Plant Phenolic Compounds Research Articles

Phenolic compounds of Bassia prostrata (Chenopodiaceae)

The composition and content of phenolic compounds in plants of the polymorphic species Bassia prostrata (Chenopodiaceae) from geographically distant populations were studied by high-performance liquid chromatography. The material for the study was the aboveground part of the plant. The plants were collected in the flowering phase in Russia (Novosibirsk region, Republic of Tyva, Khakassia, Buryatia, Altai), Kazakhstan, Armenia. The phenolic compounds were extracted by double extraction with 70% ethanol. Component composition of the phenolic complex was investigated by Agilent 1200 chromatograph. Eleven phenolic compounds, including isoquercitrin, kaempferol-3-glycoside, isoramnetin-3-rutinoside, and luteolin were found in the composition. The quantitative content of each compound could vary from 0.1 to 10.8 mg/g in different populations. Chemotypes were determined for the qualitative and quantitative content of phenolic compounds

Влияние интоксикации сероуглеродом на биохимические показатели крови и их коррекция растительными фенольными соединениями в эксперименте

Introduction. Phenolic compounds that are part of a variety of phytopreparations have an anti-radical and antioxidant effect. Aim. Studying the influence of carbon disulfide intoxication on the rat blood biochemical parameters and the possibility of their correction with natural plant phenolic compounds from viburnum. Materials and methods. The experiment was conducted on white Wistar male rats. Carbon disulfide intoxication (concentration 2.0 mg/m3) was implemented in a special exposure chamber. The animals were divided into 5 groups: the 1st group was control (intact rats); the 2nd group was carbon disulfide intoxication for 3 weeks; the 3rd group was carbon disulfide intoxication for 3 weeks, followed by discontinuation for 7 days; the 4th group was carbon disulfide intoxication for 3 weeks, followed by administration of the viburnum extract for 7 days; the 5th group was carbon disulfide intoxication for 3 weeks, followed by silymarin administration for 7 days. The drugs were administered at a dose of 100 mg of total phenols per kilogram of animal weight. Results. Carbon disulfide intoxication was accompanied by the development of intense hypercholesterolemia; an increase in the fraction of low-density lipoproteins with simultaneous decrease in high-density lipoproteins in blood serum. There was an increase in the level of malondialdehyde, decrease in the superoxide dismutase activity and reduced glutathione amount, which indicates the depletion of the body’s antioxidant defense system. During the withdrawal period of carbon disulfide intoxication for 7 days, the blood biochemical parameters did not recover, which indicates the preservation of free-radical processes. The administration of the viburnum extract and the comparison drug, silymarin, was accompanied by a recovery to the control group level of blood biochemical parameters after carbon disulfide intoxication. Conclusion. The toxic effect of carbon disulfide causes a change in the studied blood biochemical parameters. The administration of the viburnum extract and silymarin was accompanied by their restoration to the level of the control group, but a more pronounced effect was observed in the viburnum extract due to the presence of oligomeric forms of polyphenols in its composition.

Nonlinear responses of foliar phenylpropanoids to increasing O3 exposure: Ecological implications in a Populus model system

Plant phenolic compounds (phenylpropanoids) act as defense chemicals against herbivores and can mediate ecosystem processes. Tropospheric ozone (O3) pollution alters concentrations of plant phenolics; however, little is known about how these phytochemicals respond to different levels of O3 exposure. Here, we investigated the effects of five different O3 exposure levels on foliar concentrations of phenylpropanoids (53 compounds in total) and antioxidative capacity in hybrid Populus (Populus euramericana cv. ‘74/76’) saplings grown in the presence of high or low soil nitrogen (N) load. Increasing O3 exposure initially increased and then decreased total concentrations of phenolic compounds, revealing a biphasic exposure-response profile (hormetic zone: 1.1–36.3 ppm h AOT40). This biphasic response pattern was driven by changes in a subset of phenylpropanoids with high antioxidative capacity (e.g. condensed tannins) but not in phenolics with low antioxidative capacity (e.g. salicinoids). The O3 exposure-response relationships of some phenylpropanoids (e.g. flavonoids and chlorogenic acids) varied in response to soil N, with hormesis occurring in high N soil but not in low N soil. Collectively, our findings indicated that plant phenolic compounds exhibit nonlinear responses to increasing O3 exposure, and that the responses vary in relation to phenolic compound class, antioxidative capacity, and soil nitrogen conditions. Our findings further suggest that the impact of O3 on ecological processes mediated by phenolics will be concentration-dependent, highlighting the complexity of the ecological effects of ground-level O3 pollution.

Valorization of Gleditsia triacanthos Invasive Plant Cellulose Microfibers and Phenolic Compounds for Obtaining Multi-Functional Wound Dressings with Antimicrobial and Antioxidant Properties.

Gleditsia triacanthos is an aggressive invasive species in Eastern Europe, producing a significant number of pods that could represent an inexhaustible resource of raw material for various applications. The aim of this study was to extract cellulose from the Gleditsia triacanthos pods, characterize it by spectrophotometric and UHPLC–DAD-ESI/MS analysis, and use it to fabricate a wound dressing that is multi-functionalized with phenolic compounds extracted from the leaves of the same species. The obtained cellulose microfibers (CM) were functionalized, lyophilized, and characterized by ATR-FTIR and SEM. The water absorption and retention capacity as well as the controlled release of phenolic compounds with antioxidant properties evaluated in temporal dynamics were also determined. The antimicrobial activity against reference and clinical multi-drug-resistant Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloacae, Candida albicans, and Candida parapsilosis strains occurred immediately after the contact with the tested materials and was maintained for 24 h for all tested microbial strains. In conclusion, the multi-functionalized cellulose microfibers (MFCM) obtained from the reproductive organs of an invasive species can represent a promising alternative for the development of functional wound dressings with antioxidant and antimicrobial activity, as well as being a scalable example for designing cost-effective, circular bio-economy approaches to combat the accelerated spread of invasive species.

Tomato Domestication Attenuated Responsiveness to a Beneficial Soil Microbe for Plant Growth Promotion and Induction of Systemic Resistance to Foliar Pathogens.

Crop domestication events followed by targeted breeding practices have been pivotal for improvement of desirable traits and to adapt cultivars to local environments. Domestication also resulted in a strong reduction in genetic diversity among modern cultivars compared to their wild relatives, though the effect this could have on tripartite relationships between plants, belowground beneficial microbes and aboveground pathogens remains undetermined. We quantified plant growth performance, basal resistance and induced systemic resistance (ISR) by Trichoderma harzianum, a beneficial soil microbe against Botrytis cinerea, a necrotrophic fungus and Phytophthora infestans, a hemi-biotrophic oomycete, in 25 diverse tomato genotypes. Wild tomato related species, tomato landraces and modern commercial cultivars that were conventionally or organically bred, together, representing a domestication gradient were evaluated. Relationships between basal and ISR, plant physiological status and phenolic compounds were quantified to identify potential mechanisms. Trichoderma enhanced shoot and root biomass and ISR to both pathogens in a genotype specific manner. Moreover, improvements in plant performance in response to Trichoderma gradually decreased along the domestication gradient. Wild relatives and landraces were more responsive to Trichoderma, resulting in greater suppression of foliar pathogens than modern cultivars. Photosynthetic rate and stomatal conductance of some tomato genotypes were improved by Trichoderma treatment whereas leaf nitrogen status of the majority of tomato genotypes were not altered. There was a negative relationship between basal resistance and induced resistance for both diseases, and a positive correlation between Trichoderma-ISR to B. cinerea and enhanced total flavonoid contents. These findings suggest that domestication and breeding practices have altered plant responsiveness to beneficial soil microbes. Further studies are needed to decipher the molecular mechanisms underlying the differential promotion of plant growth and resistance among genotypes, and identify molecular markers to integrate selection for responsiveness into future breeding programs.

Metabolite Fingerprinting of Kersting's Groundnut [Macrotyloma geocarpum (Harms) Maréchal & Baudet] Seeds Using UPLC-qTOF-MS Reveals the Nutraceutical and Antioxidant Potentials of the Orphan Legume.

The identification and subsequent quantification of phenolic compounds in plants is the first step toward harnessing their associated nutritional and health benefits. Due to their diverse phenolic compound compositions, grain legumes are known for their high nutritional and health values. The aim of this study was to assess the inter-variations in chemical composition, phytochemical content, and antioxidant capacity of seed extracts from eight Kersting's groundnut [Macrotyloma geocarpum (Harms) Marechal & Baudet] landraces. The chemical profiles were evaluated using UPLC-qTOF-MS. Total phenolics and flavonoids content were determined by the Folin-Ciocalteu and aluminum chloride methods, respectively. The antioxidant capacities in the forms of DPPH and ABTS were evaluated using spectrophotometric methods. Principal component analysis was used to define similarities/differences between the landraces. Based on untargeted metabolomics analysis, 57 metabolites were identified, with phenolics, triterpenes, fatty acids, and sphingolipids being the most predominant. The results showed that the black seeded KG1 (Puffeun) had the highest total phenolic (9.44 mg GAE/g) and flavonoid (3.01 mg QE/g) contents, as well as antioxidant capacity (9.17 μg/mL and 18.44 μg/mL based on DDPH and ABTS assays, respectively). The concentrations of ferulic acid hexoside, procyanidin B2, eryodictyiol-7-rutinoside and quercetin pentoside ranged from 51.78–441.31, 1.86–18.25, 3.26–13.95 to 5.44–63.85 μg/mg, respectively. This study presents a useful report on the phytochemical characterization of Kersting's groundnuts and shows that the grains can be used as a source of nutraceuticals for human consumption.

Innovation and Application of the Type III Secretion System Inhibitors in Plant Pathogenic Bacteria.

Many Gram-negative pathogenic bacteria rely on a functional type III secretion system (T3SS), which injects multiple effector proteins into eukaryotic host cells, for their pathogenicity. Genetic studies conducted in different host-microbe pathosystems often revealed a sophisticated regulatory mechanism of their T3SSs, suggesting that the expression of T3SS is tightly controlled and constantly monitored by bacteria in response to the ever-changing host environment. Therefore, it is critical to understand the regulation of T3SS in pathogenic bacteria for successful disease management. This review focuses on a model plant pathogen, Dickeya dadantii, and summarizes the current knowledge of its T3SS regulation. We highlight the roles of several T3SS regulators that were recently discovered, including the transcriptional regulators: FlhDC, RpoS, and SlyA; the post-transcriptional regulators: PNPase, Hfq with its dependent sRNA ArcZ, and the RsmA/B system; and the bacterial second messenger cyclic-di-GMP (c-di-GMP). Homologs of these regulatory components have also been characterized in almost all major bacterial plant pathogens like Erwinia amylovora, Pseudomonas syringae, Pectobacterium spp., Xanthomonas spp., and Ralstonia spp. The second half of this review shifts focus to an in-depth discussion of the innovation and development of T3SS inhibitors, small molecules that inhibit T3SSs, in the field of plant pathology. This includes T3SS inhibitors that are derived from plant phenolic compounds, plant coumarins, and salicylidene acylhydrazides. We also discuss their modes of action in bacteria and application for controlling plant diseases.

Establishment of a UPLC-PDA/ESI-Q-TOF/MS-Based Approach for the Simultaneous Analysis of Multiple Phenolic Compounds in Amaranth (A. cruentus and A. tricolor).

We used ultraperformance liquid chromatography coupled with a photodiode-array detector and electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-PDA/ESI-Q-TOF/MS) to rapidly and accurately quantify 17 phenolic compounds. Then, we applied this method to the seed and leaf extracts of two Amaranthus species to identify and quantify phenolic compounds other than the 17 compounds mentioned above. Compounds were eluted within 30 min on a C18 column using a mobile phase (water and acetonitrile) containing 0.1% formic acid, and the specific wavelength and ion information of the compounds obtained by PDA and ESI-Q-TOF/MS were confirmed. The proposed method showed good linearity (r2 > 0.990). Limits of detection and quantification were less than 0.1 and 0.1 μg/mL, respectively. Intra- and interday precision were less than 2.4% and 1.8%, respectively. Analysis of amaranth seed and leaf extracts using the established method showed that the seeds contained high amounts of 2,4-dihydroxybenzoic acid and kaempferol, and leaves contained diverse phenolic compounds. In addition, six tentatively new phenolic compounds were identified. Moreover, seeds potentially contained 2,3-dihydroxybenzaldehyde, a beneficial bioactive compound. Thus, our method was an efficient approach for the qualitative and quantitative analysis of phenolic compounds, and could be used to investigate phenolic compounds in plants.

Purification and characterization of peroxidases from garden cress sprouts and their roles in lignification and removal of phenol and p-chlorophenol.

The study aims to evaluate the relation between peroxidases of day-6 garden cress sprouts and phenolic compounds. Three cationic, three anionic, and two unbounded peroxidases were separated from day-6 garden cress sprouts. Cationic (GCP1) and anionic (GCP2) peroxidases were purified with molecular masses of 25 and 40kDa, respectively. The Km values of GCP1 toward H2 O2 and guaiacol were lower than GCP2. The anionic GCP2 exhibited high affinity toward some lignin monomers, sinapyl alcohol, coniferyl alcohol, cinnamic and ferulic acids. Therefore, GCP2 is considered as a lignin peroxidase and contributed in lignin synthesis. The activity of GCP1 and GCP2 was stable at a wide pH range 5.5-8.0 and 6.0-7.5, respectively. Both peroxidases showed the same thermal stability range 20-50°C. GCP2 was more resistant against the effect of metal ions than GCP1. GCP2 showed high ability to remove of phenol and p-chlorophenol from effluent compared to GCP1. PRACTICAL APPLICATIONS: Generally, garden cress is used as a test plant to conduct biomonitoring of pollution in urban soil on a wide scale because of its simplicity, sensitivity, and cost-effectiveness. Peroxidase is an important antioxidant enzyme, which elevated when plant subjected to pollution. Recently, we reported that the increase of peroxidase activity was strongly correlated with high phenolic content and antioxidant activity during the germination of garden cress. In the present study, anionic peroxidase GCP2 may play an important role in lignification process and removal of phenol and p-chlorophenol from polluted soil/wastewater as well as resisted the harmful effect of heavy metals. Cationic peroxidase GCP1, as a natural scavenger, had high affinity toward H2 O2 coupled to oxidation of some plant phenolic compounds suggesting its role in consuming of excess H2 O2 .

Discerning morpho-physiological and quality traits contributing to salinity tolerance acquisition in sorghum [Sorghum bicolor (L.) Moench]

Soil salinization has become a major constraint affecting crop production worldwide. Salinity induces complex metabolic processes that involves ion toxicity, osmotic stress, biochemical and physiological perturbations. Sorghum is a gluten-free cereal crop, well adapted to semi-arid tropics, highly biomass productive and water-efficient. Sorghum crop's growing is an efficient way to utilize saline soils. Therefore, the present study aimed to assess the tolerance behavior of sorghum genotypes under different salinity levels (60, 80, 100, 120, 140 mM NaCl) concerning the performance of physiological, biochemical, and quality traits. Amongst 23 screened sorghum genotypes and 300 lines of sorghum germplasm, SSG59–3 was identified as salt-tolerant and PC-5 as salt susceptible genotype based on germination studies. The photochemical quantum yield (PC-5: 39.1% and SSG59–3: 12.7% reduction), chlorophyll content (SPAD units), relative water content and chlorophyll stability index (PC-5: 65.3% and SSG59–3: 54.9%) were significantly higher in SSG59–3 (SSG59–3 was identified as salt tolerant). Similarly, significant percent reductions in plant height (SSG59–3: 76%, PC-5: 86%), fresh and dry weight were observed with increasing salinity levels from 60 to 140 mM NaCl. Total phenols and soluble sugars (SSG59–3: 62.5%, PC-5: 46.7%) exhibited an upward trend, while flavanoids and flavanols showed a reverse trend. Salinity also affected the nutritive value of sorghum adversely, but the effect was less pronounced in SSG59–3. Quality traits viz. crude protein (SSG59–3: 5.16% and PC-5: 3.22%) and in-vitro dry matter digestibility reduced with increasing salinity levels from 60 to 140 mM NaCl. Reversibly, HCN content increased with every increment of salt stress, from 121.12–133.55 μg/g but were under the threshold level. Based on the above results, it was concluded that SSG59–3 performed better by retaining higher plant water status, photosynthetic rate and phenolic compounds, thereby alleviating stress, which may be utilized as genetic resource to establish sorghum cultivars with improved quality in saline soils.

Recent advances and possibilities for the use of plant phenolic compounds to manage ageing-related diseases

• Ageing-related diseases represent growing global health and economic burden. • Plant phenolic compounds exhibit a beneficial effect on ageing-related diseases. • Phenolic compounds module several signalling pathways involved in ageing-related diseases. • Phenolic compounds can be a complementary and alternative tool to manage ageing-related diseases. Ageing is an emerging global public health concern due to the increasing number of elderly people and ageing-related degenerative disorders. Given the absence of effective treatments to manage ageing-related diseases, increasing efforts have been directed to find ways to reduce the risk of developing these disorders. Among them, plant phytochemicals, such as phenolic compounds, are considered potential anti-ageing agents due to their multifaceted biochemical actions. In this review, we focus on presenting the results of the last few years and pioneer researches mainly with animal models and human trials showing the key role of phenolic compounds as potential anti-ageing agents. Recent advances demonstrated that several phenolic compounds can reduce the risk and/or delay ageing-related disorders, including neurodegenerative diseases, metabolic syndromes, and cancers particularly by modulating signalling pathways involved in inflammation, oxidative damage, autophagy, and apoptosis. Therefore, plant phenolic compounds can be a complementary and alternative tool for managing ageing-related diseases.

Hybrid bacterial cellulose‐collagen membranes production in culture media enriched with antioxidant compounds from plant extracts

AbstractBioactive, structural, and mechanical properties were measured of a cellulose biopolymer produced by Gluconacetobacter xylinus using hydrolyzed collagen and phenolic compounds from teas and grape pomace (GP) in an optimized culture medium. Biopolymers were impregnated with an antibiotic to investigate possible antibacterial activities. Hybrid bacterial cellulose (BC)‐collagen membranes obtained from cultures with green tea and a ternary mixture (TM) of teas with GP presented a high concentration of phenolic compounds (879.7 and 1312.8 mg gallic acid equivalent per liter) and antioxidant activity (973.3 and 575.9 mmol/g), respectively. BC membranes included a nanodimensional network of microfibrils, and the addition of hydrolyzed collagen in the TM of teas in situ resulted in thicker structures with improved mechanical properties. BC‐collagen membranes pretreated with cephalexin exhibited significant inhibition against Escherichia coli and Staphylococcus aureus. The enrichment of the culture media with plant phenolic compounds and collagen resulted in the formation of hybrid BC membranes in a shorter time when compared to those produced without these components. Membranes modified with bioactive compounds in situ and antibiotics ex situ can be turned into potential products for application in biomaterials with antioxidant activity.

Responses of Lolium spp. to glufosinate ammonium application at different temperatures

AbstractAn experiment to investigate why glufosinate ammonium control of Lolium spp. is more effective at cooler temperatures than warmer temperatures was conducted at Welgevallen Experimental Farm, Stellenbosch University. Wild Lolium spp. was grown at 10/15, 15/20, 20/25 and 25/30°C (night and day) temperature regimes and treated with glufosinate ammonium at 0, 300, 600, 900 and 1,200 g a.i./ha, 6 weeks after planting. Control of Lolium spp. decreased with increasing temperature. Results from elemental analysis, scanning electron microscopy (SEM), fluorescence imaging and gas chromatography–mass spectrometry (GCMS) investigations allude to calcium accumulation, cuticle thickness and plant phenolic compounds playing roles in the response of Lolium spp. to this herbicide. Increased cuticle thickness and calcium accumulation as temperatures increase indicate promotion of plant defence mechanisms through increased phenolic compound production, which is induced by herbicide stress, hence resulting in poor control of Lolium spp. under warmer temperatures.

Distribution of enzymatic and alkaline oxidative activities of phenolic compounds in plants

In this study, we screened 287 plant tissue samples from 175 plant species for their phenolic profiles. The samples were oxidized enzymatically in planta or at high pH in vitro to determine how these two oxidative conditions would alter the initial polyphenol profiles of the plant. Compounds that contained a pyrogallol or dihydroxyphenethyl group were highly active at pH 10. Enzymatic oxidation favored compounds that contained a catechol group, whereas compounds containing a pyrogallol group or monohydroxysubstituted phenolic moieties at most were oxidized less frequently. This study gives a broad overview of the distribution and alkaline oxidative activities of water-soluble phenolic compounds in plants as well as the enzymatic oxidative activities of various plant tissues.

Polyphenols as Natural Antioxidants in Skin Aging

Skin aging is a complex biological process influenced by a combination of intrinsic and extrinsic factors, leading to cumulative alterations of skin struture, function and appearance. Polyphenols represent a superfamily of diverse naturally occurring phytochemicals. Current research reveals that phenolic compounds in plants possess high antioxidant activity and free radical scavenging capacity and can prevent the body from oxidative damage over human life span. This review focuses on present understanding of skin aging and the effects of polyphenols in the context of anti-agieng activity.

Plant Phenolics as Pathogen-Carrier Immunogenicity Modulator Haptens.

BackgroundPathogens use multiple mechanisms to disrupt cell functioning in their host and allow pathogenesis. These mechanisms involve communication between the pathogen and the host cell through protein-protein interactions.MethodsProtein-protein interactions chains referred to as signal transduction pathways are the processes by which a chemical or physical signal transmits through a cell as series of molecular events so the pathogen needs to intercept these molecular pathways at few positions to induce pathogenesis such as pathogen viability, infection or hypersensitivity.ResultsThe pathogen nodes of interception are not necessarily the most immunogenic; so that novel immunogenicity-improvement strategies need to be developed thought a chemical conjugation of the pathogen-carrier nodes to develop an efficient immune response in order to block pathogenesis. On the other hand, if pathogen-carriers are immunogens; toleration ought to be induced by this conjugation avoiding hypersensitivity. Thus, this paper addresses the biological plausibility of plant-phenolics as pathogen-carrier immunogenicity modulator haptens.ConclusionThe plant-phenolic compounds have in their structure functional groups such as hydroxyl, carbonyl, carboxyl, ester, or ether, capable of reacting with the amino or carbonyl groups of the amino acids of a pathogen-carrier to form conjugates. Besides, the varied carbon structures these phenolic compounds have; it is possible to alter the pathogen-carrier related factors that determine the immunogenicity: 1) Structural complexity, 2) Molecular size, 3) Structural heterogeneity, 4) Accessibility to antigenic determinants or epitopes, 5) Optical configuration, 6) Physical state, or 7) Molecular rigidity.

UV radiation increases phenolic compound protection but decreases reproduction in Silene littorea.

Plants respond to changes in ultraviolet (UV) radiation both morphologically and physiologically. Among the variety of plant UV-responses, the synthesis of UV-absorbing flavonoids constitutes an effective non-enzymatic mechanism to mitigate photoinhibitory and photooxidative damage caused by UV stress, either reducing the penetration of incident UV radiation or acting as quenchers of reactive oxygen species (ROS). In this study, we designed a UV-exclusion experiment to investigate the effects of UV radiation in Silene littorea. We spectrophotometrically quantified concentrations of both anthocyanins and UV-absorbing phenolic compounds in petals, calyces, leaves and stems. Furthermore, we analyzed the UV effect on the photosynthetic activity in hours of maximum solar radiation and we tested the impact of UV radiation on male and female reproductive performance. We found that anthocyanin concentrations showed a significant decrease of about 20% with UV-exclusion in petals and stems, and a 30% decrease in calyces. The concentrations of UV-absorbing compounds under UV-exclusion decreased by approximately 25% in calyces and stems, and 12% in leaves. Photochemical efficiency of plants grown under UV decreased at maximum light stress, reaching an inhibition of 58% of photosynthetic activity, but their ability to recover after light-stress was not affected. In addition, exposure to UV radiation did not affect ovule production or seed set per flower, but decreased pollen production and total seed production per plant by 31% and 69%, respectively. Our results demonstrate that UV exposure produced opposing effects on the accumulation of plant phenolic compounds and reproduction. UV radiation increased the concentration of phenolic compounds, suggesting a photoprotective role of plant phenolics against UV light, yet overall reproduction was compromised.

Regulation of induction of phenylalanine ammonia lyase and its role in production of phenolic compounds in plants

Phenylalanine ammonia lyase or PAL is known to be the first committed enzyme of phenylpropanoid pathway which produces trans-cinnamic acid, the precursor of polyphenol biosynthesis. Some facts related to the physiology, enzymology and biochemistry of Phenylalanine ammonia lyase (PAL) from different organisms has been reviewed. Emphasis is given on the biological aspects of regulation of the induction of PAL by various stimuli and its role in producing polyphenolic compounds in plants. Levels of the enzyme are mainly affected by light, wounding, infection, ethylene level, concentration of plant growth regulators and metals. The possibility that PAL is involved in the control of polyphenol production has also been examined.

De Novo Biosynthesis of Caffeic Acid from Glucose by Engineered Saccharomyces cerevisiae.

Caffeic acid is a plant phenolic compound possessing extensive pharmacological activities. Here, we identified that p-coumaric acid 3-hydroxylase from Arabidopsis thaliana was capable of hydroxylating p-coumaric acid to form caffeic acid in Saccharomyces cerevisiae. Then, we introduced a combined caffeic acid biosynthetic pathway into S.cerevisiae and obtained 0.183 mg L-1 caffeic acid from glucose. Next we improved the tyrosine biosynthesis in S.cerevisiae by blocking the pathway flux to aromatic alcohols and eliminating the tyrosine-induced feedback inhibition resulting in caffeic acid production of 2.780 mg L-1. Finally, the medium was optimized, and the highest caffeic acid production obtained was 11.432 mg L-1 in YPD medium containing 4% glucose. This study opens a route to produce caffeic acid from glucose in S.cerevisiae and establishes a platform for the biosynthesis of caffeic acid derived metabolites.

Protective Effects of Anethum graveolens Seed's Oil Nanoemulsion Against Cadmium-Induced Oxidative Stress in Mice.

The cadmium (Cd) is a toxic heavy metal that induces oxidative stress in both humans and animals. The plant phenolic compounds are capable of alleviating the toxicity of heavy metals. The encapsulation of plant bioactive compounds using nanoemulsion technology could enhance their bioefficacy. In this study, the protective effects of Anethum graveolens seed's oil nanoemulsion (AGN) against cadmium-induced oxidative stress in mice were studied. The results showed that the major bioactive compounds of essential oil were carvone and limonene. The result of particle size analysis revealed the pseudo-spherical droplets with nanometer size (148.8 ± 9.48nm), homogenous dispersion, and physical colloidal stability. The Cd intoxication in mice (5mg/kg BW for 30days) reduced the body weight gain; however, treatment of the mice with different concentration of AGN (0.125, 0.25, and 0.5mg/L, 30days) through drinking water improved the body weight loss, liver Cd deposition, lipid peroxidation, cellular antioxidant redox potential, and inflammation in the liver, kidney, and brain of the mice challenged by cadmium-induced oxidative stress. The results of the present study revealed that drinking the essential oil of Anethum graveolens nanoemulsion containing carvone and limonene could be a promising strategy to protect the tissues against cadmium-induced oxidative damage.