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PubMed2006

The effect of lemon, orange and bergamot essential oils and their components on the survival of Campylobacter jejuni, Escherichia coli O157, Listeria monocytogenes, Bacillus cereus and Staphylococcus aureus in vitro and in food systems.

AIMS: To investigate the effectiveness of oils and vapours of lemon (Citrus limon), sweet orange (Citrus sinensis) and bergamot (Citrus bergamia) and their components against a number of common foodborne pathogens. METHODS AND RESULTS: The disc diffusion method was used to screen the oils and vapours against Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Escherichia coli O157 and Campylobacter jejuni. The survival of each species, demonstrated to be susceptible in the in vitro studies, was tested on cabbage leaf for 60 s by direct contact and on chicken skin for 10 min by direct contact and 24 h by vapour. The results indicate that bergamot was the most inhibitory essential oil (EO) and citral and linalool mimicked its effect (P > 0.001). Citral and linalool vapours produced 6 log reductions in L. monocytogenes, Staph. aureus and B. cereus populations on cabbage leaf after 8-10 h exposure but bergamot vapour exposure, while producing a similar reduction in L. monocytogenes and B. cereus populations, had no effect on Staph. aureus. CONCLUSIONS: Bergamot was the most effective of the oils tested and linalool the most effective anti-bacterial component. Gram-positive bacteria were more susceptible than Gram-negative bacteria in vitro, although Camp. jejuni and E. coli O157 were inhibited by bergamot and linalool oils and by linalool vapour. All bacteria tested were less susceptible in food systems than in vitro. Of the Gram-positive bacteria tested Staph. aureus was the least susceptible to both the oils and the components tested. SIGNIFICANCE AND IMPACT OF THE STUDY: Results suggest the possibility that citrus EOs, particularly bergamot, could be used as a way of combating the growth of common causes of food poisoning.

Animals↗
PubMed2005

Antimicrobial effects of essential oils in combination with chlorhexidine digluconate.

The aim of the present study was to compare antimicrobial effects of essential oils alone and in combination with chlorhexidine digluconate against planktonic and biofilm cultures of Streptococcus mutans and Lactobacillus plantarum. The essential oils included cinnamon, tea-tree (Melaleuca alternifola), manuka (Leptospermum scoparium), Leptospermum morrisonii, arnica, eucalyptus, grapefruit, the essential oil mouthrinse Cool Mint Listerine and two of its components, menthol and thymol. Cinnamon exhibited the greatest antimicrobial potency (1.25-2.5 mg/ml). Manuka, L. morrisonii, tea-tree oils, and thymol also showed antimicrobial potency but to a lesser extent. The combination effect of the essential oil-chlorhexidine was greater against biofilm cultures of both S. mutans and L. plantarum than against planktonic cultures. The amount of chlorhexidine required to achieve an equivalent growth inhibition against the biofilm cultures was reduced 4-10-fold in combination with cinnamon, manuka, L. morrisonii, thymol, and Listerine. We conclude that there may be a role for essential oils in the development of novel anticaries treatments.

Anti-Infective Agents, Local↗
PubMed2006

Effects of essential oils from fennel (Foeniculi aetheroleum) and caraway (Carvi aetheroleum) in pigs.

The ban of antibiotics as a feed additive requires alternatives to stabilize the health and performance particularly of the young animals. Essential oils obtained from fennel seed (Foeniculi aetheroleum) and caraway seed (Carvi aetheroleum) were tested in diets for weaned piglets in comparison with either a diet without feed additive or with a combination of formic acid and copper (positive control). Four groups of sixteen piglets (live weight 7 kg, age 26 days) received diets without (1) or with supplements of 7.5 g formic acid + 160 mg Cu/kg (2), 100 mg fennel oil/kg (3) or 100 mg caraway oil/kg (4) during 3 weeks after weaning. In the subsequent 4 weeks, all piglets were fed a diet without these additions. Fennel oil contained almost 2/3 anethol, approximately 1/5 fenchon and the remaining part consisting of alpha + beta-pinen, limonen (p-mentha-1,8-dien) and estragol. In the caraway oil, half of the contents was represented by limonen and the other half by carvon. There were no piglet losses and only few cases of diarrhoea. The combination of formic acid and copper increased feed consumption by 27% and daily weight gain by 25%. There were no differences in the performance between the group fed fennel oil and the control without additives. Piglets fed caraway oil tended to consume less feed and to gain approximately 10% less. In feed choice experiments, pigs consumed the same two diets from two troughs with 50% of total feed amount, as expected. The diets containing fennel or caraway oils were consumed at less than 50%. If the diet contained 100 mg fennel oil/kg, the decrease of percentual feed intake was significant. The results of the feeding experiment and of the feed choice experiment question the classification of fennel and caraway oils as flavour additives or as 'appetite promoters' in diets for weaned piglets.

Animal Feed↗
PubMed1993

Investigations on the antibacterial effect of conifer needle oils on bacteria isolated from the feces of captive Capercaillies (Tetrao urogallus L., 1758).

In winter, free-living Capercaillies feed almost exclusively upon needles of various conifer species. An important part of the energy and protein requirements of captive Capercaillies, however, is supplied by food rich in starch and proteins. The fecal flora of captive Capercaillies is considerably different from the flora of free-living Capercaillies. Bacterial diseases are frequent in captivity. The aim of the present study is to determine whether the essential oils from conifer needles possess antibacterial properties against several bacteria, some of which are facultatively pathogenic for Capercaillies. Needles of Pinus sylvestris contain few tannins, which could be a reason for the Capercaillies' preference for these needles. The needles of Abies alba contain high amounts of tannins and essential oils, which could explain the refusal of Capercaillies to eat these needles. The antibacterial effect of commercially available essential oils on the bacteria is investigated with a filter paper disc method and in a liquid medium. The essential oils possess a bacteriostatic or a bactericidal effect against some of the tested bacteria. Feeding on natural forage plants may help prevent the colonization of the intestines by facultatively pathogenic bacteria. The authors discuss why Capercaillies, especially young birds that are to be released, should be fed with natural forage plants.

Animal Feed↗
PubMedDate not supplied

Inhibition of growth of dermatophytes by Indian hair oils.

A survey on the use of hair oils for hair dressings by the Indian population revealed that mustard oil is preferred by males and coconut oil by females. Amla oil is used equally by both. These oils contain different percentages of various saturated and unsaturated fatty acids which largely determine their toxicity against dermatophytes. For Microsporum canis, M. gypseum and Trichophyton rubrum, amla oil was most toxic, followed by cantharidine and coconut oil, while Trichophyton mentagrophytes was most susceptible to coconut oil followed by amla and cantharidine oil. Mustard oil showed least toxicity to all four test species. The rarity of tinea capitis in India has been concluded to be due to the common use of hair oils by the Indian population.

Adolescent↗
PubMedDate not supplied

Fungitoxicity of essential oils against dermatophytes.

Sixteen essential oils were screened in vitro for their fungitoxicity against the two dermatophytes Trichophyton rubrum and Microsporum gypseum. Five oils (from Artemisia nelagrica, Caesulia axillaris, Chenopodium ambrosioides, Cymbopogon citratus and Mentha arvensis) showed strong activity and were assessed for their fungitoxicity against eight other dermatophytes as well as against Aspergillus fumigatus and Cladosporium trichoides. These five essential oils by formulation of ointments were able to cure experimental ringworm in guinea pigs within 7 to 12 days. Artemisia oil was found to be the most effective essential oil.

Animals↗
PubMed1998

Influence of cedar essence on spontaneous activity and sleep of rats and human daytime nap.

We investigated whether exposure to the odor of extracted cedar essence (CE) has (i) an influence on spontaneous activity and sleep-wake states of rats and (ii) a sleep-promoting effect on human daytime nap after taking an ordinary night's sleep. In rats exposed to CE, spontaneous activities and amount of wake were significantly decreased, while the amount of non-rapid eye movement (NREM) sleep was significantly increased. In human daytime nap, NREM sleep stage 2 latency was significantly shortened after exposure to CE.

Animals↗
PubMed1995

Antimicrobial effects of tea-tree oil and its major components on Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes.

Major components of two tea-tree oil samples were identified using thin layer and gas-liquid chromatography (TLC and GLC). Using a TLC-bioautographic technique, the tea-tree oils, terpinen-4-ol, alpha-terpineol and alpha-pinene were found to be active against Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes whereas cineole was inactive against these organisms. The MIC values of the three active compounds increased in the order alpha-terpineol < terpinen-4-ol < alpha-pinene for all three micro-organisms. MIC values of the tea-tree oils and terpinen-4-ol were lower for P. acnes than for the two staphylococci. This study supports the use of tea-tree oil in the treatment of acne, and demonstrates that terpinen-4-ol is not the sole active constituent of the oil.

Anti-Infective Agents, Local↗
PubMed2004

Five essential oils from aromatic plants of Cameroon: their antibacterial activity and ability to permeabilize the cytoplasmic membrane of Listeria innocua examined by flow cytometry.

AIMS: To investigate the antibacterial effect of five essential oils (EO) extracted from aromatic plants (Cymbopogon citratus, Ocimumbasilicum, Ocimum gratissimum, Thymus vulgaris and Zingiber officinale) of Cameroon against strains of Listeria monocytogenes, L. innocua and Staphylococcus aureus. The ability of selected EO to permeabilize the cytoplasmic membrane of L. innocua was also examined. METHODS AND RESULTS: The antibacterial activity of the EO determined by the agar diffusion method showed that T. vulgaris had the highest activity followed by O. gratissimum and C. citratus. Lowest activity was recorded from Z. officinale and O. basilicum. Significant differences in sensitivity between strains of Listeria and S. aureus were observed. Flow cytometry of L. innocua stained with carboxy-fluorescein diacetate showed that the fluorescence intensity of cells exposed to EO decreased faster than nonexposed cells, indicating that EO permeabilized the cytoplasmic membrane with the leakage of carboxy-fluorescein. CONCLUSIONS: Almost all the EO tested showed antibacterial activity to a different extent. The antibacterial effect was due to permeabilization of the cytoplasmic membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has identified the preservative potential of the EO examined. The use of sensitive method, such as flow cytometry, is advantageous for quick generation of data on the antibacterial effect of EO.

Anti-Bacterial Agents↗
PubMed1998

Anxiogenic-like effects of Tagetes minuta L essential oil on T-maze and tonic immobility behaviour in domestic chicks.

In a first experiment, four doses (ranging between 0.04 and 0.45 mg/kg of body weight) of the essential oil from Tagetes minuta L. were subcutaneously injected in two-day-old chicks and a dose-response curve assessed for escape performance in a T-maze test. The 0.1, 0.25 and 0.45 mg/kg doses impaired the first escape performance suggesting an anxiogenic-like effect of the essential oil. After 3 h the same chicks were tested for a second escape performance, without being injected again, and no differences were observed compared to controls, suggesting that the essential oil did not affect retention. Furthermore, the effects of the essential oil were observed in the three sections of the T-maze apparatus. So, the performance was impaired in the isolation chamber section, suggesting the induction of increased anxiogenic behaviour, and also in the mirror section, suggesting that the social reinstatement behaviour was modified by an increased anxiety level. Changes in the principal corridor section were not observed, suggesting that the locomotor activity was not affected by these oil doses. The second escape performance was not affected in any of the T-maze sections, confirming that these doses did not affect learning ability. In a second experiment, a middle dose of the essential oil (0.25 mg/kg) increased the tonic immobility reaction in 15 days old chicks similarly to an anxiogenic dose of FG 7142 (1 mg/kg), while an anxiolytic dose of diazepam (0.08 mg/kg) did not affect this behaviour. Taken together, the present results suggest that the essential oil from Tagetes minuta L. may exert a negative modulation on the GABAergic function without affecting the learning ability.

Animals↗
PubMed2006

Natural oils affect the human skin integrity and the percutaneous penetration of benzoic acid dose-dependently.

Natural oils are extensively used in cosmetics and as treatment for a growing number of more or less specific ailments. Skin irritation and cases of allergy have repeatedly been described in the literature following exposure to these oils. The present study evaluated the extent to which three natural oils (eucalyptus oil, tea tree oil, peppermint oil) would affect the skin integrity and the percutaneous penetration of benzoic acid when applied topically in relevant concentrations. An experimental in vitro model using static diffusion cells mounted with human breast or abdominal skin was applied. The three natural oils decreased the skin integrity dose-dependently. Concomitant dermal exposure to low concentrations of peppermint oil reduced the percutaneous penetration of benzoic acid. The present study lends support to the notion that low concentrations of peppermint oil may act protective against percutaneous penetration of some chemicals, whereas higher concentrations may decrease the integrity of the dermal barrier.

Adult↗
PubMed2003

Essential oils as components of a diet-based approach to management of Helicobacter infection.

An increased density of Helicobacter pylori in the gastric mucosa can be associated with more severe gastritis and an increased incidence of peptic ulcers. Therefore, people with asymptomatic gastritis would certainly benefit from a nutritional approach to help them manage the infection and therefore decrease the risk of development of associated pathologies. We analyzed the activities of 60 essential oils against H. pylori P1 and identified 30 oils that affected growth, with in vitro inhibition zones ranging between 0.7 and 6.3 cm in diameter. We further analyzed the effects of 16 oils with different activities on H. pylori P1 viability. Fifteen showed strong bactericidal activities, with minimal bactericidal concentrations after 24 h ranging from 0.02 to 0.1 g/liter at pH 7.4. Even though slight variations in activities were observed, the essential oils that displayed the strongest bactericidal potentials against H. pylori P1 were also active against other Helicobacter strains tested. Among the pure constituents of different essential oils tested, carvacrol, isoeugenol, nerol, citral, and sabinene exhibited the strongest anti-H. pylori activities. Although oral treatment of H. pylori SS1-infected mice with carrot seed oil did not result in significant decreases in the bacterial loads in the treated animals compared to those in the control animals, in all experiments performed, the infection was cleared in 20 to 30% of carrot seed oil-treated animals. Our results indicate that essential oils are unlikely to be efficient anti-Helicobacter agents in vivo. However, their effects may not be irrelevant if one plans to use them as food additives to complement present therapies.

Animal Feed↗