Comprehensive assessment of antioxidant activity of essential oils

Essential oils have been studied for their unique ability to act as antioxidants. Antioxidant activities of 423 essential oils of 48 different botanical families were evaluated for their antioxidant activities as free radical scavenging agents using the 1,1-diphenyl-2-picrylhydrazyl method. Seventy-three oils showed 50% or more inhibition at a concentration of 1.25 mg/mL. The 73 most active oil samples were further evaluated for their scavenging activities using series of dilutions to estimate their EC(50) . The EC(50) of the 73 most active oils ranged from 4 to 2000 μg/mL. Oils having an EC(50) of less than 300 μg/mL (20 selected samples) were subjected to β-carotene bleaching antioxidant activity test and more detailed analysis including thin layer chromatography, gas chromatography/mass spectrometry, high performance liquid chromatography and bioautography. Essential oils of the botanical families Lamiaceae and Myrtaceae were the most effective antioxidants. Thymol and carvacrol were the major constituents in most of the essential oils of the family Lamiaceae and eugenol was the major terpene in all of the essential oils of the family Myrtaceae. Practical Applications: Supplementation of food with spices containing essential oils may counteract and retard the process of oxidative damage, lipid oxidation and elevate antioxidant activity of the final product.     

Salvia spp. plants-from farm to food applications and phytopharmacotherapy

Salvia is one of the largest genera of the family Lamiaceae. It is widely distributed in the temperate, subtropical, and tropical regions all over the world. Besides its ethnobotanical importance, some species such as S. officinalis (sage, common sage), S. sclarea (clary sage), S. lavandulifolia (Spanish sage), S. miltiorrhiza (danshen), and S. hispanica (chia) are traded on the market as a food and because of the interest in their essential oils and/or popularity in traditional medicine. The high diversity of the Salvia genus and phytochemical richness generate great interest for discovering new biological active compounds, including those found in essential oils. Salvia plant essential oils exhibit broad-spectrum pharmacological activities and represent great interest for food preservation as potential natural products. Thus, this review describes the phytochemical composition of essential oils from different Salvia spp. according to the geographic regions, plant organ, and phenological stage. Moreover, the cultivation and growing conditions of Salvia plants have been also revised. Finally, the interest on Salvia plants for food and pharmaceutical applications has been covered, through reporting their biological properties, including as antioxidant, antimicrobial, anti-alzheimer, hypotensive, anti-hyperglycemia, anti-hyperlipidemia, anti-cancer, and skin curative agents.     

青兰属植物的化学成分及药理作用研究进展

唇形科(Labiatae)青兰属(Dracocephalum)植物约有60种,主要分布于亚洲温带,化学成分主要包括挥发油类、黄酮及黄酮苷类、植物甾醇及三萜类、有机酸及酯类等,具有抗缺氧、抗氧化、保护心血管、抗肿瘤和清除自由基等多种药理作用,近年来对其化学成分的研究受到很大的关注。本文综述主要青兰属植物的化学成分和药理活性的研究进展。     

Biologically Active Compounds from Hops and Prospects for Their Use

Although female cones of the hop plant (Humulus lupulus) are known primarily as raw material supplying characteristic bitterness and aroma to beer, their equally significant health‐promoting effects have been known to mankind for several thousand years and hop is a plant traditionally utilized in folk medicine. This paper summarizes the scientific knowledge on the effects of all 3 major groups of secondary metabolites of hops; polyphenols, essential oils, and resins. Because of their chemical diversity, it is no coincidence that these compounds exhibit a wide range of pharmacologically important properties. In addition to antioxidant, anti‐inflammatory, and anticancer‐related properties, particular attention is being paid to prenylflavonoids that occur almost exclusively in hops and are considered to be some of the most active phytoestrogens known. Hop oils and resins are well known for their sedative and other neuropharmacological properties, but in addition, these compounds exhibit antibacterial and antifungal effects. Recently, alpha bitter acids have been shown to block the development of a number of complex lifestyle diseases that are referred to by the collective name “metabolic syndrome.” Information presented in this review confirms the significant potential for the use of hops in the pharmaceutical industry and provides an understanding of beer as a natural drink that, although moderately consumed, may become a source of many health‐promoting compounds.     

Composition and radical‐scavenging activity of Thymus glabrescens Willd. (Lamiaceae) essential oil

BACKGROUND: Knowledge about the chemical and therapeutic properties of Thymus glabrescens Willd. (Lamiaceae) is scarce and inconsistent. Therefore the main objectives of this study were to determine the yield and chemical composition of essential oils from wild‐growing T. glabrescens populations, to assess their radical scavenging activity and to correlate the results with published data in order to deduce which components are responsible for the activity. RESULTS: The plant material yielded between 4.0 and 8.0 mL kg^?1 of essential oil. All samples contained considerable but variable concentrations of thymol (22.3–55.1%), depending on the source. Radical‐scavenging activities of the oils were estimated by 1,1‐diphenyl‐2‐picrylhydrazyl free radical (DPPH) assay against butylated hydroxytoluene (BHT) and thymol as positive controls. The observed activities (IC₅₀ values ranged from 94 to 230 µg mL^?1) were strongly influenced by thymol concentration, as verified by rapid screening for DPPH radical‐scavenging activity on thin layer chromatography (TLC) plates and regression analysis. CONCLUSION: These results represent the first report on the free radical‐scavenging activity of T. glabrescens essential oil and one of the first comprehensive reports on its composition. Thymus glabrescens could be used in the food industry for seasoning purposes or for preserving processed foods from oxidative degradation. Copyright © 2008 Society of Chemical Industry     

Plant Essential Oils as Active Antimicrobial Agents

Essential oils derived from plants have been recognized for decades to exhibit biological activities, including antioxidant, anticancer, and antimicrobial attributes. Antimicrobial activities of these natural plant materials have been intensively explored in recent years, mainly in response to the overwhelming concern of consumers over the safety of synthetic food additives. Gram-negative organisms are believed to be slightly less sensitive to essential oils than Gram-positive bacteria. Generally, a higher concentration is required to obtain the same efficacy in foods than in synthetic media. The combinations of different types of essential oils or with other food additives have been found to potentially exhibit synergistic if not additive effects. This suggests a cost-efficient and wholesome alternative to both food industry and consumers, at the same time adhering to the hurdle technology in inhibiting proliferation of foodborne pathogens. This review aims to examine the conventional methods commonly used for assessment of antimicrobial activities of essential oils and phytochemicals, the use of these substances as antimicrobials in food products, factors that affect their efficacy, synergism between components or with available food preservatives as well as the challenges and future directions of using essential oils and phytochemicals as natural food preservatives.     

Biological activities of Agave by‐products and their possible applications in food and pharmaceuticals

Agave leaves are considered a by‐product of alcoholic beverage production (tequila, mezcal and bacanora) because they are discarded during the production process, despite accounting for approximately 50% of the total plant weight. These by‐products constitute a potential source of Agave extracts rich in bioactive compounds, such as saponins, phenolic compounds and terpenes, and possess different biological effects, as demonstrated by in vitro and in vivo tests (e.g. antimicrobial, antifungal, antioxidant, anti‐inflammatory, antihypertensive, immunomodulatory, antiparasitic and anticancer activity). Despite their positive results in biological assays, Agave extracts have not been widely evaluated in food systems and pharmaceutical areas, and these fields represent a potential route to improve the usage of Agave plants as food additives and agents for treating medical diseases. © 2017 Society of Chemical Industry     

In vitro antifungal activity of terpinen-4-ol,eugenol, carvone, 1,8-cineole (eucalyptol) and thymol against mycotoxigenic plant pathogens

The aim of this study was to examine the effect of five naturally occurring compounds from essential oils on 10 different species of mycotoxigenic fungi involved in several plant diseases. The antifungal activities of terpinen-4-ol, eugenol, carvone, 1,8-cineole (eucalyptol) and thymol were observed in vitro on Fusarium subglutinans, Fusarium cerealis, Fusarium verticillioides, Fusarium proliferatum, Fusarium oxysporum, Fusarium sporotrichioides, Aspergillus tubingensis, Aspergillus carbonarius, Alternaria alternata and Penicillium sp. The naturally occurring compounds tested showed toxic effects on in vitro mycelium growth of all fungal species but with different level of potency. The results are encouraging for further investigations of in planta antifungal activities of these essential oils components.     

Nutritional value, functional properties and nutraceutical applications of black cumin (Nigella sativa L.): an overview

Non‐conventional seeds are being considered because their constituents have unique chemical properties and may augment the supply of nutritional and functional products. Black cumin (Nigella sativa L.) seeds and its crude or essential oils have been widely used in traditional nutritional and medicinal applications. Consequently, black cumin has been extensively studied for its nutritional value and biological activities. The black cumin oilseed had been shown to be anticancer, antidiabetic, antiradical and immunomodulator, analgesic, antimicrobial, anti‐inflammatory, spasmolytic, bronchodilator, hepatoprotective, antihypertensive and renal protective. Moreover, black seeds have many antioxidative properties and activities. In consideration of potential utilisation, detailed knowledge on the composition of black cumin oilseed is of major importance. The diversity of applications to which black cumin can be put gives this oilseed great industrial importance. This review summarises the nutritional value, functional properties and nutraceutical applications of black cumin (N. sativa L.) oilseeds.     

Evidences and perspectives in the utilization of CLNA isomers as bioactive compounds in foods

Conjugated alpha linolenic acid (CLNA) isomers are promising lipids owing to their similarities with conjugated linoleic acid (CLA) but exerting their bioactivity at lower doses; some isomers also belong to omega 3 family. This review aims to summarize the state of the art about the utilization of CLNA as a functional ingredient. Indeed, in vitro and in vivo studies reported that CLNA exerted anticancer, anti-inflammatory, anti-obese, and antioxidant activities. However, CLNA has not been tested in humans. These compounds are naturally present in meat and milk fat from ruminants but the highest concentrations are found in vegetable oils. Their incorporation in foodstuffs is one of the most effective strategies to elaborate CLNA-enriched products together with the microbiological production. Lactobacilli, propionibacteria, and bifidobacteria strains have been assayed to produce CLNA isomers but at the current moment there are not high CLNA concentration products elaborated using these strains. Furthermore, it is known that CLNA isomers are highly prone to oxidation when compared with linoleic acid and CLA, but the possible effects of elaboration and storage on high CLNA productsare unknown.The utilization of CLNA as a functional compound still remains a challenge and requires more research to address all of its technological and bioactivity aspects.     

Natural antimicrobial/antioxidant agents in meat and poultry products as well as fruits and vegetables: A review

Synthetic preservatives are widely used by the food industry to control the growth of spoilage and pathogenic microorganisms and to inhibit the process of lipid oxidation extending the shelf-life, quality and safety of food products. However, consumer's preference for natural food additives and concern regarding the safety of synthetic preservatives prompted the food industry to look for natural alternatives. Natural antimicrobials, including plant extracts and their essential oils, enzymes, peptides, bacteriocins, bacteriophages, and fermented ingredients have all been shown to have the potential for use as alternatives to chemical antimicrobials. Some spices, herbs and other plant extracts were also reported to be strong antioxidants. The antimicrobial/antioxidant activities of some plant extracts and/or their essential oils are mainly due to the presence of some major bioactive compounds, including phenolic acids, terpenes, aldehydes, and flavonoids. The proposed mechanisms of action of these natural preservatives are reported. An overview of the research done on the direct incorporation of natural preservatives agents into meat and poultry products as well as fruit and vegetables to extend their shelf-life is presented. The development of edible packaging materials containing natural preservatives is growing and their applications in selected food products are also presented in this review.     

Plant products as fumigants for stored-product insect control

Research studies on plant essential oils and their constituents as fumigants, i.e., compounds acting on target insects in the vapour or gaseous phase, against stored-product insects have been reviewed. Fumigant toxicity tests conducted with essential oils of plants (mainly belonging to Apiaceae, Lamiaceae, Lauraceae and Myrtaceae) and their components (cyanohydrins, monoterpenoids, sulphur compounds, thiocyanates and others) have largely focused on beetle pests such as Tribolium castaneum, Rhyzopertha dominica, Sitophilus oryzae and Sitophilus zeamais but little or no attention has been paid towards moths such as Corcyra cephalonica and Sitotroga cerealella. Adults were generally susceptible, whereas, eggs were either tolerant or highly susceptible depending on insect species and the type of essential oil or component. The essential oils proved effective in mixture with CO₂ or ethyl formate. Mode of action studies on monoterpenoids indicate inhibition of acetylcholinesterase enzyme activity as the major site of action. Although, in laboratory tests with adult insects, some of the plant compounds have shown insect toxicity comparable to methyl bromide or chloropicrin, their physical properties such as high molecular weight as well as high boiling point and very low vapour pressure are barriers for application in large-scale fumigations. Plant products, therefore, have the potential for small-scale treatments, space fumigations and as adjuvants for conventional fumigants. The constraints including lack of data for single or multiple components of essential oils on sorption, tainting and residues in food commodities, and registration protocols have been highlighted. The use of egg and pupal stages or preferably mixed-age cultures of target insects in screening tests with any new plant essential oil/compound has also been stressed.     

Natural phenolic antioxidants electrochemistry: Towards a new food science methodology

Natural phenolic compounds are abundant in the vegetable kingdom, occurring mainly as secondary metabolites in a wide variety of chemical structures. Around 10,000 different plant phenolic derivatives have been isolated and identified. This review provides an exhaustive overview concerning the electron transfer reactions in natural polyphenols, from the point of view of their in vitro antioxidant and/or pro‐oxidant mode of action, as well as their identification in highly complex matrixes, for example, fruits, vegetables, wine, food supplements, relevant for food quality control, nutrition, and health research. The accurate assessment of polyphenols’ redox behavior is essential, and the application of the electrochemical methods in routine quality control of natural products and foods, where the polyphenols antioxidant activity needs to be quantified in vitro, is of the utmost importance. The phenol moiety oxidation pathways and the effect of substituents and experimental conditions on their electrochemical behavior will be reviewed. The fundamental principles concerning the redox behavior of natural polyphenols, specifically flavonoids and other benzopyran derivatives, phenolic acids and ester derivatives, quinones, lignins, tannins, lignans, essential oils, stilbenes, curcuminoids, and chalcones, will be described. The final sections will focus on the electroanalysis of phenolic antioxidants in natural products and the electroanalytical evaluation of in vitro total antioxidant capacity.     

Chemical Composition and Antioxidant, Antimicrobial Activities of the Essential Oils of Thymus marschallianus Will. and Thymus proximus Serg.

ABSTRACT: Chemical composition and antioxidant, antimicrobial activities of the essential oils from Thymus marschallianus Will. and Thymus proximus Serg. growing in the wild in Xinjiang were studied. Samples were collected from the aerial parts of the plants with simultaneous distillation-extraction apparatus. The yields ranged between 1.22%± 0.01 and 0.16%± 0.01 (weight/dry weight), respectively, 53 and 60 kinds of volatiles, representing 99.6% and 99.7% of the essential oils, respectively, were identified in extracts from T. marschallianus and T. proximus by GC/MS analysis. The main components were Thymol (28.0% to 32.9%), p-Cymene (7.7% to 25.4%), and γ-Terpinene (18.0% to 22.4%). Antioxidant activities of the oils were evaluated using metal chelating, reductive potential, 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, and modified thiobarbituric acid reactive substances assay. Antimicrobial activities of the oils were investigated on Escherichia coli, Staphylococcus aureus, Bacillus subtilis, yeast, Rhizopus, and Penicillium. The inhibition zones (IZ) and minimum inhibitory concentration (MIC) values were 5.0 to 35.7 mm in diameter and 1.81 to 4.52 μL/mL, respectively. Practical Application: Due to the economical impacts of spoiled foods and the consumer's concerns over the safety of foods, a lot of attention has been paid to naturally derived compounds. Fresh and dried Thymus species as well as their processed products have been widely used as flavorings since ancient times; however, during the last few decades, they also have become a subject for a search of natural antioxidants and antimicrobial agents. Biological activities of Thymus essential oils depend on their chemical composition, which is determined by the genotype and influenced by environmental conditions. Recent studies have showed that Thymus species have strong antimicrobial and antioxidant activities. To the best of our knowledge, the properties of Thymus species growing wild in the Xinjiang have not been reported before.     

The influence of organ,season and drying method on chemical composition and antioxidant and antimicrobial activities of Juniperus phoenicea L. essential oils

BACKGROUND: Juniperus phoenicea is an important medicinal plant. In the present study, essential oils (18 samples) from leaves and berries of Juniperus phoenicea L. (Cupressaceae), obtained by various drying methods and in different collection months, were analysed by gas chromatography–mass spectrometry and also evaluated for in vitro antimicrobial and antioxidant activities. Correlations were studied between antimicrobial activity and the chemical composition of essential oils. RESULTS: Sixty‐seven compounds were identified in essential oils, representing 97.7–100%. Essential oils were dominated by monoterpenes and sesquiterpenes, which presented 35.0–93.3% and 6.7–62.0%, respectively, depending of organ, season and drying method. Antimicrobial tests showed that essential oils strongly inhibited the growth of Gram‐positive microorganisms and Mucor ramamnianus, but was inactive against Gram‐negative strains. Antioxidant activity was tested using the ABTS radical‐scavenging assay. Most samples showed good activity (the best IC₅₀ = 41.7 ± 1.5 mg L^?1). CONCLUSIONS: It could be concluded that drying of leaves of J. phoenicea in the sun and berries in oven‐drying was more suitable and was recommended for obtaining higher essential oil yield, but for a higher percentage of some special components such as α‐pinene and δ‐3‐carene shade‐drying was more suitable. Copyright © 2009 Society of Chemical Industry     

植物挥发油对黄曲霉毒素产生菌及其毒素合成的影响

黄曲霉毒素(AFT)是由黄曲霉(Aspergillus flavus)和寄生曲霉(Aspergillus parasiticus)等曲霉属真菌产生的次生代谢产物,具有致畸、致癌、致突变等作用.AFT污染多种粮食作物及食品,其极强的毒性严重威胁到人体健康.寻找各种黄曲霉毒素抑制剂已成为国内外研究的热点.部分抗生素类药物及化学杀菌剂虽然具有较强的抗黄曲霉作用,但鉴于其毒副作用较明显,使用范围非常有限.近二十年来,人们开始从天然产物中寻找毒副作用低、易降解并且安全性高的黄曲霉抑制剂.本文对天然植物挥发油及其单体成分抑制黄曲霉和寄生曲霉生长并抑制AFT合成,以及在粮食、食品及其包装等方面的应用情况进行综述,为进一步研究植物挥发油类成分的抑菌机制和产品开发提供参考.     

Designing novel industrial and functional foods using the bioactive compounds from Nigella sativa L. (black cumin): Biochemical and biological prospects toward health implications

Nigella sativa is one of the nutraceuticals that has gained popularity and studied extensively in recent decades as it is considered a safe medicinal plant for use as a dietary supplement. N. sativa contains a wide variety of bioactive substances, which include polyphenols, volatile oils (thymoquinone and p-cymene), proteins, and peptides. The biological attributes of N. sativa include antioxidant, antimicrobial, antifungal, anti-inflammatory, anticancer, antidiabetic, antihypertensive, hypolipidemic, and antioxidant activities, which have potential applications for the prevention of a variety of chronic diseases. In the food industry, N. sativa improves the sensory qualities, shelf life, strength, and freshness of foods, such as bread, pizza, biscuits, cookies, and cakes. This review discusses the industrial use of N. sativa, which includes processing technologies to enhance its health-promoting properties as well as the isolation of nutraceutical components.     

Essential oils of Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart collected from three localities of north Tunisia—Krib, Bargou and Nefza—were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin–Ciocalteu method, and antioxidant effectiveness, using the 2,2‐diphenyl‐1‐picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p‐cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), γ‐terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC₅₀, ranged from 59 to 80 mg L^?1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg^?1 dry weight, varied from 9.37 to 17.70 g kg^?1 dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p‐cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated. Copyright © 2010 Society of Chemical Industry     

植物精油在包装领域的研究应用进展

近年来,人们对在食品中使用天然抗菌剂代替化学防腐剂的兴趣日益增加。就此而言,精油这种具有挥发性且安全无害的天然植物次生代谢产物无疑将会在食品功能包装领域得到广泛的研究和应用。目前大量研究表明,加入精油后的食品包装可增强食品的抗菌和抗氧化活性、减缓酶促褐变、改变食品周围的气体环境以及水蒸气渗透等效果。本文特以此为切入点,介绍了植物精油的生物学效应,以及植物精油作为一种活性成分在当前的研究、开发和应用。因此,开发植物精油用作生物基食品包装,将精油本身与纳米乳液纳入活性或智能包装中,加入到产品或包装表面涂层、充入气调包装中、在包装内添加小袋和加入到包装膜上等,无疑可以用来改善产品品质的影响,减少食品行业的浪费。该研究还涵盖了植物精油在食品包装中的常见技术应用,如可降解的生物薄膜、微胶囊包埋、纳米乳液和静电纺丝等,以期为植物精油在包装领域的应用提供新途径。     

Chitosan coatings enriched with essential oils: Effects on fungi involved in fruit decay and mechanisms of action

BackgroundPesticides have a negative impact on the health of consumers and on the environment, and as a consequence, the use of naturally occurring antimicrobial agents have become more popular to prevent food spoilage. An alternative is the use of chitosan, because of its antimicrobial, antioxidant activities and its capacity to form films having good mechanical properties. Chitosan has been used in the preparation of films and coatings for the preservation of different food products, and the addition of essential oils have been shown to be a good strategy to improve its antimicrobial activity in situ.Scope and approachThis review compiles information related to studies and research that employ chitosan as matrix for films, coatings and nanogels with essential oils extracted from plants, as antifungal agent. A special emphasis has been addressed to the effect exerted on the most pathogenic fungi for crops, also highlighting the mechanisms of action that researchers attribute to the composite, together with inhibition data.Key Findings and ConclusionEffective natural treatments, using chitosan-essential oils films or nano-emulsions, improve the preservation of fruit in terms of fungal decay. The effect is particularly dependent on the ability to release the antimicrobial compounds from the polymer matrix, the type of essential oils, the fungal species, and the incubation temperature. Several efforts are still required to understand in detail the mechanism of degradation of perishable food, how the chitosan-essential oils composites control or inhibit food decay, the effects on other pathogenic and non-pathogenic moulds as well as on the production of mycotoxins.