Contact and Gastric Effect of Peppermint Oil on Selected Pests and Aphid Predator Harmonia axyridis Pallas.

Peppermint essential oil (EO) has been extensively tested to date in reducing stored-product insects and insects of public health concern with very promising results, while only a few studies target important crop pests. There is also very little information on the effects of peppermint EO on non-target organisms, especially concerning contact and gastric effects at the same time. The goal of the investigation was the determination of the effect of peppermint EO on the mortality of Aphis fabae Scop.; the feeding intensity and weight gain of Leptinotarsa decemlineata Say. larvae; and the mortality and voracity of non-target organism Harmonia axyridis Pallas larvae. Our research indicates promising use for the M. piperita EO against aphids and young larvae (second instars) of the Colorado potato beetle. M. piperita EO showed good insecticidal efficacy against A. fabae with LC50 = 0.5442% for nymphs and 0.3768% for wingless females after 6 h. Over time, the LC50 value decreased. For the second instar larvae of L. decemlineata, the LC50 values were 0.6278%, 0.3449%, and 0.2020% after 1, 2, and 3 days of the experiment, respectively. On the other hand, older larvae (fourth instar) were characterized by significant resistance to the tested oil concentrations with LC50 value = 0.7289% after 96 h. M. piperita oil (contact and gastric effects) at a concentration of 0.5% was found to be toxic to young larvae (2 and 5 days old) of H. axyridis, while EO at a concentration of 1% was toxic to 8-day-old larvae. Thus, for the sake of ladybug safety, it would be advisable to use EO from M. piperita against aphids at concentrations lower than 0.5%.

Lavandula × intermedia-A Bastard Lavender or a Plant of Many Values? Part I. Biology and Chemical Composition of Lavandin.

This review article is the first in a series that provides an overview of the biology, chemistry, biological effects, and applications of Lavandula × intermedia (lavandin, LI). Despite its prevalence in cultivation and on the essential oil market, lavandin has received limited attention from the scientific community. Remarkably more attention is paid to Lavandula angustifolia (LA), which is commonly regarded as the superior lavender and has been extensively researched. Our goal is to provide a comprehensive review of LI, as none currently exists, and assess whether its inferior status is merited. In the first part, we outline the biological and chemical characteristics of the plant and compare it to the parent species. The chemical composition of lavandin oil is similar to that of LA but contains more terpenes, giving camphor notes that are less valued in perfumery. Nevertheless, lavandin has some advantages, including a higher essential oil yield, resulting in reduced production cost, and therefore, it is a preferred lavender crop for cultivation.

Lavandula x intermedia-A Bastard Lavender or a Plant of Many Values? Part II. Biological Activities and Applications of Lavandin.

This review article is the second in a series aimed at providing an in-depth overview of Lavandula x intermedia (lavandin). In part I, the biology and chemistry of lavandin were addressed. In part II, the focus is on the functional properties of lavandin and its applications in industry and daily life. While reviewing the biological properties, only original research articles employing lavandin were considered. Lavandin essential oil has been found to have antioxidant and biocidal activity (antimicrobial, nematicidal, antiprotozoal, insecticidal, and allelopathic), as well as other potential therapeutic effects such as anxiolytic, neuroprotective, improving sleep quality, antithrombotic, anti-inflammatory, and analgesic. Other lavandin preparations have been investigated to a much lesser extent. The research is either limited or inconsistent across all studies, and further evidence is needed to support these properties. Unlike its parent species-Lavandula angustifolia (LA)-lavandin essential oil is not officially recognized as a medicinal raw material in European Pharmacopeia. However, whenever compared to LA in shared studies, it has shown similar effects (or even more pronounced in the case of biocidal activities). This suggests that lavandin has similar potential for use in medicine.

Bio-Herbicidal Potential of Nanoemulsions with Peppermint Oil on Barnyard Grass and Maize.

Bio-based nanoemulsions are part of green pest management for sustainable agriculture. This study assessed the physicochemical properties and the herbicidal activities of the peppermint essential oil nanoemulsions (PNs) in concentrations 1.0-10% stabilized by Eco-Polysorbate 80 on germinating seeds and young plants of maize and barnyard grass. Based on the design of experiment (DOE) results, the final nanoemulsion formulations were obtained with 1, 1.5, 2, and 5% of essential oil concentration. Biological analyses were conducted to select the most promising sample for selective control of barnyard grass in maize. Seedlings growing in the presence of PNs displayed an overall inhibition of metabolism, as expressed by the calorimetric analyses, which could result from significant differences in both content and composition of carbohydrates. Concentration-response sub estimation showed that leaf-sprayed concentration of PN causing 10% of maize damage is equal to 2.2%, whereas doses causing 50% and 90% of barnyard grass damage are 1.1% and 1.7%, respectively. Plants sprayed with PN at 5% or 10% concentration caused significant drops in relative water content in leaves and Chlorophyll a fluorescence 72 h after spraying. In summary, peppermint nanoemulsion with Eco-Polysorbate 80 at 2% concentration is a perspective preparation for selective control of barnyard grass in maize. It should be analyzed further in controlled and field conditions.

Microencapsulated Caraway Essential Oil Affects Initial Growth of Maize Cultivars.

Caraway (Carum carvi L.) essential oil is a candidate for botanical herbicides. A hypothesis was formulated that the sand-applied maltodextrin-coated caraway oil (MCEO) does not affect the growth of maize (Zea mays L.). In the pot experiment, pre-emergence application of five doses of MCEO was tested on four maize cultivars up to the three-leaf growth stage. The morphological analyses were supported by the measurements of relative chlorophyll content (SPAD), two parameters of chlorophyll a fluorescence, e.g., Fv/Fm and Fv/F0, and fluorescence emission spectra. The analyzed MCEO contained 6.5% caraway EO with carvone and limonene as the main compounds, constituting 95% of the oil. The MCEO caused 7-day delays in maize emergence from the dose of 0.9 g per pot (equal to 96 g m-2). Maize development at the three-leaf growth stage, i.e., length of roots, length of leaves, and biomass of shoots and leaves, was significantly impaired already at the lowest dose of MCEO: 0.4 g per pot, equal to 44 g m-2. A significant drop of both chlorophyll a fluorescence parameters was noted, on average, from the dose of 0.7 g per pot, equal to 69 g m-2. Among the tested cultivars, cv. Rywal and Pomerania were less susceptible to the MCEO compared to the cv. Kurant and Podole. In summary, maize is susceptible to the pre-emergence, sand-applied MCEO from the dose of 44 g m-2.

Candida albicans Impairments Induced by Peppermint and Clove Oils at Sub-Inhibitory Concentrations.

Members of Candida species cause significant health problems, inducing various types of superficial and deep-seated mycoses in humans. In order to prevent from Candida sp. development, essential oils are more and more frequently applied, due to their antifungal activity, low toxicity if used appropriately, and biodegrability. The aim of the study was to characterize the early alterations in Candida albicans metabolic properties in relation to proteins and chromosomal DNA profiles, after treatment with peppermint and clove oils at sub-inhibitory concentrations. The yeasts were affected by the oils even at a concentration of 0.0075% v/v, which resulted in changes in colony morphotypes and metabolic activities. Peppermint and clove oils at concentrations ranging from 0.015× MIC (minimal inhibitory concentration) to 0.5× MIC values substantially affected the enzymatic abilities of C. albicans, and these changes were primarily associated with the loss or decrease of activity of all 9 enzymes detected in the untreated yeast. Moreover, 29% isolates showed additional activity of N-acetyl-ß-glucosaminidase and 14% isolates-α-fucosidase in comparison to the yeast grown without essential oils addition. In response to essential oils at 0.25-0.5× MIC, extensive changes in C. albicans whole-cell protein profiles were noted. However, the yeast biochemical profiles were intact with the sole exception of the isolate treated with clove oil at 0.5× MIC. The alterations were not attributed to gross chromosomal rearrangements in C. albicans karyotype. The predominantly observed decrease in protein fractions and the yeast enzymatic activity after treatment with the oils should be considered as a phenotypic response of C. albicans to the essential oils at their sub-inhibitory concentrations and may lead to the reduction of this yeast pathogenicity.

A comparative study on composition and antioxidant activities of supercritical carbon dioxide, hexane and ethanol extracts from blackberry (Rubus fruticosus) growing in Poland.

BACKGROUND: Large quantities of blackberry seeds are produced as a pomace during the processing of juice and jam production; this by-product is a very interesting raw material both for oil manufacturing and as a source of bioactive compounds. In this work the composition, yield and antioxidant activity of three types of Rubus fructicosus pomace extracts isolated by liquid extraction using solvents of different polarity, as well with supercritical CO2 fluid extraction have been compared. RESULTS: The highest extract yield was reported for Soxhlet extraction using ethanol as a solvent (14.2%). Supercritical carbon dioxide and hexane extracts were characterised by the highest content of phytosterols (1445 and 1583 mg 100 g-1 of extract, respectively) among which ß-sitosterol was the main one, while the concentration of tocopherols, with predominant γ-isomer, was the highest for both hexane and ethanol extracts, being 2364 and 2334 mg 100 g-1 , respectively. Using a GC-MS method 95 volatiles, in which non-saturated aldehydes were predominant, were identified in the essential oil of seed pomace and in the volatile oil isolated from supercritical extract. The ethanolic extract which is characterised by the highest phenolic content (9443 mg GAE 100 g-1 ) exhibited the highest antioxidant activity (according to the ABTS•+ and DPPH• assays). CONCLUSION: All pomace extracts examined were of high quality, rich in essential omega fatty acids and with a very high content of bioactive compounds, such as phytosterols and tocopherols. The high nutritional value of extracts from berry seed pomace could justify the commercialisation of specific extracts not only as food additives but also as cosmetic components. © 2017 Society of Chemical Industry.