Showing papers in "Phytochemistry Reviews in 2016"
TL;DR: The aim of this review is to summarize the various naturally occurring chalcone compounds which have been isolated from different plants to initiate further pharmacobotanical, biotechnological and medicinal studies on the field of chal cone research.
Abstract: The aim of this review is to summarize the various naturally occurring chalcone compounds which have been isolated from different plants. Chalcones considered as obligate intermediated in flavonoid biosynthesis but they do not accumulate to appreciable degree in most plants. The largest number of natural chalcones has been isolated from species of the Leguminosae, Asteraceae and Moraceae families. Chalcone accumulating plants have often been used in traditional medicine and chalcones have therefore been studied and reported to possess many beneficial biological effects including anti-inflammatory, antimicrobial, antifungal, antioxidant, cytotoxic, antitumor and chemopreventive activities. Previously published reviews on this topic survey the biological activities of natural and synthetic chalcones but there are no comprehensive contributions on occurrence and biological activities of natural chalcones. The present study provides an overview of hydroxy or/and methoxy-substituted chalcones, methylated, prenylated, geranylated and other monomeric derivatives, chromeno- and furanochalcones, dimeric chalcones and dihydrochalcone derivatives focusing on their biosynthesis, natural sources and biological activities. On the basis of 608 references, this review covers the phytochemistry and biological activity of natural chalcones, describing 646 compounds have been appeared in the literature since 1975. The summary is aimed to initiate further pharmacobotanical, biotechnological and medicinal studies on the field of chalcone research. This contribution reviews some of the general aspects of naturally occurring chalcones including their chemical categories, focusing on plant sources and biological activities. The review covers the major works appeared in the literature from 1975 up to 2014, relating to 608 references and 646 compounds.
228 citations
TL;DR: Recent advances in plant-based mass spectrometry imaging, general aspects of instrumentation, analytical approaches, sample preparation and the current trends in respective plant research are covered.
Abstract: Mass spectrometry imaging (MSI) is a developing technique to measure the spatio-temporal distribution of many biomolecules in tissues. Over the preceding decade, MSI has been adopted by plant biologists and applied in a broad range of areas, including primary metabolism, natural products, plant defense, plant responses to abiotic and biotic stress, plant lipids and the developing field of spatial metabolomics. This review covers recent advances in plant-based MSI, general aspects of instrumentation, analytical approaches, sample preparation and the current trends in respective plant research.
203 citations
TL;DR: The qualitative and quantitative metabolic output of the gut microbiota depends to a large extent on the metabolic capacity of individual taxa, which emphasizes the need for assessment of functional analysis in conjunction with determinations of gut microbiota compositions.
Abstract: Gut microbiota contribute to the metabolism of dietary polyphenols and affect the bioavailability of both the parent polyphenols and their metabolites. Although there is a large number of reports of specific polyphenol metabolites, relatively little is known regarding the chemistry and enzymology of the metabolic pathways utilized by specific microbial species and taxa, which is the focus of this review. Major classes of dietary polyphenols include monomeric and oligomeric catechins (proanthocyanidins), flavonols, flavanones, ellagitannins, and isoflavones. Gut microbial metabolism of representatives of these polyphenol classes can be classified as A- and C-ring cleavage (retro Claisen reactions), C-ring cleavage mediated by dioxygenases, dehydroxylations (decarboxylation or reduction reactions followed by release of H2O molecules), and hydrogenations of alkene moieties in polyphenols, such as resveratrol, curcumin, and isoflavones (mediated by NADPH-dependent reductases). The qualitative and quantitative metabolic output of the gut microbiota depends to a large extent on the metabolic capacity of individual taxa, which emphasizes the need for assessment of functional analysis in conjunction with determinations of gut microbiota compositions.
142 citations
TL;DR: It is shown how within-plant distribution modulates the exposure of different herbivore feeding guilds to these defenses, and how benzoxazinoids may act as toxins, feeding deterrents and digestibility-reducing compounds under different conditions.
Abstract: Benzoxazinoids are a class of indole-derived plant chemical defenses comprising compounds with a 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one skeleton and their derivatives. These phytochemicals are widespread in grasses, including important cereal crops such as maize, wheat and rye, as well as a few dicot species, and display a wide range of antifeedant, insecticidal, antimicrobial, and allelopathic activities. Although their overall effects against insect herbivores are frequently reported, much less is known about how their modes of action specifically influence insect physiology. The present review summarizes the biological activities of benzoxazinoids on chewing, piercing-sucking, and root insect herbivores. We show how within-plant distribution modulates the exposure of different herbivore feeding guilds to these defenses, and how benzoxazinoids may act as toxins, feeding deterrents and digestibility-reducing compounds under different conditions. In addition, recent results on the metabolism of benzoxazinoids by insects and their consequences for plant-herbivore interactions are addressed, as well as directions for future research.
141 citations
TL;DR: The knowledge achieved in the past 30 years of the MIA pathway in C. roseus is reviewed, with the aim to fully unravel the MIA biosynthesis, its regulation and the function of the alkaloids in the plant from a systems biology point of view.
Abstract: As the only source for the low-abundance antitumor agents vinblastine and vincristine, Catharanthus roseus is highly valued and has been studied extensively as a model for medicinal plants improvement. The biosynthesis of these monoterpenoid indole alkaloids (MIAs) is a complex multistep enzymatic network that is tightly regulated by developmental and environmental factors. Here we review the knowledge achieved in the past 30 years of the MIA pathway in C. roseus, from genetic to metabolic aspects. Two early precursor pathways and a late mono-/bis-indole alkaloid pathway have been largely elucidated and established, as well as their intercellular and subcellular compartmentation. Many genes encoding constitutive structural biosynthetic enzymes, transcription factors, and transporters involved in these pathways have been cloned, characterized and applied in metabolic engineering strategies to improve the MIA production. However, genetic modification in the pathway in C. roseus resulted in complicated changes of both secondary and primary metabolism, affecting not only the MIA pathway but also other pathways. Research at metabolic level is required to increase the knowledge on the genetic regulation of the whole metabolic network connected to the MIA biosynthesis. Nuclear magnetic resonance-based metabolomics (metabolic profiling, fingerprinting and flux analyses) in combination with other “omics” have been implemented in studies of C. roseus for pathway elucidation, including among others, understanding stress response, cross talk between pathways, and diversion of carbon fluxes, with the aim to fully unravel the MIA biosynthesis, its regulation and the function of the alkaloids in the plant from a systems biology point of view.
123 citations
TL;DR: The level of evidence for a beneficial effect in humans of phenolic compounds on the prevention of CDs is weak and need to be strengthened by additional studies addressing potential confounding factors, such as interaction of phenols with other bioactive substances in foods and potential pro-oxidant effects.
Abstract: The objective of this review was to assess, based on human data, the role of phenolic compounds in selected plant foods consumed as part of the Mediterranean diet in the prevention of chronic diseases (CDs) like cardiovascular disease, cancer and neurodegenerative conditions. Fruits and vegetables are rich sources of phenolic compounds and based on scientific data it would be expected that their consumption, as part of the diet, would be responsible for their documented preventive role of chronic diseases. The results of the review of scientific literature on human clinical trials revealed that in some studies polyphenols exert a positive effect in the prevention of cardiovascular disease, essentially blood pressure and arterial dilation, certain types of cancer and neurodegenerative disorders. However, such effects are not consistent with other clinical studies in which no effect has been found. Therefore, the level of evidence for a beneficial effect in humans of phenols on the prevention of CDs is weak and need to be strengthened by additional studies addressing potential confounding factors, such as interaction of phenols with other bioactive substances in foods and potential pro-oxidant effects.
92 citations
TL;DR: In this paper, literature data concerning chemistry and biological activity of steroidal saponins from the Allium genus has been reviewed.
Abstract: Steroidal saponins are widely distributed among monocots, including the Amaryllidaceae family to which the Allium genus is currently classified. Apart from sulfur compounds, these are important biologically active molecules that are considered to be responsible for the observed activity of Allium species, including antifungal, cytotoxic, enzyme-inhibitory, and other. In this paper, literature data concerning chemistry and biological activity of steroidal saponins from the Allium genus has been reviewed.
80 citations
TL;DR: This review summarizes some systems that are ideal for testing synergistic plant defenses and utilizes a focused meta-analysis to examine studies that have tested effects of multiple compounds on insects.
Abstract: Synergistic effects of multiple plant secondary metabolites on upper trophic levels constitute an underexplored but potentially widespread component of coevolution and ecological interactions. Examples of plant secondary metabolites acting synergistically as insect deterrents are not common, and many studies focus on the pharmaceutical applications of natural products, where activity is serendipitous and not an evolved response. This review summarizes some systems that are ideal for testing synergistic plant defenses and utilizes a focused meta-analysis to examine studies that have tested effects of multiple compounds on insects. Due to a dearth of ecological synergy studies, one of the few patterns for synergy that we are able to report from the meta-analysis is that phytochemical mixtures have a larger overall effect on generalist herbivores than specialist herbivores. We recommend a focus on synergy in chemical ecology programs and suggest future hypothesis tests and methods. These approaches are not focused on techniques in molecular biology to examine mechanisms at the cellular level, rather we recommend uncovering the existence of synergy first, by combining the best methods in organic synthesis, isolation, chemical ecology, bioassays, and quantitative analyses. Data generated by our recommended methods should provide rigorous tests of important hypotheses on how intraclass and interclass compounds act synergistically to deter insects, disrupt the immune response, and ultimately contribute to diversification. Further synergy research should also contribute to determining if antiherbivore synergy is widespread among plant secondary metabolites, which would be consistent with the hypothesis that synergistic defenses are a key attribute of the evolved diverse chemical mixtures found in plants.
76 citations
TL;DR: Considering the presence of diverse biologically active phytochemicals in the sage plants, they can be suggested as suitable candidates for the formulation of valuable natural medicines.
Abstract: The plants of the genus Salvia L. are important medicinal herbs of the Lamiaceae family and some of them such as S. officinalis (sage), S. miltiorrhiza (red sage, Danshen) and S. sclarea (clary sage) have been used as medicinal plants in the folk medicine of several countries. In this review, we discuss the reports that have examined Salvia species with the aim of isolation of pure compounds with different biological activities. The phytochemical analyses of various sage plants have reported 10 monoterpenoids (1–10), 1 sesquiterpenoid (11), 8 labdane (13–20), 15 ent-kaurane (21–35), 82 abietane, rearranged abietane and tanshinone (36–117), 3 icetexane (118–120), 43 clerodane (121–163), and 3 pimarane (164–166) diterpenoids with cytotoxic and antimicrobial, antiprotozoal, antioxidant, phytotoxic and insecticide effects. The other heavier terpenoids, including 3 sesterterpenes (167–169), 10 triterpenoids and β-sitosterol (170–180) have been introduced as minor bioactive compounds in the sage plants. Sahandinone (107), 6,7-dehydroroyleanone, 7-α-acetoxyroyleanone (40), and tanshinone like diterpenoids have been isolated from the roots’ extracts of different Salvia species. On the other hand, several radical scavenger phenolic compounds like simple phenolics and caffeic acid derivatives (181–201) including rosmarinic acid, flavonoids (202–217) as well as phenolic diterpenoids, such as carnosol and carnosic acid have been isolated from the aerial parts of these plants. One pyrrole (218) and 3 antimicrobial oxylipins (219–221) are among the other less detected constituents in the members of Salvias. Furthermore, sages also synthesize antifungal, antileishmanial and antimalarial phytochemicals in their roots and shoots, which are reviewed in this paper. We also examine the allelopathic phenomena and the ecologically important phytochemicals identified in different parts of the sage plants. Finally, antifeedant and insecticide phenomena, which are due to the presence of volatile monoterpenes and clerodane diterpenes in these plants, are discussed. Considering the presence of diverse biologically active phytochemicals in the sage plants, they can be suggested as suitable candidates for the formulation of valuable natural medicines.
76 citations
TL;DR: Several HupA-related features are addressed in this review, including not only its therapeutic properties, but also its chemistry, biological and chemical sources, structure–activity relationship, pharmacokinetics and toxicology, which are discussed in detail covering the literature published from 1962 to 2014.
Abstract: The use and popularity of herbal medicines has been increasing worldwide. In fact, today, the traditional Chinese medicine offers a vast repertory for pharmaceutical research, as is the case of Huperzia serrata, a member of Huperziaceae family. This review reports the Lycopodium alkaloids that have been isolated from this plant. However, it was mainly focused on the huperzine A (HupA), a promising therapeutic option in several acute and chronic disorders. The major therapeutic interest described for HupA has been directed to the treatment of acetylcholine-deficit dementia, including Alzheimer’s disease. However, HupA was also shown to be effective on cerebrovascular dementia and other neurodegenerative disorders with an ischemic component, as well as on other kind of cognitive impairments; the value of HupA on myasthenia gravis, organophosphate poisoning and schizophrenia has also been described. In addition, many other pharmacological properties have been ascribed to HupA, namely its anti-inflammatory, antinociceptive and anticonvulsant properties, which was recently identified, promoting a growing interest on HupA research. Furthermore, its particular chemical structure and the fact that HupA is well tolerated in humans, even at doses well above those clinically required, along with its favorable pharmacokinetics, also boosted an intense research in the pharmaceutical industry. Therefore, several HupA-related features are addressed in this review, including not only its therapeutic properties, but also its chemistry, biological and chemical sources, structure–activity relationship, pharmacokinetics and toxicology, which are discussed in detail covering the literature published from 1962 to 2014.
75 citations
TL;DR: An overview of the techniques used for the analysis, isolation, and separation of imperatorin from plant material from the practical perspective is presented.
Abstract: Imperatorin, a furanocoumarin derivative, has many documented pharmacological properties which make it a candidate for possible drug development. In this review, the activity on the central nervous system, the anticancer and antiviral properties and the influence on the cardiovascular system are described. The aim of this review is also to present an overview of the techniques used for the analysis, isolation, and separation of imperatorin from plant material from the practical perspective.
TL;DR: The special morphology of adventitious roots hampers the scale-up processes, which needs modifications with the existing bioreactors to facilitate proper mixing, aeration and which can overcome shear stress.
Abstract: Adventitious roots are natural roots which develop from the differentiated cells of any organ such as leaf, root or stem. These roots are attractive source of phytochemicals due to their genetic and biosynthetic stability. Their stability offers new scope for the in vitro production of valuable secondary metabolites. In the past two decades, adventitious roots have been induced from different plant systems and the suspension cultures have been established. However, the special morphology of adventitious roots hampers the scale-up processes, which needs modifications with the existing bioreactors to facilitate proper mixing, aeration and which can overcome shear stress. Various modifications have been done with the stirred tank and air-lift bioreactors and successfully used for the cultivation of adventitious roots. The progress made in this area is tremendous, in few cases adventitious root cultures are succeeded up to commercial scale with step-wise viz. small scale to large-scale by establishing the standards with various parameters which affect the biomass accumulation and metabolite productivity. This review addresses the recent progresses made in this area and discusses the potential applications and limitations.
TL;DR: These findings create an excellent starting point for investigations into (poly)methoxylated flavone metabolism in more and less distantly related taxa, which would shed light on the evolution of this biosynthetic capacity.
Abstract: Lipophilic flavones with several methoxyl residues occur in various clades of land plants, from liverworts to core eudicots. Their chemodiversity is mediated by the manifold combinations of oxygenation and methoxylation patterns. In the Lamiaceae, Asteraceae, and Rutaceae, (poly)methoxylated flavones are thought to be produced by secretory tissues and stored externally or in oil cavities. They exhibit an array of bioactivities in vitro and in vivo, and may constitute part of the plants’ chemical defense mechanisms and represent promising natural lead molecules for the development of potent antiproliferative, antidiabetic, or anti-inflammatory drugs. The biosynthesis of (poly)methoxylated flavones in sweet basil (Ocimum basilicum L.) has been largely elucidated in the past few years. The knowledge obtained in those studies can be used for enzymatic semi-synthesis of these flavones as well as for further cell biological and physiological studies of basil trichome metabolism. In addition, these findings create an excellent starting point for investigations into (poly)methoxylated flavone metabolism in more and less distantly related taxa, which would shed light on the evolution of this biosynthetic capacity.
TL;DR: The use of mass spectrometers as an investigative tool for plant metabolomics has recently been explored and initial results show a promising direction that plant metabolites could be heading to with the use of these mass directed imaging techniques as discussed by the authors.
Abstract: Imaging mass spectrometry (MSI) has contributed important information to several scientific fields and more recently to the biological sciences. The use of MSI as an investigative tool for plant metabolomics has recently been explored and initial results show a promising direction that plant metabolomics could be heading to with the use of these mass directed imaging techniques. Matrix assisted laser desorption ionisation (MALDI), secondary ion mass spectrometry and desorption electrospray ionisation mass spectrometry are the best-known MSI techniques used currently. MALDI-MSI is the most common used technique for molecular imaging. With new developments, spatial resolution capabilities have reached 5 μm which has resulted in a significant improvement in the data outputs for MSI analysis. Developments in the improvement of sample preparation techniques, instrumental improvements and more efficient and effective data analysis, have had a dramatic improvement in the obtained informational content. More recent developments on instrumentation and applications are seeing a change in direction towards the imaging of lower mass range metabolites. The unique feature that MSI brings to bio-analytical analysis is the possibility to analyse the distribution of hundreds of plant metabolites across a sample without any significant sample preparation. This has highlighted the potential of MSI techniques as ideal for metabolome analysis with the additional advantage of generating crucial spatial distribution information as well. The further development of MSI for the use in plant metabolomics is at an exciting time and the prospects for interesting new discoveries are very evident.
TL;DR: A comprehensive review of naturally occurring thiophenes can be found in this paper, where the sources, physical and spectral data, and biological activities of these compounds are discussed. But, the authors focus on the thiophene-containing compounds, which possess a wide range of biological properties such as antimicrobial, antiviral, HIV-1 protease inhibitor, antileishmanial, nematicidal, insecticidal, phototoxic and anticancer activities.
Abstract: Thiophenes are a class of heterocyclic aromatic compounds based on a five-membered ring made up of one sulfur and four carbon atoms. The thiophene nucleus is well established as an interesting moiety, with numerous applications in a variety of different research areas. Naturally occurring thiophenes are characteristic secondary metabolites derived from plants belonging to the family Asteraceae, such as Tagetes, Echinops, Artemisia, Balsamorhiza, Blumea, Pluchea, Porophyllum and Eclipta. Furthermore, naturally occurring thiophenes are generally composed of one to five thiophene rings that are coupled together through their α-carbons, and carry alkyl chains on their free ortho-positions. Thiophene-containing compounds possess a wide range of biological properties, such as antimicrobial, antiviral, HIV-1 protease inhibitor, antileishmanial, nematicidal, insecticidal, phototoxic and anticancer activities. This review focuses on naturally occurring thiophene derivatives; their sources, physical and spectral data, and biological activities.
TL;DR: An overview of the chemistry of secondary metabolites isolated from nutmeg kernel and mace including common methods for analysis of extracts and pure compounds as well as recent approaches towards total synthesis of some of the major constituents are provided.
Abstract: Nutmeg is a valued kitchen spice that has been used for centuries all over the world. In addition to its use in flavoring foods and beverages, nutmeg has been used in traditional remedies for stomach and kidney disorders. The antioxidant, antimicrobial and central nervous system effects of nutmeg have also been reported in literature. Nutmeg is a rich source of fixed and essential oil, triterpenes, and various types of phenolic compounds. Many of the secondary metabolites of nutmeg exhibit biological activities that may support its use in traditional medicine. This article provides an overview of the chemistry of secondary metabolites isolated from nutmeg kernel and mace including common methods for analysis of extracts and pure compounds as well as recent approaches towards total synthesis of some of the major constituents. A summary of the most significant pharmacological investigations of potential drug leads isolated from nutmeg and reported in the last decade is also included.
TL;DR: The recent identification of norbelladine 4′-O-methyltransferase (N4OMT), an Amaryllidaceae alkaloid biosynthetic enzyme, and the assembly of transcriptomes for Narcissus sp.
Abstract: Amaryllidaceae alkaloids are an example of the vast diversity of secondary metabolites with great therapeutic promise. The identification of novel compounds in this group with over 300 known structures continues to be an area of active study. The recent identification of norbelladine 4'-O-methyltransferase (N4OMT), an Amaryllidaceae alkaloid biosynthetic enzyme, and the assembly of transcriptomes for Narcissus sp. aff. pseudonarcissus and Lycoris aurea highlight the potential for discovery of Amaryllidaceae alkaloid biosynthetic genes with new technologies. Recent technical advances of interest include those in enzymology, next generation sequencing, genetic modification, nuclear magnetic resonance spectroscopy (NMR), and mass spectrometry (MS).
TL;DR: Alkamides are natural products formed by connecting straight-chain, mostly unsaturated, aliphatic acids with various amines by an amide linkage as discussed by the authors and are known from eight plant families consisting of various combinations of 200 acids with 23 amines.
Abstract: Alkamides are natural products formed by connecting straight-chain, mostly unsaturated, aliphatic acids with various amines by an amide linkage. More than 300 derivatives are known from eight plant families consisting of various combinations of 200 acids with 23 amines. Apart from a few saturated derivatives alkamides with unsaturated acid parts are grouped into compounds with purely olefinic patterns and those with olefinic and acetylenic linkages. Derived from C18 oleic acid the acid parts are modified either by chain elongations to C28 or by oxidative shortenings to C4 acid residues. Substrate and regiospecific desaturases and acetylenases are responsible for their characteristic patterns of unsaturation. Amine parts are derived from various amino acids by decarboxylation. Beside the widespread isobutylamines alkamides with six- and five-membered ring amines and those with phenylalanine derived amines are characteristic for the Asteraceae and Piperaceae while benzylamines are restricted to the Brassicaceae. Within the Asteraceae 2-methylbutylamine distinguishes the tribe Heliantheae from Anthemideae characterized by ring amines. Alkamides with elongated olefinic acid parts are mainly found in Piperaceae and Brassicaceae while acetylenic acid parts are typical for Asteraceae. A wide variety of biological activities ranges from the characteristic pungent/tingling property and high insecticidal toxicity to significant antifungal, antibacterial, antiprotozoal, molluscicidal, cercaricidal, and acaricidal activity. They also act as plant growth-promoting substances. Position and stereochemistry of the double bonds are essential for the different qualities of the pungent taste. Medically alkamides possess anti-inflammatory and analgesic properties and are responsible for immuno-modulatory and cannabinomimetic effects.
TL;DR: This work focuses on reviewing progresses achieved in understanding biosynthetic pathway, genetic breeding, metabolic engineering, and synthetic biology, and discusses multiple fundamental questions and challenges of artemisinin biosynthesis.
Abstract: Artemisinin-based combination therapy (ACT) forms the frontline treatment of malaria. Artemisinin, an endoperoxide sesquiterpenoid lactone biosynthesized by Artemisia annua, is the effective medicine that kills malarial parasites. Due to insufficient production of artemisinin for ACT, millions of people lost their lives in past years worldwide. To solve this severe problem, numerous studies have been undertaken to understand artemisinin biosynthesis and to innovate metabolic engineering technology to increase artemisinin yield. Here, we focus on reviewing progresses achieved in understanding biosynthetic pathway, genetic breeding, metabolic engineering, and synthetic biology. Furthermore, based on current knowledge, we discuss multiple fundamental questions and challenges.
TL;DR: The recent discoveries made on new steps in monoterpenoid indole alkaloid biosynthesis within Catharanthus roseus are described and placed in context of the existing literature on regulation and production of MIAs in whole plants compared to cell and organ cultures.
Abstract: There has been remarkable progress in the discovery of specialized metabolism pathways in the past few years. This has largely been due to the advent of inexpensive high throughput sequencing technologies, improved gene annotation methods and the development of tools for testing candidate genes for their involvement in particular biosynthetic pathways. This review describes the recent discoveries made on new steps in monoterpenoid indole alkaloid (MIA) biosynthesis within Catharanthus roseus. The review also places these discoveries in context of the existing literature on regulation and production of MIAs in whole plants compared to cell and organ cultures.
TL;DR: This review summarizes the current knowledge of staphylococcal efflux pumps and potential strategies to overcome them and suggests this mechanism may be a good target for new drugs based on synergistic interactions of antibiotics with plant extracts, essential oils, or their constituents with efflux pump inhibitory activity.
Abstract: The alarming growth of the number of antibiotic resistant bacteria and in the same time limited possibilities to develop new antimicrobial compounds, lead to an urgent need to keep the sensitivity of bacteria against currently used antibiotics. Bacterial efflux pumps are an important mechanism of antibiotic resistance as the bacteria use efflux pumps for the extrusion of different types of antibiotics and chemicals. The knowledge about inhibitors of efflux pumps from natural sources suggests that this mechanism may be a good target for new drugs based on synergistic interactions of antibiotics with plant extracts, essential oils, or their constituents with efflux pump inhibitory activity. This review summarizes the current knowledge of staphylococcal efflux pumps and potential strategies to overcome them. Natural inhibitors of efflux pumps and their synergistic interactions with antibiotics are summarized.
TL;DR: The present review reveals the scarcity of available identification methods for genipin, that should be taken into account to fulfill the recovery and quantification process ofgenipin.
Abstract: Genipin is a secoiridoid that may be obtained directly from Genipa americana and after geniposide hydrolysis from Gardenia jasminoides fruits. It is well known that genipin is a high added value product which has a great potential for its application in different fields, such as medicine and food industry. A lack of information and research about the development of novel methods for the environmental friendly recovery and purification of genipin exists, focused on the green recovery of genipin through emerging technologies that lead to the sustainable extraction. In the present review, the available methods for recovery of genipin and geniposide are enlisted and described, as well as the reaction mechanism of genipin, and the developed methods for genipin and geniposide identification and quantification based on HPLC analysis. Moreover, this work reveals the scarcity of available identification methods for genipin, that should be taken into account to fulfill the recovery and quantification process of genipin.
TL;DR: A number of in vitro systems of R. rosea are being developed as sources of pharmaceutically valuable secondary metabolites, greatly facilitated by advances in elucidation of the biosynthetic pathways and the enzymes, which catalyse the production of these secondary metabolites in the plant.
Abstract: Rhodiola rosea L. is a worldwide popular plant with adaptogenic activities that have been and currently are exploited in the traditional medicine of many countries, as well as, examined in a number of clinical trials. More than 140 chemical structures have been identified which belong to several natural product classes, including phenylpropanoid glycosides, phenylethanoids, flavonoids and essential oils, and are mainly stored in the rhizomes and the roots of the plant. A number of mechanisms contribute to the adaptogenic activities of R. rosea preparations and its phytochemical constituents. Among them, the intrinsic inducible mammalian stress responses and their effector proteins, such as heat shock protein 70 (Hsp70), are the most prominent. Due to its popular medicinal use, which has led to depletion of its natural habitats, R. rosea is now considered as endangered in most parts of the world. Conservation, cultivation and micropropagation are all implemented as potential preservation strategies. A number of in vitro systems of R. rosea are being developed as sources of pharmaceutically valuable secondary metabolites. These are greatly facilitated by advances in elucidation of the biosynthetic pathways and the enzymes, which catalyse the production of these secondary metabolites in the plant. In addition, biotechnological approaches show promise towards achieving sustainable production of R. rosea secondary metabolites.
TL;DR: Phytochemical investigations have shown that Lindera plants produce 341 constituents, including sesquiterpenoids, alkaloids, butanolides, lucidones, flavonoids, and phenylpropanoids, which have shown great potential in developing antiarthritic and antinociceptive agents.
Abstract: Lindera plants not only have good ornamental and economic uses but also have great medicinal and therapeutic values. The genus Lindera consists of approximately 100 species that are widely distributed in tropical and subtropical areas throughout the world. This extensive geographical distribution allows Lindera plants to produce diverse secondary metabolites having novel structures. Phytochemical investigations have shown that Lindera plants produce 341 constituents, including sesquiterpenoids, alkaloids, butanolides, lucidones, flavonoids, and phenylpropanoids. Moreover, some Lindera plants show significant chemotaxonomic reference under family Lauraceae and tribe Litseae. Although Lindera plants have various pharmacological and biological properties, their anticancer, antihypertensive, anti-inflammatory, and analgesic properties have been focused in many studies. Butanolides and lucidones have shown great potential in developing anticancer agents while aporphine alkaloids have shown great potential in developing antiarthritic and antinociceptive agents. However, these compounds need to be assessed further by performing in-depth and systematic research.
TL;DR: In this paper, a review summarizes the research on the isolation, structural elucidation, biological activities, and biosynthesis of the naphthalene derivatives published over the last years, in terms of their sources, physical and spectral data and biological activities.
Abstract: In the recent years, discovery, identification, and development of biologically active compounds have gained a lot of importance. Naphthalenes are a class of arenes, consisting of two ortho-fused benzene rings. Naphthalene derivatives displayed a wide range biological activities, such as antimicrobial, antioxidant, cytotoxic, anti-inflammatory, anti-protozoal, and anti-platelet aggregation. This review summarizes the research on the isolation, structural elucidation, biological activities, and biosynthesis of the naphthalene derivatives published over the last years. In the present review, 122 naphthalene derivatives isolated from plants, liverworts, fungi, and insects are discussed in term of their sources, physical and spectral data, and biological activities.
TL;DR: This review highlights knowledge of direct and indirect elm defences against biotic stressors focusing on morphological, chemical and gene regulation aspects and points to the gaps of knowledge on the chemical and molecular mechanisms of elm defence against pest insects and diseases.
Abstract: Elms (Ulmus spp.) have long been appreciated for their environmental tolerance, landscape and ornamental value, and the quality of their wood. Although elm trees are extremely hardy against abiotic stresses such as wind and pollution, they are susceptible to attacks of biotic stressors. Over 100 phytopathogens and invertebrate pests are associated with elms: fungi, bacteria and insects like beetles and moths, and to a lesser extent aphids, mites, viruses and nematodes. While the biology of the pathogen and insect vector of the Dutch elm disease has been intensively studied, less attention has been paid so far to the defence mechanisms of elms to other biotic stressors. This review highlights knowledge of direct and indirect elm defences against biotic stressors focusing on morphological, chemical and gene regulation aspects. First, we report how morphological defence mechanisms via barrier formation and vessel occlusion prevent colonisation and spread of wood- and bark-inhabiting fungi and bacteria. Second, we outline how secondary metabolites such as terpenoids (volatile terpenoids, mansonones and triterpenoids) and phenolics (lignans, coumarins, flavonoids) in leaves and bark are involved in constitutive and induced chemical defence mechanisms of elms. Third, we address knowledge on how the molecular regulation of elm defence is orchestrated through the interaction of a huge variety of stress- and defence-related genes. We conclude by pointing to the gaps of knowledge on the chemical and molecular mechanisms of elm defence against pest insects and diseases. An in-depth understanding of defence mechanisms of elms will support the development of sustainable integrated management of pests and diseases attacking elms.
TL;DR: Dietary flavonoids exert their genoprotection by reducing oxidative stress and modulation of enzymes responsible for bioactivation of genotoxic agents and detoxification of their reactive metabolites.
Abstract: Human exposure to genotoxic agents has dramatically increased. Both endogenous (reactive species generated during physiological and pathological processes) and exogenous (UV light, ionizing radiation, alkylating agents, antimetabolites and topoisomerase inhibitors, air, water and food pollutants) factors can impair genomic stability. The cumulative DNA damage causes mutations involved in the development of cancer and other disorders (neuromuscular and neurodegenerative diseases, immune deficiencies, infertility, cardiovascular diseases, metabolic syndrome and aging). Dietary flavonoids have protective effects against DNA damage induced by different genotoxic agents such as mycotoxins, food processing-derived contaminants (polycyclic aromatic hydrocarbons, N-nitrosamines), cytostatic agents, other medications (estrogenic and androgenic hormones), nicotine, metal ions (Cd2+, Cr6+), radiopharmaceuticals and ionizing radiation. Dietary flavonoids exert their genoprotection by reducing oxidative stress and modulation of enzymes responsible for bioactivation of genotoxic agents and detoxification of their reactive metabolites. Data on structure–activity relationship is sometimes contradictory. Free hydroxyl groups on the B ring (catechol moiety) and C-3 position of the C ring are important structural features for the antigenotoxic activity. As dietary flavonoids are extensively metabolized, more in vivo studies are needed for a better characterization of their antigenotoxic potential.
TL;DR: This review surveys δ-lactone withanolides and emphasizes their spectral features, configurations and biosynthetic genes and includes phytochemical species.
Abstract: Withanolides are highly oxygenated natural products. These C28 steroids with ergostane-based skeletons functionalized at C-22 and C-26 form six-membered δ-lactone rings. Withanolides containing a δ-lactone side chain often occur in Solanaceae and have a variety of biological activities because of their complicated structures. Characteristic spectroscopic behaviors and biosynthesis of withanolides are conducive to their structural elucidation and “biomimetic synthesis”, respectively. However, the last review to summarize their spectroscopic features and biosynthesis was in 1996. Since then, many withanolides with novel structures have been described by their spectra with biosynthesis investigated with many bioassays. This review surveys δ-lactone withanolides and emphasizes their spectral features, configurations and biosynthetic genes. The period reviewed includes through January 2014. We also include phytochemical species.
TL;DR: Nine Brazilian Amaryllidaceae species were studied for their alkaloid composition and acetylcholinesterase (AChE) inhibitory activity via GC–MS and a modified Ellman assay, respectively, and significant differences in the orientation of the N-methyl group are shown to be related to AChE inhibition.
Abstract: Nine Brazilian Amaryllidaceae species were studied for their alkaloid composition and acetylcholinesterase (AChE) inhibitory activity via GC–MS and a modified Ellman assay, respectively. A total of thirty-six alkaloids were identified in these plants, of which Hippeastrum papilio and H. glaucescens exhibited the highest galanthamine content and the best IC50 values against AChE. Furthermore, Hippeastrum vittatum and Rhodophiala bifida also showed notable AChE inhibitory effects. X-ray crystallographic data for four galanthamine-type compounds revealed significant differences in the orientation of the N-methyl group, which are shown to be related to AChE inhibition.
TL;DR: This review will summarise the current literature data on the features of hydroxycinnamoyltransferases from the four different enzyme groups and show how the same or very similar products can be formed by enzymes from different enzyme classes and using differently activated hydroxy cinnamoysl units.
Abstract: Hydroxycinnamoyltransferases are enzymes transferring hydroxycinnamoyl units like cinnamoyl, 4-coumaroyl, caffeoyl, feruloyl and sinapoyl moieties from an activating residue such as coenzyme A or glucose or activated as hydroxycinnamoyl ester (e.g. chlorogenate) to an acceptor molecule, most commonly to an OH or NH2 group as ester or amide. The hydroxycinnamoyl groups play either a “decorating” role or are building blocks of more complex structures. Proteins catalysing hydroxycinnamoyl transfer have been known for many decades and are nowadays investigated on molecular and structural levels. At least four different protein families give rise to enzymes with hydroxycinnamoyltransferase activity: serine carboxypeptidase-like proteins, tyramine hydroxycinnamoyltransferase-like enzymes, BAHD acyltransferases and GDSL-lipase/esterase-like enzymes. Interestingly, the same or very similar products can be formed by enzymes from different enzyme classes and using differently activated hydroxycinnamoyl units. This review will summarise the current literature data on the features of hydroxycinnamoyltransferases from the four different enzyme groups.