Production and applications of rosmarinic acid and structurally related compounds

Balancing the non-linear rosmarinic acid biosynthetic pathway by modular co-culture engineering

Pathway balancing is a critical and common challenge for microbial biosynthesis using metabolic engineering approaches. Non-linear biosynthetic pathways, such as diverging and converging pathways, are particularly difficult for bioproduction optimization, because they require delicate balancing between all interconnected constituent pathway modules. The emergence of modular co-culture engineering offers a new perspective for biosynthetic pathways modularization and balancing, as the biosynthetic capabilities of individual pathway modules can be coordinated by flexible adjustment of the subpopulation ratio of the co-culture strains carrying the designated modules. This study developed microbial co-cultures composed of multiple metabolically engineered E. coli strains for heterologous biosynthesis of complex natural product rosmarinic acid (RA) whose biosynthesis involves a complex diverging-converging pathway. Our results showed that, compared with the conventional mono-culture strategy, the engineered two-strain co-cultures significantly improved the RA production. Further pathway modularization and balancing in the context of three-strain co-cultures resulted in additional production improvement. Moreover, metabolically engineered co-culture strains utilizing different carbon substrates were recruited to improve the three-strain co-culture stability. The optimized co-culture based on these efforts produced 172 mg/L RA, exhibiting 38-fold biosynthesis improvement over the parent strain used in mono-culture biosynthesis. The findings of this work demonstrate the strong potentials of modular co-culture engineering for overcoming the challenges of complex natural product biosynthesis involving non-linear pathways.

Green Ultrasound Assisted Extraction of trans Rosmarinic Acid from Plectranthus scutellarioides (L.) R.Br. Leaves

Painted nettle (Plectranthus scutellarioides (L.) R.Br.) is an ornamental plant belonging to Lamiaceae family, native of Asia. Its leaves constitute one of the richest sources of trans-rosmarinic acid, a well-known antioxidant and antimicrobial phenolic compound. These biological activities attract interest from the cosmetic industry and the demand for the development of green sustainable extraction processes. Here, we report on the optimization and validation of an ultrasound-assisted extraction (USAE) method using ethanol as solvent. Following preliminary single factor experiments, the identified limiting extraction parameters (i.e., ultrasound frequency, extraction duration, and ethanol concentration) were further optimized using a full factorial design approach. The method was then validated following the recommendations of the association of analytical communities (AOAC) to ensure the precision and accuracy of the method used to quantify trans-rosmarinic acid. Highest trans-rosmarinic acid content was obtained using pure ethanol as extraction solvent following a 45-minute extraction in an ultrasound bath operating at an ultrasound frequency of 30 kHz. The antioxidant (in vitro radical scavenging activity) and antimicrobial (directed toward Staphylococcus aureus ACTT6538) activities were significantly correlated with the trans-rosmarinic acid concentration of the extract evidencing that these key biological activities were retained following the extraction using this validated method. Under these conditions, 110.8 mg/g DW of trans-rosmarinic acid were extracted from lyophilized P. scutellarioides leaves as starting material evidencing the great potential of this renewable material for cosmetic applications. Comparison to other classical extraction methods evidenced a clear benefit of the present USAE method both in terms of yield and extraction duration.

Metabolic engineering of microorganisms for production of aromatic compounds

Metabolic engineering has been enabling development of high performance microbial strains for the efficient production of natural and non-natural compounds from renewable non-food biomass. Even though microbial production of various chemicals has successfully been conducted and commercialized, there are still numerous chemicals and materials that await their efficient bio-based production. Aromatic chemicals, which are typically derived from benzene, toluene and xylene in petroleum industry, have been used in large amounts in various industries. Over the last three decades, many metabolically engineered microorganisms have been developed for the bio-based production of aromatic chemicals, many of which are derived from aromatic amino acid pathways. This review highlights the latest metabolic engineering strategies and tools applied to the biosynthesis of aromatic chemicals, many derived from shikimate and aromatic amino acids, including L-phenylalanine, L-tyrosine and L-tryptophan. It is expected that more and more engineered microorganisms capable of efficiently producing aromatic chemicals will be developed toward their industrial-scale production from renewable biomass.

Rosmarinic Acid Analogue-11 Induces Apoptosis of Human Gastric Cancer SGC-7901 Cells via the Epidermal Growth Factor Receptor (EGFR)/Akt/Nuclear Factor kappa B (NF-κB) Pathway

BACKGROUND According to the latest statistics from the American Cancer Society, there will be 1.73 million cancer cases and more than 600 000 cancer deaths in the United States in 2018, among which there will be 26 240 new cases of gastric cancer and around 10 800 deaths arising from gastric cancer. The objective of this study was to use RAA-11 to intervene in SGC-7901 cells to understand its effects on cell proliferation and apoptosis, and to explore the apoptosis mechanism. MATERIAL AND METHODS MTT assay was used to detect the survival of human gastric mucosal epithelial GES-1 cells and human gastric cancer SGC-7901 cells. Colony formation assay was used to observe the colony forming ability in SGC-7901 cells. The apoptotic rate of SGC-7901 cells was evaluated by Hoechst33258 staining and flow cytometry. qRT-PCR was used to analyze the epidermal growth factor receptor (EGFR) mRNA expression level in SGC-7901 cells. Western blot was used to examine the expression levels of caspase-3, Bcl-2, BAX, EGFR, Akt, p-Akt, and NF-κB in SGC-7901 cells. RESULTS RAA-11 is capable of inhibiting the proliferation and inducing the apoptosis of SGC-7901 cells in a time- and dose-dependent manner. Western blot showed that the expression levels of caspase-3 and BAX were upregulated, while the expression levels of Bcl-2, EGFR, Akt, p-Akt, and NF-κB in the SGC-7901 cells were downregulated. CONCLUSIONS Apoptosis can be induced in SGC-7901 cells by RAA-11, potentially via the EGFR/Akt/NF-κB pathway, indicating that RAA-11 might be a potent agent for cancer treatment.

Chemical Eustress Elicits Tailored Responses and Enhances the Functional Quality of Novel Food Perilla frutescens

Consumer demand for fresh and functional horticultural products is on the rise. Perilla frutescens, L. Britt (Lamiaceae) is a potential specialty/niche crop for consumption and therapeutic uses with high contents of phenolic and volatile compounds. Plant growth, mineral composition, polyphenol profile and aroma volatile components of two perilla genotypes in response to salinity (non-salt control, 10, 20 or 30 mM NaCl) applied as chemical eustressor were assessed. Salinity suppressed growth and yield of both genotypes, although the red-pigmented genotype was less sensitive than the green-pigmented one. Mild (10 mM NaCl) and moderate (20 and 30 mM NaCl) salinity suppressed foliar potassium, magnesium, nitrate and chlorophyll a concentrations of both genotypes and increased the levels of rosmarinic acid, total polyphenols and target aroma volatile components. Green perilla showed higher yield and biomass production and higher content of protein, dry matter, calcium, magnesium, perilla ketone and cis-jasmone, whereas red perilla exhibited higher content of potassium, chlorophyll a, rosmarinic acid, total polyphenols, perilla aldehyde and benzaldehyde. Our findings support that chemical eustressors such as mild to moderate salinity offer valuable means to manipulate phytochemical and aroma profiles.

Biosynthesis, Chemistry, and Pharmacology of Polyphenols from Chinese Salvia Species: A Review

Salvia species find widespread application in food and pharmaceutical products owing to their large polyphenol content. The main polyphenols in Chinese Salvia species are phenolic acids and flavonoids, which exhibit anti-oxygenation, anti-ischemia-reperfusion injury, anti-thrombosis, anti-tumour, and other therapeutic effects. However, there are few peer-reviewed studies on polyphenols in Chinese Salvia species, especially flavonoids. This review is a systematic, comprehensive collation of available information on the biosynthesis, chemistry, and pharmacology of Chinese Salvia species. We believe that our study makes a significant contribution to the literature because this review provides a detailed literary resource on the currently available information on various polyphenolic components of Chinese Salvia species, including their bioactivities and structures. In addition, the study provides information that would encourage further investigation of this plant material as a natural resource with potential for a broad range of applications in various industries, such as the food and pharmaceutical industries.

An overview of the neuroprotective potential of rosmarinic acid and its association with nanotechnology-based delivery systems: A novel approach to treating neurodegenerative disorders

Neurodegenerative disorders (ND) are characterized by slow and progressive neuronal dysfunction induced by the degeneration of neuronal cells in the central nervous system (CNS). Recently, the neuroprotective effects of natural compounds with anti-inflammatory and antioxidant activities has been clearly demonstrated. This appears to be an attractive therapeutic approach for ND, particularly regarding the use of polyphenols. In this review, we present an overview of the neuroprotective potential of rosmarinic acid (RA) and discuss the use of nanotechnology as a novel approach to treating ND. RA presents a variety of biological important activities, i.e. the modulation of pro-inflammatory cytokine expression, prevention of neurodegeneration and damage reduction. However, its poor bioavailability represents a limitation in terms of pharmacodynamics. In this sense, nanotechnology-based carriers could allow for the administration of higher but still safe amounts of RA, aiming for CNS delivery. Nasal administration could be a pleasant route for delivery to the CNS, as this represents a direct route to the CNS. With these advantages, RA-loaded nanotechnology-based therapy through the nasal route could be promising approach for the treatment of ND.

Phytochemical profiling, polyphenol composition, and antioxidant activity of the leaf extract from the medicinal halophyte Thespesia populnea reveal a potential source of bioactive compounds and nutraceuticals

The present study evaluated the phytochemical constituents, nutritional attributes, and the antioxidant capacity of the medicinal halophyte Thespesia populnea. The metabolite profiling by GC-QTOF-MS analysis identified 37 metabolites among which sucrose, malic acid, and turanose were the most abundant. A total of 18 polyphenols and 17 amino acids were identified by the HPLC-DAD analysis. The most abundant polyphenols in T. populnea were gallic acid, catechin, and myricetin. Other polyphenols like protocatechuic acid, epigallocatechin gallate, rosmarinic acid, ellagic acid, rutin, and naringenine were also detected in ample amounts. The leaf extract demonstrated higher antioxidant as well as lipid peroxidation inhibition activities. A correlation analysis revealed a positive correlation between the antioxidant capacity and the phenolic compounds viz. gallic acid, catechin, myricetin, quercetin, apigenin, cinnamic acid, and coumarin which indicates that these phenolic compounds are the main contributors of the antioxidant potential of T. populnea. The results of this study establish T. populnea as a potential source of nonconventional functional food. PRACTICAL APPLICATIONS: The data presented here indicate that T. populnea can be considered as a nonconventional functional food and potential source of energy, antioxidants, minerals, essential amino acids, and bioactive compounds in herbal formulations, food supplements, or nutraceuticals. The metabolites identified from this halophyte have pharmacological and nutraceutical potentials, suggesting T. populnea as an ideal candidate for application in the food and phytopharmaceutical industries to produce health-promoting products, functional foods, and herbal medicines.

Cytogenetic and genotoxic effects of Rosmaniric Acid on Allium cepa L. root meristem cells

Rosmarinic acid (RA) is a natural polyphenol carboxylic acid, an ester of caffeic acid with 3,4-dihydroxyphenyllactic acid, found in many species. Current study was aimed to investigate the mitotic division, chromosomal and genotoxic effects of RA on Allium cepa root meristematic cells. In Allium root growth inhibition test, EC50 value was found as 100 ppm. Three concentrations (50, 100, and 200 ppm) of RA under different exposure periods (24, 48, 72 and 96 h) were employed to onion tuber roots. Distilled water and methyl methane sulfonate (MMS, 10 ppm) were used as a negative and positive control, respectively. 100 (except 24 h) and 200 ppm of RA significantly decreased mitotic index (MI). There was an increase of total chromosomal aberrations (CAs) at 50 ppm and simultaneous decrease of CAs at 200 ppm concentrations (p < 0.05). A significant increase in DNA damage was also observed at 200 ppm by Comet assay. Quantitative analysis of RA in A. cepa root meristem cells was also done by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Further investigations are required to explore the molecular mechanism involved in the cytotoxicity and genotoxicity of RA on plants.

Phytochemical Profiles of Alpine Plant Horminum pyrenaicum L. during Phenological Growth Stages

Horminum pyrenaicum L. is a medicinal, aromatic and ornamental plant native to the Pyrenees and Alps. The phytochemical composition is affected by various ecological factors, climatic conditions and cultivating factors, and especially phenological growth stages. Flavonoids, phenolic acids and triterpenic acids were identified and quantified in the above-ground parts of H. pyrenaicum during the phenological stages. The massive flowering was distinguished with the greatest total amounts of phenolic compounds (22232.8 μg/g), and rosmarinic acid was the predominant compound. The amounts of triterpenic compounds were at the lowest during the intense growth stage and significantly increased up to the massive flowering. The prevailing compounds were ursolic acid and betulinic acid, 12092.4 μg/g and 2618.9 μg/g, respectively. The major essential oil compounds were β-phellandrene (56.6%), caryophyllene oxide (5.9%), (Z)-caryophyllene (4.4%), myrcene (4.1%) and thymol (3.6%). Selecting the optimal harvesting time could ensure the herbal raw material rich with preferred bioactive compounds.

Rosmarinic acid compromises human sperm functions by an intracellular Ca2+ concentration-related mechanism

Rosmarinic acid (RA), a natural phenolic ester, is cytoprotective for male reproduction in animal models. The present study investigated the in vitro actions of RA on human sperm functions. Human sperm were exposed to 1, 10, 100, and 1000 μM RA in vitro and sperm functions were examined. The results showed that although RA did not affect human sperm viability, RA at 10-1000 μM dose-dependently reduced sperm motility, penetration ability, capacitation, and spontaneous acrosome reaction. In addition, the intracellular Ca2+ concentration ([Ca2+]i), which serve as a key regulator of sperm function, was decreased by RA (10-1000 μM) in a dose-dependent manner. Furthermore, the current of the sperm-specific potassium channel, KSPER, which is predominant for Ca2+ influx in sperm, was dose-dependently inhibited by 10-1000 μM RA. Therefore, we conclude that in vitro exposure to RA can compromise human sperm functions by decreasing sperm [Ca2+]i through the suppression of KSPER current.

Spices: Potential Therapeutics for Alzheimer's Disease

India has traditionally been known to all over the world for spices and medicinal plants. Spices exhibit a wide range of pharmacological activities. In contemporary, Indian spices are used to rustle up delicious delicacies. However, the Indian spices are more than just adjuvant which adds aroma and fragrance to foods. A few spices are very widely used and grown commercially in many countries, contain many important chemical constituents in the form of essential oil, oleoresin, oleogum, and resins, which impart flavor, pungency, and color to the prepared dishes, simultaneously exerts diverse therapeutic benefits. Ayurveda, the traditional systems of medicine in India has many evidences for the utilization of spices to cure various diseases. Some of the activities have been scientifically proven. Among various indications central nervous system disorders are of prime importance and it has been evident in traditional books and published reports that spices in fact protect and cure neuronal ailments. Likewise there are many spices found in India used for culinary purpose and have been found to have reported specific activities against brain disorders. About 400 B.C., Hippocrates rightly said "Let food be thy medicine and medicine thy food." This review focuses on the importance of spices in therapeutics and the till date scientific findings of Indian spices in CNS pharmacology and explores the potential of Indian spices to cure CNS disorders.

Novel Phenolic Constituents of Pulmonaria officinalis L. LC-MS/MS Comparison of Spring and Autumn Metabolite Profiles

Lungwort (Pulmonaria officinalis L., Boraginaceae) is considered to possess therapeutic properties and it has been traditionally used as a remedy against various lung disorders in many countries. Nevertheless, very few data concerning its phytochemical composition are available. This research aims to provide a detailed description of specialized metabolites from the aerial parts of lungwort. Nine previously undescribed and 36 known phenolic compounds were detected in the 50% methanolic extract. Following multistep preparative procedures, structures of newly discovered compounds were determined using one- and two-dimensional techniques of NMR spectroscopy. Among the identified compounds were caffeic acid esters with aliphatic hydroxycarboxylic acids, conjugates of dicaffeic acid with rosmarinic acid, and previously unknown isomers of isosalvianolic acid A and yunnaneic acid E, as well as other lignans. Concentrations of all identified phenolic derivatives in the investigated herbal material were estimated using a method based on liquid chromatography with high-resolution mass spectrometry detection. Seasonal changes in the concentration of metabolites were also investigated using targeted and untargeted metabolomics techniques.

Anticancer potential of rosmarinic acid and its improved production through biotechnological interventions and functional genomics

Rosmarinic acid (RA) is a highly valued natural phenolic compound that is very commonly found in plants of the families Lamiaceae and Boraginaceae, including Coleus blumei, Heliotropium foertherianum, Rosmarinus officinalis, Perilla frutescens, and Salvia officinalis. RA is also found in other members of higher plant families and in some fern and horned liverwort species. The biosynthesis of RA is catalyzed by the enzymes phenylalanine ammonia lyase and cytochrome P450-dependent hydroxylase using the amino acids tyrosine and phenylalanine. Chemically, RA can be produced via methods involving the esterification of 3,4-dihydroxyphenyllactic acid and caffeic acid. Some of the derivatives of RA include melitric acid, salvianolic acid, lithospermic acid, and yunnaneic acid. In plants, RA is known to have growth-promoting and defensive roles. Studies have elucidated the varied pharmacological potential of RA and its derived molecules, including anticancer, antiangiogenic, anti-inflammatory, antioxidant, and antimicrobial activities. The demand for RA is therefore, very high in the pharmaceutical industry, but this demand cannot be met by plants alone because RA content in plant organs is very low. Further, many plants that synthesize RA are under threat and near extinction owing to biodiversity loss caused by unscientific harvesting, over-collection, environmental changes, and other inherent features. Moreover, the chemical synthesis of RA is complicated and expensive. Alternative approaches using biotechnological methodologies could overcome these problems. This review provides the state of the art information on the chemistry, sources, and biosynthetic pathways of RA, as well as its anticancer properties against different cancer types. Biotechnological methods are also discussed for producing RA using plant cell, tissue, and organ cultures and hairy-root cultures using flasks and bioreactors. The recent developments and applications of the functional genomics approach and heterologous production of RA in microbes are also highlighted. This chapter will be of benefit to readers aiming to design studies on RA and its applicability as an anticancer agent.

A novel, simplified and stability-indicating high-throughput ultra-fast liquid chromatography method for the determination of rosmarinic acid in nanoemulsions, porcine skin and nasal mucosa

Currently, there is an increasing interest on the development of topical formulations containing rosmarinic acid (RA) due to its well-documented antioxidant activity. This study aimed to develop and validate a stability-indicating ultra-fast liquid chromatography (UFLC) method for the determination of RA in nanoemulsions, porcine skin and nasal mucosa intended to be applied in permeation/retention studies and for development of topical nanoemulsions. Chromatographic separation was carried out using a C18 column packed with 2.6 μm particle size in isocratic conditions using as mobile phase water:acetonitrile (83:17, v/v), acidified with 0.1% trifluoracetic acid (v/v), with a total time of analysis of 3.5 min and detection at 330 nm. RA analysis was specific in the presence of both non-biological (blank nanoemulsion and receptor fluid) and biological matrices (porcine ear skin and porcine nasal mucosa). No interference of degradation products of RA was verified after different stress conditions such as acidic, alkaline, oxidative, light exposure (UV-A and UV-C) and thermal demonstrating the method stability-indicating property. The analytical (0.1-10.0 μg·mL-1) and bioanalytical (0.5-10.0 μg·mL-1) linearity was proved by analysis of the calibration curves of RA and no matrix effect was observed. The method was sensitive, precise and accurate, and showed recovery higher than 85%. The method was considered robust as evaluated by a Plackett-Burman experimental design. In the validated conditions, the RA was determined in the nanoemulsions obtained by spontaneous emulsification procedure (1.007 ± 0.040 mg·mL-1), porcine ear skin (1.13 ± 0.19 μg·cm-2) and nasal mucosa (22.46 ± 3.99 μg·cm-2) after retention/permeation studies. Thus, a highly sensitive, simple, fast and stability-indicating method was developed for RA analysis during the development of topical nanoemulsions and bioanalytical assays in complex matrices.

Ethyl rosmarinate inhibits lipopolysaccharide-induced nitric oxide and prostaglandin E2 production in alveolar macrophages

In this study, a series of rosmarinic acid and analogs were investigated for their anti-inflammatory potential against LPS-induced alveolar macrophages (MH-S). Our results showed that, among the test compounds, ethyl rosmarinate (3) exhibited the most potent inhibitory effect on NO production in LPS-induced MH-S cells, with low cytotoxicity. Compound 3 exhibited remarkable inhibition of the production of PGE2 in LPS-induced MH-S cells. The inhibitory potency of compound 3 against LPS-induced NO and PGE2 release was approximately two-fold higher than that of dexamethasone. Compound 3 significantly decreased the mRNA and protein expression of iNOS and COX-2 and suppressed p65 expression in the nucleus in LPS-induced MH-S cells. These results suggested that compound 3 inhibited NO and PGE2 production, at least in part, through the down-regulation of NF-κB activation. Analysis of structure-activity relationship revealed that the free carboxylic group did not contribute to inhibitory activity and that the alkyl group of the corresponding alkyl ester analogs produced a strong inhibitory effect. We concluded that compound 3, a structurally modified rosmarinic acid, possessed potent inhibitory activity against lung inflammation, which strongly supported the development of this compound as a novel therapeutic agent for the treatment of macrophage-mediated lung inflammatory diseases, such as COPD.

Rosmarinic acid: modes of action, medicinal values and health benefits

The supplementation of livestock rations with herbs containing bioactive components, such as rosmarinic acid (RA), have shown promising results as a natural feed additive in promoting growth, productive and reproductive performance, feed utilization, fertility, anti-oxidant status and immunologic indices. Furthermore, RA reportedly reduces the risks of various animal diseases and mitigates side effects of chemical and synthetic drugs. RA is a natural polyphenol present in several Lamiaceae herbs like Perilla frutescens, and RA is becoming an integral component of animal nutrition as it counters the effect of reactive oxygen species induced in the body as a consequence of different kinds of stressors. Studies have further ascertained the capability of RA to work as an anti-microbial, immunomodulatory, anti-diabetic, anti-allergic, anti-inflammatory, hepato- and renal-protectant agent, as well as to have beneficial effects during skin afflictions. Additionally, RA is favored in meat industries due to enhancing the quality of meat products by reportedly improving shelf-life and imparting desirable flavor. This review describes the beneficial applications and recent findings with RA, including its natural sources, modes of action and various useful applications in safeguarding livestock health as well as important aspects of human health.

Protective effects of rosmarinic acid against hydrogen peroxide‑induced cellular senescence and the inflammatory response in normal human dermal fibroblasts

Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) that induces numerous cellular events, including cellular senescence and inflammatory responses. Therefore, the aim of this study was to investigate the protective effect of Rosmarinic acid (RA) in H2O2‑induced oxidative stress in normal human dermal fibroblasts (NHDFs). Cytotoxicity assays were performed using a water‑soluble tetrazolium salt, and senescence‑associated β‑galactosidase activity was determined to investigate the proportion of senescent cells. Antioxidant capacities were evaluated via H2O2‑scavenging activity, reverse transcription‑quantitative polymerase chain reaction, NRF2 luciferase reporter gene activity and intracellular ROS scavenging assays. Cytokine‑coded gene expression analysis and nuclear factor‑κB luciferase activity were determined to verify the anti‑inflammatory effect of RA. As a result, the present study demonstrated that rosmarinic acid inhibited H2O2‑induced oxidative stress and inflammatory responses in normal human dermal fibroblasts. Initially, the doses of RA that exerted minimal cytotoxic effects in NHDFs were determined using a cytotoxicity assay. Subsequently, pretreatment with the appropriate doses of RA significantly reversed the H2O2‑induced decrease in NHDF cell viability and decreased cellular senescence of NHDFs. In addition, RA inhibited H2O2‑induced ROS production in NHDFs, as determined by a ROS scavenging assay. The protective effects of RA were mediated by the inhibition of nuclear factor erythroid‑derived 2‑like 2, a transcription factor that functions as a key regulator of redox sensitivity. Furthermore, RA suppressed H2O2‑induced inflammation in NHDFs and significantly rescued H2O2‑induced downregulation of sirtuin 1. RA also inhibited nuclear factor (NF)‑κB transcriptional activity and the expression of NF‑κB target genes, including tumor necrosis factor‑α and interleukin‑6, in H2O2‑exposed NHDFs. Taken together, these data indicate that RA inhibits H2O2‑induced cellular damage in NHDFs.

A tyrosine aminotransferase involved in rosmarinic acid biosynthesis in Prunella vulgaris L

Rosmarinic acid (RA) and its derivants are medicinal compounds that comprise the active components of several therapeutics. We isolated and characterised a tyrosine aminotransferase of Prunella vulgaris (PvTAT). Deduced PvTAT was markedly homologous to other known/putative plant TATs. Cytoplasmic localisation of PvTAT was observed in tobacco protoplasts. Recombinantly expressed and purified PvTAT had substrates preference for L-tyrosine and phenylpyruvate, with apparent K m of 0.40 and 0.48 mM, and favoured the conversion of tyrosine to 4-hydroxyphenylpyruvate. In vivo activity was confirmed by functional restoration of the Escherichia coli tyrosine auxotrophic mutant DL39. Agrobacterium rhizogenes-mediated antisense/sense expression of PvTAT in hairy roots was used to evaluate the contribution of PvTAT to RA synthesis. PvTAT were reduced by 46-95% and RA were decreased by 36-91% with low catalytic activity in antisense transgenic hairy root lines; furthermore, PvTAT were increased 0.77-2.6-fold with increased 1.3-1.8-fold RA and strong catalytic activity in sense transgenic hairy root lines compared with wild-type counterparts. The comprehensive physiological and catalytic evidence fills in the gap in RA-producing plants which didn't provide evidence for TAT expression and catalytic activities in vitro and in vivo. That also highlights RA biosynthesis pathway in P. vulgaris and provides useful information to engineer natural products.

Fermentative Production of Phenolic Glucosides by Escherichia coli with an Engineered Glucosyltransferase from Rhodiola sachalinensis

Three rosmarinic acid analogs produced by recombinant Escherichia coli, two xanthones from fungi and honokiol from plants, were explored as the substrates of E. coli harboring a glucosyltransferase mutant UGT73B6^FS to generate phenolic glucosides. Six new and two known compounds were isolated from the fermentation broth of the recombinant strain of the feeding experiments, and the compounds were identified by spectroscopy. The biotransformation of rosmarinic acid analogs and xanthones into corresponding glucosides was presented for the first time. This study not only demonstrated the substrate flexibility of the glucosyltransferase mutant UGT73B6^FS toward aromatic alcohols but also provided an effective and economical method to produce phenolic glucosides by fermentation circumventing the use of expensive precursor UDP-glucose.

Differential activation of pregnane X receptor by carnosic acid, carnosol, ursolic acid, and rosmarinic acid

Pregnane X receptor (PXR) regulates the expression of many genes, including those involved in drug metabolism and transport, and has been linked to various diseases, including inflammatory bowel disease. In the present study, we determined whether carnosic acid and other chemicals in rosemary extract (carnosol, ursolic acid, and rosmarinic acid) are PXR activators. As assessed in dual-luciferase reporter gene assays, carnosic acid, carnosol, and ursolic acid, but not rosmarinic acid, activated human PXR (hPXR) and mouse PXR (mPXR), whereas carnosol and ursolic acid, but not carnosic acid or rosmarinic acid, activated rat PXR (rPXR). Dose-response experiments indicated that carnosic acid, carnosol, and ursolic acid activated hPXR with EC50 values of 0.79, 2.22, and 10.77μM, respectively. Carnosic acid, carnosol, and ursolic acid, but not rosmarinic acid, transactivated the ligand-binding domain of hPXR and recruited steroid receptor coactivator-1 (SRC-1), SRC-2, and SRC-3 to the ligand-binding domain of hPXR. Carnosic acid, carnosol, and ursolic acid, but not rosmarinic acid, increased hPXR target gene expression, as shown by an increase in CYP3A4, UGT1A3, and ABCB1 mRNA expression in LS180 human colon adenocarcinoma cells. Rosmarinic acid did not attenuate the extent of hPXR activation by rifampicin, suggesting it is not an antagonist of hPXR. Overall, carnosic acid, carnosol, and ursolic acid, but not rosmarinic acid, are hPXR agonists, and carnosic acid shows species-dependent activation of hPXR and mPXR, but not rPXR. The findings provide new mechanistic insight on the effects of carnosic acid, carnosol, and ursolic acid on PXR-mediated biological effects.

Yunnaneic Acid B, a Component of Pulmonaria officinalis Extract, Prevents Peroxynitrite-Induced Oxidative Stress in Vitro

Our work reveals that the aerial parts of Pulmonaria officinalis L. are a new source of yunnaneic acid B. We studied antioxidant activity and cytotoxicity of this compound (1-50 μg/mL) and its contents in various plant extracts. This is the first study confirming the presence of yunnaneic acid B in P. officinalis L. and Pulmonaria obscura Dumort and hence in the Boraginaceae family. Determination of 1,1-diphenyl-2-picrylhydrazyl radical reduction and peroxynitrite-scavenging efficacy in inorganic experimental systems provided EC₅₀ values of 7.14 and 50.45 μg/mL, respectively. Then we examined the antioxidant action of yunnaneic acid B in blood plasma under peroxynitrite-induced oxidative stress in vitro. Yunnaneic acid B effectively diminished oxidative damage to blood plasma proteins and lipids. Furthermore, it was able to prevent the peroxynitrite-induced decrease in nonenzymatic antioxidant capacity of blood plasma. Additionally, cytotoxicity of yunnaneic acid B (at concentrations ≤50 μg/mL) toward peripheral blood mononuclear cells was excluded.

Rosmarinic acid suppresses colonic inflammation in dextran sulphate sodium (DSS)-induced mice via dual inhibition of NF-κB and STAT3 activation

Ulcerative colitis (UC), a type of inflammatory bowel disease (IBD), is a chronic inflammatory disorder of the colon. Although UC is generally treated with anti-inflammatory drugs or immunosuppressants, most of these treatments often prove to be inadequate. Rosmarinic acid (RA) is a phenolic ester included in various medicinal herbs such as Salvia miltiorrhiz and Perilla frutescens. Although RA has many biological and pharmacological activities, the anti-inflammatory effect of RA in colonic tissue remains unclear. In this study, we investigated the anti-inflammatory effects and underlying molecular mechanism of RA in mice with dextran sulphate sodium (DSS)-induced colitis. In the DSS-induced colitis model, RA significantly reduced the severity of colitis, as assessed by disease activity index (DAI) scores, colonic damage, and colon length. In addition, RA resulted in the reduction of the inflammatory-related cytokines, such as IL-6, IL-1β, and IL-22, and protein levels of COX-2 and iNOS in mice with DSS-induced colitis. Furthermore, RA effectively and pleiotropically inhibited nuclear factor-kappa B and signal transducer and activator of transcription 3 activation, and subsequently reduced the activity of pro-survival genes that depend on these transcription factors. These results demonstrate that RA has an ameliorative effect on colonic inflammation and thus a potential therapeutic role in colitis.

Rosmarinic acid protects rat hippocampal neurons from cerebral ischemia/reperfusion injury via the Akt/JNK3/caspase-3 signaling pathway

Cerebral ischemia/reperfusion injury can result in neuronal death, which further results in brain damage and can even lead to death. Although recent studies showed that rosmarinic acid (RA) exerts neuroprotective effects and attenuates ischemia-induced brain injury and neuronal cell death, little is known about the precise mechanisms that occur during cerebral ischemia/reperfusion (I/R). Therefore, the aim of this study was to examine the underlying mechanism of the neuroprotective effects of RA against ischemic brain injury induced by cerebral I/R. Transient global brain ischemia was induced by 4-vessel occlusion in adult male Sprague-Dawley rats. We randomly divided rats into five groups: sham, I/R, I/R+RA, I/R+Vehicle and I/R+RA+LY. Open-field, closed-field and Morris water maze tests were carried our separately to examine the anxiety and cognitive behavior of each group. Cresyl violet staining was used to examine the survival of hippocampal CA1 pyramidal neurons. The levels of p-Akt, p-JNK3 and cleaved caspase-3 in the hippocampus were also examined by Western blotting. Our results showed that administration of RA protected locomotive ability, relieved anxiety behavior and protected cognitive ability in cerebral I/R-injured rats. Additionally, RA significantly protected neurons in the hippocampal CA1 region against cerebral I/R-induced damage. Furthermore, RA increased the phosphorylation of Akt1, downregulated the phosphorylation of JNK3 and reduced the expression of cleaved caspase-3. Finally, the Akt inhibitor LY294002 reversed all the protective effects of RA, indicating that RA protects neurons in the hippocampal CA1 region from ischemic damage through the Akt/JNK3/caspase-3 signaling pathway.

Hydroxycinnamic Acids and Their Derivatives: Cosmeceutical Significance, Challenges and Future Perspectives, a Review

Bioactive compounds from natural sources, due to their widely-recognized benefits, have been exploited as cosmeceutical ingredients. Among them, phenolic acids emerge with a very interesting potential. In this context, this review analyzes hydroxycinnamic acids and their derivatives as multifunctional ingredients for topical application, as well as the limitations associated with their use in cosmetic formulations. Hydroxycinnamic acids and their derivatives display antioxidant, anti-collagenase, anti-inflammatory, antimicrobial and anti-tyrosinase activities, as well as ultraviolet (UV) protective effects, suggesting that they can be exploited as anti-aging and anti-inflammatory agents, preservatives and hyperpigmentation-correcting ingredients. Due to their poor stability, easy degradation and oxidation, microencapsulation techniques have been employed for topical application, preventing them from degradation and enabling a sustained release. Based on the above findings, hydroxycinnamic acids present high cosmetic potential, but studies addressing the validation of their benefits in cosmetic formulations are still scarce. Furthermore, studies dealing with skin permeation are scarcely available and need to be conducted in order to predict the topical bioavailability of these compounds after application.

Phenolic profile, antioxidant activity and enzyme inhibitory activities of extracts from aromatic plants used in Mediterranean diet

The antioxidant and enzyme inhibitory properties of methanolic extracts from four aromatic plants used in traditional medicine and food [Calamintha nepeta (L.) Savi subsp. nepeta, Helichrysum italicum subsp. picardii Franco, Mentha spicata L. and Origanum vulgare subsp. virens (Hoffmanns. & Link) Bonnier & Layens] were evaluated. The extract from O. vulgare exhibited the strongest DPPH (IC50 of 4.65 ± 0.12 µg/ml) and ABTS (1479.56 ± 12.29 µmolTE/gextract) scavenging capacities, as well as the largest ferric reducing ability (1746.76 ± 45.11 µmolAAE/gextract). This extract also showed the highest total phenolic content (1597.20 ± 24.10 µmolGAE/gextract) and although HPLC-DAD analysis revealed rosmarinic acid as the main compound of the extract, other compounds seem to be involved in the antioxidant activity. Furthermore, the extract from H. italicum, which was found to be rich in caffeoylquinic and dicaffeoylquinic acids and in pinocembrin, showed the highest inhibitory potential against acetylcholinesterase, tyrosinase and α-glucosidase. Overall, the results obtained validate the usefulness of the studied plants as valuable sources of natural agents beneficial for human health.

Exploiting members of the BAHD acyltransferase family to synthesize multiple hydroxycinnamate and benzoate conjugates in yeast

BACKGROUND

BAHD acyltransferases, named after the first four biochemically characterized enzymes of the group, are plant-specific enzymes that catalyze the transfer of coenzyme A-activated donors onto various acceptor molecules. They are responsible for the synthesis in plants of a myriad of secondary metabolites, some of which are beneficial for humans either as therapeutics or as specialty chemicals such as flavors and fragrances. The production of pharmaceutical, nutraceutical and commodity chemicals using engineered microbes is an alternative, green route to energy-intensive chemical syntheses that consume petroleum-based precursors. However, identification of appropriate enzymes and validation of their functional expression in heterologous hosts is a prerequisite for the design and implementation of metabolic pathways in microbes for the synthesis of such target chemicals.

RESULTS

For the synthesis of valuable metabolites in the yeast Saccharomyces cerevisiae, we selected BAHD acyltransferases based on their preferred donor and acceptor substrates. In particular, BAHDs that use hydroxycinnamoyl-CoAs and/or benzoyl-CoA as donors were targeted because a large number of molecules beneficial to humans belong to this family of hydroxycinnamate and benzoate conjugates. The selected BAHD coding sequences were synthesized and cloned individually on a vector containing the Arabidopsis gene At4CL5, which encodes a promiscuous 4-coumarate:CoA ligase active on hydroxycinnamates and benzoates. The various S. cerevisiae strains obtained for co-expression of At4CL5 with the different BAHDs effectively produced a wide array of valuable hydroxycinnamate and benzoate conjugates upon addition of adequate combinations of donors and acceptor molecules. In particular, we report here for the first time the production in yeast of rosmarinic acid and its derivatives, quinate hydroxycinnamate esters such as chlorogenic acid, and glycerol hydroxycinnamate esters. Similarly, we achieved for the first time the microbial production of polyamine hydroxycinnamate amides; monolignol, malate and fatty alcohol hydroxycinnamate esters; tropane alkaloids; and benzoate/caffeate alcohol esters. In some instances, the additional expression of Flavobacterium johnsoniae tyrosine ammonia-lyase (FjTAL) allowed the synthesis of p-coumarate conjugates and eliminated the need to supplement the culture media with 4-hydroxycinnamate.

CONCLUSION

We demonstrate in this study the effectiveness of expressing members of the plant BAHD acyltransferase family in yeast for the synthesis of numerous valuable hydroxycinnamate and benzoate conjugates.

Rosmarinic acid is anticonvulsant against seizures induced by pentylenetetrazol and pilocarpine in mice

Epilepsy is a chronic neurological disease characterized by spontaneous recurrent seizures (SRS). Current anticonvulsant drugs are ineffective in nearly one-third of patients and may cause significant adverse effects. Rosmarinic acid is a naturally occurring substance which displays several biological effects including antioxidant and neuroprotective activity. Since oxidative stress and excitotoxicity play a role in the pathophysiology of seizures, we aimed the present study to test the hypothesis that rosmarinic acid displays anticonvulsant and disease-modifying effects. Female C57BL/6 mice received rosmarinic acid (0, 3, 10, or 30mg/kg; p.o.) 60min before the injection of pentylenetetrazol (PTZ, 60mg/kg; i.p.) or pilocarpine (300mg/kg, i.p.). Myoclonic and generalized tonic-clonic seizure latencies and generalized seizure duration were analyzed by behavioral and electroencephalographic (EEG) methods. The effect of acute administration of rosmarinic acid on mice behavior in the open-field, object recognition, rotarod, and forced swim tests was also evaluated. In an independent set of experiments, we evaluated the effect of rosmarinic acid (3 or 30mg/kg, p.o. for 14days) on the development of SRS and behavioral comorbidities in the pilocarpine post-status epilepticus (SE) model of epilepsy. Rosmarinic acid dose-dependently (peak effect at 30mg/kg) increased the latency to myoclonic jerks and generalized seizures in the PTZ model and increased the latency to myoclonic jerks induced by pilocarpine. Rosmarinic acid (30mg/kg) increased the number of crossings, the time at the center of the open field, and the immobility time in the forced swim test. In the chronic epilepsy model, treatment with rosmarinic acid did not prevent the appearance of SRS or behavioral comorbidities. In summary, rosmarinic acid displayed acute anticonvulsant-like activity against seizures induced by PTZ or pilocarpine in mice, but further studies are needed to determine its epilepsy-modifying potential.

Kazakh Ziziphora Species as Sources of Bioactive Substances

Ziziphora species represent the prototypical example of the Lamiaceae family. The phytochemicals present in Ziziphora include monoterpenic essential oils, triterpenes and phenolic substances belonging to the flavonoids. In Kazakh traditional medicine, Ziziphora species possess several medicinal uses. In particular, Z. bungeana Lam. and Z. clinopodioides Lam. are used for the treatment of illnesses related to the cardiovascular system or to combat different infections. Unfortunately, the majority of the information about the complex Ziziphora species is only available in Russian and Chinese language, therefore, we decided gather all available information on Kazakhstan Ziziphora, namely its content compounds, medicinal uses and published patents, to draw the attention of scientists to this very interesting plant with high medicinal potential.

Synthesis of rosmarinic acid analogues in Escherichia coli

OBJECTIVES

To produce rosmarinic acid analogues in the recombinant Escherichia coli BLRA1, harboring a 4-coumarate: CoA ligase from Arabidopsis thaliana (At4CL) and a rosmarinic acid synthase from Coleus blumei (CbRAS).

RESULTS

Incubation of the recombinant E. coli strain BLRA1 with exogenously supplied phenyllactic acid (PL) and analogues as acceptor substrates, and coumaric acid and analogues as donor substrates led to production of 18 compounds, including 13 unnatural RA analogues.

CONCLUSION

This work demonstrates the viability of synthesizing a broad range of rosmarinic acid analogues in E. coli, and sheds new light on the substrate specificity of CbRAS.

Nanomolar Inhibitors of Trypanosoma brucei RNA Triphosphatase

Eukaryal taxa differ with respect to the structure and mechanism of the RNA triphosphatase (RTPase) component of the mRNA capping apparatus. Protozoa, fungi, and certain DNA viruses have a metal-dependent RTPase that belongs to the triphosphate tunnel metalloenzyme (TTM) superfamily. Because the structures, active sites, and chemical mechanisms of the TTM-type RTPases differ from those of mammalian RTPases, the TTM RTPases are potential targets for antiprotozoal, antifungal, and antiviral drug discovery. Here, we employed RNA interference (RNAi) knockdown methods to show that Trypanosoma brucei RTPase Cet1 (TbCet1) is necessary for proliferation of procyclic cells in culture. We then conducted a high-throughput biochemical screen for small-molecule inhibitors of the phosphohydrolase activity of TbCet1. We identified several classes of chemicals-including chlorogenic acids, phenolic glycopyranosides, flavonoids, and other phenolics-that inhibit TbCet1 with nanomolar to low-micromolar 50% inhibitory concentrations (IC50s). We confirmed the activity of these compounds, and tested various analogs thereof, by direct manual assays of TbCet1 phosphohydrolase activity. The most potent nanomolar inhibitors included tetracaffeoylquinic acid, 5-galloylgalloylquinic acid, pentagalloylglucose, rosmarinic acid, and miquelianin. TbCet1 inhibitors were less active (or inactive) against the orthologous TTM-type RTPases of mimivirus, baculovirus, and budding yeast (Saccharomyces cerevisiae). Our results affirm that a TTM RTPase is subject to potent inhibition by small molecules, with the caveat that parallel screens against TTM RTPases from multiple different pathogens may be required to fully probe the chemical space of TTM inhibition.

IMPORTANCE

The stark differences between the structure and mechanism of the RNA triphosphatase (RTPase) component of the mRNA capping apparatus in pathogenic protozoa, fungi, and viruses and those of their metazoan hosts highlight RTPase as a target for anti-infective drug discovery. Protozoan, fungal, and DNA virus RTPases belong to the triphosphate tunnel metalloenzyme family. This study shows that a protozoan RTPase, TbCet1 from Trypanosoma brucei, is essential for growth of the parasite in culture and identifies, via in vitro screening of chemical libraries, several classes of potent small-molecule inhibitors of TbCet1 phosphohydrolase activity.

Engineered synthesis of rosmarinic acid in Escherichia coli resulting production of a new intermediate, caffeoyl-phenyllactate

OBJECTIVES

To achieve high production of rosmarinic acid and derivatives in Escherichia coli which are important phenolic acids found in plants, and display diverse biological activities.

RESULTS

The synthesis of rosmarinic acid was achieved by feeding caffeic acid and constructing an artificial pathway for 3,4-dihydroxyphenyllactic acid. Genes encoding the following enzymes: rosmarinic acid synthase from Coleus blumei, 4-coumarate: CoA ligase from Arabidopsis thaliana, 4-hydroxyphenyllactate 3-hydroxylase from E. coli and D-lactate dehydrogenase from Lactobacillus pentosus, were overexpressed in an L-tyrosine over-producing E. coli strain. The yield of rosmarinic acid reached ~130 mg l(-1) in the recombinant strain. In addition, a new intermediate, caffeoyl-phenyllactate (~55 mg l(-1)), was also produced by the engineered E. coli strain.

CONCLUSION

This work not only leads to high yield production of rosmarinic acid and analogues, but also sheds new light on the construction of the pathway of rosmarinic acid in E. coli.