Biological activities of the essential oil and methanolic extract of Micromeria fruticosa (L) Druce ssp serpyllifolia (Bieb) PH Davis plants from the eastern Anatolia region of Turkey

The in vitro antimicrobial and antioxidant activities of the essential oil and methanolic extract of Micromeria fruticosa ssp serpyllifolia as well as the composition of the essential oil were examined. The essential oil exhibited activity against 14 bacteria, three fungi and a yeast, with minimal inhibitory concentration (MIC) values ranging from 31.25 to 125 µl ml^?1, whilst the methanolic extract was inactive. Antioxidant activity was measured by two methods, namely scavenging of the free radical DPPH and inhibition of linoleic acid oxidation. The methanolic extract exhibited significant antioxidant activity in both assays, providing 50% inhibition at 70.9 ± 0.5 µg ml^?1 concentration in the DPPH assay and inhibiting linoleic acid oxidation to 59% at 2 mg ml^?1 concentration, whilst the essential oil showed activity only at higher concentrations. The gallic acid equivalent total phenolic content of the methanolic extract was found to be 55.2 ± 2.00 µg mg^?1 dry weight extract (5.5% w/w). The chemical composition of the hydrodistilled essential oil was analysed by means of GC/MS. Twenty‐nine constituents were identified, the main ones being piperitenone (50.61%) and pulegone (29.19%). Copyright © 2004 Society of Chemical Industry     

Antifungal activity of some essential oil components

Fifteen essential oil components were evaluated for antifungal activity towards five spoilage-causing fungi. In liquid shake cultures, unsaturated aldehydes (citral, cinnamic aldehyde and cittronellal) followed by geraniol, an unsaturated alcohol were most inhibitory to Aspergillus niger, Fusarium oxysporum and Penicillium digitatum; their minimal inhibitory concentrations (MIC) was 100 μg ml⁻¹. Menthol, a terpene alcohol was most inhibitory to Rhizopus stolonifer and Mucor sp. with a MIC of 200 μg ml⁻¹. Hydrocarbons like camphene, limonene and α-terpinene were least inhibitory. When incorporated in agar medium different patterns of activity were found. Thus citral, cinnamic aldehyde, citronellal, geraniol and menthol not only failed to completely inhibit A. niger, F. oxysporum and P. digitatum but were more active against R. stolonifer and Mucor sp. than in liquid medium. The differences were due to the vapour of the volatile test compounds which accumulated over the agar medium. The growth inhibition due to the vapours alone was measured by using structurally modified petri-plates. The vapours were more active against R. stolonifer and Mucor sp. than against A. niger, F. Oxysporum and P. digitatum. Fungal growth inhibition by volatile compounds in agar medium reflects the combined activity of the vapour and the compound incorporated in the medium and the inhibition is different from that obtained in liquid medium. Regarding the structure-activity relationship of citral, the-CHO group in conjugation with a carbon to carbon double bond (C=C) was found to be responsible for the antifungal activity of the molecule.     

Antifungal activity of peppermint and sweet basil essential oils and their major aroma constituents on some plant pathogenic fungi from the vapor phase

The vapors of peppermint oil and two of its major constituents (menthol and menthone), and sweet basil oil and two of its major constituents (linalool and eugenol), were tested against Sclerotinia sclerotiorum (Lib.), Rhizopus stolonifer (Ehrenb. exFr.) Vuill and Mucor sp. (Fisher) in a closed system. These fungi cause deterioration and heavy decay of peach fruit during marketing, shipping and storage. The essential oils, their major individual aroma constituents and blends of the major individual constituents at different ratios inhibited the growth of the fungi in a dose-dependent manner. Menthol was found to be the individual aroma constituent responsible for the antifungal properties of peppermint essential oil, while menthone alone did not show any effect at all doses. In the case of basil oil, linalool alone showed a moderate antifungal activity while eugenol showed no activity at all. Mixing the two components in a ratio similar to their concentrations in the original oil was found to enhance the antifungal properties of basil oil indicating a synergistic effect.     

Application of plant essential oils in prevention of fungal growth on Para rubber wood

Antifungal activities of essential oils (cinnamon, clove, eucalyptus, peppermint and lemongrass oils) against moulds (Penicillium sp., Aspergillus niger and Aspergillus versicolor) isolated from rubber wood surfaces were examined. Clove oil possessed consistent antifungal activity with the minimal inhibitory concentration (MIC) of 5 μl ml^?1 against all these fungi, while cinnamon oil had MICs from 2.5 to 10 μl ml^?1. However, only dip treatment with cinnamon oil inhibited the growth of A. niger on rubber wood for at least 25 weeks.     

The in vitro antioxidant and antimicrobial activities of the essential oil and various extracts of Origanum syriacum L var bevanii

The present work examines the in vitro antioxidant and antimicrobial properties of the essential oil and various extracts from the herbal parts of Origanum syriacum L var bevanii. Polar subfractions of methanol extracts from both deodorised and non‐deodorised materials showed the highest DPPH (2,2‐diphenyl‐l‐picrylhydrazyl) radical‐scavenging activity, with IC₅₀ values of 21.40 and 26.98 µg ml^?1 respectively, whereas the IC₅₀ of the essential oil was 134.00 µg ml^?1. The antioxidant potential of the extracts appeared to be closely related to the presence of polar phenolics. However, the inhibitive effect on linoleic acid oxidation might be promoted by the presence of non‐polar phenolics, as both hexane and dichloromethane extracts showed high antioxidant activities. The antimicrobial activity of the essential oil was superior to those of the other extracts. Nineteen compounds representing 962 g kg^?1 of the essential oil were identified; carvacrol (669 g kg^?1) was the main component. Overall, the results suggest that the essential oil and extracts from the herbal parts of O syriacum could be used as natural preservative ingredients in the food industry. Copyright © 2004 Society of Chemical Industry     

Antibacterial and antioxidant activities of the essential oil and methanol extracts of Bidens frondosa Linn

Antibacterial and antioxidant potential of essential oil, extract and its fractions of Bidens frondosa Linn were evaluated. Sixty‐one components representing 95.41% of the total oil were identified. The essential oil (7.5 μL disc^?1), methanol extract and its different organic subfractions (0.5 μg disc^?1) of B. frondosa displayed a great potential of antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes ATCC 19116, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella enteritidis KCTC 12021 and Enterobacter aerogenes KCTC 2190. Antioxidant activity was evaluated by using 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay. The free radical scavenging activity of ethyl acetate (EtOAc) fraction was superior to all other fractions (IC₅₀ = 11.96 μg mL^?1), which was higher than synthetic antioxidant butylated hydroxyanisole, (IC₅₀ = 18.27 μg mL^?1). Furthermore, the amount of total phenolic compounds was determined and its content in EtOAc fraction was the highest as compared to methanol extract or other fractions. The results indicate that the oil and extracts of B. frondosa could serve as an important bio‐resource of antimicrobial agents and antioxidants for using in the food industries.     

Simulation and modelling of the effect of small inoculum size on time to spoilage by Bacillus stearothermophilus

Mathematical models developed in predictive food microbiology typically use large (approx. 10⁵cfu ml⁻¹) inoculum sizes. Real food systems may contain low microbial loads (1–10 cfu ml⁻¹) introducing an additional uncertainty unaccounted for by model predictions. This research investigated the effects of very low inoculum sizes on the time to spoilage of Bacillus stearothermophilus ATCC 12980 spores. Microtiter plates (96-well) were filled with tryptic soy broth and inoculated with various concentrations of B. stearothermophilus spores. Time to spoilage was defined as colour change of the medium containing bromcresol purple (corresponding to c. 10⁸cfu ml⁻¹) from purple to yellow. A Poisson distribution best described the number of spores in a well. Spoilage times showed maximum variability (7·25–17 h) at 1 spore well⁻¹, and negligible variability (c. 6·5 h) at 500 spores well⁻¹. A simplified Gompertz function described spoilage kinetics. Mathematical modelling and simulation approaches were used to study spoilage times. The modelling approach had a fail-safe bias in its predictions and provided greater accuracy than the simulation, which was fail-dangerous. The simulation approach provided potentially greater mechanistic insight into the causes of spoilage time variability, and supported the notion that the effects of biovariability and interactions among individual spores manifest at very low inoculum sizes.     

Inactivation of yeast and filamentous fungi by the lactoperoxidase-hydrogen peroxide-thiocyanate-system

The antifungal activity of the lactoperoxidase (LPO) system with glucose oxidase (GOD) as source of hydrogen peroxide was determined in salt solution and in apple juice. The test organisms Rhodutorula rubra and Saccharomyces cerevisiae were cultivated aerobically in apple juice, Mucor rouxii was grown on wort agar adjusted to pH 4.5. Aspergillus niger and Byssochlamys fulva were kept on malt extract agar. Spores of the filamentous fungi were harvested by suspension in salt solution supplemented with Tween 80® and checked microscopically. The antifungal activity of the combined enzyme system was tested with initial counts of approx. 10⁵ cfu · ml^?1 (yeast cells or spores) suspended in salt solution supplemented with 25 mg · l^?1 thiocyanate and 20 g · l^?1 glucose or in apple juice supplemented with the same amount of thiocyanate. The tests were performed with 25 ml of the medium in 100 ml Erlenmeyer flasks shaken at 28 °C under aerobic conditions. Inactivation was achieved for all test organisms in both media. The yeast strains were found to be least stable while B. fulva was most resistant. A combination of 5 U · ml^?1 LPO with 0.5 to 1 U · ml^?1 GOD was sufficient for complete inactivation of this mold in salt solution within 2 h. The enzyme system also showed antifungal activity in apple juice at acid pH (3.2), although its effectiveness was reduced. In this medium, B. fulva was inactivated by 20 U · ml^?1 LPD and 1 U · ml^?1 GOD within 4 h. R. rubra and S. cerevisiae were unable to survive in apple juice at 5 U · ml^?1 LPO combined with 1 U · ml^?1 GOD. For inhibition by GOD alone, higher amounts of this enzyme were needed and even then only M. rouxii and R. rubra have been affected within the concentration range tested (maximum 3 U · ml^?1).     

Evaluation of the Chemical Composition and Antioxidant Activity of the Peel Oil of Citrus nobilis

Peel oil of Citrus nobilis (Lour) was analyzed for determining its chemical composition. Fourteen identified components accounted for 99.1% (GC) and 100.0% (FID) of the total oil. Major component of the oil was limonene (76.8%-GC and 86.2%-FID). Essential oil was also evaluated for its antioxidant activity in four complementary test systems namely; β-carotene/linoleic acid, DPPH radical scavenging, reducing power and metal chelating activities. In the first system, antioxidant activity increased with the increasing concentration. At 20.0 mg.ml^?1 concentration, antioxidant property of the oil was 96.8% ± 0.2 and as strong as the positive controls BHT and α-tocopherol. Scavenging effect of the oil was superior to the positive controls BHT and α-tocopherol at 1.5 mg.ml^?1 concentration (96.4% ± 0.1). Reducing power and chelating effect of the essential oil increased with the increasing concentration.     

Chemical composition of Ocimum basilicum L. essential oil and its efficacy as a preservative against fungal and aflatoxin contamination of dry fruits

The study presents fungal and aflatoxin contamination of some dry fruits and Ocimum basilicum essential oil (EO) as a plant‐based preservative. During mycoflora analysis, 2045 fungal isolates were recorded from dry fruits and 40% isolates of Aspergillus flavus were toxigenic in nature. The EO of O. basilicum exhibited strong fungitoxicity against toxigenic strain of A. flavus. Its minimum inhibitory concentration (MIC) was recorded at 1.0 μL ml^?1, and it completely inhibited aflatoxin B₁ production at 0.5 μL ml^?1. The oil exhibited broad fungitoxic spectrum and considerably reduced A. flavus isolates from dry fruits when used as fumigant in closed storage containers at 1.0 μL ml^?1. The chemical profile of the EO was standardised through GC–MS analysis. Based on antifungal potency, antiaflatoxigenicity and efficacy as fumigant during storage conditions, O. basilicum EO may be recommended as a botanical preservative for enhancing the shelf life of dry fruits and edible products during storage.     

Testing matrix, inoculum size, and incubation temperature affect monolaurin activity againstListeria monocytogenes

Current literature reports conflicting minimal inhibitory concentrations (MIC) (range 10–96 g ml⁻¹) of glycerol monolaurate (monolaurin) againstListeria monocytogenes. To resolve these disagreements, the individual MIC of monolaurin against eightL. monocytogenesstrains was determined using the standard agar dilution technique on three commercial media (trypticase soy agar, plate count agar, and Oxford modified medium), and a catfish-based medium using three inocula sizes and three incubation temperatures. Mean MIC was 16 g ml⁻¹on commercial media at 25 and 35°C. Endpoints at 15°C were twofold lower (8 g ml⁻¹) than at 25 and 35°C. On catfish-based medium, MIC values were four- to eightfold higher (64–128 g ml⁻¹) compared with commercial media and depended on incubation temperature and size of inoculum tested. Poor solubility of monolaurin (85 g ml⁻¹) in aqueous solutions and its reduced activity in the presence of food components limits its application as an antimicrobial agent in foods.     

Chemical composition and in vitro antimicrobial activity of the essential oil of Origanum minutiflorum O Schwarz & PH Davis

The essential oil obtained by hydrodistillation from the aerial parts of Origanum minutiflorum O Schwarz & PH Davis, an endemic species in Turkey, was analysed for its antimicrobial activity in vitro. Gas chromatography/mass spectrometry analysis of the essential oil resulted in the identification of 34 constituents accounting for 961.5 mL L^?1 of the oil, the major compounds present being carvacrol (793.4 mL L^?1), p‐cymene (32.6 mL L^?1) and γ‐terpinene (21.4 mL L^?1). The in vitro antimicrobial activity of the essential oil was investigated in order to evaluate its efficacy against 16 bacteria and two yeasts, using disc diffusion and minimum inhibitory concentration methods. The essential oil showed strong antimicrobial activity against all test micro‐organisms except Pseudomonas aeruginosa. Its main components carvacrol and p‐cymene were also assayed for their antimicrobial activities. Carvacrol exhibited comparable activity to the crude oil, proving it to be the main component responsible for the biological activity observed. This study demonstrates the in vitro antimicrobial activity of the essential oil of this endemic remedy against a wide spectrum of clinically important micro‐organisms, including pathogenic yeasts, being the first report on the anticandidal properties of the essential oil of O. minutiflorum. Copyright © 2006 Society of Chemical Industry     

In vitro inhibitory effect of tetrahydrocurcuminoids on Fusarium proliferatum growth and fumonisin B1 biosynthesis

Many plant pathogens produce toxic metabolites when growing on food and feed. Some antioxidative components seem to prevent fungal growth and mycotoxin formation. Recently, we synthesized a new class of powerful antioxidative compounds, i.e. tetrahydrocurcuminoids, and its structure/antioxidant activity relationships have been established. The South West of France produces large amounts of corn, which can be infected by Fusarium species, particularly F. proliferatum. In this context, the efficiency of tetrahydrocurcuminoids, which can be obtained from natural curcuminoids, was investigated to control in vitro the growth of F. proliferatum and the production of its associated mycotoxin, fumonisin B₁. The relation between structure and antifungal activity was studied. Tetrahydrocurcumin (THC1), with two guaiacyl phenolic subunits, showed the highest inhibitory activity (measured as radial growth on agar medium) against the F. proliferatum development (67% inhibition at a concentration of 13.6?µmol?ml^?1). The efficiencies of THC2 (36% at a concentration of 11.5?µmol?ml^?1), which contains syringyl phenolic units, and THC3 (30% at a concentration of 13.6?µmol?ml^?1), which does not have any substituent on the aromatic rings, were relatively close. These results indicate that the simultaneous presence of guaiacyl phenols and the enolic function of the β-diketone moiety play an important role in the inhibition mechanisms. The importance of this combination was confirmed using n-propylguaiacol and acetylacetone as molecular models. Under the same conditions, ferulic acid and eugenol, other natural phenolic antioxidants, were less efficient in inhibiting fungal growth. THC1 also reduced fumonisin B₁ production in liquid medium by approximately 35, 50 and 75% at concentrations of 0.8, 1.3, and 1.9?µmol?ml^?1, respectively. These very low inhibitory concentrations show that tetrahydrocurcuminoids could be one of the most promising biobased molecules for the control of mycotoxinogen fungal strains.     

Chemical composition and antimicrobial activity of the essential oil of Amomum tsao‐ko

BACKGROUND: The chemical composition of the essential oil obtained by hydrodistillation from the dried fruits of Amomum tsao‐ko was analysed by gas chromatography/mass spectroscopy (GC/MS). The antimicrobial activity of the oil was evaluated against 16 micro‐organisms using agar disc diffusion and broth microdilution methods. RESULTS: Seventy‐three compounds, constituting about 97.56% of the total oil, were identified. The main components were 1,8‐cineole (45.24%), ρ‐propylbenzaldehyde (6.04%), geraniol (5.11%), geranial (4.52%), α‐terpineol (3.59%) and α‐phellandrene (3.07%). The essential oil showed a broad spectrum of antimicrobial activity against all the tested micro‐organisms, including Gram‐positive and Gram‐negative bacteria, and fungi. The oil exerted the strongest bactericidal activity against Staphylococcus aureus CCTCC AB91118, with minimum inhibitory and bactericidal concentrations of 0.20 g L^?1. CONCLUSION: Our study suggests that the Amomum tsao‐ko essential oil could be one of new medicinal resources for antibacterial and antifungal agents. Copyright © 2008 Society of Chemical Industry     

Biogenic amines in alcoholic beverages produced in Taiwan

The biogenic amines tyramine, putrescine, cadaverine, 2-phenylethylamine, histamine and tryptamine were determined in 13 kinds of alcoholic beverages produced in Taiwan. They were derivatised with dansyl chloride and analysed using a high-performance liquid chromatographic method. Total amine content ranged from 0.23 to 11.4 μg ml^?1 with Charng Chuen liqueur containing the highest level and Mei Kwei Lu the lowest. Tryptamine was found in all samples in amounts between 0.01 and 1.79 μg ml^?1. The levels of the other five amines in the tested samples were 0-7.0 μg ml^?1 for 2-phenylethylamine, 0-3.0 μg ml^?1 for putrescine, 0-2.9 μg ml^?1 for cadaverine, 0-4.5 μg ml^?1 for histamine, and 0-1.4 μg ml^?1 for tyramine. These levels seem unlikely to have adverse effects on human health.     

Glucoamylase Biosynthesis by Cells of Aspergillus niger C58-III Immobilized in Sintered Glass and Pumice Stones

A simple method of A. niger C_58-III cell immobilization is described. This strain produces extracellular glucoamylase. According to the proposed method A. niger spores were first immobilized by adsorption in sintered glass Rasching rings (RR) or pumice stones (PS). Growing out from spores, A. niger cells produced extracellular glucoamylase. This technique facilitates the culture growth in a filamentous spongy structure of the supports with a continuous accumulation of biomass. After every 24 h it was possible to obtain culture liquid rich in glucoamylase. This procedure can be repeated 30 times using the same sample of immobilized A. niger culture without any loss of glucoamylase activity in the liquid medium. In a 96 h period immobilized A. niger cells produced 300 units × ml⁻¹ whereas a shake culture of this fungus produced only 186 units × ml⁻¹.     

THE INFLUENCE OF PANTOTHENATE CONCENTRATION AND INOCULUM SIZE ON THE FERMENTATION OF A DEFINED MEDIUM BY SACCHAROMYCES CEREVISIAE

Laboratory fermentations were carried out using defined media containing from 0.02 to 0.40 mg pantothenate 1^?1 and a brewing strain of Saccharomyces cerevisiae at inocula of 1 × 10⁶ to 1 × 10⁷ cells ml^?1, Cell size, increase in cell number, increase in yeast weight, production of ethanol. n-propanol, isobutanol, isoamyl alcohols, acetaldehyde and ethyl acetate were measured. All the properties were influenced to some extent by pantothenate concentration and/or inoculum size but no general correlations were found. At high inoculum levels variation in the pantothenate concentration above 0.1 mg 1^?1 did not have a major effect on the total quantity of volatile compounds produced but did alter the relative proportions of the individual compounds.     

Chemical composition and antimicrobial activity of the essential oils from four Ruta species growing in Algeria

Antimicrobial properties of plants essential oils have been investigated in order to suggest them as potential tools to overcome the microbial drug resistance and the increasing incidence of food borne diseases problems. The aim of this research is to study the antibacterial and antifungal effects of four traditional plants essential oils, Ruta angustifolia, Ruta chalepensis, Ruta graveolens and Ruta tuberculata, against standard bacterial and fungal strains. The chemical compounds of the oils were examined by GC/MS. Results revealed a powerful antifungal activity against filamentous fungi. Aspergillus fumigatus and Cladosporium herbarum are the most sensitive strains to these oils with MIC values less than 3.5 μg ml⁻¹ for certain oils, reaching 7.8 μg ml⁻¹ for other. GC/MS essay exhibited ketones as the most abundant constituent of these oils except for R. tuberculata essential oil which has a completely different composition, monoterpenes alcohols being the most abundant. These compositions explain their potential antifungal activity.     

Different concentrations of grape seed extract affect in vitro starch fermentation by porcine small and large intestinal inocula

BACKGROUND: Grape seed extract (GSE) phenolics have potential health‐promoting properties, either from compounds present within the extract, or metabolites resulting from gastrointestinal tract (GIT) fermentation of these compounds. This study describes how GSE affected the kinetics and end‐products of starch fermentation in vitro using pig intestinal and fecal inocula. Six GSE concentrations (0, 60, 125, 250, 500, and 750 µg ml^?1 were fermented in vitro by porcine ileal and fecal microbiota using starch as the energy source. Cumulative gas production, and end‐point short chain fatty acids and ammonia were measured. RESULTS: GSE phenolics altered the pattern (gas kinetics, and end‐products such as SCFA and NH ) of starch fermentation by both inocula, at concentrations above 250 µg ml^?1. Below this level, neither inoculum showed any significant (P > 0.05) effect of the GSE. CONCLUSION: The results show that GSE phenolics at a concentration over 250 µg ml^?1 can have measurable effects on microbial activity in an in vitro fermentation system, as evidenced by the changes in kinetics and end‐products from starch fermentation. This suggests that fermentation patterns could be conceivably shifted in the actual GIT, though further evidence will be required from in vivo studies. Copyright © 2012 Society of Chemical Industry     

Seasonal variation in content,chemical composition and antimicrobial and cytotoxic activities of essential oils from four Mentha species

BACKGROUND: The aim of the present study was to appraise variation in the chemical composition, and antimicrobial and cytotoxic activities of essential oils from the leaves of four Mentha species—M. arvensis, M. piperita, M. longifolia and M. spicata—as affected by harvesting season. Disc diffusion and broth microdilution susceptibility assays were used to evaluate the antimicrobial activity of Mentha essential oils against a panel of microorganisms. The cytotoxicity of essential oils was tested on breast cancer (MCF‐7) and prostate cancer (LNCaP) cell lines using the MTT assay. RESULTS: The essential oil contents of M. arvensis, M. piperita, M. longifolia and M. spicata were 17.0, 12.2, 10.8 and 12.0 g kg^?1 from the summer and 9.20, 10.5, 7.00 and 9.50 g kg^?1 from the winter crops, respectively. Gas chromatographic–mass spectrometric analysis revealed that mostly quantitative rather than qualitative variation was observed in the oil composition of each species. The principal chemical constituents determined in M. arvensis, M. piperita, M. longifolia and M. spicata essential oils from both seasons were menthol, menthone, piperitenone oxide and carvone, respectively. The tested essential oils and their major components exhibited notable antimicrobial activity against most of the plant and human pathogens tested. The tested essential oils also exhibited good cytotoxicity potential. CONCLUSION: Of the Mentha essential oils tested, M. arvensis essential oil showed relatively better antimicrobial and cytotoxic activities. A significant variation in the content of most of the chemical components and biological activities of seasonally collected samples was documented. Copyright © 2010 Society of Chemical Industry