Antibacterial Activity Of Essential Oils Research Articles

Exploring the Antibacterial Properties and Chemical Profiles of Essential Oils from Syzygium aromaticum and Nigella sativa Against MDR Bacteria

For centuries, plants have been studied for their healing properties. Recently, the rise of antibiotic resistance in bacteria has prompted scientists to explore herbal remedies. Syzygium aromaticum, from the Myrtaceae family, has been utilized as a histological clearing agent. In contrast, Nigella sativa (black cumin), a member of the Ranunculaceae family, has long been utilized in traditional medicine dating back to ancient times. The current study investigates the chemical composition and antibacterial activity of essential oils from Syzygium aromaticum (clove) and Nigella sativa (black cumin) against multidrug-resistant (MDR) bacteria. Using the agar well diffusion method, Syzygium aromaticum exhibited significant antibacterial activity, particularly against Salmonella typhi (30.66 mm inhibition zone), while Nigella sativa was effective only against Staphylococcus aureus (19 mm). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for Syzygium aromaticum ranged from 3.53 to 7.06 mg/mL, indicating stronger antibacterial properties than Nigella sativa (MIC: 12.7 mg/mL, MBC: 22.5 mg/mL). GC-MS analysis revealed that Syzygium aromaticum contained bioactive compounds like Diglycolic acid (76.59%) and Eugenol (2.06%), while Nigella sativa was dominated by Heptasiloxane (80.83%) and Thymoquinone (2.66%). These findings suggest that Syzygium aromaticum essential oil could serve as a potent natural antimicrobial agent against MDR pathogens.

The Composition, Antioxidant and Antibacterial Activity of Essential Oils from Five Species of the Magnoliaceae Family.

The leaves of Magnoliaceae family plants contain abundant essential oils (EOs), and these species can be used in many fields due to their high industrial, medicinal, and ornamental values. This study aims to identify the main compounds of the EOs from the leaves of five common Magnoliaceae species (Michelia maudiae, Michelia hedyosperma, Michelia macclurei, Manglietia lucida, Manglietia conifer) using hydrodistillation, GC-MS analysis, and in vitro tests. Additionally, the antioxidant and antibacterial activities of the EOs were also evaluated. The results show that 151 compounds were identified across five species, with sesquiterpenes being dominant. Some key compounds (such as β-caryophyllene, δ-amorphene, β-guaiene, globulol, and β-acorenol) were common among all the species, highlighting their crucial roles in plant physiology and resilience. Other compounds (like valeranone and nerolidol in M. maudiae and β-elemene in M. macclurei) were specific, indicating different functions. Among the five species, the essential oil of M. macclurei contains β-elemene and nerolidyl acetate, and it has the weakest antioxidant activity (IC50 value: 2918.61~21,341.98 μg/mL) but the strongest antibacterial activity (inhibition zone diameter: 8.55 ± 0.93~22.92 ± 0.46 mm; LC50 value: 0.02~0.78 mg/mL). Meanwhile, the EO of M. maudiae demonstrated the best antioxidant activity (the IC50 value was 1283.58~6258.32 μg/mL) and the second-best antibacterial activity (the inhibition zone diameter ranged from 7.61 ± 0.02 to 26.92 ± 0.46 mm, and the LC50 value was 0.03~2.28 mg/mL). Overall, the EO of M. maudiae had the best comprehensive performance. Therefore, the EOs of M. macclurei and M. maudiae showed different performances in biological activity categories, and they could be developed and used in different fields, with the possibility of discovering new applications. This brings inspiration to the potential commercial and industrial uses of sesquiterpenes in Magnoliaceae.

First Report on Salvia Sahendica Boiss & Buhs roots biocomponents characterization by GC-MS and HPLC and Antibacterial Potency

Treatment of bacterial infections with antibiotic resistance is complicated. For this reason, new therapeutic methods are needed to control bacterial infections. Therefore, it is necessary to discover new antibiotics from medicinal plants that can destroy drug-resistant bacteria. Essential oils (EO) of some medicinal plants have antimicrobial effects and can be used as antimicrobial agents in the treatment of infections and food industries. The aim of this study was to determine the EO composition and antimicrobial effects of EO and polyphenols profile of Salvia Sahendica roots for the first time. Chemical compounds and antibacterial activity of EOs against Staphylococcus aureus and Bacillus cereus as gram-positive and Escherichia coli and Pseudomonas aeruginosa as gram- negative bacteria were evaluated using microtiter broth dilution method. Studied organs of S. sahendica showed significant diversity in terms of type and percentage of essential oil and polyphenol compounds. Overall, 44, 46, 42, and 45 compounds were identified in the essential oil of leaves, flowers, stems, and roots of this plant, which constituted 99.6, 99.3, 98.2, and 99.4% of total oil composition, respectively. The current study collectively demonstrated inhibitory effects ranged from strong (S. aureus) to low inhibition (P. aeruginosa). According to the HPLC result, the amounts of coumaric acid, chlorogenic acid, and gallic acid compounds in the root are higher than in other plant parts, which indicate that the root can be a suitable source for the production of these valuable polyphenol compounds. Due to the results, it is possible to hope for the application of EO from S. sahendica as natural antibacterial in the pharmaceutical and food industries.

In vitro antibacterial activity of essential oils from Cymbopogon flexuosus and Cymbopogon winterianus

The objective of the study was to identify and quantify chemical compounds present in the essential oils of C. flexuosus and C. winterianus and evaluate their antibacterial action on Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. This is an in vitro experimental study using essential oils of Cymbopogon flexuosus and Cymbopogon winterianus. The gram-negative strains E. coli (ATCC 25922) and P. aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923) were used as a Gram-positive strain for the analysis of the antibacterial properties of essential oil. Oil analyzes were carried out using gas chromatography coupled to mass spectrometry (GC/MS). The antibacterial activity of lemongrass (Cymbopogon flexuosus) and citronella (Cymbopogom winterianus) essential oils against bacteria of pathological relevance was confirmed, denoting the potential of using plant essential oils as antibacterial agents, an important alternative considering the emergence of antibiotic resistance.

Chemical composition and antibacterial activity of essential oils extracted from fresh and dried aerial parts of Rosmarinus officinalis L. Pistacia lentiscus L. and Thymus vulgaris L. from Algeria

ABSTRACT The aim of this study was to determine the chemical composition and antibacterial activity of essential oils (EOs) extracted from local plant by steam distillation from the aerial parts (fresh – dried) of rosemary (Rosmarinus officinalis L.), pistachio (Pistacia lentiscus L.) and thyme (Thymus vulgaris L.). Monoterpenes were identified by GC-MS as main compounds, namely 1,8-cineole (34.5–35 %), α-pinene (36.2–36.6 %) and thymol (42.2–42.1 %). Our results showed that EOs tested had antibacterial effects at different levels, with MICs ranging from 1.56 to 6.25 mg.mL−1. Fresh rosemary EO was synergistic against Pseudomonas aeruginosa ATCC 27,853 when combined with dried rosemary EO and fresh pistachio EO, with MICs half those of oils alone (from 6.25 to 3.12 mg.mL−1). In addition, antagonistic, additive and indifferent effects were recorded at 1 %, 3 % and 93 %, respectively. Our findings provide new data on antimicrobial potential of local plants and possibilities of their use as food preservatives.

Constituents and Antibacterial Activity of Essential Oil of Nyctanthes arbor-tristis Flower

Constituents and Antibacterial Activity of Essential Oil of Nyctanthes arbor-tristis Flower

Evaluation of anti-diabetic, anti-oxidant and anti-bacterial activities of essential oil collected from wildly growing Calotropis gigantea (Linn.) Aiton f. and its therapeutic applications: insights from chemical profiling, in-vitro and in-silico studies

Calotropis gigantea, often known as giant milkweed, the plant is widely known for producing herbal essential oils that are used as traditional and complementary medicine to cure various ailments. The aim of the present study was evaluation of anti-diabetic, anti-oxidant and anti-bacterial activities of essential oil collected from wildly growing Calotropis gigantea and its its therapeutic applications via chemical profiling, in-vitro and in-silico studies. After Calotropis gigantea (CEO) essential oil was extracted by hydro-distillation, its phytochemical, antioxidant, antibacterial, and anti-diabetic properties were assessed. Fingerprint analysis and GC-FID were used to create a chemical profile. Various tests for antioxidants, such as DPPH, nitric oxide radical, and iron chelating activity, were conducted. The disk diffusion approach was used for antibacterial efficacy against Gram-negative (G-) bacteria. The test of α-amylase inhibition was utilized to investigate anti-diabetic efficacy. In-silico analysis was also conducted to find out interaction of some components to α-amylase enzyme. Chemical profiling indicated the presence of phytol (24%), stearic acid (10%), and cyclohexyl ketone (6%), as predominant components. There was notable antioxidant activity ranged from 82 to 97% for various assays. IC50 values for various assays were iron chelating activity: 18.610, DPPH scavenging activity: 28.246, nitric oxide radical scavenging activity: 58.113. CEO showed a zone of inhibition value of 0.5 cm and significant antibacterial activity against Gram-negative (G-) bacteria. CEO blocked α-amylase in dose-dependent way. At a higher amount of 250 µl, CEO inhibition was 63% and mode of inhibition un-competitive. In-silico analysis validated the blocking of α-amylase and interaction of phytocomponents to α-amylase enzyme which were further validated by UV and fluorescent quenching techniques. It was determined that CEO may be extensively used in many different industries, including as food, herbal medicine, cosmetics.

Chemical composition and antibacterial activity of the leaf essential oil of Litsea mekongensis Lecomte growing wild in Lam Dong Province, Vietnam

Litsea mekongensis Lecomte is a native species that originated in Vietnam and Laos. To date, the volatile components and antibacterial activity of the essential oils derived from L. mekongensis leaves have not yet been reported. This study aims to investigate the chemical composition and antibacterial activity of L. mekongensis leaf essential oil. The chemical constituents were analyzed by gas chromatography-mass spectroscopy (GC-MS), and the antibacterial activity was evaluated using the agar well diffusion method. The GC-MS analysis showed that fifty-four volatile components were detected, of which sesquiterpene hydrocarbons accounted for almost 65% of the total, while the proportion of monoterpene hydrocarbons was 19.84%. Germacrene D (16.17%), γ-elemene (7.82%), β-phellandrene (6.76%), α-pinene (6.62%), and δ-cadinene (5.68%) were identified as major components. The essential oil exhibited strong antibacterial activity against Salmonella typhi, Staphylococcus aureus, and Escherichia coli. S. aureus was the most sensitive species, but no inhibitory activity against Pseudomonas aeruginosa was recorded. These findings revealed information on the chemical constituents of the essential oil prepared from L. mekongensis and its potential antibacterial activity against several pathogenic bacteria.

Laboratory Efficacy of Essential Oils Against Pectobacterium carotovorum Subsp. carotovorum and Pectobacterium atrosepticum Causing Soft Rot of Potato Tubers

AbstractThe antibacterial activity of essential oils (EOs) from Carum carvi, Cinnamomum zeylanicum, Cuminum cyminum, Eugenia caryophyllus, Foeniculum vulgare, Melaleuca alternifolia, Mentha × piperita, Origanum vulgare, Rosmarinus officinalis and Thymus vulgaris was tested against Pectobacterium carotovorum subsp. carotovorum (Pcc) and Pectobacterium atrosepticum (Pa), which cause soft rot of potato tubers. In disc diffusion, minimum inhibitory concentration and minimum bactericidal concentration (MBC) tests, cinnamon EO was found to be most effective against both bacteria. The inhibition zones ranged from 20.46 to 29.58 mm for a concentration of 100 μL/mL. The minimum inhibitory concentration was 0.5 μL/mL, and MBC was between 0.5 and 5 μL/mL. The higher sensitivity of bacteria was manifested in clove (Pcc and Pa), mint (Pcc), oregano (Pa) and thyme (Pa) EOs. Rosemary EO was the least effective. The results of the in vivo test were not entirely consistent with those of the in vitro tests. The most significant antibacterial effect was achieved with mint EO. The treatment of potato tuber discs with mint EO at a concentration of 3 μL/mL for Pcc and 3–10 μL/mL for Pa was 100% effective. The efficacy of the essential oils of caraway (5–10 μL/mL), thyme (10 μL/mL) and oregano (5 μL/mL) also ranged from 95.7 to 99.7%. Based on the results of the in vivo test, it may be recommended that mint EO and potentially caraway, oregano and thyme EOs be further tested for pickling potato tubers against bacteria of the genus Pectobacterium.

Chemical composition and antibacterial activity of essential oils from Daucus sahariensis Murb. roots and stems

Daucus genus (Apiaceae) comprises economically relevant plants distributed in temperate regions. These plants are used mainly as food but are also known for their biological properties. Here, the essential oils (EOs) obtained by hydro-distillation of roots and stems of D.sahariensis Murb. growing in Algerian Sahara were studied by GC-MS analysis. Fifty-two and fifty-five compounds were identified from the roots and stems, representing 95.1% and 93.8% of the whole EOs respectively. The main constituents of the EO from roots were myristicin (29.2%), (E)-anethole (14.2%), cis-chrysanthenyl acetate (8%) and estragol (7.5%). In the EO from stems, the main constituents were α-pinene (18.6%), myrcene (16.7%), limonene (13.7%) and myristicin (8%). The antibacterial activity of EOs was evaluated by disc diffusion method and tested against Gram-positive and Gram-negative bacteria. Results showed a mild activity against Bacillus subtilis and Klebsiella pneumoniae for both EOs, which can be potentially used as antibacterial in phytotherapy.

In Vitro Methods for Assessing the Antibacterial and Antibiofilm Properties of Essential Oils as Potential Root Canal Irrigants-A Simplified Description of the Technical Steps.

Essential oils have gained in significance due to their various biological activities, and there is a growing demand for them in many industries. The present article focuses on the technical steps for an in vitro evaluation of the antibacterial and antibiofilm activities of essential oils for potential use as root canal irrigant in dentistry. The bioactivities of the essential oil were investigated through in vitro assays. The gram-positive bacterium Enterococcus faecalis was used as a micro-organism model. The antibacterial activity of the essential oil was assessed using the microdilution method, and resazurin staining to determine the minimal inhibition concentrations (MICs) and the minimal bactericidal concentrations (MBCs). The antibiofilm effect was evaluated spectrophotometrically at 570 nm using the microplate cultivation technique and crystal violet staining. This article features a detailed in vitro protocol to facilitate the preparation of the essential oil samples, the bacterial suspension, and the methods used for assessment of the antibiofilm and antibacterial activities of the essential oil. The advantages of these approaches are presented in relation to the limits linked to the choice of the bacteria and the essential oil.

SESELI LIBANOTIS (L.) W.D.J. KOCH (APIACEAE): CHEMICAL COMPOSITION OF ESSENTIAL OILS, THEIR ANTIBACTERIAL AND CYTOTOXIC ACTIVITIES

Introduction. Infectious diseases and cancer remain among the leading causes of death worldwide. In this regard, the search for biologically active molecules from among synthetic and natural compounds for the purpose of creating medicines remains an urgent task of modern science. Plants that have impressive natural and biotechnological resource potential, taking into account modern advances in the field of ex situ, in situ and in vitro cultiva-tion, remain a promising source of native substances. One of the promising sources of biologically active substances is a perennial plant, the Seseli libanotis (L.) W.D.J. Koch, Apiaceae, growing in central, eastern Europe and Asia in dry pastures and forest edges. The main components of the genus Seseli L. are furo- and pyranocoumarins, essential oils and polyacetylene compounds, which exhibit antibacterial, antifungal, insecticidal, diuretic, antiviral, anti-inflammatory, and antitumor properties. The aim – study of the chemical composition, antibacterial and cytotoxic activities of S. libanotis roots essential oil. Material and methods. The roots were collected in places of natural growth in September 2022, during the fruiting period (Irkutsk region, Maloye Goloustnoye village). The voucher specimen is stored in the herbarium of the Institute of Ecological Ecology SB RAS (UUH 020438). Obtaining essential oils. Essential oils were obtained by hydrodistillation. The qualitative composition and quantitative content of essential oil compo-nents were studied by GC/MS. The study of the antibacterial activity of essential oils was carried out in vitro on test cultures of gram-positive and gram-negative bacteria (Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomona saeruginosa, Salmonella enterica) using the disc diffusion method. Cell viability assay was performed on HeLa cell lines using trypan blue. Results. The composition and quantitative content of the components of essential oils of the roots of S. libanotis of the Baikal flora were studied for the first time. 28 components of predominantly monoterpene nature have been identified, the main ones being limonene (57,60%), α-pinene (6,88%), cis-β-ocimene (6,75%). Also found were fatty acids, polyacetylene-falcorinol and 7-isopen-tinyloxycoumarin. Essential oils of S libanotis have antibacterial activity against gram-positive bacteria Staphylococcus aureus, Streptococcus pyogenes and gram-negative bacteria Escherichia coli. Cultivation of Hela with S. libanotis essential oils resulted in decreased viability in the concentration range of 0.04–2.56 μL/mL for 72 hours. Conclusions. Essential oils of roots of S. libanotis, with high yield, containing falcarinol and coumarin, have antibacterial and cytotoxic activity.

Solidago virgaurea L.: Chemical composition, antibacterial, and antileishmanial activity of essential oil from aerial part

Solidago virgaurea L. popularly called Goldenrod is a member of the Asteraceae family. S. virgaurea sample were obtained from Binsar, Almora (Indian state of Uttarakhand). The essential oil from the aerial part was distilled out using steam distillation, and GC and GC-MS were employed for analysis. A total of 27 constituents from aerial part were identified constituting 92.92% of total oil composition. The aerial parts of S. virgaurea were found to contain limonene (25.57%), α-humulene (12.19%), linalool oxide (8.65%), benzyl salicylate (6.40%), 1,4-cineole (6.22%) and humulene epoxide (II) (5.93%). The antibacterial activity of this essential oil was studied using disk diffusion and broth microdilution methods on five human pathogen bacteria and six plant pathogenic bacteria. There was moderate to good antibacterial activity in the oil sample extracted from the entire aerial portion of the plant. We did the antileishmanial activity of essential oils with Leishmania donovani (Dd8) promastigotes and intracellular amastigotes. EO was safer on the J774.A1 macrophages and lethal to promastigotes and intracellular amastigotes at different concentrations (10, 50, and 100 μg/ mL). These findings support the traditional uses of S. virgaurea and suggest its potential as a natural remedy for bacterial infections and leishmaniasis.

Chemical constituents, antioxidant and antibacterial activities of essential oil from the flowering aerial parts of Heracleum moellendorffii Hance

Chemical constituents, antioxidant and antibacterial activities of essential oil from the flowering aerial parts of <i>Heracleum moellendorffii</i> Hance

Investigation of chemical composition, anticholinesterase, antioxidant, antihemolytic and antibacterial activities of essential oil and ethanol extract from aerial parts of Algerian Ammoides verticillata (Brot.) Breistr

ABSTRACT The essential oil (EO) and ethanolic extract (EE) of Algerian Ammoides verticillata (Brot.) Breistr. were investigated for chemical composition and biological activities. GC and GC/MS analyses of the EO revealed thymol, carvacrol, p-cymene, limonene, and γ-terpinene as major compounds. HPLC/DAD/UV analysis of EE identified luteolin 7-O-glucoside as the most prominent component. The EO showed moderate inhibition activity against acetyl and butyrylcholinesterase (AChE and BChE) compared to galanthamine, while no activity for EE was observed. Both extracts showed higher to similar antioxidant activity to that of BHT in DPPH and ABTS•+ radical scavenging activity and ferric and copper reduction power. Nevertheless, weak β-carotene bleaching inhibition activity was noted for both extracts. Additionally, the EE displayed a significant antihemolytic effect against AAPH-induced hemolysis. Moreover, EO and EE showed high and no antibacterial activities, respectively. Thus, A. verticillata might represent a useful material in pharmaceutical, nutraceutical, and cosmetic applications.

Antioxidant and antibacterial activities of geranium (pelargonium graveolens L’Hér.) essential oil as affected by the growing biotope

ABSTRACT This study investigated the variability of antioxidant and antibacterial activities of essential oil (EO) from geranium (Pelargonium graveolens) aerial parts, collected from four Tunisian regions. The highest EO yield was obtained in Korba, followed by Beja, Tozeur and Sfax. In all regions, geranium EO was rich in oxygenated monoterpenes mainly due to the predominance of citronellol and geraniol. Antioxidant potential of geranium EO was evaluated by DPPH, ABTS, iron reducing power and β-carotene bleaching assays. Independently of region, geranium EO showed a weak antioxidant potential as compared to the positive control BHT. However, geranium EO was endowed with important antibacterial properties. In fact, Escherichia coli and Staphylococcus aureus were the most sensitive strains than Serratia marcescens, Pseudomonas aeruginosa, Pseudomonas aeruginosa and Enterococcus hirae. These findings suggested that geranium EO could be used as new and rich potential sources of many future multipurpose products for food preservation, pharmaceutical, and industrial applications.

Essential oils: a systematic review on revolutionizing health, nutrition, and omics for optimal well-being.

Essential oils from various plants have diverse therapeutic properties and are researched extensively. They have applications in medicine, aromatherapy, microbiology, agriculture, livestock, and the food industry, benefiting the population. This systematic review followed the PRISMA verification protocol. The study focused on the anti-inflammatory effects, nutraceutical properties, antioxidant and antibacterial activity of essential oils in lemon, orange, cumin, cinnamon, coriander, rosemary, thyme, and parsley. We also looked at their presence in the diet, their effect, their mechanism of action on health, and the most important active compounds. The search was conducted in the PubMed database for the last 12 years of publications, including in vitro, in vivo, and online cell model tests. Essential oils have been shown to have multiple health benefits, primarily due to their antimicrobial and anti-inflammatory effects. The mechanism of action of cinnamon oil alters bacterial membranes, modifies lipid profiles, and inhibits cell division, giving a potential benefit in protection against colitis. On the other hand, a significant improvement was observed in the diastolic pressure of patients with metabolic syndrome when supplementing them with cumin essential oil. The antimicrobial properties of coriander essential oil, especially its application in seafood like tilapia, demonstrate efficacy in improving health and resistance to bacterial infections. Cumin essential oil treats inflammation. Parsley essential oil is an antioxidant. Orange peel oil is antibacterial, antifungal, antiparasitic, and pro-oxidative. Lemon essential oil affects mouse intestinal microbiota. Thyme essential oil protects the colon against damage and DNA methylation. Carnosic acid in rosemary oil can reduce prostate cancer cell viability by modifying the endoplasmic reticulum function. Essential oils have many therapeutic and antiparasitic properties. They are beneficial to human health in many ways. However, to understand their potential benefits, more research is needed regarding essential oils such as coriander, parsley, rosemary, cumin, and thyme. These research gaps are relevant since they restrict understanding of the possible benefits of these crucial oils for health-related contexts.

Chemical composition and antibacterial activity of essential oil kaffir lime (Citrus hystrix DC) leaves from East Borneo

Kaffir lime (Citrus hystrix DC) leaves are a versatile plant with high commercialization potential. In the pharmaceutical industry, kaffir lime leaf essential oil is used to stimulate appetite, as a cosmetic ingredient, and as an antibacterial agent. Although most studies have concentrated on the essential oil of kaffir lime leaves, its components and biological activities need to be considered based on the growing location. The chemical components and biological activity of kaffir lime leaf essential oil are affected by differences in growth location. This research was conducted to determine the chemical composition and antibacterial activity of the essential oil of kaffir lime leaf essential oil from East Borneo. Fresh and dried kaffir lime leaves were extracted by steam distillation method and chemical compound analysis by Gas Chromatography-Mass Spectrometry (GC-MS) and the antibacterial activity of essential oils was analyzed by disc diffusion method. There are twenty-five compounds in the essential oil of fresh and dried kaffir lime leaves. The main components of fresh kaffir lime leave essential oil were citronellal (77.29%), linalool (4.88%), sabinene (4.83%), citronellol (3.41%), β-myrcene (1.23%), and citronellal (74.09%), sabinene (5.54%), linalool (3.59%), citronellol (3.56%), caryophyllene (2.26%) were the main components of the essential oil of dried kaffir lime leaves. The antibacterial activity of essential oils against Staphylococcus aureus ATCC 25925 and Escherichia coli ATCC 8733, with zones of inhibition of 21.75 and 19.17 mm, respectively. The minimum inhibitory concentration on all antibacterial activities was 6.25 μL/mL. The presence of strong antibacterial activity in dried and fresh kaffir lime leaf plant extracts was associated with the presence of citronellal compounds found in essential oil kaffir lime leaves

Chemical Composition, Anti-bacterial Activity and Molecular Docking Studies of Essential Oil Isolated from Sa Sam Nam (Launaea sarmentosa).

Launaea sarmentosa, also known as Sa Sam Nam, is a widely used remedy in Vietnamese traditional medicine and cuisine. However, the chemical composition and bioactivity of its essential oil have not been elucidated yet. In this study, we identified 40 compounds (98.6% of total peak area) in the essential oil via GC-MS analysis at the first time. Among them, five main compounds including Thymohydroquinone dimethyl ether (52.4%), (E)-α-Atlantone (9.0%), Neryl isovalerate (6.6%), Davanol D2 (isomer 2) (3.9%), and trans-Sesquisabinene hydrate (3.9%) have accounted for 75.8% of total peak area. The anti-bacterial activity of the essential oil against 4 microorganisms including Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa has also investigated via agar well diffusion assay. The results showed that the essential oil exhibited a strong antibacterial activity against Bacillus subtilis with the inhibition zones ranging from 8.2 to 18.7 mm. To elucidate the anti-bacterial effect mechanism of the essential oil, docking study of five main compounds of the essential oil (Thymohydroquinone dimethyl ether, (E)-α-Atlantone, Neryl isovalerate, Davanol D2 (isomer 2), and trans-Sesquisabinene hydrate) against some key proteins for bacterial growth such as DNA gyrase B, penicillin binding protein 2A, tyrosyl-tRNA synthetase, and dihydrofolate reductase were performed. The results showed that the main constituents of essential oil were highly bound with penicillin binding protein 2A with the free energies ranging -27.7 to -44.8 kcal/mol, which suggests the relationship between the antibacterial effect of essential oil and the affinity of main compounds with penicillin binding protein. In addition, the free energies of main compounds of the essential oil with human cyclooxygenase 1, cyclooxygenase 2, and phospholipase A2, the crucial proteins related with inflammatory response were less than diclofenac, a non-steroidal antiinflammatory drug. These findings propose the essential oil as a novel and promising anti-bacterial and anti-inflammatory medicine or cosmetic products.

Anti-bacterial activity of essential oils against multidrug-resistant foodborne pathogens isolated from raw milk.

The presence of pathogenic bacteria in food is considered as a primary cause of food-borne illness and food quality deterioration worldwide. The present study aimed to determine the effectiveness of five essential oils (EOs) against multidrug-resistant foodborne pathogens. In the current study Gram-negative bacteria (Escherichia, Enterobacter, Citrobacter, Proteus, Pseudomonas, and Klebsiella) and the Gram-positive bacteria Staphylococcus were isolated from raw milk and biochemically characterized. The anti-bacterial effect of different antibiotics and EOs (thyme, oregano, lemongrass, mint, and rosemary) was determined using the standard disc diffusion method. The antibiogram study revealed that Gram-negative bacteria were highly resistant to penicillin while Staphylococcus was resistant to streptomycin, amoxicillin, and lincomycin. Moderate resistance was observed to doxycycline, amikacin, enrofloxacin, kanamycin and cefixime. Isolates were found less resistant to gentamycin, chloramphenicol, and ciprofloxacin. EOs showed a broad range of antimicrobial activity against all bacteria except P. aeruginosa. Of these, thyme was more effective against most of the multi-drug resistant bacterial strains and formed the largest zone of inhibition (26 mm) against Escherichia followed by oregano oil (18 mm) against Staphylococcus (p<0.05). Klebsiella spp and Citrobacter spp showed resistance to mint and lemongrass oil respectively. The EOs such as lemongrass, mint and rosemary were less active against all the bacteria. The findings of the recent study suggest the use of EOs as natural antibacterial agents for food preservation.