatory effects. However, most studies have confirmed the efficacy of its water extract but not that of its other extracts. Therefore, in this study, Cinnamomum japonicum Siebold branches (CJB: 70% EtOH extract) were separated using hexane, chloroform, ethyl acetate (CJB3), butanol, and water. Then, their antioxidative activities and phenolic contents were measured. Results revealed that the antioxidant activities and phenolic contents of CJB3 were higher than those of the other extracts. Further, the inhibitory and anti-inflammatory effect of CJB3 on lipopolysaccharide (LPS)-induced reactive oxygen species (ROS) production and LPS-activated macrophages, respectively, was determined. CJB3 suppressed oxidative stress in LPS-activated cells and dose-dependently decreased LPS-stimulated ROS production. CJB3 reduced oxidative stress and reversed the glutathione decrease in LPS-activated RAW264.7 cells. The inhibitory and reducing effect of CJB3 on LPS-induced nitric oxide (NO) production and inducible NO synthase protein and messenger RNA levels, respectively, was investigated. CJB3 inhibited LPS-induced cytokine production and p38 and c-Jun N-terminal kinase (JNK) phosphorylation but not extracellular signal-regulated kinase phosphorylation. Overall, the study results suggest that CJB3 may exert its anti-inflammatory effects via the suppression of p38, JNK, and c-Jun activation.

Seasonal Variation in the Essential Oil Yield and Composition of Cinnamomum parthenoxylon (Jack) Meisner.

Cinnamomum parthenoxylon (Jack) Meisner is an important natural aromatic plant because its leaves are rich in essential oil. Linalool chemotype C. parthenoxylon was used as the research material in the present study. The leaf essential oil yield, the main chemical components, and their content were measured every month from January to December 2018 to study the seasonal variation in the yield and chemical components of C. parthenoxylon leaf essential oil. The results revealed that the essential oil yield and the main chemical component linalool in the essential oil of C. parthenoxylon leaves showed significant differences among months. The leaf essential oil yield and linalool content decreased to the lowest in March and increased rapidly from April to May. The leaf essential oil yield was the highest in May, and a relatively high yield was maintained from April to August. The linalool content in leaf essential oil was stable in other months except March. The leaf essential oil yield of C. parthenoxylon had a very significant positive correlation with monthly rainfall and monthly average temperature. Intense rainfall and high monthly average temperature were conducive to the synthesis and accumulation of C. parthenoxylon leaf essential oil. This study provided a theoretical basis for cultivating C. parthenoxylon as a raw material for spices and determining the best harvest time.

Essential Oil Chemotypes and Genetic Variability of Cinnamomum verum Leaf Samples Commercialized and Cultivated in the Amazon.

Cinnamomum verum (Lauraceae), also known as "true cinnamon" or "Ceylon cinnamon" has been widely used in traditional folk medicine and cuisine for a long time. The systematics of C. verum presents some difficulties due to genetic variation and morphological similarity between other Cinnamomum species. The present work aimed to find chemical and molecular markers of C. verum samples from the Amazon region of Brazil. The leaf EOs and the genetic material (DNA) were extracted from samples cultivated and commercial samples. The chemical composition of the essential oils from samples of C. verum cultivated (Cve1-Cve5) and commercial (Cve6-c-Cv9-c) was grouped by multivariate statistical analysis of Principal Component Analysis (PCA). The major compounds were rich in benzenoids and phenylpropanoids, such as eugenol (0.7-91.0%), benzyl benzoate (0.28-76.51%), (E)-cinnamyl acetate (0.36-32.1%), and (E)-cinnamaldehyde (1.0-19.73%). DNA barcodes were developed for phylogenetic analysis using the chloroplastic regions of the matK and rbcL genes, and psbA-trnH intergenic spacer. The psbA-trnH sequences provided greater diversity of nucleotides, and matK confirmed the identity of C. verum. The combination of DNA barcode and volatile profile was found to be an important tool for the discrimination of C. verum varieties and to examine the authenticity of industrial sources.

Effects of rhizosphere fungi on the chemical composition of fruits of the medicinal plant Cinnamomum migao endemic to southwestern China.

BACKGROUND: This study examined how rhizosphere fungi influence the accumulation of chemical components in fruits of a small population species of Cinnamomum migao. RESULTS: Ascomycota and Basidiomycota were dominant in the rhizosphere fungal community of C. migao. Pestalotiopsis and Gibellulopsis were associated with α-Terpineol and sabinene content, and Gibellulopsis was associated with crude fat and carbohydrate content. There were significant differences in rhizosphere fungal populations between watersheds, and there was no obvious change between fruiting periods. Gibberella, Ilyonectria, Micropsalliota, and Geminibasidium promoted sabinene accumulation, and Clitocybula promoted α-Terpineol accumulation. CONCLUSION: The climate-related differentiation of rhizosphere fungal communities in watershed areas is the main driver of the chemical composition of C. migao fruit. The control of the production of biologically active compounds by the rhizosphere fungal community provides new opportunities to increase the industrial and medicinal value of the fruit of C. migao.

Urease Inhibitory Kinetic Studies of Various Extracts and Pure Compounds from Cinnamomum Genus.

Urease is an enzyme that plays a significant role in the hydrolysis of urea into carbonic acid and ammonia via the carbamic acid formation. The resultant increase in pH leads to the onset of various pathologies such as gastric cancer, urolithiasis, hepatic coma, hepatic encephalopathy, duodenal ulcers and peptic ulcers. Urease inhibitors can reduce the urea hydrolysis rate and development of various diseases. The Cinnamomum genus is used in a large number of traditional medicines. It is well established that stem bark of Cinnamomum cassia exhibits antiulcerogenic potential. The present study evaluated the inhibitory effect of seven extracts of Cinnamomum camphora, Cinnamomum verum and two pure compounds Camphene and Cuminaldehyde on urease enzyme. Kinetic studies of potential inhibitors were carried out. Methanol extract (IC50 980 µg/mL) of C. camphora and a monoterpene Camphene (IC50 0.147 µg/mL) possess significant inhibitory activity. The Lineweaver Burk plot analysis suggested the competitive inhibition by methanol extract, hexane fraction and Camphene. The Gas Chromatography-Mass Spectroscopy (GC-MS) analysis of hexane fraction revealed the contribution of various terpenes. The present study targets terpenes as a new class of inhibitors that have potential therapeutic value for further development as novel drugs.

Thermal Degradation of Linalool-Chemotype Cinnamomum osmophloeum Leaf Essential Oil and Its Stabilization by Microencapsulation with ß-Cyclodextrin.

The thermal degradation of linalool-chemotype Cinnamomum osmophloeum leaf essential oil and the stability effect of microencapsulation of leaf essential oil with ß-cyclodextrin were studied. After thermal degradation of linalool-chemotype leaf essential oil, degraded compounds including ß-myrcene, cis-ocimene and trans-ocimene, were formed through the dehydroxylation of linalool; and ene cyclization also occurs to linalool and its dehydroxylated products to form the compounds such as limonene, terpinolene and α-terpinene. The optimal microencapsulation conditions of leaf essential oil microcapsules were at a leaf essential oil to the ß-cyclodextrin ratio of 15:85 and with a solvent ratio (ethanol to water) of 1:5. The maximum yield of leaf essential oil microencapsulated with ß-cyclodextrin was 96.5%. According to results from the accelerated dry-heat aging test, ß-cyclodextrin was fairly stable at 105 °C, and microencapsulation with ß-cyclodextrin can efficiently slow down the emission of linalool-chemotype C. osmophloeum leaf essential oil.

Evaluation of Motor Coordination and Antidepressant Activities of Cinnamomum osmophloeum ct. Linalool Leaf Oil in Rodent Model.

Cinnamomum plants (Lauraceae) are a woody species native to South and Southeast Asia forests, and are widely used as food flavors and traditional medicines. This study aims to evaluate the chemical constituents of Cinnamomum osmophloeum ct. linalool leaf oil, and its antidepressant and motor coordination activities and the other behavioral evaluations in a rodent animal model. The major component of leaf oil is linalool, confirmed by GC-MS analysis. Leaf oil would not induce the extra body weight gain compared to the control mice at the examined doses after 6 weeks of oral administration. The present results provide the first evidence for motor coordination and antidepressant effects present in leaf oil. According to hypnotic, locomotor behavioral, and motor coordination evaluations, leaf oil would not cause side effects, including weight gain, drowsiness and a diminishment in the motor functions, at the examined doses. In summary, these results revealed C. osmophloeum ct. linalool leaf essential oil is of high potential as a therapeutic supplement for minor/medium depressive syndromes.

Cinnamtannin D1 attenuates autoimmune arthritis by regulating the balance of Th17 and treg cells through inhibition of aryl hydrocarbon receptor expression.

The suppression of the abnormal systemic immune response constitutes a primary strategy for treatment of rheumatoid arthritis (RA); toward this end, the identification of natural compounds with immunosuppressive activity represents a promising strategy for RA drug discovery. Cinnamtannin D1 (CTD-1), a polyphenolic compound isolated from Cinnamomum tamala, was previously reported to possess good immunosuppressive activity. However, the beneficial effect of CTD-1 on RA is currently unknown. The aim of this study was to evaluate the anti-arthritic effect of CTD-1 in collagen-induced arthritis (CIA) mice and clarify the underlying mechanisms. CTD-1 treatment significantly alleviated the severity of CIA mice, affording reduced clinical scores and paw swelling, along with reduced inflammatory cell infiltration and cartilage damage in the joints; in addition, the serum levels of IL-17, IL-6, and IL-1ß were decreased whereas those of TGF-ß and IL-10 were increased. CTD-1-treated mice exhibited lower frequency of Th17 cells and higher frequency of Treg cells compared to those in untreated mice, indicating that the balance of Th17/Treg cells may serve as the target for CTD-1. Consistent with this, in ex vivo assays, CTD-1 inhibited Th17 cell differentiation through the downregulation of phospho-STAT3/RORγt, whereas it promoted Treg differentiation by upregulating phospho-STAT5/Foxp3 in response to the stimulation of collagen type II. Moreover, in an in vitro naïve CD4+ T cell differentiation assay, CTD-1 directly inhibited Th17 cell differentiation and promoted Treg differentiation, suggesting that CTD-1 regulated the balance of Th17 and Treg cells to inhibit excessive immune response. Furthermore, the regulation effect of CTD-1 on Th17 and Treg cells was dependent on Ahr expression, as this effect was abolished when Ahr was knocked down and was impaired when Ahr was overexpressed. Together, our results indicated that CTD-1 treatment benefits CIA mice by regulating Th17 and Treg differentiation through the inhibition of AHR expression, and suggested a potential application of CTD-1 toward RA treatment.

In vitro activity of essential oils against adult and immature stages of Ctenocephalides felis felis.

Essential oils (EOs) are considered a new class of ecological products aimed at the control of insects for industrial and domestic use; however, there still is a lack of studies involving the control of fleas. Ctenocephalides felis felis, the most observed parasite in dogs and cats, is associated with several diseases. The aim of this study was to evaluate the in vitro activity, the establishment of LC50 and toxicity of EOs from Alpinia zerumbet (Pers.) B. L. Burtt & R. M. Sm, Cinnamomum spp., Laurus nobilis L., Mentha spicata L., Ocimum gratissimum L. and Cymbopogon nardus (L.) Rendle against immature stages and adults of C. felis felis. Bioassay results suggest that the method of evaluation was able to perform a pre-screening of the activity of several EOs, including the discriminatory evaluation of flea stages by their LC50. Ocimum gratissimum EO was the most effective in the in vitro assays against all flea stages, presenting adulticide (LC50 = 5.85 µg cm-2), ovicidal (LC50 = 1.79 µg cm-2) and larvicidal (LC50 = 1.21 µg cm-2) mortality at low doses. It also presented an excellent profile in a toxicological eukaryotic model. These findings may support studies involving the development of non-toxic products for the control of fleas in dogs and cats.

Chemical Compositions, Mosquito Larvicidal and Antimicrobial Activities of Essential Oils from Five Species of Cinnamomum Growing Wild in North Central Vietnam.

Members of the genus Cinnamomum (Lauraceae) have aromatic volatiles in their leaves and bark and some species are commercially important herbs and spices. In this work, the essential oils from five species of Cinnamomum (C. damhaensis, C. longipetiolatum, C. ovatum, C. polyadelphum and C. tonkinense) growing wild in north central Vietnam were obtained by hydrodistillation, analyzed by gas chromatography and screened for antimicrobial and mosquito larvicidal activity. The leaf essential oil of C. tonkinense, rich in ß-phellandrene (23.1%) and linalool (32.2%), showed excellent antimicrobial activity (MIC of 32 µg/mL against Enterococcus faecalis and Candida albicans) and larvicidal activity (24 h LC50 of 17.4 µg/mL on Aedes aegypti and 14.1 µg/mL against Culex quinquefasciatus). Cinnamomum polyadelphum leaf essential oil also showed notable antimicrobial activity against Gram-positive bacteria and mosquito larvicidal activity, attributable to relatively high concentrations of neral (11.7%) and geranial (16.6%). Thus, members of the genus Cinnamomum from Vietnam have shown promise as antimicrobial agents and as potential vector control agents for mosquitoes.

Vapors of Volatile Plant-Derived Products Significantly Affect the Results of Antimicrobial, Antioxidative and Cytotoxicity Microplate-Based Assays.

Volatile plant-derived products were observed to exhibit broad spectrum of biological effects. However, due to their volatility, results of conventional microplate-based bioassays can be significantly affected by the vapors. With aim to demonstrate this phenomenon, antimicrobial, antioxidant, and cytotoxic activities of three essential oils (Alpinia elegans, Cinnamomum iners, and Xanthostemon verdugonianus), one supercritical CO2 extract (Nigella sativa), and four plant-derived compounds (capsaicin, caryophyllene oxide, 8-hydroxyquinoline, and thymoquinone) were evaluated in series of experiments including both ethylene vinyl acetate (EVA) Capmat sealed and nonsealed microplates. The results clearly illustrate that vapor transition to adjoining wells causes false-positive results of bioassays performed in nonsealed microtiter plates. The microplate layout and a duration of the assay were demonstrated as the key aspects defining level of the results affection by the vapors of volatile agents. Additionally, we reported biological activities and chemical composition of essential oils from A. elegans seeds and X. verdugonianus leaves, which were, according to our best knowledge, analyzed for the first time. Considering our findings, certain modifications of conventional microplate-based assays are necessary (e.g., using EVA Capmat as vapor barrier) to obtain reliable results when biological properties of volatile agents are evaluated.