Effects of feeding diets containing essential oils and betaine to heat-stressed growing-finishing pigs

This study was to evaluate the effects of dietary essential oils (EO) and betaine on growth performance, nutrient digestibility and serum hormones in growing-finishing pigs under heat stress conditions. A total of 96 crossed pigs [(Landrace × Yorkshire) × Duroc] with an initial body weight (BW) of 24.7 ± 0.27 kg were used in an 18-week trial. Pigs were randomly allocated to four treatments according to BW and gender. There were six replication pens in each treatment, with four pigs (two barrows and two gilts) per pen. Treatment groups were: (1) control group (CON), basal diet + 23°C for 24 h; (2) heat stress group (HC) with basal diet + 37°C for 9 h, 23°C for 15 h; (3) group HEO, HC with 0.01% EO; (4) group HBE, HC with 0.1% betaine. During the overall period, groups HEO and HBE had higher (p < 0.05) average daily gain than group HC. At week 6, group HC had a lower apparent total tract digestibility (ATTD) of dry matter (DM) (p < 0.05), but at week 12, this group had lower ATTD of DM, nitrogen and gross energy than group HEO (p < 0.05). At week 12 and 18, dietary EO decreased (p < 0.05) serum cortisol and norepinephrine concentration. At week 18, dietary EO and betaine decreased (p < 0.05) epinephrine concentration. Conclusively, dietary EO may be a potential nutritional strategy to alleviate heat stress in growing-finishing pigs.     

Sensitivity of two greenhouse pests to vapours of essential oils

Vapours of essential oils extracted from cumin, Cuminum cyminum L., anise, Pimpinella anisum L., oregano, Origanum syriacum var bevanii (Holmes) Ietswaart and eucalyptus, Eucalyptus camaldulensis Dehn., were found to be toxic to two greenhouse pests, viz. the carmine spider mite, Tetranychus cinnabarinus (Boisd.) (Tetranychidae, Tetranychini) and cotton aphid, Aphis gossypii Glov. (Aphididae, Aphidini). In general, a minimum dose of 0.5 µl/l air and 2–3 days of exposure was required for 99% mortality using essential oils of the first three plants.     

Sensitivity of nonfermentative gram-negative bacteria to essential oils of different origin

The sensitivity of MDR (multi drug resistant) strains of Stenotrophomonas maltophilia, Acinetobacter baumannii, and Pseudomonas aeruginosa to essential oils and their individual components was studied; bacteriostatic and bactericidal concentrations of 16 substances were determined. Crimean rose oil exhibited the highest activity, with the minimum inhibitory concentration of 1.95 μL/ mL. Growth of bacterial batch cultures in the presence of subinhibitory concentrations of essential oils or their individual components was studied. Kinetic models analysis revealed positive correlations of growth characteristics of the studied bacteria the effects of essential oils (p-level < 0.05). Correlations between lag phase duration and the death of bacterial cultures and correlations between the concentration of linalool (a component of essential oils) and the degree of growth suppression for S. maltophilia and A. baumannii were revealed.     

Sensitivity of yeasts to lithium

A wide range of tolerance to Li⁺ has been found among 12 different yeasts. Concentrations that do not allow long-term growth also arrest growth of an actively growing culture within 2–5 h. At the same concentrations protein and RNA synthesis are inhibited with little or no lag period (<50 min) but respiration is not affected at these concentrations. Lower concentrations that do not inhibit growth, may impair sporulation. For given extracellular conditions, intracellular Li⁺ concentrations are lower in the more tolerant yeast strains.     

Recovery of heat-stressed yeasts in media containing plant oleoresins

C onner , D.E. & B euchat , L.R. 1985. Recovery of heat-stressed yeasts in media containing plant oleoresins. Journal of Applied Bacteriology 59 , 49–55.
Oleoresins from seven plants (allspice, cinnamon, clove, garlic, onion, oregano, and thyme) were tested for their effects on eight genera of sublethally heated food-spoilage and industrially important yeasts ( Candida lipolytica, Debaryomyces han-senii, Hansenula anomala, Kloeckera apiculata, Lodderomyces elongisporus, Rhodotorula rubra, Saccharomyces cerevisiae, and Torulopsis glabrata ). All heat-stressed yeasts had increased sensitivity to oleoresins in recovery media. Heated cells were most sensitive to cinnamon oleoresin, a lethal effect being observed to concentrations as low as 5 μg/ml. Results indicate that all eight yeasts underwent metabolic and/or structural injury as a result of exposure to elevated temperature. Whilst changes in sensitivity to oleoresins were not the same for all yeasts, it is concluded that the oleoresins may have a pronounced synergistic or additive effect on thermal inactivation of yeasts in foods. Furthermore, carryover of oleoresins in low dilutions of food to enumeration media could adversely influence the recovery of heat-stressed cells, thus resulting in apparent low populations.     

Repellency of essential oils of some Kenyan plants against Anopheles gambiae

Essential oils of six plants growing in Kenya were screened for repellent activities against Anopheles gambiae sensu stricto. The oils of Conyza newii (Compositeae) and Plectranthus marrubioides (Labiateae) were the most repellent (RD50=8.9 x 10(-5) mg cm(-2), 95% CI) followed by Lippia javanica (Verbenaceae), Lippia ukambensis (Verbenaceae), Tetradenia riparia, (Iboza multiflora) (Labiateae) and Tarchonanthus camphoratus (Compositeae). Eight constituents of the different oils (perillyl alcohol, cis-verbenol, cis-carveol, geraniol, citronellal, perillaldehyde, caryophyllene oxide and a sesquiterpene alcohol) exhibited relatively high repellency. Four synthetic blends of the major components (present in > or = 1.5%) of the essential oils were found to exhibit comparable repellent activity to the parent oils.     

Mosquito repellent activity of essential oils of aromatic plants growing in Argentina

Mosquitoes are important vectors of diseases and nuisance pests. Repellents minimize contact with mosquitoes. Repellents based on essential oils (EO) are being developed as an alternative to DEET (N,N-diethyl-m-methylbenzamide), an effective compound that has disadvantages including toxic reactions, and damage to plastic and synthetic fabric. This work evaluated the repellency against Aedes aegypti of EO from aromatic plants that grow in Argentina: Acantholippia seriphioides, Achyrocline satureioides, Aloysia citriodora, Anemia tomentosa, Baccharis spartioides, Chenopodium ambrosioides, Eucalyptus saligna, Hyptis mutabilis, Minthostachys mollis, Rosmarinus officinalis, Tagetes minuta and Tagetes pusilla. Most EO were effective. Variations depending on geographic origin of the plant were detected. At a 90% EO concentration, A. satureoides and T. pusilla were the least repellent. At concentrations of 12.5% B. spartioides, R. officinalis and A. citriodora showed the longest repellency times. Comparisons of the principal components of each EO suggest that limonene and camphor were the main components responsible for the repellent effects.     

Larvicidal activity of essential oils from Brazilian plants against Aedes aegypti L

Aedes aegypti L. is the major vector of dengue fever, an endemic disease in Brazil. In an effort to find effective and affordable ways to control this mosquito, the larvicidal activities of essential oils from nine plants widely found in the Northeast of Brazil were analyzed by measurement of their LC50. The essential oils were extracted by steam distillation and their chemical composition determined by GL-chromatography coupled to mass spectroscopy. The essential oils from Cymbopogon citratus and Lippia sidoides, reported in the literature to have larvicidal properties against A. aegypti, were used for activity comparison. The results show that Ocimum americanum and Ocimum gratissimum have LC50 of 67 ppm and 60 ppm respectively, compared to 63 ppm for L. sidoides and 69 ppm for C. citratus. These results suggest a potential utilization of the essential oil of these two Ocimum species for the control of A. aegypti.     

Composition and anti-plasmodial activities of essential oils from some Cameroonian medicinal plants

In a search for new plant-derived biologically active compounds against malaria parasites, five essential oils extracted from the Cameroonian plants Xylopia phloiodora, Pachypodanthium confine, Antidesma laciniatum, Xylopia aethiopica, and Hexalobus crispiflorus were evaluated in regard to their anti-plasmodial activity against the W2 strain of Plasmodium falciparum. The oils were obtained from the plants with 0.12, 0.13, 0.18, 0.6 and 0.1% yields (relatively to dried material weight) respectively. Analysis by gas chromatography and mass spectrometry identified mainly terpenoids, among which alpha-copaene, gamma-cadinene, delta-cadinene, alpha-cadinol, spathulenol and caryophyllene oxide were most commonly found. The five oils were active against Plasmodium falciparum in culture. The most effective was the oil of Hexalobus crispiflorus, with an IC50 of 2 microg/ml.     

Effect of essential oils from some higher plants against fungi causing damping-off disease

A screening of leaves of 25 taxa of angiosperms was made for their volatile toxicity against damping-off fungi. The volatile substances fromHyptis suaveolens andOcimum canum were toxic againstPythium aphanidermatum, P. debaryanum andRhizoctonia solani. The fungitoxicity of the leaves persisted for 15 d of storage. The volatile substances from the leaves ofO. canum were thermostable, while those fromH. suaveolens were thermolabile. The essential oils exhibited strong potency against the pathogens tested, non-phytotoxic nature to the host plants and superiority over commonly used synthetic fungicidesAgrosan G.N. andCaptan. The findings indicate the possibility to use these essential oils as potential natural fungicides in management of damping-off pathogens.     

Inhibitory effects of essential oils of medicinal plants from growth of plant pathogenic fungi

Plant cells produce a vast amount of secondary metabolites. Production of some compounds is restricted to a single species. Some compounds are nearly always found only in certain specific plant organs and during a specific developmental period of the plant. Some secondary metabolites of plants serve as defensive compounds against invading microorganisms. Nowadays, it is attempted to substitute the biological and natural agents with chemically synthesized fungicides. In the present research, the antifungal activities of essential oils of seven medicinal plants on mycelial growth of three soilborne plant pathogenic fungi were investigated. The plants consisted of Zataria multiflora, Thymus carmanicus, Mentha pieperata, Satureja hortensis, Lavandual officinolis, Cuminum cyminum and Azadirachta indica. The first five plants are from the family Labiatae. Examined fungi, Fusarium oxysporum f.sp. lycopersici, Fusarium solani and Rhizoctonia solani are the causal agents of tomato root rot. Essential oils of Z. multiflora, T. carmanicus, M. pieperata, S. hortensis and C. cyminum were extracted by hydro-distillation method. Essential oils of L. officinalis and A. indica were extracted by vapor-distillation method. A completely randomized design with five replicates was used to examine the inhibitory impact of each concentration (300, 600 and 900 ppm) of each essential oil. Poisoned food assay using potato dextrose agar (PDA) medium was employed. Results showed that essential oils of A. indica, Z. multiflora, T. carmanicus and S. hortensis in 900 ppm at 12 days post-inoculation, when the control fungi completely covered the plates, prevented about 90% from mycelial growth of each of the fungi. While, the essential oils of M. pieperata, C. cyminum and L. officinalis in the same concentration and time prevented 54.86, 52.77 and 48.84%, respectively, from F. solani growth. These substances did not prevent from F. oxysporum f.sp. lycopersici and R. solani growth. Minimum inhibitory concentration (MIC) of essential oils of T. carmanicus, Z. multiflora and A. indica from R. solani and F. solani growth was 900 and 600 ppm, respectively. In addition, the MIC of essential oils of these plants and essential oil of S. hortensis from F. oxysporum f.sp. lycopersici growth was 900 ppm. The MIC of essential oils of M. pieperata, C. cyminum and L. officinalis from F. solani growth was 900 ppm.     

Trypanocidal and cytotoxic activities of essential oils from medicinal plants of Northeast of Brazil

Chagas disease, caused by Trypanosoma cruzi, is an important cause of mortality and morbidity in Latin America. There are no vaccines available, the chemotherapy used to treat this illness has serious side effects and its efficacy on the chronic phase of disease is still a matter of debate. In a search for alternative treatment for Chagas disease, essential oils extracted from traditional medicinal plants Lippia sidoides, Lippia origanoides, Chenopodium ambrosioides, Ocimum gratissimum, Justicia pectorales and Vitex agnus-castus were investigated in vitro for trypanocidal and cytotoxic activities. Essential Oils were extracted by hydrodistillation and submitted to chemical analysis by gas chromatography/mass spectrometry. The concentration of essential oils necessary to inhibit 50% of the epimastigotes or amastigotes growth (IC(50)) and to kill 50% of trypomastigote forms (LC(50)) was estimated. The most prevalent chemical constituents of these essential oils were monoterpenes and sesquiterpenes. All essential oils tested demonstrated an inhibitory effect on the parasite growth and survival. L. sidoides and L. origanoides essential oils were the most effective against trypomastigote and amastigote forms respectively. No significant cytotoxic effects were observed in mouse peritoneal macrophages incubated with essential oils which were more selective against the parasites than mammalian cells. Taken together, our results point towards the use of these essential oils as potential chemotherapeutic agent against T. cruzi.     

Comparative larvicidal activity of essential oils from three medicinal plants against Aedes aegypti L

This work aimed at comparing larvicidal activity of essential oils extracted from the dried leaves of Alpinia speciosa, Cymbopogon citratus, and Rosmarinus officinalis against Ae. aegypti larvae. The larvae were observed for 4 h and at 24 h according to a completely randomized design with three replications and the following concentrations [μl/ml]: 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and controls were distilled water, and commercial standard citral, camphor, eucalyptol, α‐pinene, and β‐myrcene. The essential oil of C. citratus had the lowest LC₅₀ (0.28) and LC₉₀ (0.56) values, followed by that of A. speciosa (0.94 and 1.2, resp.) and of R. officinalis (1.18 and 1.67, resp.), and only the commercial standards citral and α‐pinene were larvicidal.     

Sensitivity of various yeasts to crude cellulolytic enzyme complexes fromTrichoderma reesei

Summary Twenty-six yeast strains, representative of different yeast genera, were tested for their sensitivity to crude extracellular cellulolytic enzyme complexes obtained from the fungusTrichoderma reesei QM 9414 and its mutants M 6 and MHC 22 (Microcrystalline cellulose was the sole carbon source.) Practically all the yeast strains tested were found to be sensitive, exhibiting signs of cellwall weakening and lysis during prolonged incubation with the emzymes fromTrichoderma. Under growth conditions, the effect of cellulolytic enzymes on yeast cells and their growth rates was much less pronounced. However, at increased cellulase concentrations (5 mg/ml) in the growth medium, lysis of stationary phase yeast cells was observed.     

Antioxidant properties of essential oils

By the method of capillary gas-liquid chromatography, we studied the antioxidant properties and stability during the storage of hexane solutions of 14 individual essential oils from black and white pepper (Piper nigrum L.), cardamom (Elettaria cardamomum L.), nutmeg (Myristica fragrans Houtt.), mace (Myristica fragrans Houtt), juniper berry (Juniperus communis L.), fennel seed (Foeniculum vulgare Mill., var. dulce Thelling), caraway (Carvum carvi L.), dry cinnamon leaves (Cinnamomum zeylanicum Bl.), marjoram (Origanum majorana L.), laurel (Laurus nobilis L.), ginger (Zingiber officinale L.), garlic (Allium sativum L.), and clove bud (Caryophyllus aromaticus L.). We assessed the antioxidant properties by the oxidation of aliphatic aldehyde (trans-2-hexenal) into the corresponding carbonic acid. We established that essential oils of garlic, clove bud, ginger and leaves of cinnamon have the maximal efficiency of inhibiting hexenal oxidation (80!–93%), while black pepper oil has the minimal (49%). Antioxidant properties of essential oils with a high content of substituted phenols depended poorly on their concentrations in model systems. We studied the changes in the composition of essential oils during the storage of their hexane solutions for 40 days in light and compared it with the stability of essential oils stored for a year in darkness.     

Photosynthesis is improved by exogenous calcium in heat-stressed tobacco plants

Effects of exogenous calcium chloride (CaCl₂) (20 mM) on photosynthetic gas exchange, photosystem II photochemistry, and the activities of antioxidant enzymes in tobacco plants under high temperature stress (43 °C for 2 h) were investigated. Heat stress resulted in a decrease in net photosynthetic rate (P_n), stomatal conductance as well as the apparent quantum yield (AQY) and carboxylation efficiency (CE) of photosynthesis. Heat stress also caused a decrease of the maximal photochemical efficiency of primary photochemistry (F_v/F_m). On the other hand, CaCl₂ application improved P_n, AQY, and CE as well as F_v/F_m under high temperature stress. Heat stress reduced the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), whereas the activities of these enzymes either decreased less or increased in plants pretreated with CaCl₂; glutathione reductase (GR) activity increased under high temperature, and it increased more in plants pretreated with CaCl₂. There was an obvious accumulation of H₂O₂ and O₂⁻ under high temperature, but CaCl₂ application decreased the contents of H₂O₂ and O₂⁻ under heat stress conditions. Heat stress induced the level of heat shock protein 70 (HSP70), while CaCl₂ pretreatment enhanced it. These results suggested that photosynthesis was improved by CaCl₂ application in heat-stressed plants and such an improvement was associated with an improvement in stomatal conductance and the thermostability of oxygen-evolving complex (OEC), which might be due to less accumulation of reactive oxygen species.     

High-value oils from plants

The seed oils of domesticated oilseed crops are major agricultural commodities that are used primarily for nutritional applications, but in recent years there has been increasing use of these oils for production of biofuels and chemical feedstocks. This is being driven in part by the rapidly rising costs of petroleum, increased concern about the environmental impact of using fossil oil, and the need to develop renewable domestic sources of fuel and industrial raw materials. There is also a need to develop sustainable sources of nutritionally important fatty acids such as those that are typically derived from fish oil. Plant oils can provide renewable sources of high-value fatty acids for both the chemical and health-related industries. The value and application of an oil are determined largely by its fatty acid composition, and while most vegetable oils contain just five basic fatty acid structures, there is a rich diversity of fatty acids present in nature, many of which have potential usage in industry. In this review, we describe several areas where plant oils can have a significant impact on the emerging bioeconomy and the types of fatty acids that are required in these various applications. We also outline the current understanding of the underlying biochemical and molecular mechanisms of seed oil production, and the challenges and potential in translating this knowledge into the rational design and engineering of crop plants to produce high-value oils in plant seeds.     

Sensitivity of Aedes aegypti adults (Diptera: Culicidae) to the vapors of Eucalyptus essential oils

Vapors of essential oils extracted from various species of Eucalyptus (E. gunnii, E. tereticornis, E. grandis, E. camaldulensis, E. dunnii, E. cinerea, E. saligna, E. sideroxylon, E. globulus ssp. globulus, E. globulus ssp. maidenii, E. viminalis and the hybrids E. grandis × E. tereticornis and E. grandis × E. camaldulensis) and their major components were found to be toxic to Aedes aegypti adults, the yellow fever mosquito.An aliquot of each oil was placed in a cylindrical test chamber and the number of knocked-down mosquitoes was recorded as function of time. Knockdown time 50% was then calculated. Results showed that E. viminalis had the fastest knockdown time at of 4.2 min, on the same order as dichlorvos, a standard knockdown agent. A correlation was observed between the content of 1,8-cineole in the Eucalyptus essential oils and the corresponding toxic effect.The correlation between KT₅₀ values and calculated vapor pressures of the essential oil components showed that the fumigant activity of simple organic compounds in insects is correlated with their volatility.     

Sensitivity assessment of thyme and lavender essential oils against clinical strains of Escherichia coli for their resistance

Strong antiseptic activity of plant essential oils and extracts has been known for a long time. The antibacterial activity of thyme and lavender essential oils were tested against 30 clinical bacterial strains of Escherichia coli from patients with different clinical conditions. The agar diffusion method was used for microbial growth inhibition at various concentrations of the oils from Thymus vulgaris and Lavandula angustifolia. Susceptibility testing to antibiotics and chemotherapeutics was carried out using disc-diffusion method. The results of experiments showed that the both oils, from T. vulgaris and L. angustifolia were active against all of the clinical strains, but thyme oil demonstrated the highest activity. Thyme and lavender essential oils were active against multi drug resistant clinical strains of Escherichia coli genera. The results of experiments justify a study related to activity other essential oils against different genus of bacteria.