Search Results (11)

The conventional agricultural industry largely relies on pesticides to maintain healthy and viable crops. Application of fungicides, both pre- and post-harvest of crops, is the go-to method for avoiding and eliminating Botrytis cinerea, the fungal pathogen responsible for gray mold. However, conventional fungicides and their residues have purported negative environmental and health impacts. Natural products, such as essential oils, are viewed as a promising alternative to conventional fungicides. The current research is an in vitro study on the antifungal activity of a natural water-based fungicide (N.F.), which uses a blend of essential oils (ajowan, cassia, clove, eucalyptus, lemongrass, oregano) as the active ingredients against B. cinerea. Compared to conventional fungicides tested at the same concentration (50 μL/mL), those with active ingredients of myclobutanil or propiconazole; the N.F. demonstrated significant (F(3,16) = 54, p = <0.001) and complete fungal growth inhibition. While previous research has largely focused on the antifungal properties of single essential oils and/or isolated compounds from essential oils, this research focuses on the efficacy of using a blend of essential oils in a proprietary delivery system. This research is of importance to the fields of agronomy, ecology, and health sciences. Full article

Listeria monocytogenes is a foodborne pathogen with a high tolerance to a wide range of environmental conditions, making its control in the food chain a particular challenge. Essential oils have recently been considered as potential antilisterial agents. In this study, the antilisterial effects of 57 EOs were tested on 13 different L. monocytogenes. Thirty-seven EOs were found to be effective in a strain and temperature-dependent manner. At 37 °C, all EOs were effective against at least one strain of L. monocytogenes. However, at 14 °C and 23 °C, 12 EOs, such as Minth, Nutmeg, Neroli, Pepperminth, etc., became drastically ineffective. The efficacy of the EOs increased at the lowest temperature, as only four EOs, such as Dill seed, Juniper, lemon eucalyptus, and sandalwood, were found to be ineffective at 4 °C. Ajowan and thyme were the only EOs that were antibacterial against each strain at all temperatures tested (4, 14, 23, 37 °C). Biofilm-inhibition tests with 57 EOs, performed on polystyrene plates with different surface qualities and stainless steel, using 0.1% and 0.5% final concentrations, showed the outstanding inhibitory abilities of ajowan, geranium, Lime oil, melissa, palmarosa, rose geranium, sandalwood, and thyme. Fennel, lemon eucalyptus, and chamomile had the potential to inhibit biofilm formation without affecting live bacterial cell counts. Ajowan, geranium, thyme, and palmarosa reduced the biofilm to the optical density of 0.0–0.08, OD: 0.0–0.075, 0.0–0.072, and 0.0–0.04, respectively, compared to the bacterium control 0.085–0.45. The mature antibiofilm eradication ability of the EOs revealed the outstanding features of ajowan, geranium Lime, melissa, palmarosa, rose geranium, and thyme by suppressing the established biofilm to one tenth. The different sensitivities of the isolates and the temperature-dependent antilisterial effect of the tested EOs have to be taken into account if an EO-based food preservation technology is to be implemented, as several L. monocytogenes become resistant to different EOs at medium temperature ranges such as 14 °C and 23 °C. Full article

Ajowan (Trachyspermum ammi) is an important spice in the food industry, as a well as a medicinal plant with remarkable antioxidant properties. In this study, its essential oil content, chemical composition, flavonoid content, phenolic content, and antioxidant capacity were evaluated under three irrigation regimes (50, 70, and 90% field capacity) and different amounts of nano silicon (0, 1.5, and 3 mM) in ten populations of ajowan. Based on the GC–MS analysis, thymol, carvacrol, p-cymene, and γ-terpinene were determined as the main components of the oil. The thymol content ranged from 34.16% in the Ardabil population (irrigation at 50% and nano silicon at 1.5 mM) to 65.71% in the Khorbir population (without nano silicon and irrigation at 50%). The highest phenolic content was in Khormo with irrigation at 90% and without nano silicon (172.3 mg TAE/g DW), while the lowest was found in Hamedan (irrigation at 50% and without nano silicon (7.2 mg TAE/g DW)). Irrigation at 50% and no nano silicon treatment led to an increase in total flavonoids in Ardabil (46.786 mg QUE/g DW). The antioxidant activity of ajowan was evaluated using the DPPH assay. Accordingly, the highest antioxidant capacity was observed in Khormo (irrigation at 90% without nano silicon; 4126 µg/mL). Moreover, the highest thymol content was observed in the Khorbir population with irrigation at 50% and without nano silicon treatment. Furthermore, correlation and principal component analysis (PCA) provide new insights into the production of ajowan from their substrates under nano silicon treatment and water deficit conditions. Finally, the results revealed information on how to improve the desired essential oil profile and antioxidant capacity of extracts for industrial producers. Full article

Ajowan (Trachyspermum ammi L.) is considered a valuable spice and medicinal herb. In this study, the essential oil content and composition of the aerial parts of ajowan were investigated under different drying treatments (sun, shade, oven at 45 °C, oven at 65 °C, microwave, and freeze drying). Moreover, the phenolic content, flavonoid content, and antioxidant capacity of samples were also assessed. Fresh samples produced the highest essential oil content (1.05%), followed by those treated under sun (0.7%) and shade drying (0.95%). Based on gas chromatography–mass spectrometry (GC–MS), thirty compounds were determined in which thymol (34.84–83.1%), carvacrol (0.15–32.36%), p-cymene (0.09–13.66%), and γ-terpinene (3.12–22.58%) were the most abundant. Among the drying methods, freeze drying revealed the highest thymol content, followed by drying in a 45 °C oven. The highest TPC (total phenolic content) and TFC (total flavonoid content) were obtained in the fresh sample (38.23 mg TAE g⁻¹ dry weight (DW)) and in the sample oven-dried at 45 °C (7.3 mg QE g⁻¹ DW), respectively. Based on the HPLC results, caffeic acid (18.04–21.32 mg/100 gDW) and ferulic acid (13.102–19.436 mg/100 g DW) were the most abundant phenolic acids, while among flavonoids, rutin constituted the highest amount (10.26–19.88 mg/100 gDW). Overall, freeze drying was the most promising method of drying for preserving the phenolic (TPC) and flavonoid (TFC) compounds and oil components. Full article

In the present research, 28 populations of ajowan (Trachyspermum ammi L.) were evaluated for agro-morphological traits and essential oil yield in two consecutive years. Then, selected ajowan populations from these two years were used for further morphophysiological and biochemical studies under different salinity levels (control, 60, 90, and 120 mM NaCl). The main components of the oil were thymol (32.7–54.29%), γ-terpinene (21.71–32.81%), and p-cymene (18.74–26.16%). Salt stress caused an increase in essential oil content in the Esfahfo and Qazvin populations. The highest total phenolic and flavonoid contents were found in the Arak population grown in 60 mM NaCl (183.83 mg TAE g⁻¹ DW) and the Yazd population grown in 90 mM NaCl (5.94 mg QE g⁻¹ DW). Moreover, the Yazd population exhibited the strongest antioxidant activity based on DPPH (IC₅₀ = 1566 µg/mL) under 60 mM NaCl and the highest reducing power (0.69 nm) under 120 mM NaCl. The results revealed that low and moderate salt stress improves the phytochemicals of ajowan seeds, which are useful for pharmaceutical and food applications. In this research, some morphological traits, as well as essential oil yield, were evaluated in open pollinated versus self-pollinated plants. As a result, plant height, number of flowering branches, and crown diameter significantly decreased in some populations, while a significant increase was obtained for number of flowers per umbel and seed numbers per umbel. Finally, self-pollination of ajowan might provide new insights for further breeding programs to increase oil or thymol content in ajowan. Full article

Ajowan (Trachyspermum ammi L.) is considered a valuable spice plant with a high thymol content. Seed yield, essential oil constituents, polyphenolic composition, and antioxidant capacity of ajowan (Trachyspermum ammi L.) populations were evaluated in three (normal, moderate, and severe) water irrigation regimes. The highest essential oil content (5.55%) was obtained under normal condition in the Yazd population. However, both essential oil and seed yield showed significant reductions as a result of water stress. According to gas chromatography–mass spectrometry (GC–MS) analysis, thymol (61.44%), γ-terpinene (26.96%), and p-cymene (20.32%) were identified as the major components of the oil. The highest (89.01%) and the lowest (37.54%) thymol contents were in Farsmar and Hamadan populations in severe stress condition, respectively. Based on HPLC analysis, chlorogenic (3.75–47.35 mg/100 g), caffeic (13.2–40.10 mg/100 g), and ferulic acid (11.25–40.10 mg/100 g) were identified as the major phenolic acids, while rutin was determined as the major flavonoid (11.741–20.123 mg/100 g). Moreover, total phenolic and flavonoid contents were elevated under drought stress treatment, while antioxidants responded inconsistently to stress based on two model systems. Overall, the Yazd population exhibited a superior response to water stress, as evidenced by its less reduced thymol and oil yield content, while Arak and Khormo had the highest accumulation of polyphenolic compounds. Full article

Dermatophyte infections represent an important public health concern, affecting up to 25% of the world’s population. Trichophyton rubrum and T. mentagrophytes are the predominant dermatophytes in cutaneous infections, with a prevalence accounting for 70% of dermatophytoses. Although terbinafine represents the preferred treatment, its clinical use is hampered by side effects, drug–drug interactions, and the emergence of resistant clinical isolates. Combination therapy, associating terbinafine and essential oils (EOs), represents a promising strategy in the treatment of dermatophytosis. In this study, we screened the potential of selected Apiaceae EOs (ajowan, coriander, caraway, and anise) to improve the antifungal activity of terbinafine against T. rubrum ATCC 28188 and T. mentagrophytes ATCC 9533. The chemical profile of EOs was analyzed by gas chromatography. The minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of EOs/main compounds were determined according to EUCAST-AFST guidelines, with minor modifications. The checkerboard microtiter method was used to identify putative synergistic combinations of EOs/main constituents with terbinafine. The influence of EOs on the viability and pro-inflammatory cytokine production (IL-1β, IL-8 and TNF-α) was determined using an ex vivo human neutrophils model. The binary associations of tested EOs with terbinafine were found to be synergistic against T. rubrum, with FICI values of 0.26–0.31. At the tested concentrations (6.25–25 mg/L), EOs did not exert cytotoxic effects towards human neutrophils. Anise EO was the most potent inhibitor of IL-1β release (46.49% inhibition at 25 mg/L), while coriander EO displayed the highest inhibition towards IL-8 and TNF-α production (54.15% and 54.91%, respectively). In conclusion, the synergistic combinations of terbinafine and investigated Apiaceae EOs could be a starting point in the development of novel topical therapies against T. rubrum-related dermatophytosis. Full article

Ajowan (Trachyspermum ammi L.) is a spice traditionally used in Middle Eastern medicine and contains a valuable essential oil (EO) exploited in different fields, such as pharmaceutics, agrochemicals and food additives. This EO is mostly characterized by the thymol to which most of its biological properties are related. Given the economic value of ajowan and its increasing demand across the globe, the extraction method used for its EO is of paramount importance in terms of quality and quantity of the final product. In the present study, we used the design of experiment (DoE) approach to study and optimize the extraction of the ajowan EO using the microwave-assisted extraction (MAE), a novel extraction technique with high efficiency, low energy consumption, short process length and low environmental impact. A two-step DoE (screening followed by surface response methodology) was used to reduce the number of experiments and to improve the cost/benefit ratio. Reliable mathematical models, relating the more relevant EO features with the extraction conditions, were obtained and used to identify the best experimental conditions able to maximize the yield and thymol concentration. The optimized MAE procedure assures an EO with a higher yield and thymol amount compared with the standard hydrodistillation procedure. Full article

The increasing bacterial resistance to antibiotics is a worldwide concern. Essential oils are known to possess remarkable antibacterial properties, but their high chemical variability complicates their development into new antibacterial agents. Therefore, the main purpose of this study was to standardize their chemical composition. Several commercial essential oils of ajowan (Trachyspermum ammi L.) and thyme (chemotype thymol) (Thymus vulgaris L.) were bought on the market. GC–MS analysis revealed that thyme essential oils have a chemical composition far more consistent than ajowan essential oils. Sometimes thymol was not even the major compound. The most abundant compounds and the homemade mixtures were tested against two Staphylococcus aureus strains. The antibacterial property of β-caryophyllene presented no direct activity against S. aureus LMG 15975, but in association with thymol or carvacrol at equal percentages an MIC of 125 μg/mL was observed. The mixture of those three compounds at equivalent percentages also decreased by 16-fold the MIC of the penicillin V. Against S. aureus LMG 21674, β-caryophyllene presented an MIC of 31.3 μg/mL and decreased by 267-fold the MIC of the penicillin V. These observations led us to question the benefits of using a complex chemical mixture instead of one active compound to fight bacterial resistance. Full article

There is a huge concern in the medical field concerning the emergence of bacterial resistance to antibiotics. Essential oils are a source of antibacterial compounds that can overcome this problem. Ten essential oils that are commercially available were investigated in the present study: ajowan, basil, German chamomile, Chinese cinnamon, coriander, clove, lemongrass, Spanish lavender, oregano and palmarosa. Their direct, synergistic and indirect antibacterial activities were evaluated against different human pathogenic Gram-positive and Gram-negative strains. To evaluate their possible use in clinics, the cytotoxicity of these essential oils was also tested on keratinocyte and epithelial cell lines. Except for the Chinese cinnamon, coriander and lemongrass, all other essential oils presented no cytotoxicity at 32 and 16 μg/mL. The highest indirect antibacterial activities were observed with the palmarosa and Spanish lavender in association with penicillin V. These two associations presented a 64-fold decrease against a resistant strain of Staphylococcus aureus, however, at a cytotoxic concentration. It can also be highlighted that when tested at a non-cytotoxic concentration, the activity of oregano in association with penicillin V presented an eight-fold decrease. These results show the interest to use essential oils in combination with antibiotics to reduce their concentrations inside drugs. Full article

We investigated the repellent effect of 12 Apiaceae plant essential oils on nymphal and adult (male and female) forms of the bean bug, Riptortus clavatus (Thunberg) (Hemiptera: Alydidae), using a four-arm olfactometer. Among the essential oils tested, ajowan (Trachyspermum ammi Sprague) essential oil showed the strongest repellent activity against the nymphal and adult bean bugs. For female adults, the repellent activity was significantly different between an ajowan oil-treated chamber and an untreated chamber down to a concentration of 14.15 μg/cm². We also investigated the repellent activity of individual ajowan essential oil constituents. Of the compounds examined, carvacrol and thymol showed the most potent repellent activity against the nymphal and adult bean bugs. Carvacrol and thymol exhibited 73.08% and 70.0% repellent activity for the bean bug nymph at 0.71 and 2.83 μg/cm², respectively, and 82.6% and 80.7% at 5.66 and 11.32 μg/cm², respectively, for male adults. Carvacrol and thymol exhibited strong repellent activity against female adult bean bugs down to a concentration of 2.83 μg/cm². Ajowan essential oil, thymol and carvacrol elicited a negative electroantennogram (EAG) response from adult bean bugs. This could explain the repellent activity of ajowan essential oil and its constituents. Our results indicate that ajowan essential oil and its constituents carvacrol and thymol can be potential candidates as the ‘push’ component in a ‘push-pull’ strategy for bean bug control. Full article