Bark Essential Oil Research Articles

Essential Oils from the Leaves and Stem Barks of Pluchea Indica (L.) Less.: Chemical Analysis, Cytotoxicity, Anti-inflammation, Antimicrobial Activity, Molecular Docking, and ADMET Profiling.

Pluchea indica (L.) Less. is a medicinal plant native to Asia. Traditionally, it is known for numerous traditional uses, such as treatments for fever, cough, and digestive issues. The present investigation aims to determine the chemical compositions of essential oils from its fresh leaves and stem barks. By using hydro-distillation and the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis, the studied samples were dominated by sesquiterpene hydrocarbons (76.8-82.2 %) and their oxygenated derivatives (8.4-19.0 %). β-Selinene (42.0-43.5 %) and silphinene (21.1-22.9 %) were the main compounds. Significantly, the stem bark essential oil strongly monitored the growth of four cancer cell lines K562, HeLa, HepG2, and MCF-7 with IC50 values of 2.89-7.34 μg/mL. Both studied samples showed strong anti-inflammatory activity against NO (nitric oxide) production with IC50 values of 21.81-23.18 μg/mL. The studied sample also exhibited antimicrobial activity at different levels. The molecular docking study revealed that β-selinene exhibited the strongest binding affinity for all four cancer-related protein targets: epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), Abelson tyrosine-protein kinase 1 (ABL1), and phosphatidylinositol 3-kinase (PI3 K-α). The ADMET profiles of the major compounds were also predicted to provide insights for further research considerations.

Cinnamon essential oil incorporated chitosan submicron emulsion as a sustainable alternative for extension of mango shelf life

In the present study, cinnamon bark essential oil (CEO)-incorporated chitosan-based submicron emulsion coatings (CEO-CSSEs) were successfully prepared by an ionic gelation method using sodium tripolyphosphate (STPP) as a crosslinking agent and Tween 20 as a surfactant. A chitosan:CEO mass ratio ≤1:0.5 was found to have a unimodal and narrow size distribution. The FTIR absorption bands confirmed the successful encapsulation of CEO into the chitosan particles, which exhibited a spherical shape and aggregated regions with cracks. Acute oral toxicity tests revealed that the cinnamon bark essential-loaded chitosan submicron emulsion was nontoxic and could be used for coating mango fruits. Postharvest submicron emulsion coatings on mangos significantly delay physio-chemical changes linked to ripening. However, mangos coated with CEO-CSSEs at 1:0.75 and 1:1 ratios remained unripen, while those coated with CEO-CSSEs at 1:0.5 ratio ripened slowly, implying a negative impact of CEO at higher concentrations on mango quality and shelf quality. Therefore, it is concluded that CEO-CSSEs at 1:0.5 successfully slowed different physio-chemical parameters linked to the deterioration of mango quality; thus, treatments can be suggested to extend the shelf life to 18 days during ambient storage at 25 ± 2 °C and 65% RH.

The Influence of Physical Fields (Magnetic and Electric) and LASER Exposure on the Composition and Bioactivity of Cinnamon Bark, Patchouli, and Geranium Essential Oils.

In recent years, essential oils (EOs) have received increased attention from the research community, and the EOs of cinnamon, patchouli, and geranium have become highly recognized for their antibacterial, antifungal, antiviral, and antioxidant effects. Due to these properties, they have become valuable and promising candidates for addressing the worldwide threat of antimicrobial resistance and other diseases. Simultaneously, studies have revealed promising new results regarding the effects of physical fields (magnetic and electric) and LASER (MEL) exposure on seed germination, plant growth, biomass accumulation, and the yield and composition of EOs. In this frame, the present study aims to investigate the influence of MEL treatments on cinnamon, patchouli, and geranium EOs, by specifically examining their composition, antimicrobial properties, and antioxidant activities. Results showed that the magnetic influence has improved the potency of patchouli EO against L. monocytogenes, S. enteritidis, and P. aeruginosa, while the antimicrobial activity of cinnamon EO against L. monocytogenes was enhanced by the electric and laser treatments. All exposures have increased the antifungal effect of geranium EO against C. albicans. The antioxidant activity was not modified by any of the treatments. These findings could potentially pave the way for a deeper understanding of the efficiency, the mechanisms of action, and the utilization of EOs, offering new insights for further exploration and application.

Determination of chemical components, antibacterial activity, and mold inhibitory activity of the cinnamon bark (cinnamomum) essential oils

Determination of chemical components, antibacterial activity, and mold inhibitory activity of the cinnamon bark (cinnamomum) essential oils

Inactivation of Listeria monocytogenes on a laboratory medium and enoki mushrooms using organic acid and essential oil vapors

The aim of this study was to determine the antimicrobial activity of organic acid (OA) and essential oil (EO) vapors against Listeria monocytogenes on a laboratory medium and enoki mushrooms. Among 14 OA and 8 EO vapors tested, 3 OA vapors (acetic, formic, and propionic acid) and 3 EO vapors (cinnamon bark, citronella, and lemongrass) showed relatively strong antilisterial activity. On tryptic soy agar (TSA), all three OA vapors had a minimum inhibitory concentration (MIC) of 12.5 mg/L, while the minimum lethal concentration (MLC) of formic acid vapor was the lowest, at 50 mg/L, followed by acetic acid vapor (200 mg/L) and propionic acid vapor (400 mg/L). The MIC values of lemongrass, cinnamon bark, and citronella EO vapors were 25, 100, and 100 mg/L, respectively. The MLC of lemongrass EO vapor was 100 mg/L and MLCs of other EO vapors were >400 mg/L. Formic acid and lemongrass EO vapors showed a partial synergism on TSA (fractional inhibitory concentration index of 0.7500). For L. monocytogenes inoculated on enoki mushrooms, formic acid vapor at a concentration of ≥50 mg/L, as well as formic acid and lemongrass vapors in combination (1:2 vol ratio) at ≥ 75 mg/L, inactivated L. monocytogenes. These results indicate that formic acid vapor is effective at controlling the growth of L. monocytogenes on enoki mushrooms.

Chemical composition and antimicrobial activity of leaf, twig, fruit bark and seed essential oils of Michelia tonkinensis A. Chev from Vietnam

Essential oils isolated from leaves, twigs, fruit bark and seeds of Michelia tonkinensis collected in Muong Nhe Nature Reserve, Dien Bien province were obtained by hydrodistillation with yields of 1.5, 0.42, 0.16 and 4.6% respectively (v/w on dry weight basis). After analysis through GC, GC-MS and 13C NMR, 30, 34, 31 and 13 compounds (representing 96.4%, 96.8%, 97.1% and 99.9% of the whole composition, respectively) were identified in the leave, twig, fruit bark and seed essential oils. The main components were limonene (43.2%) and germacrene D (32.7%) in the leaf oil; limonene (67.1%) and germacrene D (10.4%) in the twig oil; limonene (66%) in the fruit bark oil; and safrole (90%) in the seed oil. Essential oils from the leaves and twigs showed strong inhibition against Staphyloccocus aureus. The fruit bark essential oil exhibited greater antibacterial potential against all 3 tested microorganisms (S. aureus, Escherichia coli and Candida albicans). The essential oil from seed displayed weak antibacterial activity against the three tested microorganisms.

Extraction of essential oil from cinnamon (Cinnamomum burmannii) bark using microwave assisted extraction method

Cinnamon is one of the essential commodities that is very prospective and rich in benefits. The demand for cinnamon bark essential oil is always increasing every year. This condition indicates that the potential utilization of cinnamon bark essential oil is still wide open along with the development of the food, cosmetic and drug industries. The goal of this research is to extract the essential oil from cinnamon bark using Microwave Assisted Extraction (MAE) method, as well as to determine the best operation condition that can result the optimum yield of essential oil. This research was carried out with a variation of solvents of aquadest, 70% ethanol and ethyl acetate; variations of microwave power of 180, 300 and 450 W; and variations in extraction time of 60, 75 and 90 minutes. The results showed that the best solvent for extracting cinnamon bark essential oil was 70% ethanol. Furthermore, the best operating conditions were obtained using a microwave power of 300 W and an extraction time of 90 minutes, with an essential oil yield of 6.92 %. The physical properties of the essential oil obtained are a density of 1.1041 g/mL; refractive index 1.416; pH 6, light yellow color and a distinctive cinnamon aroma.

Essential oil from Cinnamomum cassia Presl bark regulates macrophage polarization and ameliorates lipopolysaccharide-induced acute lung injury through TLR4/MyD88/NF-κB pathway

Cinnamomum cassia Presl, a traditional Chinese medicine recorded in "Shennong's Herbal Classic," has been historically used to treat respiratory diseases and is employed to address inflammation. The essential oil derived from Cinnamomum cassia bark is a primary anti-inflammatory agent. However, there remains ambiguity regarding the chemical composition of cinnamon bark essential oil (BCEO), its principal anti-inflammatory components, and their potential efficacy in typical inflammatory respiratory conditions, such as acute lung injury (ALI). This study aimed to unveil the chemical composition of BCEO. In addition, the mechanism of action of BCEO in ameliorating ALI and regulating macrophage polarization through the TLR4/MyD88/NF-κB pathway was elucidated. BCEO was extracted using supercritical fluid extraction (SFE) and characterized through gas chromatography-mass spectrometry (GC-MS) analysis. Acute oral toxicity was observed in C57BL/6 J mice. The pharmacological effects and underlying mechanisms of BCEO were evaluated in a mouse model of ALI, which was induced by administering 5 mg/kg of lipopolysaccharide (LPS) through intratracheal instillation. GC-MS analysis revealed 99.08% of the constituents of BCEO. The primary components of BCEO were trans-cinnamaldehyde, o-methoxycinnamaldehyde, (+)-α-muurolene, δ-cadinene, and copaene. Oral acute toxicity tests indicated that the maximum tolerated dose of BCEO was 12 g/kg/day. BCEO treatment significantly reduced lung W/D ratio, total protein concentration in BALF, levels of TNF-α, IL-6, and IL-1β in BALF, WBC count and NEU% in peripheral blood, and lung histological damage. Pulmonary function, IL-10 levels, and LYM% in peripheral blood also showed improvement. BCEO effectively decreased the proportion of M1 phenotype macrophages in BALF, M1/M2 ratio, and apoptotic cells in the lung tissue while increasing the proportion of M2 phenotype macrophages in BALF. Furthermore, BCEO treatment led to reduced protein and mRNA levels of TLR4, MyD88, and p-p65, alongside increased p65 expression, suggesting its potential to impede the TLR4/MyD88/NF-κB signaling pathway. SFE-extracted BCEO or its major constituents could serve as a viable treatment for ALI by reducing lung inflammation, improving pulmonary function, and protecting against LPS-induced ALI in mice. This therapeutic effect is achieved by inhibiting M1 macrophage polarization, promoting M2 macrophage polarization, and suppressing the TLR4/MyD88/NF-κB signaling pathway.

Chemical variability and insect repellent effects of lemon catnip essential oil and related phytochemicals against Cimex lectularius L

Plants are sources of natural products that reflect the ecological interactions that shaped their secondary metabolism. Among those, phytochemicals with insect repellent activity have shown potential to be part of integrated pest management programs. In this study, we performed an initial screening of the repellent activities of five commercially available essential oils, as well as the essential oil of lemon catnip (Nepeta cataria var. citriodora Dumoulin ex Lej.) and related natural products against the common bed bug (Cimex lectularius L.). Additionally, we studied the effects of two different growing locations (Upper Deerfield and Pittstown, state of New Jersey, United States) on the chemical composition of three lemon catnip lines (commercial lemon catnips Richters and Jelitto, and lemon-scented catnip line CN5). The chemical composition of the essential oils was determined by gas chromatography-mass spectrometry (GC-MS) and the repellent activity was assessed by the petri dish method. Cinnamon bark, clove buds, citronella and geranium essential oils were as effective as N,N-diethyl-meta-toluamide (DEET), the gold standard of insect repellents, against bed bugs after one hour of exposure in vitro. The essential oil of lemon catnip and its major compounds citronellol and geraniol were also as repellent as DEET using the same test. Citral shows promising short-term repellency but is inferior to geraniol and citronellol for extended duration of repellency. As for the chemical variability of lemon catnip lines in different growing locations, CN5 line was not significantly affected by the different locations, while both commercial lines Richters and Jelitto had significantly higher proportions of geraniol when grown in Upper Deerfield. Richters lemon catnip produced more nepetalactone in its essential oil when cultivated in Pittstown. This study is the first report of the activity of lemon catnip essential oil as an insect repellent and emphasized the importance of ecological conditions for the production of natural products for pest control applications.

Antimicrobial and Antioxidant Activities of Sesquiterpenes-Rich Essential Oil of Trichilia monadelpha (Thonn) J.J. De Wilde of Root Bark

Trichilia monadelpha (Thonn) J.J. De Wilde (Meliaceae) is used in traditional medicine for the treatment of ulcers, cough and inflammatory disorders such as arthritis. In this present study, the essential oil of T. monadelpha root bark was obtained by hydrodistillation using an all-glass Clevenger apparatus. The identification and characterisation were done using Gas Chromatography-Mass Spectrometry. We also, aimed to evaluate the antimicrobial activity of the essential oil against ten micro-organisms using the Agar diffusion method and the free radical scavenging capacity was determined using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) methods. Twenty (20) different compounds made up the hydrodistilled essential oil, which made up 99.0% of the entire oil content. Sesquiterpene compounds made up about 73.3% of the essential oil from the root bark of T. monadelpha, which was described as sesquiterpenes-rich. Sesquiterpenes' most abundant constituents include (E)-Longipinene (18%), 10s,11s-Himachala-3-(12),4-diene (15.26%), Aromadendrene (11.12%), Alloaromadendrene oxide-(1) (8.82%), and β-Caryophyllene (5.92%). The essential oil inhibited growth against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aerugunosa, Candida albicans, Aspergillus niger, Klebsiella Pneumonia and Salmonella typhi at concentrations of 200 mg/mL to 50 mg/mL with an inhibitory zone of 20 – 10 mm while the antioxidant analysis of the essential oil revealed low scavenging activity which reveals that the synthetic antioxidants were more effective with an Ascorbic acid; IC50 value of 1.47 mgmL-1, Butyl hydroxyanisole; 1.88 mgmL-1, α-Tocopherol; 4.83 mgmL-1 followed by the essential oil with an IC50 value of 9.95 mgmL-1. T. monadelpha root bark essential oil contains notable chemical compounds that are responsible for its antioxidant and antimicrobial activities.

Oral Rinses: Some Kill and Some Cripple Candida albicans

Introduction: Oral healthcare professionals play a crucial role in guiding patients toward evidence-based choices among the many available oral rinses. In this study, we explored how specific oral rinse formulations affect the viability and modulate critical virulence traits of the opportunistic fungal pathogen Candida albicans. Materials and Methods: We assessed the effects of these oral rinses on the production of germ tube, production of phospholipase and hemolysin, as well as biofilm formation. Results: We found that oral rinses containing cetylpyridinium chloride (CPC) and chlorhexidine (CHX) showed the greatest fungicidal activity with the lowest minimum fungicidal concentrations (0.38% and 0.78%, respectively). Oral rinses based on zinc chloride and sodium fluoride with Miswak bark extract (MIS) or essential oils (EO) had much lower fungicidal activity (8–16 times lower) compared to CHX and CPC. However, they had a significantly greater impact on the virulence traits of C. albicans. They reduced germ tube production by 86–89% (vs. 42% for CHX and 29% for CPC), completely inhibited phospholipase and hemolysin production, and together with the CPC-based oral rinse, exerted the greatest reductions in biofilm formation across all tested concentrations. This was in contrast to both the controls and CHX, which had a minimal effect on biofilm formation. Conclusion: By inhibiting the virulence factors, the oral rinse can have a crippling effect on C. albicans, weakening this opportunistic pathogen and hindering its potential to cause infection.

Enzyme-Based Antiviral Potential of Cinnamomum verum J. Presl. Essential Oil and Its Major Component (E)-Cinnamaldehyde.

In the present study, Cinnamomum verum J. Presl. bark essential oil and its main component cinnamaldehyde was evaluated in vitro for neuraminidase (NA), transmembrane serine protease (TMPRSS2), and angiotensin converting enzyme 2 (ACE2) inhibitory activities. The chemical composition of C. verum essential oil was confirmed by both gas chromatography-mass spectrometry (GC/MS), and gas chromatography-flame ionization detection (GC-FID), where 75.9% (E)-cinnamaldehyde was the major component. The ACE2, NA, and TMPRSS2 enzyme inhibitions of C. verum bark essential oil at 20 μg/mL concentration, and (E)-cinnamaldehyde (5 μg/mL) were calculated and compared in the range of 54.2-89.9%. Molecular docking results supported that (E)-cinnam-aldehyde was specific to ACE2 with 89.9% inhibition. Our findings suggest further in vivo studies to confirm the effective and safe use of the essential oil as well as the (E)-cinnamaldehyde.

Essential oils on the control of fungi causing postharvest diseases in mango.

The use of fungicides in the postharvest treatment of mangoes has been widespread due to the incidence of pathogens, but awareness of the health risks arising from their use has increased, driving the search for more sustainable treatments. This study aimed to evaluate the activity of antifungal treatment of seven essential oils (EO) against four fungi that cause postharvest diseases in mangoes and define the minimum inhibitory concentration (MIC) and chemical composition, analyzed by gas chromatography (GC-MS). The results showed that the EOs of oregano, rosemary pepper, cinnamon bark, and clove inhibited 100% of the mycelial growth of the studied pathogens, with MIC ranging from 250 to 2000 μL.L-1. The main compound found in oregano was carvacrol (69.1%); in rosemary and pepper oil, it was thymol (77.2%); cinnamaldehyde (85.1%) was the main constituent of cinnamon bark, and the eugenol (84.84%) in cloves. When evaluating the antifungal activity of these compounds, thymol and carvacrol showed greater inhibitory activity against fungi. Therefore, this study showed the great potential of oregano, clove, rosemary pepper, and cinnamon bark essential oil as alternative treatments to synthetic fungicides in controlling postharvest diseases in mangoes.

Evaluation of a push-and-pull strategy using volatiles of host and non-host plants for the management of pear psyllids in organic farming.

Pear decline (PD) is one of the most devastating diseases of Pyrus communis in Europe and North America. It is caused by the pathogen 'Candidatus Phytoplasma pyri' and transmitted by pear psyllids (Cacopsylla pyri, C. pyricola, and C. pyrisuga). Identifying attractant and repellent volatile organic compounds (VOCs) could improve the development of alternative plant protection measurements like push-pull or attract-and-kill strategies against pear psyllids. Our objective was to investigate which chemical cues of the host plant could influence the host-seeking behavior of pear psyllids, and if cedarwood (CWO) and cinnamon bark (CBO) essential oils could serve as repellents. Based on the literature, the five most abundant VOCs from pear plants elicited EAG responses in both C. pyri and C. pyrisuga psyllid species. In Y-olfactometer trials, single compounds were not attractive to C. pyri. However, the main compound mixture was attractive to C. pyri and C. pyrisuga females. CWO and CBO were repellent against C. pyri, and when formulated into nanofibers (NF), both were repellent in olfactometer trials. However, CBO nanoformulation was ineffective in masking the odors of pear plants. In a field trial, attractive, repellent CWO and blank formulated NF were inserted in attractive green sticky traps. C. pyri captures in traps with CWO NF were statistically lower than in traps with the attractive mixture. Nevertheless, no statistical differences in the numbers of caught specimens were observed between CWO NF and those captured in green traps baited with blank NF. Transparent traps captured fewer psyllids than green ones. In a second field study with a completed different design (push-and-count design), dispensers filled with CBO were distributed within the plantation, and attractive green sticky traps were placed around the plantation. The numbers of trapped pear psyllids increased significantly in the border of the treated plantation, showing that psyllids were repelled by the EOs in the plantation. Although further field evaluation is needed to assess and improve their effectiveness, our results show that these aromatic compounds, repellent or attractive both in nanoformulations and marking pen dispensers, offer great potential as an environmentally sustainable alternative to currently applied methods for managing pear decline vectors.

Effect of afforestation of the coastal savannah of Pointe-Noire (Congo-Brazzaville) on the chemical composition of leaves and stem bark essential oils from Xylopia aethiopica (Dunal) A. Rich

Effect of afforestation of the coastal savannah of Pointe-Noire (Congo-Brazzaville) on the chemical composition of leaves and stem bark essential oils from Xylopia aethiopica (Dunal) A. Rich

Phytochemical constituents of bark essential oils of Cinnamomum zeylanicum Blume and effects on liver tissue of rats

Cinnamomum zeylanicum Blume is an evergreen tropical tree belonging to the Lauraceae family; it is a useful plant in traditional and modern medicines. Essential oils of Cinnamomum zeylanicum were prepared and identified using gas chromatography–mass spectrometry (GC-MS). For histological study 80 adult male rats were employed in this study. It is the same weight (30 ±5 gm) and 75 days in age. The animals were divided into 4 groups, with ten rats in each group. The results indicated that C. zeylanicum bark contained 27 different phytochemical components. The main components included Cinnamaldehyde (2-Propenal, 3-phenyl-) (46.46%), 9-Methoxybicyclo, [6.1.0] nona-2,4,6-triene (31.31%), alpha-, Muurolene (7.14%) and Copaene (1.63%). Sections of livers were examined for histological abnormalities, such as the breakdown of the liver architecture and increased inflammation, in comparison to control samples, some hepatocytes were swollen with pyknotic, large nuclei and dilated sinusoids. As well as in the rats treated with noticed sever congestion of central vein (CV), degeneration and sluggish of endothelial lining larger, Bile ducts hyperplasia and necrotic hepatocytes. It can be deduced that the main component of cinnamon bark oil is cinnamaldehyde and the liver displayed some tissue changes, including hepatocyte necrosis and the existence of steatosis foci. Histological and cellular changes in liver tissue were dramatically attenuated by C. zeylanicum essential oil.

Transcriptional Response of Pectobacterium carotovorum to Cinnamaldehyde Treatment.

Cinnamaldehyde is a natural compound extracted from cinnamon bark essential oil, acclaimed for its versatile properties in both pharmaceutical and agricultural fields, including antimicrobial, antioxidant, and anticancer activities. Although potential of cinnamaldehyde against plant pathogenic bacteria like Agrobacterium tumefaciens and Pseudomonas syringae pv. actinidiae causative agents of crown gall and bacterial canker diseases, respectively has been documented, indepth studies into cinnamaldehyde's broader influence on plant pathogenic bacteria are relatively unexplored. Particularly, Pectobacterium spp., gram-negative soil-borne pathogens, notoriously cause soft rot damage across a spectrum of plant families, emphasizing the urgency for effective treatments. Our investigation established that the Minimum Inhibitory Concentrations (MICs) of cinnamaldehyde against strains P. odoriferum JK2, P. carotovorum BP201601, and P. versatile MYP201603 were 250 μg/ml, 125 μg/ml, and 125 μg/ml, respectively. Concurrently, their Minimum Bactericidal Concentrations (MBCs) were found to be 500 μg/ml, 250 μg/ml, and 500 μg/ml, respectively. Using RNA-sequencing analysis, we identified 1,907 differentially expressed genes in P. carotovorum BP201601 treated with 500 μg/ml cinnamaldehyde. Notably, our results indicate that cinnamaldehyde upregulated nitrate reductase pathways while downregulating the citrate cycle, suggesting a potential disruption in the aerobic respiration system of P. carotovorum during cinnamaldehyde exposure. This study serves as a pioneering exploration of the transcriptional response of P. carotovorum to cinnamaldehyde, providing insights into the bactericidal mechanisms employed by cinnamaldehyde against this bacterium.

Chemical profiling and biological assessment of trunk bark essential oil from Eucalyptus camaldulensis: In vitro study coupled with chemoinformatics calculations

The aim of this study was to identify the chemical composition of the essential oil of Eucalyptus camaldulensis trunk bark (ECEO) and to investigate its in vitro antioxidant, anti-5-lipoxygenase, anti-acetylcholinesterase, anti-butyrylcholinesterase and anti-α-amylase activities. The chemical composition of the essential oil extracted from trunk bark of E. camaldulensis was analyzed by GC-FID and GC/MS, twenty-one compounds were identified accounting for 96.3% of total oil. The phytochemical profile of this essential oil was distinguished by the dominance of oxygenated monoterpenes (58.4%) with Δ8,9-dehydro-4-hydroxythymoldimethyl ether (31.4%), thymohydroquinone methyl ether (21.9%), and modephen-8-β-ol (12.9%) as major compounds. Additionally, the ECEO was examined for its antioxidant activity using three in vitro tests (DPPH, ABTS•+ radicals and H2O2 assays). ECEO showed the highest effect in the hydrogen peroxide assay (IC50= 33.55 ± 2.10 µg/mL). Additionally, ECEO exhibited significant anti-α-amylase and anti-acetylcholinesterase activities (IC50= 10.02 ± 1.88 and 5.88 ± 0.81 μg/mL, respectively). In silico analysis was in agreement with the in vitro studies in which most potent components of ECEO showed strong interactions into the binding sites of the enzymes (PDBs: 4EY6 (acetylcholinesterase), and 7TAA (α-amylase)) and good ADMET properties. Our results might be due to the synergistic effect of constituents present in this essential oil or acting separately. The obtained results pave the way for the promising applications the essential oil obtained from E. camaldulensis trunk bark in food and the pharmaceutical fields.

IN VITRO ANTIFUNGAL EFFECT OF TWELVE ESSENTIAL OILS ON PENICILLIUM EXPANSUM GROWTH

The questionable safety of food spoiled by microorganisms is and should be the subject of attention and investigation. Pathogens such as Penicillium expansum are more difficult to control due to their resistance and ubiquity. Awareness of plant essential oils (EOs) as alternative natural preservatives is increasing because of their significant antimicrobial activity. The aim of this research work was therefore to contribute to this topic with new results. The antifungal activity of twelve EOs was tested in vitro against five strains of Penicillium expansum, using the vapour-phase diffusion method. Three EOs, from bergamot, star anise and rosaline, inhibited colony growth during two-week cultivation with a partial efficacy, all other EOs showed complete (100%) inhibitory activity at a concentration of 625 μL.L-1. These (EOs from clove, cinnamon, cinnamon bark, laurel, lemongrass, peppermint, Mitcham mint, spearmint, and lavender) were included in the second part of the trial, the aim of which was to determine their minimum inhibitory doses (MIDs). In the case of peppermint, Mitcham mint, spearmint and lavender EOs, some strains of P. expansum grew already at a concentration of 500 μL.L-1. Clove EO stopped the fungal growth of two strains at 250 μL.L-1. Laurel EO was 100% effective at MID 250 μL.L-1 throughout the cultivation period. EOs from lemongrass and cinnamon bark had similar efficacy on the strains. Both EOs were able to inhibit one strain at a MID of 125 μL.L-1, cinnamon bark EO inhibited the remaining strains at 250 μL.L-1, lemongrass EO inhibited three strains at 250 μL.L-1 and one at 500 μL.L-1. The lowest MID was recorded for cinnamon EO, which effectively inhibited two strains at 125 μL.L-1, two strains at 62.5 μL.L-1 and one strain even at 31.25 μL.L-1. The sensitivity of the strains used in this study varied according to the EOs used.

Chemical composition, in vitro antioxidant assessment and toxicity test of the essential oils of Bridelia ferruginea Benth

Bridelia ferruginea Benth is a plant usually found in Savannah regions, used in ethno-medicine for treatment of dysentery, elephantiasis, intestinal and bladder disorder. Chemical compounds present in the leaf, twig, stem bark, stem wood and root wood of Bridelia ferruginea essential oils, their antioxidant and toxicity assays are been reported. The essential oils were obtained by hydro-distillation and analysed by means of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The antioxidant assay was conducted using 1,1-diphenyl-2-picrylhydrazyl (DPPH) while the brine shrimp lethality test was carried out using Artemia salina eggs. Leaf, twig, stem bark, stem wood and root wood essential oils gave yields of 0.44%, 0.42%, 0.51%, 0.20% and 0.26% respectively. A total of eighty-two (82) compounds were identified in the five essential oils. Ethyl salicylate was the dominant constituent of the leaf essential oil (41.15%) while methyl salicylate was most abundant in the twig (33.33%) and stem bark (24.67%) essential oils. Stem wood oil contained ethyl salicylate (12.60%) while the root wood oil was composed mostly of 1-octadecene (18.53%). The antioxidant assay showed that stem bark had the most activity (53.12 μg/mL) while the least activity was recorded for twig oil (1037.14 μg/mL). The brine shrimp lethality test revealed that lethal concentration at 50% level (LC50) for leaf essential oil was non-toxic (74361.99 μg/mL). Bridelia ferruginea is rich in antioxidants; significant amounts of monoterpenoids and sesquiterpenes in the essential oils support the use of the plants in ethno-medicine.