Insecticidal activity of Origanum majorana L. essential oil as anti‐cholinergic agent

The present study was focused on exploring the presence of active compounds in Origanum majorana essential oil (OmEO), and its various knock‐down effects against the rice moth, Corcyra cephalonica. GC–MS analysis detected the existence of major compounds such as monoterpenes, cis‐β‐terpineol and terpinen‐4‐ol with the total proportion of 52.16%. Fumigant toxicity against adult and larvae was calculated with an LC₅₀ value of 11.31 and 49.83 μL/L air, respectively. The contact toxicity against adult, pupa, larvae and eggs was observed with LC₅₀ value 2.54, 0.95, 2.78, and 0.49 μL/L, respectively. Furthermore, the influential repellent behavior against adults has been observed. Acetylesterase (AChE) inhibition activity of OmEO was observed against adult and larvae of C. cephalonica with an IC₅₀ value of 35.89 and 118.54 μL/mL, respectively. Moreover, computational docking study revealed the binding affinity of Cis‐β‐terpineol and terpinen‐4‐ol towards the active binding sites of AChE. On the other hand, Fluorescence‐assisted cytometry and comet assay confirmed the cytotoxic and genotoxic effect of OmEO at various concentrations on C. cephalonica. Altogether, the results showed the knock‐down effect of OmEO against C. cephalonica, and it could be a potential biocontrol measure against the stored product pest.     

Repellent efficacy of essential oils and plant extracts against Tribolium castaneum and Plodia interpunctella

This study was conducted to investigate the repellent efficacy of essential oils (Origanum vulgare, Pimpinella anisum, and Tanacetum cinerariifolium) and four plant extracts (Agastache rugosa, Capsicum annuum, Citrus reticulata, and Ginkgo biloba) against Tribolium castaneum (adults and larvae) and Plodia interpunctella (larvae). Gas chromatography/mass spectrometry analysis revealed the presence of carvacrol, anethole, and jasmolin I as the predominant constituent in O. vulgare, P. anisum, and T. cinerariifolium, respectively. Furthermore, ethyl hexopyranoside, 9,12‐octadecadienoic acid, cyclopentanol, and 2‐cresol were identified in A. rugosa, C. annuum, C. reticulata, and G. biloba, respectively. The repellent efficacy of each essential oil, plant extract, and the combination of oils was evaluated using a specially designed cylinder trap for 120 h. Among the three oils, O. vulgare and T. cinerariifolium had greatest repellent efficacy against P. interpunctella larvae. T. cinerariifolium exhibited effective repellence against the adults and larvae of T. castaneum. Therefore, O. vulgare (O) and T. cinerariifolium (T) were selected for further investigation of combined effects. Two essential oils were mixed in three different ratios of OT1 (1:3), OT2 (1:1), and OT3 (3:1). The repellent efficacies of OT1 and OT2 against the adults of T. castaneum were significantly greater than that of OT3. OT1 was effective against the larvae of T. castaneum, whereas OT2 was effective against the larvae of P. interpunctella. OT1 enhanced the repellent efficacy by approximately five times against larvae of T. castaneum, compared with that of T. cinerariifolium. Overall, OT1 was selected as the best repellent substance against all the tested insects.     

Chemical composition and protective effect of oregano (Origanum heracleoticum L.) ethanolic extract on oxidative damage and on inhibition of NO in LPS-stimulated RAW 264.7 macrophages

The present study shows the chemical profile and the in vitro properties (antioxidant and inhibition of nitric oxide production) of the Origanum heracleoticum L. (Lamiaceae). The ethanolic extract of the aerial parts is characterized by terpenes and fatty acids. The extract, with high total phenol and flavonoid content, showed a significant radical-scavenging activity (IC₅₀ value of 12.8 μg/mL) using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test and an interesting antioxidant activity with the β-carotene bleaching test (IC₅₀ values of 12.9 and 14.1 μg/mL at 30 and 60?min of incubation, respectively). The test for the inhibition of NO production, performed using the murine monocytic macrophage RAW 264.7 cell line, showed that the extract had significant activity with an IC₅₀ value of 108.5 μg/mL. The cytotoxic effect of O. heracleoticum extract in presence of lipopolysaccharide (LPS) (1 μg/mL) was evaluated but found to be negligible.     

Contemporary seasonal and altitudinal variations of leaf structural features in oregano (Origanum vulgare L.)

The effects of elevation (200, 950 and 1760 m) and season (April-October) on leaf morphological, anatomical, ultrastructural, morphometrical and photosynthetic parameters were studied in Origanum vulgare plants. Observations aimed at the determination of the alterations in leaf structure and function associated with differential growth and adaptation of plants. Raising elevation results in a progressive decrease of plant height. During the growing period, summer plants are taller than spring and autumn plants at all elevations examined. In high-altitude populations (O. vulgare ssp. vulgare), the blade size becomes reduced in June leaves as compared with October leaves, while it does not change remarkably in low-altitude populations (O. vulgare ssp. hirtum). Leaf thickness remains more or less stable during the growing period. Expanded leaves in June and October at 200 m elevation contain dark phenolics only in their epidermis, whereas leaves of August are densely filled with phenolics in all of their tissues. In June at 1760 m elevation, leaves are devoid of phenolics, which, however, occur in the epidermis of the leaves in August and October. At higher altitudes, larger mesophyll chloroplasts with more starch grains are present in June leaves, whereas in August and October leaves chloroplasts are smaller with fewer starch grains. Leaf stomata and non-glandular hairs increase in number from the lowland to the upland habitats, whereas glandular hairs decrease in number. During the growing season, the density of stomata and of glandular and non-glandular hairs progressively increases. In the low- and mid-altitude oregano populations, leaf chlorophyll a content and PSII activity significantly increase in October, whereas they simultaneously decrease in the high-altitude population, suggesting a phenomenon of chilling-induced photoinhibition. The highest photochemical efficiency of PSII appears in the mid-altitude population (having characteristics intermediate between those of O. vulgare ssp. hirtum and ssp. vulgare) where environmental conditions are more favourable. This conclusion is also confirmed by the observation that the 950 m O. vulgare population has larger and thicker leaves with highly developed palisade and spongy parenchymas.     

Effects of carvacrol upon the liver of rats undergoing partial hepatectomy

The present study aims to investigate the possible effects of carvacrol obtained from origanum oil upon the regenerative feature of the liver subsequent to partial hepatectomy in rats.Male Wistar Albino rats, weighing 230±30 g, were divided into three experiment groups. Group I (n=8) were used as sham operation group. Group II (n=8) were applied saline solution and hepatectomy. Carvacrol and hepatectomy (73 mg/kg) were applied to Group III (n=8). One dose of test material was injected 1 h before 68% partial hepatectomy. At the end of the experiments, blood and organs were removed. The liver regeneration rate of the rats was calculated measuring the weights of their liver before and after the hepatectomy. Hematoxylin and eosin, interleukin-6 (IL-6) and proliferating cell nuclear antigen (PCNA) treatments were applied to liver sections. Aspartate transaminase (AST), alanine transaminase (ALT), tumor necrosis factor-alpha (TNF-α) and IL-6 levels were determined in serum samples.The liver regeneration, mitotic index and PCNA index increased significantly in rats of Group III over the Group II at the 72nd hour after partial hepatectomy. Histological evaluations were also similar with these results of PCNA and mitotic indexes. In AST, ALT, TNF-α and IL-6 levels, there was no statistically significant difference.According to these results, it is concluded that carvacrol increases the liver regeneration rate.     

Medicinal Uses,Phytochemistry, and Pharmacology of Origanum onites (L.): A Review

Origanum onites L., known as Turkish oregano, has great traditional, medicinal, preservative, and commercial importance. It is used for the treatment of several kinds of ailments, such as gastrointestinal disorders, diabetes, high cholesterol, leukemia, bronchitis, etc. In this review, traditional use, phytochemistry, and pharmacology of O. onites reported between 1988 and 2014 were discussed. This review was prepared based on literature survey on scientific journals and books from libraries and electronic sources, such as Web of Science, PubMed, Scopus, Google Scholar, etc. All databases were searched up to June 2014. Several different classes of terpenoids, triterpene acids, phenolic acids, hydroquinones, flavonoids, hydrocarbons, sterols, pigments, fatty acids, tocopherols, and inorganic compounds were detected mainly in the aerial parts of this plant. Pharmacological studies revealed that extracts obtained from several solvents and individual compounds exhibited antimicrobial, antiviral, antioxidant, insecticidal, anticancer, hepatoprotective, genotoxic, antidiabetic, cholinesterase inhibitory, anti‐inflammatory, analgesic activities, etc. O. onites, in general, exhibited remarkable activity potential in almost all test systems. The results of toxicity studies indicated that O. onites did not show any significant toxicity and mutagenicity on Drosophila and Salmonella. Toxicity of the extracts/essential oils and also individual compounds should be evaluated on mammalian cells to ensure their safety. The bioactivity of individual compounds aside from terpenoids should also be assessed in detail. Additionally, mode of action for the bioactive compounds should be evaluated to understand the complex pharmacological effects of these phytochemicals.     

Plant odours with potential for a push–pull strategy to control the onion thrips, Thrips tabaci

We compared the efficacy of four plant essential oils to repel onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), in the presence of an attractive odour, ethyl iso‐nicotinate in a pasture field. Four horizontal white sticky plates were placed adjacent to (directions: N, S, E, W) a central horizontal white plate (C). After 24 h, in the treatment combination where the four plates were sprayed with essential oil surrounding a central sticky plate sprayed with ethyl iso‐nicotinate, fewer onion thrips were found on the plates treated with sweet marjoram [Origanum majorana L. (Labiatae)] or clove basil [Ocimum gratissimum L. (Labiatae)] (87 and 71% less, respectively) compared to the control treatment of four water‐sprayed plates surrounding a central plate with ethyl iso‐nicotinate. We also compared the distribution of onion thrips on the plates. Relative thrips numbers on each plate were compared with similar (N, S, E, W, and C) plates in the control treatment. There were relatively lower thrips numbers on the south (23% reduction) and west (26% reduction) O. majorana‐treated plates and higher numbers (37% increase) on the central attractant‐treated plate indicating a short‐distance push–pull effect. When four plates were sprayed with the thrips attractant surrounding a central sticky plate sprayed with an essential oil or water (control), only O. majorana reduced the number of thrips on the attractant‐sprayed plates (62% reduction). The distribution of thrips on the different plates within this treatment combination did not change substantially when compared to the distribution in the water‐control treatment. Other essential oils tested (wormwood [Artemisia arborescens L. (Compositae)]) and tea tree [Melaleuca alternifolia (Maiden. & Betche.) Cheel. (Myrtaceae)]) were not effective in any of the treatments. It appears that O. majorana is a promising thrips repellent which could be used for further testing in a push–pull system with the attractant ethyl iso‐nicotinate. The field setup used also proved to be a valuable tool for evaluating the potential of repellents to control onion thrips.     

Inhibitory Effect of Alcohols on Esterolytic Activity of Proteinase from Aspergillus sulphureus

(+)-Cyanofenphos was at least more than 25-fold as toxic to rice stem borer larvae as the (?)-isomer. In addition, (+)-cyanofenphos-oxon was 36-fold more potent inhibitor than the (?)-oxon toward rice stem borer larva acetylcholinesterase. The (+)-, (?)- and racemic forms of cyanofenphos were metabolized in rice stem borer larvae at almost equal rates. However, (+)-cyanofenphos produced 4- to 9-fold larger amounts of cyanofenphos-oxon in the insect body than the (?)-isomer. On the other hand, (?)-cyanofenphos-oxon was metabolized to 4-cyanophenol and its conjugate at a faster rate compared to the (+)-oxon. The difference in toxicity to rice stem borer larvae exhibited by the optical isomers of cyanofenphos is attributable to the difference in the amount and persistence of cyanofenphos-oxon isomers formed in the insect body as well as in anti-acetylcholinesterase activity of the oxon isomers.     

Antifungal effects of essential oils from oregano and fennel on Sclerotinia sclerotiorum

AIMS: The antifungal effects of essential oils of oregano (Origanum syriacum var. bevanii) and fennel (Foeniculum vulgare) were evaluated against Sclerotinia sclerotiorum. Effects of the essential oils on morphological structures of hyphae and sclerotia were studied under light and scanning electron microscopes (SEM). METHODS AND RESULTS: Inhibitory effects of volatile and contact phases of the essential oils used were determined on hyphae and sclerotia. Both essential oils have a marked antifungal effect against S. sclerotiorum. Soil amendment with essential oils has significant effect on reducing sclerotial viability. Both essential oils significantly inhibited the fungal growth in soil, thereby increasing the number of surviving tomato seedling by 69.8% and 53.3%, respectively. Light and SEM observations on pathogen hyphae and sclerotia revealed considerable morphological alterations in hyphae and sclerotia. CONCLUSIONS: The significant reduction in the mycelial growth and germination of sclerotia would greatly reduce the pathogen inoculum source. This may influence the rate of disease development in soil. SIGNIFICANCE AND IMPACT OF THE STUDY: Considering the reduction in the number of diseased plants in infested soil amended with essential oils, we concluded that oregano and fennel essential oils could be used as possible bio fungicides alternative to synthetic fungicides against phytopathogenic fungi.     

Validation of a quantitative assay of arbutin using gas chromatography in Origanum majorana and Arctostaphylos uva‐ursi extracts

Introduction – Arbutin is a skin‐whitening agent that occurs naturally in the bark and leaves of various plants. It is commonly quantified in plant extracts and skin‐whitening products by HPLC. Objective – To develop an alternative gas chromatographic method for the separation and quantification of arbutin in Origanum majorana and Arctostaphylos uva‐ursi extracts. Methodology – N,O‐Bis(trimethylsilyl)acetamide and trimethylchlorosilane were used as silylation reagents, and the gas chromatographic separation of silylated extracts and standards was performed using a DB‐5 narrow bore column. GC‐MS was used for the compound identification, and the quantification was carried out by GC‐FID. The quantitative results were compared with those of HPLC analysis. Results – The developed method gave a good sensitivity with linearity in the range 0.33–500 mg/mL and recovery >98%, allowing the quantification of arbutin in O. majorana and A. uva‐ursi extracts. The relative standard deviations (RSD) relating to intra‐day and inter‐day precision were <0.002% and <4.8%, respectively. The GC results correlated well with those obtained by HPLC analysis. Conclusion – The analysis of marjoram and bearberry samples showed that the established GC method was rapid, selective, and demonstrated that arbutin could be screened alternatively by gas chromatography. Copyright © 2009 John Wiley & Sons, Ltd.