Unveiling the cellular and molecular mode of action of Melaleuca cajuputi Powell. essential oil against aflatoxigenic strains of Aspergillus flavus isolated from stored maize samples

Chitosan-based nanoencapsulation of Toddalia asiatica (L.) Lam. essential oil to enhance antifungal and aflatoxin B1 inhibitory activities for safe storage of maize

The present study involves the chemical characterization and antifungal potential of fenugreek Trigonella foenum-graecum L. (fenugreek) seeds/leaves essential oils and their major constituents along with computational molecular docking calculations. The fenugreek seeds and leaves essential oils were extracted by hydro-distillation and characterized by Gas chromatography-mass spectrometry and Gas chromatography-flame ionization detector. Benzyl acetate (51.70%) and γ-tocopherol (42.09%), the major compounds in fenugreek seeds and leaves essential oils respectively were isolated by column chromatography. The essential oils and their major compounds were investigated for their antifungal activity against Rhizoctonia solani and Drechslera oryzae by the Poison food technique. Among all the treatments, fenugreek leaves essential oil was the most effective with ED50 values of 850 and 1120 ppm against R. solani and D. oryzae respectively. All the treatments were found more effective against R. solani than D. oryzae. Molecular docking studies of the major compounds present in the essential oils against R. solani agglutinin (PDB ID 4G9N and 4G9M) suggested that 9,19-cyclolanost-24-en-3-ol present in abundance in fenugreek leaves essential oil than the seeds essential oil bound effectively with the targeted protein with the docking score of -6.14 kcal mol−1. Overall, our combined experimental and computational study provides scientific justification for the use of fenugreek leaves essential oil as a natural antifungal agent against R. solani. Moreover, fenugreek leaves essential oil being most effective against D. oryzae may also be used as a natural antifungal agent against it.

Epaltes australis Less. has been traditionally used to treat fever and snake bites, whereas Lindera myrrha (Lour.) Merr. is well-known for addressing colds, chest pain, indigestion, and worm infestations. This study marks the first report on the chemical compositions and biological potentials of essential oils extracted from the leaves of Epaltes australis and Lindera myrrha. Essential oils obtained by hydro-distillation were analysed using the GC/MS (gas chromatography-mass spectrometry). E. australis exhibited a predominant presence of non-terpenic compounds (46.3 %), with thymohydroquinone dimethyl ether as the major compound, constituting 44.2 % of the oil. L. myrrha leaf oil contained a good proportion of sesquiterpene hydrocarbons (56.8 %), with principal compounds including (E)-caryophyllene (22.2 %), ledene (9.7 %), selina-1,3,7(11)-trien-8-one (9.6 %), and α-pinene (7.0 %). Both essential oils exhibited antimicrobial activity against the bacteria Bacillus subtilis and Clostridium sporogenes, and Escherichia coli, and the fungus Aspergillus brasiliensis. L. myrrha leaf essential oil exhibited potent control over the yeast Saccharomyces cerevisiae with a MIC of 32 μg/mL. Additionally, L. myrrha leaf oil showed strong anti-inflammatory activity with an IC50 value of 15.20 μg/mL by inhibiting NO (nitric oxide) production in LPS (lipopolysaccharide)-stimulated RAW2647 murine macrophage cells. Regarding anti-tyrosinase activity, E. australis leaf oil showed the best monophenolase inhibition with the IC50 of 245.59 μg/mL, while L. myrrha leaf oil successfully inhibited diphenolase with the IC50 of 152.88 μg/mL. From molecular docking study, selina-1,3,7(11)-trien-8-one showed the highest affinity for both COX-2 (cyclooxygenase-2) and TNF-α (tumor necrosis factor-α) receptors. Hydrophobic interactions play a great role in the bindings of ligand-receptor complexes.

Cymbopogon species essential oil (EO) carries significant importance in pharmaceuticals, aromatherapy, food, etc. The chemical compositions of Cymbopogon spp. Viz. Cymbopogon winterianus (citronella) Cymbopogon citratus (lemongrass), and Cymbopogon martini (palmarosa) were analyzed by gas chromatography-mass spectrometry (GC-MS), enantiomeric distribution by chiral GC-MS, and antimicrobial activities of some selected pure major compound and root and leaves EOs of citronella. The EO of leaves of Cymbopogon spp. showed comparatively higher yield than roots or other parts. Contrary to citral (neral and geranial) being a predominant compound of Cymbopogon spp., α-elemol (53.1%), α-elemol (29.5%), geraniol (37.1%), and citral (90.4%) were detected as major compounds of the root, root hair with stalk, leaf, and root stalk with shoot of citronella EO, respectively. Palmarosa leaves' EO contains neral (36.1%) and geranial (53.1) as the major compounds. In the roots of palmarosa EO, the prime components were α-elemol (31.5%), geranial (25.0%), and neral (16.6%). Similarly, lemongrass leaves' EO contains geraniol (76.6%) and geranyl acetate (15.2%) as major compounds, while the root EO contains a higher amount of geraniol (87.9%) and lower amount of geranyl acetate (4.4%). This study reports for the first time chiral terpenoids from Cymbopogon spp. EOs. Chiral GC-MS gave specific enantiomeric distributions of nine, six, and five chiral terpenoids in the root, root stalk with a shoot, and leaves of citronella EOs, respectively. Likewise, four and three chiral terpenoids in the root and leaves of lemongrass oil followed by two chiral terpenoids in the leaves and root of palmarosa EOs each. Additionally, the root and leaves' EOs of citronella exhibit noticeable activity on bacteria such as Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes and fungus such as Candida albicans, Microsporum canis, and Trichophyton mentagrophytes. So, geranial-, neral-, geraniol-, and citronellal-rich EOs can be used as an alternative antimicrobial agent.

Rhipicephalus annulatus is regarded as the most common tick in transmitting cattle disease. Chemical acaricides resistance and toxicity have directed research on the use of essential plant oils which have great potential for pest management for safe food production. Therefore, the current study was designed to test the larvicidal activity of essential oils (EOs) of five medicinal plants; cilantro leaves, orange leaves, Tagetes flower, geranium herb, and sweet basil herb against R. annulatus larvae using the larval packet test. Analysis of EO chemical composition using gas chromatography-mass spectrometry (GC-MS) was also carried out to justify the assigned activities. Cilantro, orange, and Tagetes EOs showed 100.0% larval mortality with lethal concerntrations that kills 50% (LC50) of 1.46%, 0.88%, and 2.94%, respectively. Geranium and sweet basil herbs EOs showed 96.33% ± 3.18% and 92.33% ± 1.45% larval mortality with LC50 of 5.28% and 7.20%, respectively. Major compounds were identified by GC-MS as follows, [2(E)-decenal (49.72%), decanal (21.47%)] from cilantro EO, [methyl methanthranilate (63.45%), γ-terpinene (18.64%)] from orange EO, [trans-β-ocimene (24.93%) and isoartemisia ketone (8.84%)] in Tagetes EO, [β-citronellol (41.83%), citronellyl formate (10.41%), geraniol (9.47%)] from geranium EO, and [β-Linalool (55.63%), 1,8-cineole (9.66%)] from sweet basil. Our results showed the potential of EOs as eco-friendly and economic acaricides for tick control.

Antibacterial mechanism of action and in silico molecular docking studies of Cupressus funebris essential oil against drug resistant bacterial strains

Spoilage of agricultural produce due to the action of Aspergillus spp. pose significant challenges to farmers and importer/exporter of agricultural produce. Aflatoxins are toxin produced by fungi and they contaminate food threatening food safety. Studies have shown that essential oils are capable of inhibiting the growth of Aspergillus spp. This study determined the chemical composition of the essential oils of Bay leaf and Cinnamon using Gas Chromatography-Mass Spectroscopy (GC-MS) techniques and evaluated the in vitro effect of the oils against Aflatoxigenic fungi (Aspergillus flavus, Aspergillus niger and Aspergillus parasiticus). Food poisoning technique was used to determine the inhibitory effect of the oils with radial mycelia growth of each observed and measured 24 hourly. The result of GC-MS analyses revealed cinnamaldehyde (5.83%), 3-Methyl- Benzofuran (14.49%), 2,6,6,9-tetramethyl-Tricycloundec-9-ene (10.59%) and other bioactive constituents as abundant in the essential oil of Cinnamon. Additionally, Bay leaf essential oil recorded Eucalyptol (12.30%), Eugenol (4.15%), and 2-octyl-Cyclopropaneoctanal (9.16%) among other bioactive compounds. Antifungal result revealed that both oils were active against the studied microorganisms as they were able to completely inhibit the growth of A. niger. Cinnamon oil had 92.69 and 91.27% inhibition against A. flavus and A. parasiticus respectively at 72 hr of observation, while essential oil from Bay leaf recorded 23.50% and 76.50% inhibition for A. flavus and A. parasiticus after 72 hr. Results from this study have further confirmed the antimicrobial potentials of essential oils against the tested Aspergillus spp. and their potential use in the development of natural antifungal products.

Essential oils have a long history in their variety of applications. Although essential oils of various herbs and spices from other parts of the world have shown antimicrobial effects, those from Malaysian herbs remain underreported. Thus, can be further utilized in the search for novel bioactive compounds as natural antimicrobials to fulfil the consumers' demand for safer, healthier, and higher‐quality foods with longer shelf life. In the present work, the essential oils from ten herbs and spices namely betel, cinnamon, clove, coriander, galangal, ginger, lemongrass, lime, nutmeg, and turmeric, selected based on their abundance and economic importance, were analysed by gas chromatography and mass spectrometry. A total of 120 bioactive compounds were detected. The major (>10%) bioactive compounds were anethole, 26.25% (betel), cinnamaldehyde, 63.39% (cinnamon), eugenol, 87.16% (clove), linalool, 54.79% (coriander), propenoic acid, 29.56% (galangal), α-zingiberene, 26.32% (ginger), geranial, 42.61% (lemongrass), limonene, 39.84% (lime), β-phellandrene, 27.80% (nutmeg), and ar-turmerone, 41.81% (turmeric). All essential oils also yielded minor (<10%) bioactive compounds of different classes. Some of these major and minor bioactive compounds have been reported to exert fungicidal/fungistatic effects and could be an excellent candidate in the development of efficient fungal spoilage control strategies such as an active food packaging system.

BackgroundThe historical use of Laurus nobilis L., the plant is native to the Mediterranean region and has been cultivated for its aromatic leaves, which are used as a flavoring agent in cooking and for their potential therapeutic properties.MethodsThe purpose of the current investigation was to characterize the essential oil composition of the fresh L. nobilis leaves from Palestine by using the gas chromatography-mass spectrometry (GC-MS) technique. DPPH (2,2-diphenyl-1-picrylhydrazyl), p-nitrophenyl butyrate, and 3,5-dinitro salicylic acid (DNSA) methods were employed to estimate the antioxidant, antiobesity, and antidiabetic effects of the essential oil. While MTS assay were used to evaluate their antiproliferative activities on panels of cell lines. Moreover, the docking studies were aided by the Prime MM GBSA method for estimating binding affinities.ResultsThe GC-MS investigation demonstrated that the fresh L. nobilis leaves essential oil has a variety of chemicals, about 31 different biochemicals were identified, and the major compounds were 1,8-cineole (48.54 ± 0.91%), terpinyl acetate (13.46 ± 0.34%), and α-terpinyl (3.84 ± 0.35%). Furthermore, the investigated oil demonstrated broad-spectrum antimicrobial activity against all tested bacterial and candidal strains and significantly inhibited the growth of MCF-7 cancerous cells more than the chemotherapeutic drug Doxorubicin. Furthermore, it contains robust DPPH free radicals, as well as porcine pancreatic α-amylase and lipase enzymes. Using the 1,8-cineole compound as the predominant biomolecule found in the L. nobilis essential oil, molecular docking studies were performed to confirm these observed fabulous results. The molecular docking simulations proposed that these recorded biological activities almost emanated from its high ability to form strong and effective hydrophobic interactions, this led to the getting of optimal fitting and interaction patterns within the binding sites of the applied crystallographic protein targets.ConclusionThe results of these experiments showed that the fresh L. nobilis leaves essential oil has outstanding pharmacological capabilities, making this oil a potential source of natural medications.

Composition and Antimicrobial Properties of Sardinian Juniperus Essential Oils against Foodborne Pathogens and Spoilage Microorganisms

The essential oil obtained by hydrodistillation of the fresh aerial parts of Sphaeranthus africanus (Vietnamese name: Cúc chân vịt) was analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 37 constituents were identified, representing 94.6% of the total composition of the essential oil. The major identified compounds were α-pinene (38.2%), 1-decen-3-ol (23.0%), τ-cadinol (8.2%), and β-caryophyllene (5.2%). The results of in vitro cytotoxic assays revealed moderate inhibitory effects of the essential oil of S. africanus aerial parts on human cancer cell lines, including SK-LU-1, MCF-7, and HepG2 with IC50 values ranging from 11.64 ± 0.37 to 21.78 ± 0.76 μg/mL. Molecular docking studies of four main components of S. africanus essential oil with binding affinity ranging from -7.09 to -4.931 kcal/mol for EGFR and -8.428 to -5.622 kcal/mol for HER2. Compound τ-cadinol exhibited notable binding affinities towards EGFR and HER2 in molecular docking studies. Furthermore, molecular dynamics simulations confirmed the binding stability of this compound with the two studied target proteins. This work is the first to investigate the cytotoxic activity of S. africanus essential oil. These findings contribute to the phytochemical compositions and bioactivities of the genus Sphaeranthus (Asteraceae family).

Antifungal activity of Allium tuberosum (AT), Cinnamomum cassia (CC), and Pogostemon cablin (Patchouli, P) essential oils against Aspergillus flavus strains 3.2758 and 3.4408 and Aspergillus oryzae was tested at 2 water activity levels (aw : 0.95 and 0.98). Main components of tested essential oils were: allyl trisulfide 40.05% (AT), cinnamaldehyde 87.23% (CC), and patchouli alcohol 44.52% (P). The minimal inhibitory concentration of the plant essential oils against A. flavus strains 3.2758 and 3.4408 and A. oryzae was 250 ppm (A. tuberosum and C. cassia), whereas Patchouli essential oil inhibited fungi at concentration > 1500 ppm. The essential oils exhibited suppression effect on colony growth at all concentrations (100, 175, and 250 ppm for A. tuberosum; 25, 50, and 75 for C. cassia; 100, 250, and 500 for P. cablin essential oil). Results of the study represent a solution for possible application of essential oil of C. cassia in different food systems due to its strong inhibitory effect against tested Aspergillus species. In real food system (table grapes), C. cassia essential oil exhibited stronger antifungal activity compared to cinnamaldehyde.

The development of natural insecticides would help to decrease the negative impact of synthetic insecticides. Fumigant toxicity of essential oil of Tagetes filifolia Lag (Asterales: Asteraceae) and its major compounds were evaluated against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). The essential oils were analyzed by gas chromatography–mass spectrometry. The essential oil and (E)-anethole were the most toxic at 24 h against adult insects (CL50= 2.4 y 2.6 µL/mL water, respectively). Changes in the products of lipid peroxidation were evidenced by an increase in malondialdehyde content. Acetylcholinesterase activity in vitro, of T. castaneum adults, was also reported. (E)-anethole and estragole showed similar acetylcholinesterase inhibition (54 and 63%, respectively at 5 mM). The present study constitutes one of the first contributions to understanding the relationship between the insecticidal action of essential oil and oxidative stress.

Aspergillus species are known to cause damage to food crops and are associated with opportunistic infections in humans. In the United States, significant losses have been reported in peanut production due to contamination caused by the Aspergillus species. This study evaluated the antifungal effect and anti-aflatoxin activity of selected plant-based essential oils (EOs) against Aspergillus flavus in contaminated peanuts, Tifguard, runner type variety. All fifteen essential oils, tested by the poisoned food technique, inhibited the growth of A. flavus at concentrations ranging between 125 and 4000 ppm. The most effective oils with total clearance of the A. flavus on agar were clove (500 ppm), thyme (1000 ppm), lemongrass, and cinnamon (2000 ppm) EOs. The gas chromatography-mass spectrometry (GC-MS) analysis of clove EO revealed eugenol (83.25%) as a major bioactive constituent. An electron microscopy study revealed that clove EO at 500 ppm caused noticeable morphological and ultrastructural alterations of the somatic and reproductive structures. Using both the ammonia vapor (AV) and coconut milk agar (CMA) methods, we not only detected the presence of an aflatoxigenic form of A. flavus in our contaminated peanuts, but we also observed that aflatoxin production was inhibited by clove EO at concentrations between 500 and 2000 ppm. In addition, we established a correlation between the concentration of clove EO and AFB1 production by reverse-phase high-performance liquid chromatography (HPLC). We demonstrate in our study that clove oil could be a promising natural fungicide for an effective bio-control, non-toxic bio-preservative, and an eco-friendly alternative to synthetic additives against A. flavus in Georgia peanuts.

The inhibitory influence of Citrus limon var. Eureka and Citrus sinensis var. Valencia essential oils (EOs) on the growth of Aspergillus flavus and AFB1 production was evaluated. The EOs were characterized by limonene (54.95% and 82.6%, respectively) as predominant component. Citrus limon EO at 1.75 mg/mL and Citrus sinensis at 2 mg/mL could totally inhibit fungal growth as well as AFB1 production. The Citrus EOs revealed wide spectrum of fungitoxicity against some isolated fungi in terms of MIC and MFC. On the other hand, the antioxidant activity was also assessed where IC50 and β-carotene/linoleic acid inhibition percentage of Citrus limon and Citrus sinensis oils were 1570.10 and 752.26 μg/mL, 36.19 and 55.56%, respectively, while the total phenolic were 16.90 and 10.53 μg/mg, respectively. Additionally, the EOs showed their non phytoxicity on wheat seeds. These findings demonstrated that EOs could be good alternatives to protect food.