Chemicals in aroids: a survey, including new results for polyhydroxy alkaloids and alkylresorcinols

The Araceae is a large, mainly tropical family, many members of which contain bioactive substances which are often either toxic or irritating. Inflorescences frequently emit strong fragrances. The active compounds have not been adequately determined nor is the chemotaxonomy of the family very well known, except for one major study of flavonoids. Two groups of compounds of known bioactivity–alkylresorcinols and nitrogenous sugar analogues–have been sought in representative species from most of the genera in the family. Although percentage sampling was necessarily small, a few examples of species containing these substances were found and some taxonomic suggestions are made and compared with results in the literature. This survey is a basis for further work on the family.     

Observations on the phytochemistry of the Aloë leaf-exudate compounds

Exudates from the cut surfaces of Aloë leaves contain compounds, many of which can be recognized by their colour reaction with fast blue B salt after separation on thin-layer chromatograms. About 90 chromatographic zones were observed from c. 240 Aloë species. These included 24 orange-staining zones, 35 purple-staining zones and a variety of zones staining shades of grey, green, blue and brown. A few of these substances have been identified as known compounds. Each of the remaining compounds is given a code according to its colour reaction and each is referred to a standard plant source in which it is prominent. Thus a convenient basis for phytochemical discussions is provided. The distribution of the known compounds in the genus as recorded in the literature is compared with present findings. Chemical relationships often followed accepted taxonomic groupings. In particular, correlations were found among shrubby African species and a group of species from Somalia.     

Rearranged labdane diterpenoids from Galeopsis angustifolia

From the aerial part of Galeopsis angustifolia collected in Spain, a labdane and three rearranged labdane diterpenoids have been isolated. The structures of these new substances have been established by chemical and spectroscopic means and by correlation with known compounds. A sample of the same species collected in Italy and other species of Galeopsis showed some remarkable chemical differences. The taxonomic significance of these results is discussed briefly.     

New skeletons and new concepts in Amaryllidaceae alkaloids

The Amaryllidaceae alkaloids, represent a group of isoquinoline alkaloids, which are produced almost solely by members of the Amaryllidaceae family. The alkaloids of this family have attracted considerable amount of interest due to some important pharmacological activities they were shown to possess. In the last decade, our phytochemical studies on four Galanthus (Amaryllidaceae) species of Turkish origin have yielded quite a number of new alkaloids with diverse structures. Among these alkaloids, gracilines and plicamines constitute two new subgroups for the Amaryllidaceae alkaloids. The gracilines contain an incorporated 10b,4a-ethanoiminodibenzo[b,d]pyrane skeleton. The plicamines are dinitrogenous compounds, where the oxygen atom in position 7 of a tazettine skeleton is replaced by a nitrogen atom substituted by a pendant 4-hydroxyphenethyl moiety. One of the new alkaloids, galanthindole, which possesses a nonfused indole ring, unlike the already known subgroups of Amaryllidaceae alkaloids, may be considered as the prototype of a third new subgroup of the Amaryllidaceae alkaloids. Additionally, two known isoquinoline alkaloids which do not possess one of the established skeletons of the Amaryllidaceae alkaloids, namely ( − )-capnoidine and (+)-bulbocapnine, have been isolated from a Turkish Galanthus species. Totally, 21 new, 20 known alkaloids and 2 known lignans have been characterized. In this review, the isolation and structure elucidation of these compounds with interesting chemical structures are described.     

Prenylated flavonols and their distribution in flowering plants

The species of angiosperms known to contain prenylated flavonols and its glycosides have been listed family wise. It is present in 19 species in 14 genera and in six families of dicots only. The glycosides are confined to just two families. This review may suggest new sources for the compounds.     

Medicinal and pharmaceutical uses of seaweed natural products: A review

In the last three decades the discovery of metabolites with biological activities from macroalgae has increased significantly. However, despite the intense research effort by academic and corporate institutions, very few products with real potential have been identified or developed. Based on Silverplatter MEDLINE and Aquatic Biology, Aquaculture & Fisheries Resources databases, the literature was searched for natural products from marine macroalgae in the Rhodophyta, Phaeophyta and Chlorophyta with biological and pharmacological activity. Substances that currently receive most attention from pharmaceutical companies for use in drug development, or from researchers in the field of medicine-related research include: sulphated polysaccharides as antiviral substances, halogenated furanones from Delisea pulchra as antifouling compounds, and kahalalide F from a species of Bryopsis as a possible treatment of lung cancer, tumours and AIDS. Other substances such as macroalgal lectins, fucoidans, kainoids and aplysiatoxins are routinely used in biomedical research and a multitude of other substances have known biological activities. The potential pharmaceutical, medicinal and research applications of these compounds are discussed.     

Natural compounds with important medical potential found in Helleborus sp.

Helleborus (family Ranunculaceae) are well-known as ornamental plants, but less known for their therapeutic benefits. Over the past few years, Helleborus sp. has become a subject of interest for phytochemistry, pharmacology and other medical research areas. On the basis of their usefulness in traditional medicine, it was assumed that their biochemical profile could be a source of metabolites with the potential to overcome critical medical issues. There are studies involving natural extracts from these species which demonstrate that Helleborus plants are a valuable source of chemical compounds with great medical potential. Some phytochemicals produced by these species have been separated and identified a few decades ago: hellebrin, deglucohellebrin, 20-hydroxyecdysone and protoanemonin. Lately, many other active compounds have been reported and considered as promising remedies for severe diseases such as cancer, ulcer, diabetes and also for common medical problems such as toothache, eczema, low immunity and arthritis. This paper is an overview of the Helleborus genus focusing on some recentlydiscovered compounds and their potential for finding new drugs and useful biochemicals derived from these species.     

Diversity and distribution of floral scent

A list of 1719 chemical compounds identified from headspace samples of floral scent is presented. The list has been compiled from some 270 published papers, including analyses of 991 species of flowering plants and a few gymnosperms, a sample including seed plants from 90 families and 38 orders. The compounds belong to seven major compound classes, of which the aliphatics, the benzenoids and phenylpropanoids, and, among the terpenes, the mono- and sesquiterpenes, occur in most orders of seeds plants. C5-branched compounds, irregular terpenes, nitrogen-containing compounds, and a class of miscellaneous cyclic compounds have been recorded in about two-thirds of the orders. Sulfur-containing compounds occur in a third of the orders, whereas diterpenes have been reported from three orders only. The most common single compounds in floral scent are the monoterpenes limonene, (E)-β-ocimene, myrcene, linalool, α- and β-pinene, and the benzenoids benzaldehyde, methyl 2-hydroxybenzoate (methyl salicylate), benzyl alcohol, and 2-phenyl ethanol, which occur in 54–71% of the families investigated so far. The sesquiterpene caryophyllene and the irregular terpene 6-methyl-5-hepten-2-one are also common and occur in more than 50% of the families. Orchidaceae are by far the best investigated family, followed by several families known to have many species with strongly scented flowers, such as Araceae, Arecaceae, Magnoliaceae, and Rosaceae. However, the majority of angiosperm families are still poorly investigated. Relationships between floral scent and pollination, chemistry, evolution, and phylogeny are briefly discussed. It is concluded that floral scent chemistry is of little use for phylogenetic estimates above the genus level, whereas the distribution and combinations of floral scent compounds at species and subspecific levels is a promising field of investigation for the understanding of adaptations and evolutionary processes in angiosperms.     

Chemical constituents and medicinal properties of Allium species

Allium species, belonging to Alliaceae family, are among the oldest cultivated vegetables used as food. Garlic, onions, leeks and chives, which belong to this family, have been reported to have medicinal properties. The Allium species constituents have been shown to have antibacterial and antioxidant activities, and, in addition, other biological properties. These activities are related to their rich organosulfur compounds. These organosulfur compounds are believed to prevent the development of cancer, cardiovascular, neurological, diabetes, liver diseases as well as allergy and arthritis. There have also been reports on toxicities of these compounds. The major active compounds of Allium species includes, diallyl disulfide, diallyl trisulfide, diallyl sulfide, dipropyl disulfide, dipropyl trisulfide, 1-propenylpropyl disulfide, allyl methyl disulfide and dimethyl disulfide. The aim of this review is to focus on a variety of experimental and clinical reports on the effectiveness, toxicities and possible mechanisms of actions of the active compounds of garlic, onions, leek and chives.

     

A Multi-species Bait for Chagas Disease Vectors

Background

Triatomine bugs are the insect vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. These insects are known to aggregate inside shelters during daylight hours and it has been demonstrated that within shelters, the aggregation is induced by volatiles emitted from bug feces. These signals promote inter-species aggregation among most species studied, but the chemical composition is unknown.

Methodology/Principal Findings

In the present work, feces from larvae of the three species were obtained and volatile compounds were identified by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). We identified five compounds, all present in feces of all of the three species: Triatoma infestans, Panstrongylus megistus and Triatoma brasiliensis. These substances were tested for attractivity and ability to recruit insects into shelters. Behaviorally active doses of the five substances were obtained for all three triatomine species. The bugs were significantly attracted to shelters baited with blends of 160 ng or 1.6 µg of each substance.

Conclusions/Significance

Common compounds were found in the feces of vectors of Chagas disease that actively recruited insects into shelters, which suggests that this blend of compounds could be used for the development of baits for early detection of reinfestation with triatomine bugs.     

The taxonomic significance of C-glycosylxanthones in flowering plants

The species of angiosperms known to contain mangiferin or other C-glycosylxanthones have been listed by family and original literature reference. The 96 species in 28 genera in 19 families are divided between the dicots and monocots 60:18:13 and 36: 10:6, respectively. Contrary to earlier claims, the compounds appear to be of little taxonomic value at any level. There is no correlation between the occurrence of C-glycosylxanthones and morphological advancement. C-Glycosylxanthones are of pharmacological interest and this review may suggest new sources for the compounds.     

Iridoids in Hydrangeaceae

The content of glycosides in Kirengeshoma palmata and Jamesia americana (Hydrangeaceae) have been investigated. The former contains loganin and secoiridoids, including the alkaloid demethylalangiside. The latter contains no iridoids, but the known glucosides arbutin, picein and prunasin. In order to futher investigate the chemotaxonomy of the family Hydrangeaceae, the distribution of the iridoid and secoiridoid glucosides as well as the known biosynthetic pathways to these compounds have been reviewed. However, only a few genera of the family has been investigated. Loganin, secologanin, and derivatives of these are common. The genus Deutzia is characteristic in containing more structurally simple iridoids in which C-10 has been lost during biosynthesis. Such compounds have so far only been reported from the genus Mentzelia (Loasaceae). The taxonomic relationships between Hydrangeaceae and the closely related Cornaceae and Loasaceae is discussed and found to agree well with recent DNA sequence results.     

The aureolic acid family of antitumor compounds: structure, mode of action, biosynthesis, and novel derivatives

Members of the aureolic acid family are tricyclic polyketides with antitumor activity which are produced by different streptomycete species. These members are glycosylated compounds with two oligosaccharide chains of variable sugar length. They interact with the DNA minor groove in high-GC-content regions in a nonintercalative way and with a requirement for magnesium ions. Mithramycin and chromomycins are the most representative members of the family, mithramycin being used as a chemotherapeutic agent for the treatment of several cancer diseases. For chromomycin and durhamycin A, antiviral activity has also been reported. The biosynthesis gene clusters for mithramycin and chromomycin A₃ have been studied in detail by gene sequencing, insertional inactivation, and gene expression. Most of the biosynthetic intermediates in these pathways have been isolated and characterized. Some of these compounds showed an increase in antitumor activity in comparison with the parent compounds. A common step in the biosynthesis of all members of the family is the formation of the tetracyclic intermediate premithramycinone. Further biosynthetic steps (glycosylation, methylations, acylations) proceed through tetracyclic intermediates which are finally converted into tricyclic compounds by the action of a monooxygenase, a key event for the biological activity. Heterologous expression of biosynthetic genes from other aromatic polyketide pathways in the mithramycin producer (or some mutants) led to the isolation of novel hybrid compounds.Felipe Lombó and Nuria Menéndez have equally contribute to this work.     

Prediction of the Ligands of the CYP9e Subfamily of Ant Cytochrome P450 with the ChEBI Ontologies of Chemical and Biological Characteristics

Cytochromes P450 are involved in the metabolism of various endogenous and exogenous compounds, and their role in the detoxification of xenobiotics has been extensively studied. CYP9e, one of the subfamilies of cytochromes P450, whose functions have been poorly studied, is amplified in the black garden ant Lasius niger. We have performed molecular modeling of 23 proteins of this family belonging to L. niger and other ant species, as well as molecular docking and virtual screening of suspected ligands. The substances used as ligands have been annotated with ChEBI ontologies to predict the chemical and biological properties of molecules forming complexes with CYP9e of ants. It has been shown that, among the ligands forming energetically favorable complexes, ChEBI ontologies of mycotoxins, phytotoxins, steroids, glycosides and terpenoids are overrepresented. Nevertheless, it has been demonstrated that in carrying out a large number of inaccurate simulations, the results of function predictions can be correlated with molecular docking and the evolutionary history of a protein family.     

From tradition to innovation: the search for novel therapeutic molecules to treat diabetes

There are over a hundred chemical substances that have been derived from plants for use as drugs and medicines; many more await and medicinal plants are the target of all the attention. The structural diversity of natural products still surpasses that from synthetic compounds and is far beyond any imagination of experts in the field. For many pharmaceutical companies, it is a good argument to investigate natural compounds. Many plants with antidiabetic virtues are known in traditional medicine over the world. The CPID (Centre de Pharmacologie et Innovation dans le Diabète) proposes a technology program to purify new natural antidiabetic substances. A large antidiabetic plant library is constructed for a high-throughput pharmacological screening with cell cultures.     

The chemical diversity and distribution of glucosinolates and isothiocyanates among plants

Glucosinolates (beta-thioglucoside-N-hydroxysulfates), the precursors of isothiocyanates, are present in sixteen families of dicotyledonous angiosperms including a large number of edible species. At least 120 different glucosinolates have been identified in these plants, although closely related taxonomic groups typically contain only a small number of such compounds. Glucosinolates and/or their breakdown products have long been known for their fungicidal, bacteriocidal, nematocidal and allelopathic properties and have recently attracted intense research interest because of their cancer chemoprotective attributes. Numerous reviews have addressed the occurrence of glucosinolates in vegetables, primarily the family Brassicaceae (syn. Cruciferae; including Brassica spp and Raphanus spp). The major focus of much previous research has been on the negative aspects of these compounds because of the prevalence of certain "antinutritional" or goitrogenic glucosinolates in the protein-rich defatted meal from widely grown oilseed crops and in some domesticated vegetable crops. There is, however, an opposite and positive side of this picture represented by the therapeutic and prophylactic properties of other "nutritional" or "functional" glucosinolates. This review addresses the complex array of these biologically active and chemically diverse compounds many of which have been identified during the past three decades in other families. In addition to the Brassica vegetables, these glucosinolates have been found in hundreds of species, many of which are edible or could provide substantial quantities of glucosinolates for isolation, for biological evaluation, and potential application as chemoprotective or other dietary or pharmacological agents.     

Natural production of fluorinated compounds and biotechnological prospects of the fluorinase enzyme

Fluorinated compounds are finding increasing uses in several applications. They are employed in almost all areas of modern society. These compounds are all produced by chemical synthesis and their abundance highly contrasts with fluorinated molecules of natural origin. To date, only some plants and a handful of actinomycetes species are known to produce a small number of fluorinated compounds that include fluoroacetate (FA), some ω-fluorinated fatty acids, nucleocidin, 4-fluorothreonine (4-FT), and the more recently identified (2R3S4S)-5-fluoro-2,3,4-trihydroxypentanoic acid. This largely differs from other naturally produced halogenated compounds, which totals more than 5000. The mechanisms underlying biological fluorination have been uncovered after discovering the first actinomycete species, Streptomyces cattleya, that is capable of producing FA and 4-FT, and a fluorinase has been identified as the enzyme responsible for the formation of the C–F bond. The discovery of this enzyme has opened new perspectives for the biotechnological production of fluorinated compounds and many advancements have been achieved in its application mainly as a biocatalyst for the synthesis of [¹⁸F]-labeled radiotracers for medical imaging. Natural fluorinated compounds may also be derived from abiogenic sources, such as volcanoes and rocks, though their concentrations and production mechanisms are not well known. This review provides an outlook of what is currently known about fluorinated compounds with natural origin. The paucity of these compounds and the biological mechanisms responsible for their production are addressed. Due to its relevance, special emphasis is given to the discovery, characterization and biotechnological potential of the unique fluorinase enzyme.     

Terpen-derivate aus Senecio-arten

Investigation of about 50 Senecio species has afforded many new substances, in addition to known compounds. Present in these plants are 23 fura     

Flavonoids and chemotaxonomy of the Commelinaceae

Diverse schemes have been proposed for the classification of the Commelinaceae on the basis of different characters. The leaf flavonoids of 152 species have been analysed. The flavone C-glycosides are the dominant compounds, found in 78% of the species examined. Flavonol O-glycosides are present in 28% of the species, quercetin being the most frequent aglycone. 6-Hydroxyluteolin was found mainly in Tradescantia but also in other species (10%). Tricin has been detected sporadically in less than 5% of the species. In spite of these variations the pattern of the family is very uniform, because the presence of C-glycoflavones and the distribution of the other compounds supports the scheme proposed by Rohweder who divided the family into Commelinieae and Tradescantieae on the basis of inflorescence characters.     

Antioxidant polyphenols from the mycelial culture of the medicinal fungi Inonotus xeranticus and Phellinus linteus

Aims:  The medicinal fungi Inonotus xeranticus and Phellinus linteus in the family Hymenochaetaceae have been used as traditional medicines for the treatment of various diseases. However, the compound responsible for the antioxidant activity is still unknown. Therefore, this study was conducted to characterize the antioxidant substances present in cultured broths made from these fungi.
Methods and Results:  Antioxidant fractions of the cultured broths obtained from I. xeranticus and P. linteus were analysed using reversed-phase HPLC, which revealed several peaks that exhibited a potent free radical scavenging activity. To identify these antioxidant peaks, an I. xeranticus strain was mass-cultured, and the cultured broth was separated using antioxidant activity-guided fractionation. Four major active substances were purified and identified as hispidin and its dimers, 3,14'-bihispidinyl, hypholomine B, and 1,1-distyrylpyrylethan based on spectroscopic analyses. All compounds exhibited a significant scavenging activity against these radical species in a concentration-dependent manner.
Conclusions:  Antioxidant substances found in the cultured broths of the medicinal fungi I. xeranticus and P. linteus were identified as hispidin and its dimers, 3,14'-bihispidinyl, hypholomine B, and 1,1-distyrylpyrylethan.
Significance and Impact of the Study:  Polyphenol antioxidants were isolated from the cultured broth of the medicinal fungi I. xeranticus and P. linteus and identified based on extensive spectroscopic analyses. These compounds exhibited a strong antioxidant activity.