Article

Antimicrobial activity of phenolic extracts from virgin olive oil

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Abstract

The antimicrobial activity of phenolic fraction of extra virgin olive oil was tested on the cell growth of Lactobacillus delbrueckii subsp, bulgaricus, Streptococcus thermophilus and Kluyveromyces marxianus and the mycelia growth of Penicillum frequentens in vitro. The phenolic extracts significantly inhibited the cell growth of S. thermophilus whereas the growth of Lb. delbrueckii subsp, bulgaricus was slightly affected in the presence of 100 mg L-1 phenolic extracts at pH 6.9. The phenolic extracts had a significant inhibitory activity against K. marxianus growth at pH 4 but not at pH 6.9 due to increased solubility of phenolics under acidic conditions (low pH). The growth of P. frequentens, expressed as mycelia wet weight was not greatly affected by the presence of phenolic extracts at varying concentrations at pH 4 and 6.9. It was concluded that the antimicrobial activity of phenolic extracts of extra virgin olive oil was dependent on concentration, pH, time and the type of micro-organism.

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... The available data from the literature show that the antibacterial effect of virgin olive oils is generally higher against Gram-positive bacteria than Gram-negative bacteria [16,29]. It has been previously documented that antimicrobial activity is highest in extra-virgin olive oils, followed by other types of olive oils and olive pomace oils [19,30]. A significant inhibitory effect was also observed for Arcobacter-like species, especially for extra-virgin olive oil extracts, which have the highest amount of phenolic compounds. ...
... Phenolic compounds have been confirmed to be a major source of the compounds with antimicrobial potential in olive oils [19,39]. The antimicrobial activity of phenolic compounds obtained from olive oil extracts has been confirmed by a number of studies [30,40,41]. It is necessary to emphasize the large differences in composition between varieties of olive oils, such as virgin olive oil, olive oil, and olive pomace oil. ...
... According to our results, olive pomace oil contains a significantly lower content of phenolic substances than other oils (p < 0.05). This is in correspondence with previous studies [19,30]. The antimicrobial activity of olive oils has been attributed to oleuropein and 2-(3,4-dihydroxyphenyl)ethanol content in particular, for many years [41][42][43]. ...
Article
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Extra-virgin olive oils contain many bioactive substances that are phenolic compounds. The survival of Arcobacter-like strains in non-buffered (WEOO) and buffered (BEOO) extracts of olive oils were studied. Time kill curves of different strains were measured in the environment of olive oil extracts of different grades. The activity of the extracts was also monitored for biofilm formation using the Christensen method. In vitro results revealed that extra-virgin olive oil extracts exhibited the strongest antimicrobial effects, especially non-buffered extracts, which exhibited strain inhibition after only 5 min of exposure. The weakest inhibitory effects were observed for olive oil extracts. A decrease in biofilm formation was observed in the environment of higher WEOO concentrations, although at lower concentrations of extracts, increased biofilm formation occurred due to stress conditions. The dialdehydic forms of oleuropein derivatives, hydroxytyrosol, and tyrosol were the main compounds detected by HPLC-CoulArray. The results indicate that not all olive oils had a similar bactericidal effect, and that bioactivity primarily depended on the content of certain phenolic compounds.
... Since cold pressed oils are produced from very clean, homogeneous, safe and high-quality materials, the oils are also high in sensory, nutritional and aroma quality. Furthermore, cold pressed oils retain the bioactive molecules originating from the starting plant material and infiltrated during the pressing into the oil; hence, they might have some functional properties including antimicrobial activity [13,18]. It was indicated that plant extracts are rich sources of phenolics and other B. Aydeniz Güneşer N.N. ...
... Since cold pressed oils are natural, unrefined and bio active rich sources, they may pose some antimicrobial activity. Some studies considered this hypothesis [1,13,18,22,27,28]. Keceli and Robinson [18] extracted the phenolic compounds from virgin olive oil, and tested their antimicrobial effects against some bacteria and fungus. ...
... Some studies considered this hypothesis [1,13,18,22,27,28]. Keceli and Robinson [18] extracted the phenolic compounds from virgin olive oil, and tested their antimicrobial effects against some bacteria and fungus. They indicated that phenolic extract inhibited the growth of Streptococcus thermophilus, Kluyveromyces marxianus and Penicillium frequentens, and the effect was dependent on concentration, pH, time and type of microorganism. ...
Article
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This study aims at determining the antimicrobial activity of cold pressed lemon, orange, and grapefruit seed oils, and to compare their activities with some antibiotic disks, flavonoid and phenolic acid standards. These oils had inhibition zones ranging from 6.62 to 11.00 mm against fifteen tested pathogenic bacteria. Only lemon seed oils and orange seed oil showed some inhibition against Candida utilis yeast. None of the oils had measurable inhibition zone against Micrococcus luteus ATCC 4698. Although most oils showed no growth inhibition even at a 100% concentration, Escherichia coli ATCC 25922 and Salmonella Enteriditis ATCC 13076 inhibited at 100% oil concentrations. Cold pressed and solvent extracted lemon seed oils inhibited growth of Staphylococcus aureus RSKK 1009 at 2% level, and cold pressed and microwave treated-cold pressed orange seed oil inhibited growth of Klebsiella pneumonia ATCC 700603 at 16 and 50%, respectively. The antibiotic disks ampicillin, sulbactam, piperacillin, tobramycin, mezlocillin, amoxicillin and cycloheximide presented 3-4 fold larger inhibition zones (10.24 - 47.00 mm) than the oil samples. Similarly, flavonoid standards naringin, naringenin, hesperidin, neohesperidin, catechin and kaempherol; and phenolic acids gallic, syringic, tr-ferulic, rosmarinic, tr-2-hydroxycinnamic and chlorogenic acids had inhibition zones like the seed oil samples. Hence citrus seed oils pose moderate levels of antimicrobial activity and could be used as antimicrobial aids.
... The high concentration of phenolic compounds in olive oil contributes significantly toward its antioxidant and antimicrobial activity (Capasso et al., 1995;Kecel & Robinson, 2002;Markin et al., 2003;Pereira et al., 2006). The antimicrobial activity of oleuropein, hydroxytyrosol and tyrosol in virgin olive oil stems from their ability to interact with phosphatidylglycerol at the surface of the bacterial cell wall (Casas-Sanchez et al., 2007;Medina et al., 2006;Soler-Rivas et al., 2000). ...
... Since proteins recovered after precipitation from the amurca extract did not inhibit the growth of tested foodborne pathogens, it is possible that the potent antimicrobial activity of amurca reported in the present study may have been caused by the phenolic compounds present (Table 6). This would be consistent with previous reports showing that phenolic compounds in olive products (olive fruit, olive oil, olive leaves) and olive oil by-products (olive oil mill waste water, olive cake) exhibited antibacterial activity (Capasso et al., 1995;Kecel & Robinson, 2002;Markin et al., 2003;Pereira et al., 2006). ...
Article
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The antimicrobial activity of a methanolic extract of amurca (olive oil lees) was determined against both Gram-positive (L. monocytogenes and S. aureus) and Gram-negative (E. coli O157:H7 and S. enteritidis) foodborne pathogens at 10 °C or 37 °C using microdilution and disk diffusion methods, and its relative activity was compared to selected antibiotics. Minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations of amurca extract ranged from 60 to 80 µl/ml at 37 °C after 24 h against all tested strains. At 10 °C, amurca was more inhibitory with MIC and MBC values of 40 and 60 µl/ml, respectively, after 7 d against tested strains. Amurca at 40 µl/ml reduced numbers of tested pathogens by 2.5 to 3.2 log10 CFU/ml at 10 °C after 7 d, but was not inhibitory at 37 °C after 24 h. Protein prepared from amurca was not antimicrobial. The relative antimicrobial activity (inhibition zone ratio) of 80 µl/mlamurca methanolic extract compared to chloramphenicol, erythromycin, gentamycin and tetracycline ranged from 0.36 to 1.0 against Gram-negative and from 0.45 to 2.0 against Gram-positive bacteria. In addition, amurca extract inhibited E. coli O157:H7 02-0628 and S. aureus 26127 which were resistant to tetracycline and chloramphenicol, respectively. © 2015, Sociedade Brasileira de Ciencia e Tecnologia de Alimentos, SBCTA. All rights reserved.
... Investigations have disclosed that these substances exert potent antioxidant activity and can reduce the oxidation of low-density lipoprotein in vitro (2), whereas results obtained in vivo were contradictory (3). A diverse range of other bioactivities has also been pointed out such as the prevention of certain cancers (4), anti-inflammatory action (5), and antimicrobials (6). ...
... Although the antimicrobial activity of the polyphenols present in the olive fruit (7), olive oil mill wastewaters (8), and olive leaves (9) is well reported, studies on olive oil are few (6,10). Besides, researchers analyzed only the minor polyphenols of the oil (simple phenols), but not the secoiridoid aglycons of oleuropein and ligstroside (11) and the lignans (12), which are the main components (Figure 1). ...
Article
The antimicrobial activity of different edible vegetable oils was studied. In vitro results revealed that the oils from olive fruits had a strong bactericidal action against a broad spectrum of microorganisms, this effect being higher in general against Gram-positive than Gram-negative bacteria. Thus, olive oils showed bactericidal activity not only against harmful bacteria of the intestinal microbiota (Clostridium perfringens and Escherichia coli) also against beneficial microorganisms such as Lactobacillus acidophilus and Bifidobacterium bifidum. Otherwise, most of the foodborne pathogens tested (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica, Yersinia sp., and Shigella sonnei) did not survive after 1 h of contact with olive oils. The dialdehydic form of decarboxymethyl oleuropein and ligstroside aglycons, hydroxytyrosol and tyrosol, were the phenolic compounds that statistically correlated with bacterial survival. These findings were confirmed by testing each individual phenolic compound, isolated by HPLC, against L. monocytogenes. In particular, the dialdehydic form of decarboxymethyl ligstroside aglycon showed a potent antimicrobial activity. These results indicate that not all oils classified as "olive oil" had similar bactericidal effects and that this bioactivity depended on their content of certain phenolic compounds.
... Antimicrobial properties of various oils were tested (Karaosmanoglu et al., 2010;Keceli & Robinson, 2002;Medina et al., 2006;Zullo et al., 2018). Virgin olive oils were more effective than olive pomace oils. ...
Article
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Flavoring olive oil is an increasing trend in olive oil processing. Growing consumer interest in flavored olive oils by natural material brings the need to evaluate the key limiting factors which is its microbiological stability. The present research compares the microbiological quality of olive oil flavored by 3 flavors (rosemary, garlic, and lemon), prepared by 3 methods to determine changes during storage. The comprehensive microbiological analyses (total number of microorganisms [TCM], anaerobic sporulates, yeasts, molds, bacteria of the family Enterobacteriaceae , bacteria of the genus Salmonella spp., Clostridium botulinum , and lactic acid bacteria) were conducted during 12 months of storage. The best results in TCM were observed in the oil flavored by fresh garlic (0.24 log CFU/mL). The highest counts of anaerobic sporulates were detected in the dried rosemary olive oil (1.10 log CFU/mL). The flavoring materials have significantly higher counts of microorganism than flavored oils ( p < .05). The obtained results demonstrated that microorganisms are capable to survive in flavored olive oil and the method of flavoring can affect their growth in a selective way according to the chemical characteristics.
... Very few studies have tried to correlate the antimicrobial activity of olive oil with specific compounds. Radford et al. (1991) and Keceli and Robinson (2002) attributed this activity to the high acidity of the oil as well as simple phenols such as hydroxytyrosol and tyrosol. However, the main phenolic compounds in olive oil are the secoiridoid aglycons of oleuropein and ligstroside, and the lignans (Montedoro et al., 1993;Brenes et al., 1999). ...
Chapter
Olive products are of great importance in Mediterranean countries, not only from their use in food but also based on their health beneficial properties. Since ancient times, olive derivatives such as extracts of olive leaves and olive oil have been used to combat diseases caused by microorganisms. This antimicrobial activity was first studied in table olives and its implication on the inhibition of lactic acid bacteria responsible for fermentation. Likewise, olive oil has also great antimicrobial activity against a broad spectrum of microorganisms. This activity has been related to the presence of phenolic compounds, in particular dialdehydic form of decarboxymethyl elenolic acid linked to tyrosol, dialdehydic form of decarboxymethyl elenolic acid linked to hydroxytyrosol, and dialdehydic form of decarboxymethyl elenolic acid. All of them have a dialdehydic structure in their molecule that confers this antimicrobial activity, which is very similar to commercial disinfectants. Therefore this activity gives the ability to inhibit foodborne microorganisms in food preparation or human health pathogens thereby olive products are good natural sources of antimicrobial compounds.
... The water content and the total polar phenols content in each olive oil represents two important factors able to modulate the enzymatic activity and viability of many olive oil yeasts. The phenolic compounds in olive oil are characterized by a specific antimicrobial activity (Keceli and Robinson, 2002). In fact, the reduction in the number of the viable cells in the three strains of Candida adriatica, Candida diddensiae and Yamadazyma terventina inoculated in virgin olive oil with a total phenolic compounds content of 89, 159 and 540 mg of caffeic acid equivalent per kg of oil was, respectively, 41%, 44% and 65%, after forty days of storage (Ciafardini and Zullo, 2015). ...
Article
This review summarizes current knowledge on virgin olive oil yeasts. Newly produced olive oil contains solid particles and micro drops of vegetation water in which yeasts reproduce to become the typical microbiota of olive oil. To date, about seventeen yeast species have been isolated from different types of olive oils and their by-products, of which six species have been identified as new species. Certain yeast species contribute greatly to improving the sensorial characteristics of the newly produced olive oil, whereas other species are considered harmful as they can damage the oil quality through the production of unpleasant flavors and triacylglycerol hydrolysis. Studies carried out in certain yeast strains have demonstrated the presence of defects in olive oil treated with Candida adriatica, Nakazawaea wickerhamii and Candida diddensiae specific strains, while other olive oil samples treated with other Candida diddensiae strains were defect-free after four months of storage and categorized as extra virgin. A new acetic acid producing yeast species, namely, Brettanomyces acidodurans sp. nov., which was recently isolated from olive oil, could be implicated in the wine-vinegary defect of the product. Other aspects related to the activity of the lipase-producing yeasts and the survival of the yeast species in the flavored olive oils are also discussed.
... Olive oil reduces LDL and increase HDL because it contain sufficient amount of o C18:1cis (Keyset al., 1986). It also contains high amounts of phenol and Vitamin E, which decline the degeneration of human body cells (Kiritsakis et al., 1998;Keceli and Robinson, 2002). Olive oil greatly stabile of against oxidation during storage is attributed to the presence of polyphenols (Argenson, 1999). ...
... Studies on substances responsible for antimicrobial effect of olive oil are scarce [13,14], and researchers analyzed only the minor polyphenols of the oil (simple phenols), but not the secoiridoid aglycons of oleuropein and ligustroside [15] and the lignans [16]. Likewise, there are numerous papers describing the antimicrobial activity of oleuropein [17], the main phenolic compound in olive fruits found in very low amounts in olive oil [18]. ...
... Very few studies have tried to correlate the antimicrobial activity of olive oil with specific compounds. Radford et al. (1991) and Keceli and Robinson (2002) attributed this activity to the high acidity of the oil as well as simple phenols such as hydroxytyrosol and tyrosol. However, the main phenolic compounds in olive oil are the secoiridoid aglycons of oleuropein and ligstroside, and the lignans (Montedoro et al., 1993;Brenes et al., 1999). ...
Chapter
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At present, both olive oil and table olives are important components of the Mediterranean diet and are largely consumed throughout the world. In addition, there are many enterprises that commercialize olive leaf extracts to treat a myriad of diseases, many of them caused by microorganisms. This chapter presents features of the main food-related bacteria pathogens investigated in relation to olive antimicrobials. It has been demonstrated that the main phenolic compound in olive brines is hydroxytyrosol, a component of the oleuropein moiety, which inhibited the growth of Lactobacillus plantarum in a model system, but its presence in the brines of both olives non-treated and treated with NaOH did not lead to an explanation for the lack of lactic acid fermentation in the former olive brines. The bactericidal action of virgin olive oil is higher than that of other foodstuffs such as wine, tea, coffee, beer and others. Olive oil could be a hurdle component in certain processed foods and exert a protective effect against foodborne pathogens when contaminated foods are ingested. The antimicrobial compounds of olive oil possess a strong anti-. H. pylori activity that could be useful for the prevention of peptic ulcers and cancers in the future.
... 18 The skin of 90% of patients with AD is colonized by this bacterium. 19,20 HT has gained particular attention owing to its antimicrobial 21,22 and bactericidal activities against gram-positive and gram-negative bacteria. 23 Topical glucocorticoids are the mainstay of drug therapy for AD because of their broad immunosuppressant and antiinflammatory effects. ...
Article
Hydrocortisone (HC) is a topical glucocorticoid for the treatment of atopic dermatitis (AD); the local as well as systemic side effects limit its use. Hydroxytyrosol (HT) is a polyphenol present in olive oil that has strong antimicrobial and antioxidant activities. HC-HT coloaded chitosan nanoparticles (HC-HT CSNPs) were therefore developed to improve the efficacy against AD. In this study, HC-HT CSNPs of 235 ± 9 nm in size and with zeta potential +39.2 ± 1.6 mV were incorporated into aqueous cream (vehicle) and investigated for acute dermal toxicity, dermal irritation, and repeated dose toxicity using albino Wistar rats. HC-HT CSNPs exhibited LD50 > 125 mg/body surface area of active, which is 100-fold higher than the normal human dose of HC. Compared with the commercial formulation, 0.5 g of HC-HT CSNPs did not cause skin irritation, as measured by Tewameter®, Mexameter®, and as observed visually. Moreover, no-observed-adverse-effect level was observed with respect to body weight, organ weight, feed consumption, blood hematological and biochemical, urinalysis, and histopathological parameters at a dose of 1000 mg/body surface area per day of HC-HT CSNPs for 28 days. This in vivo study demonstrated that nanoencapsulation significantly reduced the toxic effects of HC and this should allow further clinical investigations. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci.
... Olive oil is composed of oleat acid, palmitat acid, sterol acids, simple phenols such hydroxtyrosol, tyrosol, catechol and other which have been considered responsible of the antimicrobial activity detected in the olive oil [33][34][35]. The most bactericidal polyphenols of olive oil were HyEDA and TyEDA, in particular the latter compound which is also known as oleocanthal [36,37]. ...
Article
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Objective: This research is aimed to determine antibacterial activity of some solvents of raw propolis extracts of Trigona sp from Sulawesi, Indonesia and compare it with antibacterial activities of ethanolic and aqueous extracts. Methods: Propolis samples were extracted with water, ethanol, propylene glycol, olive oil, and Virgin Coconut Oil (VCO). An agar-well diffusion assay was used to evaluate the antimicrobial potential of propolis against Escherichia coli, Salmonella thypi, and Staphylococcus aureus. Results: The oily extract of propolis showed a potent antibacterial activity compared to the ethanol extracts against Staphylococcus aureus and Esherichia coli. Inhibition zone of Olive Oil Extracts of Propolis on S. aureus was higher (22.4 mm) than Ethanolic extracts and Water Extracts. Inhibition zone of Virgin Coconut Oil (VCO) propolis extract and Olive oil extract on E. coli were 9.5 mm and 9.3 mm, respectively. The oily extracts also showed higher action against E. coli compared with the ethanol extracts and propylene extracts. Conclusion: The propolis extracts obtained with Virgin Coconut Oil (VCO) and olive oil as solvent have higher antibacterial activity than the ethanolic extracts. So the VCO and Olive Oil can be used to extract raw propolis. © 2015, International Journal of Pharmacy and Pharmaceutical Sciences. All Rights Reserved.
... Olive compounds with a dialdehydic structure exhibited strong bactericidal activity, and in the presence of organic material, stronger bactericidal activity than the synthetic disinfectants. The ability of phenolic fractions from extra virgin olive oil to inhibit the growth of two strains of lactic acid bacteria, one strain of yeast and one mold was evaluated Keceli and Robinson, 2002). Inhibition of growth was dependent on concentration, pH (greater impact at lower pH), and microorganism (variable impact on the lactic acid bacteria, no inhibition of the mold). ...
Technical Report
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Very little data are available on the microbiological safety of edible oils including olive oil. Most of the food safety literature regarding olive oils has been published within the past few years. No outbreaks of foodborne illness linked to olive oil have been reported. There have been no surveys that have assessed the presence of foodborne pathogens in olive oils; surveys that included a determination of general bacterial populations found levels from below the limit of detection (1 to 2 log CFU/ml) to 3 log CFU/ml. Olive oils (virgin and extra virgin) are unique among the edible oils in that they contain small amounts of water in the form of tiny droplets; the pH of the water phase has been reported as generally less than pH 5. Microorganisms have been shown by microscopic evaluation to be present in this water phase but the physical size of the droplets generally constrains microbial numbers. Antimicrobials effective against a broad range of microorganisms including some foodborne pathogens have been shown to be present in extra virgin olive oils. The published studies to date are limited in the number of strains of pathogens assessed, and, in some cases, details in the methods and specifics of the olive oils were lacking. The antimicrobial components, generally ascribed to the soluble phenolic components, can vary in composition and amount for a wide range of reasons including olive variety, production practices, maturity, extraction methods, storage conditions and time. Based on the currently available literature, foodborne pathogens are not likely to occur in extra virgin or virgin olive oils. However, good manufacturing practices and other prerequisite programs that keep all microorganisms at low levels should be followed in the production of olive oil.
... Hydroxytyrosol is able to inhibit or delay the rate of growth of a range of bacteria, microfungi and pathogenic bacteria in humans, the antimicrobial activity of polyphenols containing olive fruit (Fleming, Walter, & Etchells, 1973), olive oil mill waste waters (Capasso et al., 1995), olive leaves (Markin, Duek, & Berdicevsky, 2003) and olive oil (Keceli & Robinson, 2002;Radford, Tassou, Nychas, & Board, 1991) has been reported. Medina, de Castro, Romero, and Brenes (2006) showed a strong bactericidal action of hydroxytyrosol against a broad spectrum of microorganisms, and was higher in general against Gram-positive than Gram-negative bacteria. ...
Article
Regular moderate wine consumption is often associated with reduced morbidity and mortality from a variety of chronic diseases in which inflammation is the root cause. This review is focused on three of the numerous bioactive compounds present in wine: resveratrol, hydroxytyrosol and melatonin. Resveratrol and hydroxytyrosol are polyphenols. Melatonin, recently described in wine, is an indoleamine. Their structures, concentrations in wine, bioavailability, pharmacokinetic and health promoting properties are reviewed. Resveratrol seems to be one of the most promising compounds due to its bioactivity, with wine being the main source of resveratrol in diet. Hydroxytyrosol, which its main source in diet is olive oil has been also found in both red and white wine in considerable amounts. Melatonin has been found in wine in low amounts. However, both high bioactivity and bioavailability have been attributed to it. They show antioxidant, cardioprotective, anticancer, antidiabetic, neuroprotective and antiaging activities. However, human studies are still in the initial stages and therefore further studies are needed.
... The major contributors to antibacterial activity of VOO were found to be the dialdehydic form of decarboxymethyl ligstroside aglycone and cinnamic acid [208,209]. The antibacterial activity of VOO depends not only on biophenol composition but also on the pH and time of exposure [221]. In atopic dermatitis, VOO eliminated Staphylococcus aureus infection in 6 of 12 patients (50%) [210]. ...
Chapter
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There are more than 100 different biophenols reported in olive samples. This chapter covers the chemistry, pharmacodynamics, pharmacokinetics, posology, adverse effects, and potential drug interactions of olives and major olive biophenols (OBP). Major biophenols detected in olive samples include hydroxytyrosol, tyrosol and their secoiridoid derivatives (oleuropein, oleuropein aglycone, and elenolic acid dialdehydes), verbascoside, lignans, and flavonoids. By far the majority of reports on the chemistry of OBP pertain to their ability to function as antioxidants, but other bioactivities include binding to lipids, proteins, carbohydrates, and nucleic acids. The majority of pharmacological studies have focused on just four compounds hydroxytyrosol, tyrosol, oleuropein, and verbascoside. Reported pharmacological properties include antioxidant, anti-inflammatory, cardiovascular, immunomodulatory, gastrointestinal, respiratory, autonomic, central nervous system, antimicrobial, anticancer and chemopreventive. While OBP are generally regarded as safe, further studies on potential adverse reactions may be required to demonstrate the safety of supplements with elevated levels of compounds.
... These might be due to the origin of the selected strains for each assay or the preparation methods for crude extracts and phenolic compounds. It was reported that this case was valid for several plant extracts and essential oils (Keceli and Robinson 2002;Soliman and Badeaa 2002;. At 0.1% concentration, caffeic acid indicated weak antifungal activity against the tested fungi compared with other phenolic components. ...
Article
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Olive ( Olea europaea L.) leaf extracts were obtained using water or different organic solvents such as acetone, methanol and ethyl acetate. Antimicrobial activities of the extracts and some phenolic components were investigated to screen against 30 fungal strains ( Alternaria alternata, Aspergillus chevalieri, A. chrysogenum, A. elegans, A. flavus [three strains], A. fumigatus, A. nidulans, A. niger [two strains], A. oryzae, A. parasiticus [four strains], A. tamari, P. verrucosum, A. versicolor, A. wentii, Fusarium oxysporum, F. semitectum, Mucor racemosus, Neurospora crassa, Penicillium citrinum, P. echinulatum, P. griseofulvum, P. italicum, P. roqueforti and Rhizopus oligosporus ) using the disc diffusion method. In this study, in terms of inhibition activity, it was determined that aqueous extract was the best as it completely inhibited the growth of 10 molds, followed by acetone and methanol extracts, which were effective against eight molds, and diethyl ether extract, which was effective against 7 out of 30 test fungi. The inhibition zones ranged from 7 to 21 mm. Comparing the sensitivity of the fungi with all crude olive leaf extracts and pure phenolic compounds, we found that A. parasiticus (4) was the most resistant strain while A. wentii was the most sensitive. PRACTICAL APPLICATIONS Foodborne diseases are still a major problem in the world, even in well‐developed countries. Fusarium spp., Aspergillus spp., Rhizopus spp. and Penicillium spp. have been reported as the causal agents of foodborne diseases and food spoilage. Raw and processed foods are open to contamination during the production, sale and distribution. Thus, at present, it is a necessity to the food industry to use chemical preservatives to prevent the growth of fungi in foods. Because of the economic impact of spoiled foods and consumer concerns over the safety of foods containing synthetic chemicals, considerable attention has been paid to naturally derived compounds or natural products. Recently, there has been considerable interest in using extracts from plants with antimicrobial activities to control pathogens or toxin‐producing microorganisms in foods. Olive leaves have been shown to inhibit or delay the rate of growth of a range of fungi; thus, they might be useful as natural preservatives.
... Polyphenols present in the olive fruits, olive oil waste waters, and olive leaves possess antimicrobial activity against a broad spectrum of microorganisms (3,7,15). However, studies on the antimicrobial activity of olive oil polyphenols are few (11,21) and are focused on simple phenols, which represent only a minor amount of the total content. Recently, we investigated the role of phenolic compounds on the bactericidal activity of many different olive oils (16). ...
Article
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The survival of foodborne pathogens in aqueous extracts of olive oil, virgin olive oil, vinegar, and several beverages was evaluated. Vinegar and aqueous extracts of virgin olive oil showed the strongest bactericidal activity against all strains tested. Red and white wines also killed most strains after 5 min of contact, black and green tea extracts showed weak antimicrobial activity under these conditions, and no effect was observed for the remaining beverages (fruit juices, Coca-Cola, dairy products, coffee, and beer). The phenolic compound content of the aqueous olive oil and virgin olive oil extracts could explain their antibacterial activity, which was also confirmed in mayonnaises and salads used as food models. Virgin olive oil in mayonnaises and salads reduced the counts of inoculated Salmonella Enteritidis and Listeria monocytogenes by approximately 3 log CFU/g. Therefore, olive oil could be a hurdle component in certain processed foods and exert a protective effect against foodborne pathogens when contaminated foods are ingested.
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Olive oil has always been important ingredient in daily diet of Mediterranean population, and because of its beneficial effects on health and longevity through the centuries, today it has become a synonym for healthy nutrition worldwide. The main reason for the increase in consumption of olive oil is its nutritional, preventive and therapeutic value. The beneficial effects of olive oil are attributed to the high content of monounsaturated fatty acids (especially oleic acid), but the experimental studies (in vivo and in vitro) suggest a high biological potential of olive oil phenolic compounds. Because of its high antioxidant and anti-inflammatory activity, antimicrobial and neuroprotective effects, the ability to positively regulate cell processes, these compounds has a beneficial effect on physiological processes related to health and disease.
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Olive oils were extracted from two consecutive crops (2008 and 2009) of three different varieties of olive cultivated at different geographical regions of Pakistan. The profiles of the fatty acid compositions were developed employing GC-MS techniques and then compared. The purpose of this research paper is to evaluate the olive oil constituents in Olive cultivated in different regions in order to determine the quality of olive oil and to ascertain the suitability of area for best quality products.
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Among the benefits that the consumption of olive oil can exert on human health, its antimicrobial activity emerges as a promising new property. Olive oil, in particular virgin olive oils with a high content in certain phenolic compounds, can Inhibit the growth of pathogenic bacteria, this activity being higher than that reported for foods such as tea, coffee, wine and others. Thus, its use in many roods could contribute to a decrease in roodbome illness outbreaks. Also, olive oil polyphenols, in particular the dialdehydic form of decarboxymethyl oleuropein and ligstroside aglycons possess a strong bactericidal activity in vitro against Helicobacter pylori, which opens up the possibility of considering virgin olive oil as a chemopreventive agent for peptic ulcers or gastric cancer.
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Cloudy olive oil, the fresh olive juice, is an intermediate form before full precipitation of freshly produced olive oil. Some consumers prefer it because they consider it as more natural and less processed. The cloudy form can persist for several months. The oil is a sort of dispersion/suspension system which can be also described as a micro-emulsion/suspension. Water micro-droplets were found to have a size ranging from 1 to 5 µm. Cloudiness is due to the low water content and the presence of natural emulsifiers in the oil. The suspension is formed by solid particles (5–60 µm) deriving from the olive fruit. They are present in small amounts (12–460 mg/kg oil). In the newly produced olive oil, containing 0.17–0.49% water, a number of microorganisms of different types (bacteria, yeasts, moulds) were found to survive, but at very low concentrations (<3 log cfu/mL oil). They originate from the exterior of the fruit (epiphytic microflora) and their presence is considered natural. Their enzyme activities do not seem to affect the quality of the final product.
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A simplified method for aflatoxin production studies is described. The mold was cultured in 4-dram (15 ml) vials containing 5 ml of yeast extract sucrose broth, and aflatoxin levels were determined by direct spotting of the broth on thin layer chromatography (TLC) plates and quantitating by spectrodensitometry. Equivalent levels of aflatoxins were produced in vials as compared to flasks. When compared to conventional TLC after solvent extraction, direct spotting was rapid, economical and statistically equivalent. Heating broth cultures (121°C, 15 s) before TLC improved the release of aflatoxin from mycelial mats. Aflatoxins were unstable in YES broth during 3 months of frozen storage.
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The effects of oleuropein on growth and aflatoxin production by Aspergillus parasiticus NRRL 2999 at 25°C were studied. Oleuropein at 2, 4 and 6 mg/ml of glucose ammonium nitrate (GAN) broth slightly delayed onset of growth and sporulation of A. parasiticus. However, total growth of the mould, as measured by mycelial mass, was stimulated by the presence of oleuropein. Production of aflatoxin was greadly reduced; at 6 mg/ml of oleuropein, aflatoxin production was reduced by 83-93%.
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Phenolic compounds are important in relation to nutritional and sensory characteristics and the shelflife of virgin olive oil. Four new phenolic compounds have been separated by HPLC. The compounds are two (3,4-dihydroxyphenyl)ethanol derivatives and two (p-hydroxyphenyl)ethanol derivatives. This paper reports the NMR, IR, and UV characterization of three of these phenolic compounds. The compounds identified are an isomer of oleuropeine aglycon, the dialdehydic form of elenolic acid linked to (3,4-dihydroxyphenyl)ethanol, and the dialdehydic form of elenolic acid linked to (p-hydroxyphenyl)-ethanol.
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Several inhibitory concentrations of butylated hydroxyanisole (BHA) and tertiary butylhydroquinone (TBHQ) were tested against five microorganisms in the presence of 0, 1.5, 3.0 and 4.5% (v/v) of a lipid, corn oil, or 0, 3, 6 and 9% (w/v) of a protein, casein. In all cases, casein depressed, but did not abolish, the antimicrobial activity of BHA. However, corn oil virtually eliminated the antimicrobial properties of lethal doses of BHA. In contrast, TBHQ was affected much less by the food components than BHA, retaining considerable antimicrobial activity in most cases except with Staphylococcus aureus.
Article
The death rate of Salmonella enteritidis was always faster in mayonnaise made with extra virgin olive oil than in that prepared from blended olive or sunflower oils. The acidity and the phenolic profiles of these oils differed significantly. The most acidic oils (0·5% oleic acid), the extra virgin oils, also had the most complex phenolic profiles. The acidity of sunflower and blended olive oil was 0·2% and 0·4% respectively.
Article
Oleuropein, the bitter glucoside of olives, and its hydrolysis products can possess antibacterial action. However, there is no information on the possible utilization of this polyphenolic compound; therefore studies have been made to assess its utilization as a major source of carbon. Various microorganisms associated with fermentation of olives (both desirable lactic acid bacteria and spoilage organisms) did use oleuropein, many without a significant delay in growth resulting in the appearance of a strong visible turbidity. Although the increase in oleuropein from 0.2 to 0.4% (w/v) had little or no effect on the spoilage organisms, the additional glucoside caused a delay in development of growth with some of the lactic acid bacteria. However, all of the latter cultures tested eventually grew and developed strong visible turbidity.
Article
. Treatment of green olives for 2 min with dilute hot alkali before brining increased the release of sugars, B complex vitamins, amino acids and phenolic compounds, and enhanced the establishment of lactic acid bacteria in the brine. Two components of the ethyl acetate extract of green olives, which showed an antibacterial activity, were isolated and identified as the glycoside oleuropein and its phenolic aglycone. The inhibition of Lactobacillus plantarum by the ethyl acetate extract or by oleuropein was augmented by reducing the concentration of organic nitrogenous compounds, increasing the NaCl concentration in the assay medium and decreasing the inoculum size. Besides its activity towards various bacteria, oleuropein inhibited the growth of Geotrichum candidum Link, Rhizopus sp. and Rhizoctonia solani Kühn. On the basis of these findings, an explanation for some problems in the lactic fermentation of green olives is suggested.
Article
The presence of low concentrations (0.1% w/v) of oleuropein, a phenolic compound extracted from olives, delayed the growth of Staphylococcus aureus in NZ amine A and brain heart infusion media modified by the addition of growth factors and glucose (NZA+ and BHI+), as indicated by changes in conductance, whilst higher concentrations (0.4-0.6% w/v) inhibited growth completely. Intermediate concentrations of oleuropein (0.2%) prevented growth in BHI+ but allowed growth to occur in NZA+ despite an extended lag phase (30 h). Concentrations of oleuropein > 0.2% inhibited growth and production of enterotoxin B in both types of media. Lower levels (0.1%) did not affect the final viable count and production of toxin in BHI+ but decreased the number of viable organisms and reduced the toxin production in NZA+ by eightfold. An increase in the concentration of oleuropein resulted in a decrease in the amount of glucose assimilated and consequently the amount of lactate produced. In addition, oleuropein prevented the secretion of a number of exoproteins. Addition of oleuropein during the exponential phase appeared to have no effect on the growth of Staph. aureus in NZA+.
Article
Quantitative structure activity relationships (QSARs) were obtained describing the activity of a series of benzaldehydes against three different foodborne bacteria, Listeria monocytogenes F6861, serotype 4b, Salmonella enteritidis, Phage type 4, P167807 and Lactobacillus plantarum INT.L11. MIC values at pH 6.2 and 35 degrees C were obtained for 11 phenolic benzaldehydes to produce multiple linear regression and artificial neural network models. For each organism, the models contained a steric parameter Vw and an electronic-steric parameter for ortho substituents Es degree. The benzaldehydes did not require to partition to produce their effect, shown by the lack of a lipophilic parameter in the models. This strongly suggests that they act on the outside of the cells. Substitution ortho to the carbonyl group increased their antibacterial action. Cells were treated with 2,3-dihydroxy benzaldehyde and examined for their ability to bind radiolabelled iodoacetate to envelope sulfhydryl groups that remained available. It was shown that the accumulation of radiolabelled iodoacetate was lower after treatment, indicating possible competition between these two compounds for the same target. The order of the sensitivity to benzaldehydes (Salmonella > Listeria > Lactobacillus) correlated with the number of surface sulfhydryl groups available, being highest for Salmonella.
Article
Polyphenols were isolated from sliced fresh leaves of Sempervivum tectorum. After 21 h of extraction by methanol and removal of chlorophyll, ethyl acetate was used to separate oligomeric and polymeric polyphenols: 0.07% of oligomeric and 0.13% of polymeric polyphenols were found. After acidic hydrolysis of the oligomeric polyphenols, it was established by TLC, HPLC, and FAB mass spectra that kaempferol was the unique aglycon of the three main oligomeric constituents of S. tectorum. Paper chromatography suggested delphinidol to be the only anthocyanidin detectable in the material obtained by acidic hydrolysis of the polymeric polyphenol fraction. After Haslam degradation of the same polymeric polyphenol fraction, only 4-thiobenzyl-(-)-epigallocatechin and 4-thiobenzyl-(-)-epigallocatechin-3-gallate were found and tentatively identified. We concluded that procyanidins of B2 type could be the major components of the polymeric polyphenol fraction of this plant. Antimicrobial activity of Sempervivum L. leaves against six of seven selected microorganisms was observed.