Major Components Of Essential Oil Research Articles

MODELING AND OPTIMIZATION OF THE ORANGE LEAVES OIL EXTRACTION PROCESS BY MICROWAVE-ASSISTED HYDRO-DISTILLATION: THE RESPONSE SURFACE METHOD BASED ON THE CENTRAL COMPOSITE APPROACH (RSM-CCD MODEL)

Although being a by-product after the harvest, orange leaves could be used to produce essential oil through extraction. Application of the essential oil extracted from orange leaves is diverse ranging from food flavoring to cosmetics. This study aimed to develop optimal conditions for microwave assisted hydro-distillation of essential oil from orange leaves. The selected optimization method is Response Surface Methodology in conjunction with the central composite experiment design. The factors that were varied for the production of the orange leaves oil extraction were material-to-water ratio, extraction time, and microwave power. Accordingly, a statistical model was established and Analysis of variance (ANOVA) was carried out to identify the set of factors that gives the highest essential oil yield. Optimization results revealed optimal conditions as follows, material and water ratio of 3.46:1 (mL/g), extraction time of 100.47 min and operating power of 471.58 W. These conditions correspond to the essential oil yield of 0.43% with 92.1 % reliability. In addition, we also analyze the produced essential oils by gas chromatography-mass spectrometry (GC-MS). The GC-MS results revealed that major components of essential oil were Sabinene (30.556 %), Cis-Ocimene (10.139 %), and D-Limonene (9.682 %).

Ritmo Circadiano e Atividade Larvicida contra Aedes aegypti de Óleos Essenciais de Croton piauhiensis

Croton piauhiensis, popularly known as velame, is a restricted species of Caatinga biome. In this context, this work aims to study the circadian cycle and larvicidal activity against Aedes aegypti of the essential oils of C. piauhiensis. The chemical composition of the essential oils from leaves obtained by hydrodistillation were analyzed and identified by GC-MS and GC-FID. According to the results, the circadian study showed differences in the chemical composition of oils extracted at different hours of the day from C. piauhiensis leaves. The major components of essential oils from C. piauhiensis at 8 a.m., 12 a.m and 17 p.m. were β-caryophyllene 21.58, 34.69 and 21.01%, D-limonene 13.47, 13.75 and 16.35, γ-terpinene 10.08, 8.00 and 9.60%, Germacrene D 9.56, 10.42 and 8.71%, respectively. Sesquiterpenes contents were 52.59% and 67.29% at 8h and 12h, respectively. On the other hand, at 17h there was a greater predominance of the monoterpenes (50.77%). Regarding the larvicidal activity, the essential oils of C. piauhiensis showed larvicidal activity with LC50 = 336.8 μg / mL (oil extracted at 8:00 h), LC50 = 283.9 μg/mL (oil extracted from 12:00 h) and LC50 = 252.5 μg / ml (oil extracted at 17:00 h).

Sabinene suppresses growth, biofilm formation, and adhesion of Streptococcus mutans by inhibiting cariogenic virulence factors

ABSTRACTBackground: Streptococcus mutans is one of the most important cariogenic bacteria associated with dental caries. Sabinene is a major component of several herbal essential oils. However, the anti-cariogenic effects of sabinene and the underlying mechanism remain to be elucidated.Objectives: We investigated the inhibitory effects of sabinene on the cariogenic activity and studied the underlying mechanism.Design: S. mutans were treated with various concentrations of sabinene and the inhibitory effects were evaluated based on the bacterial growth, acid production and biofilm formation. Real-time polymerase chain reaction (PCR) was performed for several virulence factors.Results: The growth and adherence of S. mutans were inhibited by sabinene. Consistent with the inhibitory effects on bacterial adhesion, gbpB level significantly decreased. Acid production and biofilm formation was also inhibited. In line with the inhibitory effects of sabinene on biofilm formation and pH tolerance, real-time PCR results showed the down regulation in the expression levels of gtfB, gtfC, gtfD, vicR, brpA, and relA. Moreover, high concentrations of sabinene exhibited bactericidal activity.Conclusion: Together our results suggest that sabinene serves as a useful component in the inhibition of the cariogenic activity of S. mutans, indicative of its possible applications in the development of oral healthcare products.

Larvicidal activity of essential oil from Vitex negundo and Vitex trifolia on dengue vector mosquito Aedes aegypti

The ability of Vitex trifolia and Vitex negundo essential oils to kill Aedes aegypti and Culex quinquefasciatus larvae was evaluated. The larvae were treated with their respective essential oils at 50-125 ppm concentration. LC50 and LC90 for V. trifolia against Ae. aegypti and C. quinquefasciatus, and those for V. negundo against Ae. aegypti were 57.7+0.4, 77.9+0.9 ppm and 55.17+3.14, 78.28+2.23 ppm, and 50.86+0.9, 73.12+1.3 ppm, respectively. Eucalyptol and caryophyllene were the major components in Vitex trifolia and Vitex negundo essential oil, respectively. This study revealed potential larvicidal properties of essential oil from V. trifolia.

In vitro mass propagation and conservation of a rare medicinal plant, Zhumeria Majdae Rech.f & Wendelbo (Lamiaceae)

Abstract The monotypic Zhumeria majdae (Lamiaceae), an endangered medicinal and aromatic plant in the south part of Iran, has a low propagation rate in natural condition and therefore an efficient method for the in vitro-propagation is required. In the present study, the effects of source and position of the explants as well as various concentrations of 6-benzylaminopurine and kinetin on inhibition of hyperhydricity and in vitro mass propagation of the plant were investigated. The best shoot formation (1.9 ± 0.07) was obtained with a Murashige and Skoog medium fortified with 17.7 µM 6-benzylaminopurine. Regenerated shoots, elongated on the MS medium containing 2.2 μM 6-benzylaminopurine, were rooted on the different tested media, with the most abundant (68.6 ± 4.1%) and strongest roots obtained on half-strength medium without plant growth regulators. Hydro-distilled essential oils of in vitro regenerated plant were analyzed by gas chromatography–mass spectrometry and compared with the essential oil of wild plant. Thirty and twenty compounds representing 98.2% and 98.7% of the total oils were identified in the oils of wild plant and in vitro regenerated plant, respectively. The major essential oil components were linalool (31.7% and 41.7%), camphor (28.0% and 32.4%), limonene (4.6% and 8.3%), camphene (4.1% and 3.5%) and E-caryophyllene (1.0% and 2.7%) in the studied (wild plant and in vitro regenerated plant) essential oils. The in vitro regeneration system could be utilized for both conservation, large-scale multiplication and production of rich linalool essential oils of Z. majdae.

Antimicrobial activity of volatile and non-volatile isolated compounds and extracts from the bark and leaves of Warburgia salutaris (Canellaceae) against skin and respiratory pathogens

Warburgia salutaris is one of the most popular trees used in traditional medicine throughout tropical southeast Africa, because of its ability to treat a wide variety of illnesses caused by fungi, bacteria, viruses and insects. The aim of the study was to test the antimicrobial activity of W. salutaris and its isolated compounds against selected skin and respiratory pathogens. Furthermore, to investigate the main chemical compounds of this species and compare their antimicrobial activities with previously published studies. Crude extracts, essential oils and isolated compounds from the bark of W. salutaris, showed antimicrobial activity against skin pathogens (Pseudomonas aeruginosa ATCC 743971 and Staphylococcus aureus ATCC 25923) and respiratory tract pathogens (Klebsiella pneumoniae ATCC 13883 and Moraxella catarrhalis ATCC 23246). Bioassay guided fractionation of the dichloromethane extract (muthi market bark sample) and essential oil (from the bark of the cultivated tree) yielded six compounds, which included the two major essential oil components drimenol (1) and E-nerolidol (2) and the less volatile drimane sesquiterpenes from the muthi market bark: 12α-acetal-polygodial (3), polygodial (4), ugandensidial (5) and warburganal (6). Noteworthy activity against M. catarrhalis was observed by 2 with a minimum inhibitory concentration of 31 μg/ml and by 4 with an MIC of 25 μg/ml against K. pneumoniae. This is the first report of 1,2 and 3 isolated from W. salutaris and the identification of these compounds could explain the traditional use of this species as an inhalation therapy to treat respiratory ailments. Despite numerous studies, the chemical composition and biological activities of the leaves and bark of W. salutaris are not yet fully explored.

Phytochemical profile, antioxidant activity, inhibition of acetylcholinesterase and interaction mechanism of the major components of the Piper divaricatum essential oil obtained by supercritical CO2

The present study reports the use of supercritical CO2 at different combinations of temperature and pressure: (35 and 55) °C, and (100, 300, and 500) bar to obtain fractions of the essential oil Piper divaricatum. The mass yields from extraction, chemical composition, antioxidant activity, and acetylcholinesterase (AChE) inhibitory activity were analyzed. The supercritical CO2 extraction showed better efficiency for obtaining essential oil compared with hydrodistillation. The isotherm of 55 °C/ 500 bar led to the highest mass yield (7.40 ± 0.08) %. methyl eugenol was the compound with the highest concentration ranging from (48.01–61.85) %, and the fraction obtained in the condition of 35 °C/ 300 bar was the most effective regarding the antioxidant activity, with values of (34.69 ± 1.38) % (DPPH) and (296.86 ± 8.96) mgTrolox/mL (ABTS), respectively. Ligands, after molecular docking, exhibited molecular poses that promoted interactions with different residues of amino acids that are important for the enzymatic catalysis with His447.

A new source of oxygenated monoterpenes with phytotoxic activity: essential oil of Cuminum Cyminum L. from Iran

Chemical constitutes and phytotoxic activity of Cuminum cymiunm L. is investigated in the present study. For this means seeds of C. cyminum L. was harvested from Ilkhchi of Iran. The major components of essential oil (EO) with more than 94% were 3-caren-10-al, cuminal, 2-Caren-10-al, γ-Terpinene, (-)-β-Pinene and p-Cymene. This study found that cumin EO displayed meaningful inhibitory impacts on germination indices and the growth of the seedlings of Amaranthus retroflexus, Lactuca sativa, and Acroptilon repens. The germination indices showed severely concentration-dependent responses. In the case of A. retroflexus and L. sativa germination indices were controlled in the 500 ppm and in the A. repens were inhibited in the 1500 ppm of EO concentration. Overall, this study suggests that EO derived from C. cyminum L. looks to be a promising candidate for its utilization as a natural herbicide in large scale.

Reporting effective extraction methodology and chemical characterization of bioactive components of under explored Platycladus orientalis (L.) Franco from semi-arid climate

The bioactive ingredients of many essential oils are complex and difficult to reproduce synthetically. In the present study, the influence of extraction method on relative extraction of bioactive compounds of essential oil of Platycladus orientalis (L.) Franco (Thuja orientalis L. is a synonym of it) leaves gathered from semi-arid climate was studied. A higher yield of essential oil was obtained by hydrodistillation (0.1%) as compared to steam distillation (0.07%) under newly optimized conditions. Initial analysis of these oils by TLC showed the presence of different polarity groups ranging from non-polar terpene hydrocarbons to polar terpenoid alcohols. GC-MS analysis revealed that major component of hydrodistilled essential oil of Platycladus orientalis (L.) Franco leaves was α-pinene (17.83%) and steam distilled essential oil contained α-cedrol (12.44%). The results obtained in the present study emphasize that suitable extraction technique should be used to obtain particular component of interest.

Essential oil of peppermint in symbiotic relationship with Piriformospora indica and methyl jasmonate application under saline condition

Peppermint (Mentha piperita L.) is one of the most important medicinal and aromatic plants that its essential oil is extensively used in fragrance, aromatherapy, flavor, and pharmaceutical properties. This study aimed to evaluate the effects of Piriformospora indica inoculation, methyl jasmonate and salinity effects on essential oil from leaves, total phenol, anthocyanin, reactive oxygen species (ROS)-scavenger activity and composition of the oil in peppermint. Treatments included inoculation, and non-inoculation of P. indica, methyl jasmonate (0 and 75 μM) and four salinity levels of irrigation water (0, 3, 6 and 9 dS m−1). Essential oil constituents have been analyzed by GC–MS. The results showed that salinity increased lipid peroxidation as well as membrane electrolyte leakage, while, membrane permeability influenced by methyl jasmonate application, P. indica inoculation and their interaction, reduced the negative effect of salinity on membrane electrolyte leakage. Fungal symbiosis and methyl jasmonate application ameliorated the negative effects of salinity on essential oil content. The results showed that monoterpenes constitute the major components of essential oil. The main oil constituents, menthol, menthone and 1,8-cineole increased considerably in P. indica and methyl jasmonate treatments. The highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and polyphenol oxidase was observed in the P. indica inoculation, however methyl jasmonate treatment gave the highest content of total phenol and anthocyanin. In general, when inoculated plants were sprayed by methyl jasmonate, antioxidant activity increased and synthesis of medicinal and anti-microbial compounds was observed.

Mexican oregano (Lippia graveolens) essential oil-in-water emulsions: impact of emulsifier type on the antifungal activity of Candida albicans.

This study examined the impact of emulsifier type on the physicochemical characteristics and antifungal capacity of oregano oil-in-water emulsions: Tween 80, hydroxylated soy lecithin, and gum arabic. GC/MS analysis showed that the major components of the Lippia graveolens essential oils were thymol (31.7%), p-cymene (18.7%), and carvacrol (14.6%). The oil-in-water emulsions were made using ultrasonic technology in which thymol and carvacrol quantities were 12.26-13.67g/L and 5.6-6.2g/L, respectively. The droplet size of the emulsions followed the next descendent order: gum arabic > lecithin > T80. The zeta potential of the emulsions favored the stability against coalescence. Finally, the antifungal activity of the emulsions was evaluated, in which, 30µL/mL of gum arabic or hydroxylated soy lecithin emulsions inhibited the growth of Candida albicans. The result suggests that Mexican oregano essential oil emulsions can be used as an antifungal against of C. albicans.

A study on essential oil yield and components of dryed and fresh foliage of peppermint (Mentha piperita L.) cultivated in Turkey

In the study, essential oil yield and its components dryed and fresh foliage obtained from peppermint [Mentha piperita L. (Lamiaceae)] cultivated in Konya ecological conditions were investigated. The yield of essential oil from dryed and fresh peppermint foliage was determined to be 3.2 % and 2.9 %, respectively. The major essential oil components of dryed and fresh foliage peppermint oil were determined as mentone (50.80 %), mentol (34.55 %) and mentone (48.18 %), mentol (21.77), respectively. The aim of this research attempts to contribute to knowledge of differences between essential oil yield and components of the dryed and fresh foliage peppermint (Mentha piperita L.) cultivated Konya ecological conditions, Turkey.

Phytochemical characterisation and bioactive properties of Solanum sodomaeum L. fruits at two stages of maturation

Summary Introduction: Solanum sodomaeum L. has been observed to have several medicinal properties, in particular, in the treatment of several types of human skin cancer. Objective: The influence of the maturation stage of S. sodomaeum fruits on the total lipid contents, fatty acid profiles, essential oil yields and compositions, as well as the antibacterial and antioxidant activities of the essential oils, was investigated. Methods: The fatty acid and essential oil constituents were identified using gas chromatography (GC) and GC–mass spectrometry (GC–MS). The antioxidant properties of essential oil and vegetal oil were assessed using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging and reducing power assays. The antibacterial activity of essential oil was tested using the disc diffusion assay for resistance in human pathogenic bacteria. Results: Mature fruits showed higher total lipid content (17%) and were characterised by polyunsaturated fatty acids (53.87%), represented mainly by linoleic acid (53.11%). Similar yields of essential oils were detected for immature (0.43%) and mature (0.45%) fruits. Tetrahydronaphthalene (41.79%) was detected as the major essential oil component at the immature stage versus dihydrocoumarin pentane (18.27%), hexadecanoic acid (17.43%) and 2-undecanone (13.20%) in mature fruits. The DPPH test showed that essential oils had better antioxidant properties; however, the vegetal oils showed better performance in the reducing power assay. Moreover, the essential oil of S. sodomaeum mature fruits was active against bacterial strains. Conclusions: S. sodomaeum fruits could be a valuable source of natural antioxidants and antibacterial agents.

Chemical Profiling and Insecticidal Activity of <em>Artemisia herba-alba</em> Essential Oil Against Papaya Mealybug <em>Paracoccus marginatus</em> ‎(Hemiptera: Pseudococcidae)

The current study aimed to investigate the chemical composition and insecticidal activity of Artemisia herba-alba essential oil obtained by hydrodistillation and solvent extraction against papaya mealybug Paracoccus marginatus. The essential oil was analysed using gas chromatography-mass spectrometry and the insecticidal activity was recorded for different times and concentrations under laboratory conditions. According to GC-MS results, the chemical components detected of essential oil isolated by ‎hydrodistillation and solvent extraction were 52 and 62 compounds of both extraction methods, the main components of essential oil of hydrodistillation method were eucalyptol (32.81%), &alpha-pinene (28.62%) and linalol (10.18%) while the major components of essential oil isolated by solvent extract were pentadecanoic acid (16.69%) and dihomo-‎‎.gamma.-linolenic acid (15.2%). The essential oil of hydrodistillation method exhibited more insecticidal ‎activity than solvent extract method against P. marginatus, 1000 mg/L of essential oil isolated by ‎hydrodistillation achieved 100% ‎mortality of papaya mealybugs after 120, ‎‎168 h of treatment with LC50 values which ‎was‎‎ 65.362 mg/L after 168 h from treatment and LT50 value which was ‎22.386 h‎‏‎‎ at 1000 mg/L.‎ The findings reveal and propose that the essential oil of A. herba-albais a rich by bioactive components and it is a prospective source of botanical insecticides.

Antifungal Activity of Eugenol Loaded Electrospun PAN Nanofiber Mats Against Candida Albicans.

Eugenol, as the major phenolic component of clove essential oil due to its desired properties in medical field, was loaded into polyacrylonitrile (PAN) nanofibers with various percentages. Our main purpose in this study was to determine the in vitro antifungal activity of eugenol loaded on PAN nanofibers against Candida albicans as the most common causative agent for candidiasis. Also, the surface morphology and the mechanical properties of nanofibers were studied by scanning electron microscope (SEM) and a tensile tester, respectively. The average diameters of nanofibers in pure PAN nanofibers were found to be 127 nm. The results showed that the average diameter of nanofibers after increasing the eugenol ratio (from 127 to 179-218 nm) was increased. Drug release profile of the samples was gradual and was completed after 150 hours. According to the results, these nanofiber mats loaded with eugenol can be used for treating cutaneous mucocutaneous candidiasis in high risk patients as a coating on a fabric substrate or temporary wound dressing.

Essential oils from unexplored aromatic plants quench biofilm formation and virulence of Methicillin resistant Staphylococcus aureus

In the current study we have evaluated the antibiofilm and antivirulent properties of unexplored essential oils (EOs) obtained from Pogostemon heyneanus and Cinnamomum tamala against Methicillin Resistant Staphylococcus aureus (MRSA) strains. The EOs from both the aromatic plants was screened for their ability to prevent biofilm formation and to disrupt preformed biofilms. The efficacy of both the EOs to disrupt the preformed biofilms of various MRSA strains was determined by Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscopy (SEM).The EOs were further able to reduce the Extracellular polymeric substance (EPS) and slime synthesis the two factors of the biofilm assemblage. The EOs was also found to be effective in reducing virulence factors like staphyloxanthin and hemolysin. In silico docking studies were performed for the major components of essential oils and dehydroxysqualene synthase of MRSA which is responsible for the synthesis of staphyloxanthin. The results suggest that (E)-nerolidol showed better binding affinity towards the enzyme. Other compounds have similar binding strengths with the enzyme. Furthermore, the synergistic effect EOs along with the commercially available DNaseI and Marine Bacterial DNase (MBD) showed that the synergistic effect had enhanced biofilm disruption ability. The results show that EOs from P. heyneanus and C. tamala has potential antivirulent and biofilm inhibitory properties against clinical and drug resistant S. aureus strains. The present study highlights the importance of bioprospecting plant based natural products as an alternative for antibiotics owing to the emergence of multi-drug resistant strains.

Synergistic interaction of β-caryophyllene with aromadendrene oxide 2 and phytol induces apoptosis on skin epidermoid cancer cells

BackgroundPamburus missionis (Wight) Swingle (Rutaceae) is traditionally used in the treatment of swellings, chronic rheumatism, paralysis and puerperal diseases. In a previous study the authors demonstrated apoptotic activity of Pamburus missionis essential oil (EO) on A431 and HaCaT cells. The major components of EO were β-caryophyllene (25.40%), 4(14),11- eudesmadiene (7.17%), aromadendrene oxide 2 (14.01%) (AO-(2) and phytol (6.88%). Purpose of studyTo investigate the role as well as the interactions among EO components inducing apoptosis in A431 and HaCaT cells. MethodsIsobolographic analysis and combination index methods were used to detect the type of interactions among the essential oil (EO) components. Cell viability was used to detect cytotoxic activity. Mechanism of cell death was studied using Annexin V-FITC/PI binding assay, cell cycle analysis, measurement of MMP and ROS generation by flow cytometry. Expression of apoptosis associated proteins was investigated by western blot. ResultsCombination of P. missionis EO components: β-caryophyllene/ aromadendrene oxide 2 (β-C/AO-(2)), β-caryophyllene/phytol (β-C/P) and aromadendrene oxide 2 /phytol (AO-(2)/P) inhibited growth and colony formation ability of skin epidermoid A431 and precancerous HaCaT cells. Synergistic interaction was observed between β-C/AO-(2) and β-C/P combination while AO-(2)/P exhibited an additive effect. Combination of components induced chromatin condensation, phosphatidylserine externalisation, increase in sub-G1 DNA content, cell cycle arrest at G0/G1 phase and intracellular ROS accumulation. Inhibition of intracellular ROS by N-acetyl cysteine treatment blocked apoptosis induced by the combinations. The combinations induced apoptosis in A431 and HaCaT cells mediated by loss of mitochondrial membrane potential (ΔΨm), increase in Bax/Bcl-2 ratio, release of cytosolic cytochrome c and activation of caspases (cleaved form of caspase-3, caspase-8, caspase-9) and by PARP cleavage. ConclusionThe present study demonstrates interactions among β-C, AO-(2) and P in the induction of apoptosis on A431 and HaCaT cells. These data suggest the combination of β-caryophyllene with aromadendrene oxide 2 and phytol could be potential therapeutics for the treatment of skin epidermoid cancer and precancerous cells.

Antibacterial activity of extracted bioactive molecules of Schinus terebinthifolius ripened fruits against some pathogenic bacteria

The aim of this work is to identify the chemical constituents and the bioactivity of essential oil (EO), acetone extract (ACE) and n-hexane extract (HexE) of S. terebinthifolius ripened fruits using GC-MS. Total phenolic content and antioxidant activity of extracts were determined using the Folin-Ciocalteu and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assays, respectively. The toxicity against the growth of Acinetobacter baumannii, Bacillus subtilis, Escherichia coli, Micrococcus flavus, Pseudomonas aeruginosa, Sarcina lutea, and Staphylococcus aureus was determined with measuring the inhibition zones (IZs) using the disc diffusion method at the concentrations from 125 to 2000 μg/mL, also, the minimum inhibitory concentrations (MICs) using 96-well micro-plates and ranged from 4 to 2000 μg/mL. The major components in EO were α-pinene (36.9%), and α-phellandrene (32.8%). The major components in ACE were oleic acid (38.7%), α-phellandrene (13.33%), and δ-cadinene (11.1%), while the major methyl esters of fatty acids detected in HexE were oleic (12.8%), and palmitic (10.9%). The EO showed good activity against the growth of Staph. aureus and P. aeruginosa with MIC values of 16 μg/mL and 32 μg/mL, the ACE showed broad activity against the studied bacterial pathogens with MIC values ranged from of 4–128 μg/mL against the studied bacterial isolates, while HexE, however, showed weak antibacterial activity. The IC50 values of EO, ACE and HexE were 15.11 ± 0.99, 118.16 ± 1.7 and 324.26 ± 2.45 μg/mL, respectively, compared to IC50 of Tannic acid (23.83 ± 1.9 μg/mL) and butylated hydroxytoluene (BHT, 2.9 ± 0.1 μg/mL). Data suggested that the ripened fruits of S. terebinthifolius have potent antioxidant and antibacterial activities.

Interaction of ascaridole, carvacrol, and caryophyllene oxide from essential oil of Chenopodium ambrosioides L. with mitochondria in Leishmania and other eukaryotes.

The antileishmanial activity of the essential oil (EO) from Chenopodium ambrosioides L. has been demonstrated in vitro and in animal models, attributed to the major components of the EO. This study focused on the effects of the three major EO compounds carvacrol, caryophyllene oxide (Caryo), and the antileishmanial endoperoxide ascaridole (Asc) on mitochondrial functions in Leishmania tarentolae promastigotes (LtP). EO and Caryo were able to partially inhibit the leishmanial electron transport chain, whereas other components failed to demonstrate a direct immediate effect. Caryo demonstrated inhibition of complex III activity in LtP and in isolated complex III from other species. The formation of superoxide radicals was studied in Leishmania by electron spin resonance spectroscopy in the presence of iron chelators wherein selected compounds failed to trigger a significant immediate additional superoxide production in LtP. However, upon prolonged incubation of Leishmania with Asc and especially in the absence of iron chelators (allowing the activation of Asc), an increased superoxide radical production and significant impairment of mitochondrial coupling in Leishmania was observed. Prolonged incubation with all EO components resulted in thiol depletion. Taken together, the major components of EO mediate their leishmanicidal activity via different mitochondrial targets and time profiles. Further studies are required to elucidate possible synergistic effects of carvacrol and Asc and the influence of minor compounds.

Eugenol derivatives: synthesis, characterization, and evaluation of antibacterial and antioxidant activities

Eugenol is the major component of clove essential oil and has demonstrated relevant biological potential with well-known antimicrobial and antioxidant action. Therefore, this work carried out the synthesis, purification, characterization, and evaluation of the antioxidant and antibacterial potential of 19 eugenol derivatives. The derivatives were produced by esterification reactions in the hydroxyl group (−OH) of eugenol with different carboxylic acids and also by addition reactions in the double bond of the allyl group. The derivatives had a promising antibacterial potential, including a lower minimum inhibitory concentration of 500 μg/mL than eugenol (1000 μg/mL). In addition, the derivatives were active against bacterial strains (Escherichia coli, Staphylococcus aureus) that eugenol itself showed no activity, thus increasing the spectrum of antibacterial action. As for the antioxidant activity, it was observed that the derivatives that involved esterification reactions in the hydroxyl group (−OH) of the eugenol molecule’s phenol resulted in a significant reduction of the antioxidant action (IC50 > 100 μg/mL) when compared with the eugenol precursor molecule (IC50 = 4.38 μg/mL). On the other hand, the structural changes located in the double bond affected much more smoothly the capacity of capturing radicals than the starting molecule, also being obtained derivatives with proximal antioxidant capacity (IC50 = 19.30 μg/mL) to commercial standards such as Trolox (IC50 = 16.00 μg/mL).