Plant cell factories in the post-genomic era: new ways to produce designer secondary metabolites

Natural complex substances: From molecules to the molecular complexes. Analytical and technological advances for their definition and differentiation from the corresponding synthetic substances

Natural complex substances (NCSs) are a heterogeneous family of substances that are notably used as ingredients in several products classified as food supplements, medical devices, cosmetics and traditional medicines, according to the correspondent regulatory framework. The compositions of NCSs vary widely and hundreds to thousands of compounds can be present at the same time. A key concept is that NCSs are much more than the simple sum of the compounds that constitute them, in fact some emerging phenomena are the result of the supramolecular interaction of the constituents of the system. Therefore, close attention should be paid to produce and characterize these systems. Today many natural compounds are produced by chemical synthesis and are intentionally added to NCSs, or to formulated natural products, to enhance their properties, lowering their production costs. Market analysis shows a tendency of people to use products made with NCSs and, currently, products made with ingredients of natural origin only are not conveniently distinguishable from those containing compounds of synthetic origin. Furthermore, the uncertainty of the current European regulatory framework does not allow consumers to correctly differentiate and identify products containing only ingredients of natural origin. The high demand for specific and effective NCSs and their high-cost offer on the market, create the conditions to economically motivated sophistications, characterized by the addition of a cheap material to a more expensive one, just to increase profit. This type of practice can concern both the addition of less valuable natural materials and the addition of pure artificial compounds with the same structure as those naturally present. In this scenario, it becomes essential for producers of natural products to have advanced analytical techniques to evaluate the effective naturalness of NCSs. In fact, synthetically obtained compounds are not identical to their naturally occurring counterparts, due to the isotopic composition or chirality, as well as the presence of different trace metabolites (since pure substances in nature do not exist). For this reason, in this review, the main analytical tests that can be performed to differentiate natural compounds from their synthetic counterparts will be highlighted and the main analytical technologies will be described. At the same time, the main fingerprint techniques useful for characterizing the complexity of the NCSs, also allowing their identification and quali-quantitative evaluation, will be described. Furthermore, NCSs can be produced through different manufacturing processes, not all of which are on the same level of quality. In this review the most suitable technologies for green processes that operate according to physical extraction principles will be presented, as according to the authors they are the ones that come closest to creating more life-cycle compatible NCSs and that are well suited to the European green deal, a strategy with the aim of transforming the EU into a sustainable and resource-efficient society by 2050.

Mass spectrometry imaging and single-cell transcriptional profiling reveal the tissue-specific regulation of bioactive ingredient biosynthesis in Taxus leaves

Taxus leaves provide the raw industrial materials for taxol, a natural antineoplastic drug widely used in the treatment of various cancers. However, the precise distribution, biosynthesis, and transcriptional regulation of taxoids and other active components in Taxus leaves remain unknown. Matrix-assisted laser desorption/ionization-mass spectrometry imaging analysis was used to visualize various secondary metabolites in leaf sections of Taxus mairei, confirming the tissue-specific accumulation of different active metabolites. Single-cell sequencing was used to produce expression profiles of 8846 cells, with a median of 2352 genes per cell. Based on a series of cluster-specific markers, cells were grouped into 15 clusters, suggesting a high degree of cell heterogeneity in T. mairei leaves. Our data were used to create the first Taxus leaf metabolic single-cell atlas and to reveal spatial and temporal expression patterns of several secondary metabolic pathways. According to the cell-type annotation, most taxol biosynthesis genes are expressed mainly in leaf mesophyll cells; phenolic acid and flavonoid biosynthesis genes are highly expressed in leaf epidermal cells (including the stomatal complex and guard cells); and terpenoid and steroid biosynthesis genes are expressed specifically in leaf mesophyll cells. A number of novel and cell-specific transcription factors involved in secondary metabolite biosynthesis were identified, including MYB17, WRKY12, WRKY31, ERF13, GT_2, and bHLH46. Our research establishes the transcriptional landscape of major cell types in T. mairei leaves at a single-cell resolution and provides valuable resources for studying the basic principles of cell-type-specific regulation of secondary metabolism.

Spatially resolved detection of small molecules from press-dried plant tissue using MALDI imaging

Premise

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a chemical imaging method that can visualize spatial distributions of particular molecules. Plant tissue imaging has so far mostly used cryosectioning, which can be impractical for the preparation of large-area imaging samples, such as full flower petals. Imaging unsectioned plant tissue presents its own difficulties in extracting metabolites to the surface due to the waxy cuticle.

Methods

We address this by using established delipidation techniques combined with a solvent vapor extraction prior to applying the matrix with many low-concentration sprays.

Results

Using this procedure, we imaged tissue from three different plant species (two flowers and one carnivorous plant leaf). Material factorization analysis of the resulting data reveals a wide range of plant-specific small molecules with varying degrees of localization to specific portions of the tissue samples, while facilitating detection and removal of signal from background sources.

Conclusions

This work demonstrates applicability of MALDI-MSI to press-dried plant samples without freezing or cryosectioning, setting the stage for spatially resolved molecule identification. Increased mass resolution and inclusion of tandem mass spectrometry are necessary next steps to allow more specific and reliable compound identification.

Molecular and genetic insights into secondary metabolic regulation underlying insect-pest resistance in legumes

Insect pests pose a major threat to agricultural production, resulting in significant economic losses for countries. A high infestation of insects in any given area can severely reduce crop yield and quality. This review examines the existing resources for managing insect pests and highlights alternative eco-friendly techniques to enhance insect pest resistance in legumes. Recently, the application of plant secondary metabolites has gained popularity in controlling insect attacks. Plant secondary metabolites encompass a wide range of compounds such as alkaloids, flavonoids, and terpenoids, which are often synthesized through intricate biosynthetic pathways. Classical methods of metabolic engineering involve manipulating key enzymes and regulatory genes to enhance or redirect the production of secondary metabolites in plants. Additionally, the role of genetic approaches, such as quantitative trait loci mapping, genome-wide association (GWAS) mapping, and metabolome-based GWAS in insect pest management is discussed, also, the role of precision breeding, such as genome editing technologies and RNA interference for identifying pest resistance and manipulating the genome to develop insect-resistant cultivars are explored, highlighting the positive contribution of plant secondary metabolites engineering-based resistance against insect pests. It is suggested that by understanding the genes responsible for beneficial metabolite compositions, future research might hold immense potential to shed more light on the molecular regulation of secondary metabolite biosynthesis, leading to advancements in insect-resistant traits in crop plants. In the future, the utilization of metabolic engineering and biotechnological methods may serve as an alternative means of producing biologically active, economically valuable, and medically significant compounds found in plant secondary metabolites, thereby addressing the challenge of limited availability.

Impact of Foliar Application of Amino Acids on Essential Oil Content, Odor Profile, and Flavonoid Content of Different Mint Varieties in Field Conditions

Mint is an industrial plant that is a good source of essential oil and many phenolic compounds that have several positive benefits to human health and can be used to prevent the development of many diseases. The aim of this research was to investigate the possibility of increasing essential oil and flavonoid content, changing the chemical composition of these compounds in different mint cultivars under foliar application with precursors (phenylalanine, tryptophan, and tyrosine) at two concentrations, 100 and 200 mg L^-1, to enable the possibilities for wider use of these plants when they are grown in field conditions. Spraying with phenylalanine at 100 mg L^-1 concentration increased essential oil content in Mentha piperita 'Granada' plants by 0.53 percentage units. Foliar application with tyrosine solutions at 100 mg L^-1 concentration most effectively influenced the essential oil odor profile Mentha spicata 'Crispa'. The highest number of total flavonoids was in Mentha piperita 'Swiss' sprayed with tyrosine at 100 mg L^-1 concentration. The flavonoid content depended on the mint cultivar, amino acids, and their concentration. The results showed that the effect of amino acid solutions on different secondary metabolites' quantitative and qualitative composition differed depending on the mint cultivar; therefore, amino acids and their concentrations must be selected based on the cultivar they are targeting.

Plants in vitro propagation with its applications in food, pharmaceuticals and cosmetic industries; current scenario and future approaches

Plant tissue culture technique employed for the identification and isolation of bioactive phytocompounds has numerous industrial applications. It provides potential benefits for different industries which include food, pharmaceutical and cosmetics. Various agronomic crops i.e., cereals, fruits, vegetables, ornamental plants and forest trees are currently being used for in vitro propagation. Plant tissue culture coupled with biotechnological approaches leads towards sustainable agricultural development providing solutions to major food security issues. Plants are the rich source of phytochemicals with medicinal properties rendering them useful for the industrial production of pharmaceuticals and nutraceuticals. Furthermore, there are numerous plant compounds with application in the cosmetics industry. In addition to having moisturizing, anti-ageing, anti-wrinkle effects; plant-derived compounds also possess pharmacological properties such as antiviral, antimicrobial, antifungal, anticancer, antioxidant, anti-inflammatory, and anti-allergy characteristics. The in vitro propagation of industrially significant flora is gaining attention because of its several advantages over conventional plant propagation methods. One of the major advantages of this technique is the quick availability of food throughout the year, irrespective of the growing season, thus opening new opportunities to the producers and farmers. The sterile or endangered flora can also be conserved by plant micro propagation methods. Hence, plant tissue culture is an extremely efficient and cost-effective technique for biosynthetic studies and bio-production, biotransformation, or bioconversion of plant-derived compounds. However, there are certain limitations of in-vitro plant regeneration system including difficulties with continuous operation, product removal, and aseptic conditions. For sustainable industrial applications of in-vitro regenerated plants on a large scale, these constraints need to be addressed in future studies.

Hairy roots: An untapped potential for production of plant products

While plants are an abundant source of valuable natural products, it is often challenging to produce those products for commercial application. Often organic synthesis is too expensive for a viable commercial product and the biosynthetic pathways are often so complex that transferring them to a microorganism is not trivial or feasible. For plants not suited to agricultural production of natural products, hairy root cultures offer an attractive option for a production platform which offers genetic and biochemical stability, fast growth, and a hormone free culture media. Advances in metabolic engineering and synthetic biology tools to engineer hairy roots along with bioreactor technology is to a point where commercial application of the technology will soon be realized. We discuss different applications of hairy roots. We also use a case study of the advancements in understanding of the terpenoid indole alkaloid pathway in Catharanthus roseus hairy roots to illustrate the advancements and challenges in pathway discovery and in pathway engineering.

Metabolic Modifications in Terpenoid and Steroid Pathways Triggered by Methyl Jasmonate in Taxus × media Hairy Roots

The in vitro cultures of Taxus spp. were one of the first plant in vitro systems proved to exert the positive effect of elicitation with methyl jasmonate (MeJA) on the biosynthesis of specialized metabolites. The main aim of the present study is to examine the effect of MeJA treatment on the steroid and triterpenoid content of two genetically different hairy root lines of Taxus × media, KT and ATMA. The results revealed that the two lines differed in the total content of steroids and triterpenoids (in the ATMA root line, their amounts were lower than those in the KT line by 43% and 30%, respectively), but not in the composition of these compounds. The metabolic response to elicitation with MeJA was different: in the KT root line, the content of steroids decreased by 18%, whereas it increased by 38% in the ATMA line. Several metabolic features were common, including the characteristic changes in the ratio of sitosterol to stigmasterol content, caused by the very sharp boost in stigmasterol levels, the increase in the amount of glycoside forms of sterols, as well as in triterpenoid and total phenolic content. It is the first report on modifications of the terpenoid biosynthetic pathway in Taxus hairy root cultures triggered by MeJA, concerning steroids and triterpenoids.

Effects Induced by the Agricultural Application of Probiotics on Antioxidant Potential of Strawberries

With the recent rapid development of the functional food sector, agriculture is looking for alternatives to improve the quality of food grown by limiting chemical fertilizers. This study evaluated the effects of two commercial plant probiotics, ProbioHumus and NaturGel, on the growth and quality of strawberry fruits. Strawberry plants were sprayed with microbial probiotics twice a year: after harvesting at the beginning of dormancy and at the stage of leaf development. Spray applications of ProbioHumus, NaturGel, and NaturGel + ProbioHumus in the organic farm fields significantly increased the fresh fruit weight up to 42%, 35%, and 37%, respectively, compared to the non-treated control. An increase in the weight of fresh strawberry fruits may be associated with an increase in dry matter accumulation. The probiotics had a positive effect on the total content of phenols, anthocyanins, and especially ascorbic acid in strawberry fruits. The increase in ascorbic acid in strawberry fruits was up to 97% compared to the non-treated control. The fruits from plants inoculated with probiotics showed significantly higher antioxidant activity. In summary, ProbioHumus and NaturGel are effective tools for improving the quality of strawberries and can be exploited in sustainable agriculture as a tool for adding value to functional food.

Distinct metabolic profiling is correlated with bisexual flowers formation resulting from exogenous ethephon induction in melon (Cucumis melo L.)

Melon (Cucumis melo L.) is an agronomically important vegetable. Most cultivars of melon are andromonoecious and bisexual flowers only emerged from the leaf axil of lateral branches. However, the regulatory mechanism contributing to the occurrence of bisexual flowers were still obscure. In this study, ethephon was applied in two common cultivars of melon. In control without ethephon treatment, no bisexual flower was made in the main stem. However, 6.56 ± 1.42 and 6.63 ± 0.55 bisexual flowers were respectively induced in main stem of 'Yangjiaocui-QX' and 'Lvbao' after ethephon treatment, and induced bisexual flowers distributed in 12-20 nodes of main stem. During the formation of bisexual flowers, 41 metabolites were significantly up-regulated and 98 metabolites were significantly down-regulated. According to the KEGG enrichment analysis of 139 different metabolites, a total of 30 pathways were mapped and KEGG terms of "Phenylalanine, tyrosine and tryptophan biosynthesis", "Phenylalanine metabolism" and "Flavone and flavonol biosynthesis" were significantly enriched. In three significantly enriched KEGG terms, shikimic acid, L-tryptophan, L-phenylalanine, and kaempferol were significantly up-regulated while L-tyrosine, 4-hydroxycinnami acid and luteolin were significantly down-regulated in ET compared to CK. Different metabolites were also classified depend on major class features and 14 classes were acquired. The results of metabonomics and endogenous hormone identification indicated that ethylene could enhance the concentration of salicylic acid, methyl jasmonate, ABA and IAA. This study provided an important theoretical foundation for inducing bisexual flowers in main stem and breeding new varieties of melon in future.

Bioactive Secondary Metabolites from Plant Sources: Types, Synthesis, and Their Therapeutic Uses

Plants are the source of various photochemicals; metabolites are used in medicinal and environmental sectors as well as being widely used in commercial and pharmaceutical products. Although they produce a number of medicinal products, either already on the market or under trial, the amounts obtained from plant sources are very minute or difficult to synthesize at an industrial level due to the complex chemical composition and chirality exhibited by these compounds. However, plant cell cultures offer a good alternative for the consistent production of desired secondary metabolites under the influence of precursors and elicitors. In this review, we discuss the various aspects of secondary metabolites, production synthesis, and sources of medical products from plant sources.

Enhancing In Vitro Production of the Tree Fern Cyathea delgadii and Modifying Secondary Metabolite Profiles by LED Lighting

The tree ferns are an important component of tropical forests. In view of this, the enhancement of in vitro production of these plants is needed. Thus, the effect of different light-emitting diodes (LEDs) as well as control fluorescent lamps (Fl) and a 3-week-long period of darkness at the beginning of in vitro culture on micropropagation of the tree fern Cyathea delgadii Sternb. was analysed. Moreover, the photosynthetic pigment content and secondary metabolite profiles were estimated. The period of darkness contributed to a high production of somatic embryo-derived sporophytes and a low production of gametophytes. The formation of new sporophytes was stimulated by RBY (35% red, 15% blue, and 50% yellow) and B (100% blue) lights when the stipe explants or whole young sporophytes were used in the culture, respectively. The elongation of the roots and leaves was stimulated by RBfR light (35% red, 15% blue, and 50% far red), while root production increased under RBY light. The RB (70% red and 30% blue) and B lights stimulated the accumulation of chlorophyll better than Fl light. The most abundant metabolite found in the plant extracts was trans-5-O-caffeoylquinic acid (1.013 µg/mg of dry weight). The extract obtained from plants growing in a greenhouse had the best antioxidant activity.

Overexpression of chalcone isomerase A gene in Astragalus trigonus for stimulating apigenin

Apigenin is one of the most studied flavonoids and is widely distributed in the plant kingdom. Apigenin exerts important antioxidant, antibacterial, antifungal, antitumor activities, and anti-inflammatory effects in neurological or cardiovascular disease. Chalcone isomerase A (chiA) is an important enzyme of the flavonoid biosynthesis pathway. In order to enhance the apigenin production, the petunia chi A gene was transformed for Astragalus trigonus. Bialaphos survived plants were screened by PCR, dot blot hybridization and RT-PCR analysis. Also, jasmonic acid, salicylic acid, chitosan and yeast extract were tested to evaluate their capacity to work as elicitors for apigenin. Results showed that yeast extract was the best elicitor for induction of apigenin with an increase of 3.458 and 3.9 fold of the control for calli and cell suspension culture, respectively. Transformed cell suspension showed high apigenin content with a 20.17 fold increase compared to the control and 6.88 fold more than the yeast extract treatment. While, transformed T1 calli derived expressing chiA gene produced apigenin 4.2 fold more than the yeast extract treatment. It can be concluded that the highest accumulation of apigenin was obtained with chiA transgenic cell suspension system and it can be utilized to enhancement apigenin production in Astragalus trigonus.

Single Wavelengths of LED Light Supplement Promote the Biosynthesis of Major Cyclic Monoterpenes in Japanese Mint

Environmental light conditions influence the biosynthesis of monoterpenes in the mint plant. Cyclic terpenes, such as menthol, menthone, pulegone, and menthofuran, are major odor components synthesized in mint leaves. However, it is unclear how light for cultivation affects the contents of these compounds. Artificial lighting using light-emitting diodes (LEDs) for plant cultivation has the advantage of preferential wavelength control. Here, we monitored monoterpene contents in hydroponically cultivated Japanese mint leaves under blue, red, or far-red wavelengths of LED light supplements. Volatile cyclic monoterpenes, pulegone, menthone, menthol, and menthofuran were quantified using the head-space solid phase microextraction method. As a result, all light wavelengths promoted the biosynthesis of the compounds. Remarkably, two weeks of blue-light supplement increased all compounds: pulegone (362% increase compared to the control), menthofuran (285%), menthone (223%), and menthol (389%). Red light slightly promoted pulegone (256%), menthofuran (178%), and menthol (197%). Interestingly, the accumulation of menthone (229%) or menthofuran (339%) was observed with far-red light treatment. The quantification of glandular trichomes density revealed that no increase under light supplement was confirmed. Blue light treatment even suppressed the glandular trichome formation. No promotion of photosynthesis was observed by pulse-amplitude-modulation (PAM) fluorometry. The present result indicates that light supplements directly promoted the biosynthetic pathways of cyclic monoterpenes.

Synthetic Mitochondria-Targeting Peptides Incorporating α-Aminoisobutyric Acid with a Stable Amphiphilic Helix Conformation in Plant Cells

In the genetic modification of plant cells, the mitochondrion is an important target in addition to the nucleus and plastid. However, gene delivery into the mitochondria of plant cells has yet to be established by conventional methods, such as particle bombardment, because of the small size and high mobility of mitochondria. To develop an efficient mitochondria-targeting signal (MTS) that functions in plant cells, we designed the artificial peptide (LURL)₃ and its analogues, which periodically feature hydrophobic α-aminoisobutyric acid (Aib, U) and cationic arginine (R), considering the consensus motif recognized by the mitochondrial import receptor Tom20. Circular dichroism measurements and molecular dynamics simulation studies revealed that (LURL)₃ had a propensity to form a stable α-helix in 0.1 M phosphate buffer solution containing 1.0 wt % sodium dodecyl sulfate. After internalization into plant cells via particle bombardment, (LURL)₃ revealed highly selective accumulation in the mitochondria, whereas its analogue (LARL)₃ was predominantly located in the vacuoles in addition to mitochondria. The high selectivity of (LURL)₃ can be attributed to the incorporation of Aib, which promotes the hydrophobic interaction between the MTS and Tom20 by increasing the hydrophobicity and helicity of (LURL)₃. The present study provided a prospective mitochondrial targeting system using the simple design of artificial peptides.

Study of dynamics of genes involved in biosynthesis and accumulation of scopoletin at different growth stages of Convolvulus prostratus Forssk

The scopoletin one of the major bioactive components of Convolvulus prostratus Forssk known to have a role in acetylcholinesterase inhibitor, memory enhancer, antimicrobial, antioxidative etc. properties are investigated in the present study. The concentration of scopoletin in C. prostratus is investigated in leaf, stem and root at different growth stages of plant development viz., 30, 45, 60 and 90 days after sowing (DAS). A highly sensitive LC-MS method was developed to quantify the scopoletin even at low concentration with LOD and LOQ of 8 and 24 ng/ml, respectively. The highest quantity of scopoletin was recorded in stem (732 μg/g dry weight) and leaf (650 μg/g dry weight) collected 90 DAS whereas lowest was recorded at 45 DAS in leaf (90.00 μg/g dry weight) and Stem (110 μg/g dry weight). Based on the highest and lowest concentration of scopoletin in stem and root tissues at 45 and 90 DAS were selected for transcriptome study. Differential gene expression analysis revealed the differential expression of genes involved in scopoletin biosynthesis. Seven genes viz., phenylalanine ammonia-lyase (PAL), 4-coumarate CoA ligase (4CL), trans-cinnamate 4-monooxygenase (TCM), shikimate O- hydroxycinnamoyl transferase (C3'H), 5-O-4-coumaroyl-D-quinate 3'-monooxygenase (HCT), caffeoyl-CoA-O-methyltransferase (CCoAOMT) and feruloyl-CoA 6'-hydroxylase (F6'H) were identified in the phenyl propanoid pathway. Expression of the novel enzyme F6'H showed down regulation in both tissues at 45 DAS. Real-time PCR showed a correlation with the expression of this F6'H genes with the accumulation of scopoletin at 90 DAS. This indicated that the growth stage of plant and expression of F6'H control the scopoletin accumulation in Convolvulus. The results of present investigation may useful in pharmaceutical, drug and cosmetic industries that the harvesting of plant part especially stem of C.prostratus at 90 DAS to get maximum quantity of scopoletin. Also, the novel gene F6'H need to be further characterized to understand its expression dynamics so that scopoletin content can be increase at the highest.

Sequencing, de novo assembly and annotation of Digitalis ferruginea subsp. schischkinii transcriptome

There is an increasing demand for elucidating the biosynthetic pathway of medicinal plants, which are capable of producing several metabolites with great potentials for industrial drug production. Digitalis species are important medicinal plants for the production of cardenolide compounds. Advancement on culture techniques is strictly related to our understanding of the genomic background of species. There are a limited number of genomic studies on Digitalis species. The goal of this study is to contribute to the genomic data of Digitalis ferruginea subsp. schischkinii by presenting transcriptome annotation. Digitalis ferruginea subsp. schischkinii has a limited distribution in Turkey and Transcaucasia, and has a high level of lanatoside C, an important cardenolide. In the study, we sequenced the cDNA library prepared from RNA pools of D. ferruginea subsp. schischkinii tissues treated with various stress conditions. Comprehensive bioinformatics approaches were used for de novo assembly and functional annotation of D. ferruginea subsp. schischkinii transcriptome sequence data along with TF families predictions and phylogenetic analysis. In the study, 58,369 unigenes were predicted and unigenes were annotated by analyzing the sequence data in the non-redundant (NR) protein database, the non-redundant nucleotide (NT) database, Gene Orthology (GO), EuKaryotic Orthologous Groups (KOG), Kyoto Encyclopedia of Genes and Genomes (KEGG), SwissProt, and InterPro databases. This study is the first transcriptome data for D. ferruginea subsp. schischkinii.

Phytostilbenes as agrochemicals: biosynthesis, bioactivity, metabolic engineering and biotechnology

Covering: 1976 to 2020. Although constituting a limited chemical family, phytostilbenes represent an emblematic group of molecules among natural compounds. Ever since their discovery as antifungal compounds in plants and their ascribed role in human health and disease, phytostilbenes have never ceased to arouse interest for researchers, leading to a huge development of the literature in this field. Owing to this, the number of references to this class of compounds has reached the tens of thousands. The objective of this article is thus to offer an overview of the different aspects of these compounds through a large bibliography analysis of more than 500 articles. All the aspects regarding phytostilbenes will be covered including their chemistry and biochemistry, regulation of their biosynthesis, biological activities in plants, molecular engineering of stilbene pathways in plants and microbes as well as their biotechnological production by plant cell systems.

Induction of promising antibacterial prenylated isoflavonoids from different subclasses by sequential elicitation of soybean

Elicited soybean (Glycine max (L.) Merrill, Leguminosae) seedlings can produce prenylated isoflavonoids from different subclasses, namely pterocarpans (glyceollins), isoflavones and coumestans. These prenylated isoflavonoids serve as defence compounds and can possess antimicrobial activity. Recently, we showed that priming with reactive oxygen species (ROS) specifically stimulated the production of glyceollins in Rhizopus spp.-elicited soybean seedlings (ROS + R). In this study, we achieved diversification of the inducible subclasses of prenylated isoflavonoids in soybean, by additional stimulation of two prenylated isoflavones and one prenylated coumestan. This was achieved by using a combination of the relatively long-lived ROS representative, H2O2, with AgNO3 prior to microbial elicitation. Microbial elicitation was performed with a live preparation of either a phytopathogenic fungus, Rhizopus spp. or a symbiotic bacterium, Bacillus subtilis. B. subtilis induced 30% more prenylated isoflavones than Rhizopus spp. in (H2O2 + AgNO3)-treated seedlings, without significantly compromising the total levels of glyceollins, compared to (ROS + R)-treated seedlings. The most abundant prenylated isoflavone induced was 6-prenyl daidzein, which constituted 60% of the total isoflavones. The prenylated coumestan, phaseol, was also induced in the (H2O2 + AgNO3)-treated and microbially elicited seedlings. Based on previously developed quantitative structure-activity relationship (QSAR) models, 6-prenyl daidzein and phaseol were predicted to be promising antibacterials. Overall, we show that treatment with H2O2 and AgNO3 prior to microbial elicitation leads to the production of promising antibacterial isoflavonoids from different subclasses. Extracts rich in prenylated isoflavonoids may potentially be applied as natural antimicrobial agents.

Infestation of Field Dodder (Cuscuta campestris Yunck.) Promotes Changes in Host Dry Weight and Essential Oil Production in Two Aromatic Plants, Peppermint and Chamomile

Peppermint (Mentha piperita L.) and chamomile (Chamomilla recutita (L.) Rausch.) are aromatic plants with considerable economic value. These plants and their essential oils are used in medicine, cosmetics, and the food industry. One of the main limiting factors in peppermint and chamomile commercial cultivation is weed competition since weeds are able to decrease both oil amount and biomass yield. The purpose of the present study was to determine the effect of parasitism by field dodder (Cuscuta campestris Yunck.) on peppermint and chamomile dry weight and their essential oil yield and composition. Essential oils from both noninfested and infested peppermint and chamomile plants were obtained by hydrodistillation and characterized chemically by gas chromatography (GC) coupled with mass spectrometry (MS). The amount of dry matter accumulated by peppermint and chamomile plants infested by field dodder was lower (25% and 63%, respectively) compared to noninfested plants. Essential oil yield increased for peppermint (3.87% (v/w) and 3.63% (v/w)), but decreased for chamomile (0.2% (v/w) and 0.5% (v/w)) both from infested and noninfested plants, respectively. The oil composition profile significantly differed in terms of content. In peppermint plants, field dodder infestation increased menthone content by 23%, and decreased the content of both menthol by 11% and pulegone by 67%. Furthermore, δ-cadinene was detected only in oil extracted from infested peppermint plants. Compared to peppermint, chamomile plants were significantly more affected by field dodder in terms of essential oil yield, as well as oil composition and plant dry weight. In chamomile plants, (E)-dendrolasin was detected in the oil of noninfested plants, and 1,4-dimethyl-7-(1-methylethyl)-azulen-2-ol was detected only in the oil of infested plants.

Can we trust biomarkers identified using different non-targeted metabolomics platforms? Multi-platform, inter-laboratory comparative metabolomics profiling of lettuce cultivars via UPLC-QTOF-MS

INTRODUCTION

Data analysis during UPLC-MS non-targeted metabolomics introduces variation as different manufacturers use specific algorithms for data treatment and this makes untargeted metabolomics an application for the discovery of new biomarkers with low confidence in the reproducibility of the results under the use of different metabolomics platforms.

OBJECTIVES

This study compared the ability of two platforms (Agilent UPLC-ESI-QTOF-MS and Waters UPLC-IMS-QTOF-MS) to identify biomarkers in butterhead and romaine lettuce cultivars.

METHODS

Two case studies by different metabolomics platforms: (1) Waters and Agilent datasets processed by the same data pre-processing software (Progenesis QI), and (2) Datasets processed by different data pre-processing software.

RESULTS

A higher number of candidate biomarkers shared between sample groups in case 2 (101) than in case 1 (26) was found. Thirteen metabolites were common to both cases. Romaine lettuce was characterised by phenolic compounds including flavonoids, hydroxycinnamate derivatives, and 9-undecenal, while Butterhead showed sesquiterpene lactones and xanthosine. This study demonstrates that high percentages of the most discriminatory entities can be obtained by using the manufacturers' embedded pre-processing software and following the recommended processing data guidelines using commercial software to normalise the data matrix.

Resveratrol: A Fair Race Towards Replacing Sulfites in Wines

In recent years, significant efforts to produce healthier wines has led to the replacement or reduction of the addition of sulfites, using alternative substances or techniques. Resveratrol and related biophenols seem to be of great interest, since beyond their protective nature and contrary to sulfites they can positively affect consumer health. These bioactive phytochemicals are naturally produced in grapes as evolutionary acquired mechanisms against pathogens and UV irradiation. However, despite the efforts made so far attempting to develop economic and industrially adopted isolation techniques, available quantities of these biophenols for commercial use are still quite limited. Therefore, such molecules are still not able to meet the needs of industrial use due to their prohibitive marketable cost. In this review we summarize the efforts that have been made to biosynthesize these molecules through alternative, innovative ways. Increasing interest in modern biotechnological approaches has shed light on the exploitation of metabolically engineered microbial factories, instead of plants, to produce molecules of industrial interest. Such approaches, also reviewed here, are expected to lower the cost and appear promising to produce enough surplus to attract further oenological experimentation upon yielding functional wines. This development is expected to attract further industrial attention, continuing the race to partially or totally replace the external addition of sulfites. We also review important physicochemical properties of resveratrol in relation to enriching wines.

Combined Effects of Water Deficit, Exogenous Ethylene Application and Root Symbioses on Trigonelline and ABA Accumulation in Fenugreek

Secondary metabolites (SMs) have high economic impact thanks to their exploitability in chemical, pharmaceutical and cosmetic industries. Trigonella foenum-graecum has an importance due to the production of bioactive compounds with pharmaceutical values. Among them, the alkaloid trigonelline is known for its role in the treatment of different human diseases. SM accumulation is influenced by environmental factors but is modulated by the application of exogenous compounds. Ethephon, a precursor of the phytohormone ethylene, was already used to influence SM accumulation. Our work is aimed at evaluating the accumulation of trigonelline and the phytohormone abscisic acid (ABA) when three factors were combined: i) two levels of water regimes (well-watered and water deficit), ii) ethephon treatments and iii) inoculation with an arbuscular mycorrhizal (AM)-based inoculum also leading to nodulation. The content of trigonelline and ABA was significantly affected by symbioses, showing high accumulation in AM-colonized plants irrespective of the water regimes applied. In terms of trigonelline accumulation with respect to ethephon treatments, while symbiotic plants showed a dose-dependent trend, non-symbiotic plants showed a significantly difference only when 550 ppm of ethephon was applied. In conclusion, our work provides new information on the effects of both ethephon and symbioses on plant growth and accumulation of valuable compounds, such as trigonelline, in fenugreek.

Optimal Duration of Drought Stress Near Harvest for Promoting Bioactive Compounds and Antioxidant Capacity in Kale with or without UV-B Radiation in Plant Factories

Among abiotic stresses, both drought and UV-B radiation effectively trigger the accumulation of secondary metabolites, and can be widely applied in plant factories. The objectives of this study were to investigate antioxidant accumulation under drought stress alone, or in combination with UV-B radiation near harvest, and to determine an optimal treatment time for maximum antioxidant production. Kale (Brassica oleracea L. var. acephala) plants were grown in a plant factory and harvested at 42 days after transplanting. The single and combination treatments lasted for 7 to 1 days and 4 to 2 days before harvest, respectively. The results of both F_v/F_m (maximal photochemical efficiency in photosystem II) and leaf water potential could ensure the function of photosynthesis and maintain normal leaf moisture in single drought treatments of less than 4 days. The total phenolic and flavonoid contents and antioxidant activities were significantly increased in both single and combination treatments for 3 to 4 days, compared to other treatments. The supplementary UV-B treatments showed no extra formation of antioxidants compared to the single drought treatments. As a result, drought for 3 days before harvest could achieve the highest potential value of kale as a source of natural antioxidants.

Agrobacterium-Mediated Genetic Transformation of the Medicinal Plant Veratrum dahuricum

Veratrum dahuricum L. (Liliaceae), a monocotyledonous species distributed throughout the Changbai mountains of Northeast China, is pharmaceutically important, due to the capacity to produce the anticancer drug cyclopamine. An efficient transformation system of Veratrum dahuricum mediated with Agrobacterium tumefaciens is presented. Murashige and Skoog (MS) medium containing 8 mg/L picloram was used to induce embryogenic calli from immature embryos with 56% efficiency. A. tumefaciens LBA4404 carrying the bar gene driven by the cauliflower mosaic virus 35S promoter was employed for embryogenic callus inoculation. A. tumefaciens cell density OD660 = 0.8 for inoculation, half an hour infection period, and three days of co-culture duration were found to be optimal for callus transformation. Phosphinothricin (PPT, 16 mg/L) was used as the selectable agent, and a transformation efficiency of 15% (transgenic plants/100 infected calli) was obtained. The transgenic nature of the regenerated plants was confirmed by PCR and Southern blot analysis, and expression of the bar gene was detected by RT-PCR and Quick PAT/bar strips. The steroid alkaloids cyclopamine, jervine, and veratramine were detected in transgenic plants, in non-transformed and control plants collected from natural sites. The transformation system constitutes a prerequisite for the production of the pharmaceutically important anticancer drug cyclopamine by metabolic engineering of Veratrum.

Nanoharvesting of bioactive materials from living plant cultures using engineered silica nanoparticles

Plant secondary metabolites are valuable therapeutics not readily synthesized by traditional chemistry techniques. Although their enrichment in plant cell cultures is possible following advances in biotechnology, conventional methods of recovery are destructive to the tissues. Nanoharvesting, in which nanoparticles are designed to bind and carry biomolecules out of living cells, offers continuous production of metabolites from plant cultures. Here, nanoharvesting of polyphenolic flavonoids, model plant-derived therapeutics, enriched in Solidago nemoralis hairy root cultures, is performed using engineered mesoporous silica nanoparticles (MSNPs, 165 nm diameter and 950 m2/g surface area) functionalized with both titanium dioxide (TiO2, 425 mg/g particles) for coordination binding sites, and amines (NH2, 145 mg/g particles) to promote cellular internalization. Intracellular uptake and localization of the nanoparticles (in Murashige and Skoog media) in hairy roots were confirmed by tagging the particles with rhodamine B isothiocyanate, incubating the particles with hairy roots, and quenching bulk fluorescence using trypan blue. Nanoharvesting of biologically active flavonoids was demonstrated by observing increased antiradical activity (using 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay) by nanoparticles after exposure to hairy roots (indicating general antioxidant activity), and by the displacement of the radio-ligand [3H]-methyllycaconitine from rat hippocampal nicotinic receptors by solutes recovered from nanoharvested particles (indicating pharmacological activity specific to S. nemoralis flavonoids). Post-nanoharvesting growth suggests that the roots are viable after nanoharvesting, and capable of continued flavonoid synthesis. These observations demonstrate the potential for using engineered nanostructured particles to facilitate continuous isolation of a broad range of biomolecules from living and functioning plant cultures.

Tylophorine: Sources, Properties, Applications and Biotechnological Production

Tylophora indica, a medicinal climber, belongs to the family, Asclepiadaceae. Roots and leaves of the plant contain several alkaloids including tylophorine, tylophorinine and tylophrinidine. The major alkaloid, tylophorine found in T. indica possesses several properties, such as immunosuppressive, antitumour, antifeedant, antibacterial, antifungal, antiamoebic, diuretic and hepatoprotective activities. In addition to this, tylophorine provides positive stimulation to adrenal cortex. Biotechnological production of tylophorine was fulfilled by inducing hairy roots mediated by Agrobacterium rhizogenes (A4 strain). It was followed by its growth in liquid suspension culture that could yield maximum biomass and tylophorine production. This type of liquid suspension culture yielded 9.8 ± 0.21 mgL⁻¹ tylophorine within 4–6 weeks of incubation. Maceration technique employed for the extraction of tylophorine was the most viable and efficient protocol. Although many reports are available regarding the biotechnological production of tylophorine, its competent and economic production still continues as a problematic issue.

Tomato's Green Gold: Bioeconomy Potential of Residual Tomato Leaf Biomass as a Novel Source for the Secondary Metabolite Rutin

At the end of the annual horticultural production cycle of greenhouse-grown crops, large quantities of residual biomass are discarded. Here, we propose a new value chain to utilize horticultural leaf biomass for the extraction of secondary metabolites. To increase the secondary metabolite content of leaves, greenhouse-grown crop plants were exposed to low-cost abiotic stress treatments after the last fruit harvest. As proof of concept, we evaluated the production of the flavonoid rutin in tomato plants subjected to nitrogen deficiency. In an interdisciplinary approach, we observed the steady accumulation of rutin in young plants under nitrogen deficiency, tested the applicability of nitrogen deficiency in a commercial-like greenhouse, developed a high efficiency extraction for rutin, and evaluated the acceptance of the proposed value chain by its key actors economically. On the basis of the positive interdisciplinary evaluation, we identified opportunities and challenges for the successful establishment of horticultural leaf biomass as a novel source for secondary metabolites.

Improvement of phytochemical production by plant cells and organ culture and by genetic engineering

Plants display an amazing ability to synthesize a vast array of secondary metabolites that are an inexhaustible source of phytochemicals, bioactive molecules some of which impact the human health. Phytochemicals present in medicinal herbs and spices have long been used as natural remedies against illness. Plant tissue culture represents an alternative to whole plants as a source of phytochemicals. This approach spares agricultural land that can be used for producing food and other raw materials, thus favoring standardized phytochemical production regardless of climatic adversities and political events. Over the past 20 years, different strategies have been developed to increase the synthesis and the extraction of phytochemicals from tissue culture often obtaining remarkable results. Moreover, the availability of genomics and metabolomics tools, along with improved recombinant methods related to the ability to overexpress, silence or disrupt one or more genes of the pathway of interest promise to open new exciting possibilities of metabolic engineering. This review provides a general framework of the cellular and molecular tools developed so far to enhance the yield of phytochemicals. Additionally, some emerging topics such as the culture of cambial meristemoid cells, the selection of plant cell following the expression of genes encoding human target proteins, and the bioextraction of phytochemicals from plant material have been addressed. Altogether, the herein described techniques and results are expected to improve metabolic engineering tools aiming at improving the production of phytochemicals of pharmaceutical and nutraceutical interest.

Optimization of cell suspension culture of transformed and untransformed lettuce for the enhanced production of secondary metabolites and their pharmaceutical evaluation

In vitro suspension culture techniques are cost effective for large-scale production of secondary metabolites. In the present study, firstly, suspension cultures of untransformed Lactuca sativa were prepared using different hormonal combinations and were subjected to different pH, temperature and salt concentrations. Maximum biomass was obtained for suspensions supplemented with 1.5 mg/L BAP and 0.1 mg/L NAA, at pH 5.8, temperature 28 °C and 0 mM NaCl concentration. Using these parameters, suspensions were produced for rol ABC- and rol C-transformed lines of L. sativa. All the transgenic lines showed prominent increase in fresh weight (FW) and dry weight (DW) with maximum values for rol ABC2 line producing 169.8 mg/mL FW and 25.3 mg/mL DW. The exudates of transformed and untransformed plants were tested for the antioxidant activity and in vivo assays on rats. Maximum phenolic content (261 μg/mL) and flavonoid content (637.6 μg/mL) were obtained for rol C1 transgenic line. Total antioxidant capacity was found maximum (1451.7 μg/mL) for untransformed lettuce, whereas rol C1 showed maximum total reducing power activity (637.6 μg/mL). In DPPH assay, maximum activity (104.7 μg/mL) was shown by rol ABC3 line. In rats analgesic assay, maximum activity (74.9%) was shown by rol C2. Line rol C1 showed maximum anti-inflammatory activity (69.2%) and maximum antidepressant activity (minimum immobility time of 55 s). Maximum anticoagulant activity was observed for rol ABC2 with maximum clotting time of 130 s. The present study could help in using lettuce suspension culture as platform for the enhanced production of important metabolites.

Sodium nitroprusside stimulated production of tropane alkaloids and antioxidant enzymes activity in hairy root culture of Hyoscyamus reticulatus L

Hyoscyamus reticulatus L. is a herbaceous biennial belonging to the solanaceae family. Hyoscyamine and scopolamine as main tropane alkaloids accumulated in henbane are widely used in medicine to treat diseases such as parkinson's or to calm schizoid patients. Hairy roots media manipulation which uses elicitors to activate defense mechanisms is one of the main strategies for inducing secondary metabolism as well as increasing the production of valuable metabolites. Cotyledon-derived hairy root cultures were transformed by Agrobacterium rhizogenes. Sodium nitroprusside (SNP), a nitric oxide donor), was used in various concentrations (0, 50, 100, 200 and 300 μM) and exposure times (24 and 48 h). Treatment with SNP led to a significant reduction in fresh and dry weight of hairy roots, compared to control cultures. ANOVA results showed that elicitation of hairy root cultures with SNP at different concentrations and exposure times significantly affected the activity of as antioxidant enzymes such as catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX). The highest hyoscyamine and scopolamine production (about 1.2-fold and 1.5-fold increases over the control) was observed at 50 and 100 μM SNP at 48 and 24 hours of exposure time, respectively. This is the first report of SNP elicitation effects on the production of tropane alkaloids in hairy root cultures.

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.

Therapeutic Protection from Hepatic Injury and Chemical Constituents of Buchanania angustifolia Roxb

Objectives

The use of modern medicines in the treatment of diseases instead of traditional medicine is causing different adverse effects. Therefore, there is need to search new bioactive compounds to treat different diseases. Buchanania angustifolia has been used in traditional medicine in the treatment of different diseases. On the basis of folkloric information, B. angustifolia aerial parts extracts have been selected for their antioxidant and hepatoprotective potentiality and phytochemical constituents.

Materials and Methods

Qualitative phytochemical screening of B. angustifolia extracts revealed the presence of phytochemical constituents such as steroids, terpenoids, flavonoids, alkaloids, glycosides, tannins, carbohydrates, oils and amino acids. BA-1 and BA-2 compounds isolated from hydroalcoholic extract using chromatography and were identified as linolenic acid and mixture of stigmasterol and β-sitosterol.

Results

Antioxidant activity was performed on superoxide, hydroxyl and 1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino) propane hydrochloride free radicals. The B. angustifolia extracts showed dose-dependent activity on free radicals. The hydroalcoholic extract showed better activity. The extracts showed hepatoprotective activity on thioacetamide-induced liver intoxication in rats, and hydroalcoholic extract exhibited significant restoration of the altered biochemical parameters due thioacetamide-induced liver intoxication.

Conclusion

Among the tested extracts of B. angustifolia, hydroalcoholic extract showed higher antioxidant and hepatoprotective activity and stigmasterol and β-sitosterol were isolated. Further research is needed to evaluate other pharmacological activities and to isolate the other bioactive compounds from B. angustifolia.

Elucidation and functional characterization of CsPSY and CsUGT promoters in Crocus sativus L

The dried stigmas of Crocus sativus constitute the saffron, which is considered to be the costliest spice of the world. Saffron is valuable for its constituents, which are mainly apocarotenoids. In order to enhance the production of apocarotenoids, it is imperative to understand the regulation of apocarotenoid biosynthetic pathway. In C. sativus, although the pathway has been elucidated, the information regarding the regulation of the pathwaygenes is scanty. During the present investigation, the characterization of promoters regulating the expression of two important genes i.e. CsPSY and CsUGT was performed. We successfully cloned the promoters of both the genes, which were functionally characterized in Crocus sativus and Nicotiana tabaccum. In silico analysis of the promoters demonstrated the presence of several important cis regulatory elements responding tolight, hormonesand interaction with transcription factors (TFs). Further analysis suggested the regulation of CsPSY promoter by Abscisic acid (ABA) and that of CsUGT by Gibberellic acid (GA). In addition, we also observed ABA and GA mediated modulation in the expression of significant TFs and CsPSY and CsUGT transcripts. Overall, the study addresses issues related to regulation of key genes of apocarotenoid pathway in C.sativus.

Rewriting the Metabolic Blueprint: Advances in Pathway Diversification in Microorganisms

Living organisms have evolved over millions of years to fine tune their metabolism to create efficient pathways for producing metabolites necessary for their survival. Advancement in the field of synthetic biology has enabled the exploitation of these metabolic pathways for the production of desired compounds by creating microbial cell factories through metabolic engineering, thus providing sustainable routes to obtain value-added chemicals. Following the past success in metabolic engineering, there is increasing interest in diversifying natural metabolic pathways to construct non-natural biosynthesis routes, thereby creating possibilities for producing novel valuable compounds that are non-natural or without elucidated biosynthesis pathways. Thus, the range of chemicals that can be produced by biological systems can be expanded to meet the demands of industries for compounds such as plastic precursors and new antibiotics, most of which can only be obtained through chemical synthesis currently. Herein, we review and discuss novel strategies that have been developed to rewrite natural metabolic blueprints in a bid to broaden the chemical repertoire achievable in microorganisms. This review aims to provide insights on recent approaches taken to open new avenues for achieving biochemical production that are beyond currently available inventions.

Heavy metals in contaminated environment: Destiny of secondary metabolite biosynthesis, oxidative status and phytoextraction in medicinal plants

Contamination of soils, water and air with toxic heavy metals by various human activities is a crucial environmental problem in both developing and developed countries. Heavy metals could be introduced into medicinal plant products through contaminated environment (soil, water and air resources) and/or poor production practices. Growing of medicinal plants in heavy metal polluted environments may eventually affect the biosynthesis of secondary metabolites, causing significant changes in the quantity and quality of these compounds. Certain medicinal and aromatic plants can absorb and accumulate metal contaminants in the harvestable foliage and, therefore, considered to be a feasible alternative for remediation of polluted sites without any contamination of essential oils. Plants use different strategies and complex arrays of enzymatic and non-enzymatic anti-oxidative defense systems to cope with overproduction of ROS causes from the heavy metals entered their cells through foliar and/or root systems. This review summarizes the reports of recent investigations involving heavy metal accumulation by medicinal plants and its effects on elicitation of secondary metabolites, toxicity and detoxification pathways, international standards regarding in plants and plant-based products, and human health risk assessment of heavy metals in soil-medicinal plants systems.

[Mutagenicity, genotoxicity and gene expression of Rad51C, Xiap, P53 and Nrf2 induced by antimalarial extracts of plants collected from the middle Vaupés region, Colombia]

INTRODUCTION

Due to Plasmodium resistance to antimalarial drugs, it is important to find new therapeutic alternatives for malaria treatment and control. Based on the knowledge of Colombian indigenous communities, we collected extracts of plants with potential antimalarial effects from the middle Vaupés region.

OBJECTIVE

To evaluate the mutagenic and genotoxic effects, as well as the gene expression of Rad51C, Xiap, P53 and Nrf2 induced by four ethanolic extracts with antimalarial activity (R001, T002, T015 and T028).

MATERIALS AND METHODS

We evaluated four ethanolic extracts with antimalarial activity using the Ames test to assess mutagenicity, and the comet assay on HepG2 cells to determine the genotoxicicity. We also evaluated the expression of Rad51C, Xiap, P53 and Nrf2 from HepG2 cells stimulated with the four extracts.

RESULTS

None of the four extracts was mutagenic in Salmonella typhimurium TA98 strain in the presence and absence of S9 metabolic activity. Extracts R001, T015 and T028 were weakly mutagenic on the TA100 strain in the presence of S9, with mutagenic indexes (MI) of 1.58, 1.53 and 1.61, respectively. The T015 strain showed the same behavior without S9 with an MI of 1.36. The results of the comet assay showed that the four extracts produced category 1 or 2 damage, with comets between 36.7 and 51.48 μm in length. However, the genetic damage index suggested that most of the cells were affected by the treatments. Regarding gene expression, extracts R001 and T028 induced an overexpression of genes Xiap and P53 with an 1.84 to 3.99 fold-change compared with untreated cells.

CONCLUSIONS

These results revealed that the T002 extract was the safest as it had antimalarial activity and was not cytotoxic on HepG2 cells. Moreover, it was not mutagenic and it only produced category 1 damage on the DNA. Also, the extract did not induce a change in the expression of the tested genes.

New horizons in the extraction of bioactive compounds using deep eutectic solvents: A review

With the rapid development of ionic liquid analogues, termed 'deep eutectic solvents' (DESs), and their application in a wide range of chemical and biochemical processes in the past decade, the extraction of bioactive compounds has attracted significant interest. Recently, numerous studies have explored the extraction of bioactive compounds using DESs from diverse groups of natural sources, including animal and plant sources. This review summarizes the-state-of-the-art effort dedicated to the application of DESs in the extraction of bioactive compounds. The aim of this review also was to introduce conventional and recently-developed extraction techniques, with emphasis on the use of DESs as potential extractants for various bioactive compounds, such as phenolic acid, flavonoids, tanshinone, keratin, tocols, terpenoids, carrageenans, xanthones, isoflavones, α-mangostin, genistin, apigenin, and others. In the near future, DESs are expected to be used extensively for the extraction of bioactive compounds from various sources.

Bioconversion of stilbenes in genetically engineered root and cell cultures of tobacco

It is currently possible to transfer a biosynthetic pathway from a plant to another organism. This system has been exploited to transfer the metabolic richness of certain plant species to other plants or even to more simple metabolic organisms such as yeast or bacteria for the production of high added value plant compounds. Another application is to bioconvert substrates into scarcer or biologically more interesting compounds, such as piceatannol and pterostilbene. These two resveratrol-derived stilbenes, which have very promising pharmacological activities, are found in plants only in small amounts. By transferring the human cytochrome P450 hydroxylase 1B1 (HsCYP1B1) gene to tobacco hairy roots and cell cultures, we developed a system able to bioconvert exogenous t-resveratrol into piceatannol in quantities near to mg L-1. Similarly, after heterologous expression of resveratrol O-methyltransferase from Vitis vinifera (VvROMT) in tobacco hairy roots, the exogenous t-resveratrol was bioconverted into pterostilbene. We also observed that both bioconversions can take place in tobacco wild type hairy roots (pRiA4, without any transgene), showing that unspecific tobacco P450 hydroxylases and methyltransferases can perform the bioconversion of t-resveratrol to give the target compounds, albeit at a lower rate than transgenic roots.