Specificity in the interaction between an epibiotic clavicipitalean fungus and its convolvulaceous host in a fungus/plant symbiotum

Ipomoea asarifolia and Turbina corymbosa (Convolvulaceae) are associated with epibiotic clavicipitalean fungi responsible for the presence of ergoline alkaloids in these plants. Experimentally generated plants devoid of these fungi were inoculated with different epibiotic and endophytic fungi resulting in a necrotic or commensal situation. A symbiotum of host plant and its respective fungus was best established by integration of the fungus into the morphological differentiation of the host plant. This led us to suppose that secretory glands on the leaf surface of the host plant may play an essential role in ergoline alkaloid biosynthesis which takes place in the epibiotic fungus.Key words: ergoline alkaloids, ipomoea, turbina, convolvulaceae, claviceps, balansia, clavicipitaceae, penicillium, plant-fungus symbiotum     

Ergoline alkaloids in convolvulaceous host plants originate from epibiotic clavicipitaceous fungi of the genus Periglandula

Ergoline (i.e., ergot) alkaloids are a group of physiologically active natural products occurring in the taxonomically unrelated fungal and plant taxa, Clavicipitaceae and Convolvulaceae, respectively. The disjointed occurrence of ergoline alkaloids seems to contradict the frequent observation that identical or at least structurally related natural products occur in organisms with a common evolutionary history. This problem has now been solved by the finding that not only graminaceous but also some dicotyledonous plants belonging to the family Convolvulaceae, such as Ipomoea asarifolia and Turbina corymbosa, form close associations with ergoline alkaloid producing fungi, Periglandula ipomoeae and Periglandula turbinae. These species belong to the newly established genus Periglandula within the Clavicipitaceae. The fungus–plant associations are likely to be mutualistic symbioses.     

An Ergot Alkaloid Biosynthesis Gene and Clustered Hypothetical Genes from Aspergillus fumigatus

The ergot alkaloids are a family of indole-derived mycotoxins with a variety of significant biological activities. Aspergillus fumigatus, a common airborne fungus and opportunistic human pathogen, and several fungi in the relatively distant taxon Clavicipitaceae (clavicipitaceous fungi) produce different sets of ergot alkaloids. The ergot alkaloids of these divergent fungi share a four-member ergoline ring but differ in the number, type, and position of the side chains. Several genes required for ergot alkaloid production are known in the clavicipitaceous fungi, and these genes are clustered in the genome of the ergot fungus Claviceps purpurea. We investigated whether the ergot alkaloids of A. fumigatus have a common biosynthetic and genetic origin with those of the clavicipitaceous fungi. A homolog of dmaW, the gene controlling the determinant step in the ergot alkaloid pathway of clavicipitaceous fungi, was identified in the A. fumigatus genome. Knockout of dmaW eliminated all known ergot alkaloids from A. fumigatus, and complementation of the mutation restored ergot alkaloid production. Clustered with dmaW in the A. fumigatus genome are sequences corresponding to five genes previously proposed to encode steps in the ergot alkaloid pathway of C. purpurea, as well as additional sequences whose deduced protein products are consistent with their involvement in the ergot alkaloid pathway. The corresponding genes have similarities in their nucleotide sequences, but the orientations and positions within the cluster of several of these genes differ. The data indicate that the ergot alkaloid biosynthetic capabilities in A. fumigatus and the clavicipitaceous fungi had a common origin.     

Molecular characterization of a seed transmitted clavicipitaceous fungus occurring on dicotyledoneous plants (Convolvulaceae)

Ergoline alkaloids (syn. ergot alkaloids) are constituents of clavicipitaceous fungi (Ascomycota) and of one particular dicotyledonous plant family, the Convolvulaceae. While the biology of fungal ergoline alkaloids is rather well understood, the evolutionary and biosynthetic origin of ergoline alkaloids within the family Convolvulaceae is unknown. To investigate the possible origin of ergoline alkaloids from a plant-associated fungus, 12 endophytic fungi and one epibiotic fungus were isolated from an ergoline alkaloid-containing Convolvulaceae plant, Ipomoea asarifolia Roem. & Schult. Phylogenetic trees constructed from 18S rDNA genes as well as internal transcribed spacer (ITS) revealed that the epibiotic fungus belongs to the family Clavicipitaceae (Ascomycota) whereas none of the endophytic fungi does. In vitro and in vivo cultivation on intact plants gave no evidence that the endophytic fungi are responsible for the accumulation of ergoline alkaloids in I. asarifolia whereas the epibiotic clavicipitaceous fungus very likely is equipped with the genetic material to synthesize these compounds. This fungus resisted in vitro and in vivo cultivation and is seed transmitted. Several observations strongly indicate that this plant-associated fungus and its hitherto unidentified relatives occurring on different Convolvulaceae plants are responsible for the isolated occurrence of ergoline alkaloids in Convolvulaceae. This is the first report of an ergot alkaloid producing clavicipitaceous fungus associated with a dicotyledonous plant.Data deposition: The sequences reported in this paper have been deposited in the GenBank (accession numbers are given in the text and in Fig. 3) Dedicated to Dr. Dr. h. c. mult. Albert Hofmann, the great pioneer of ergot research, on the occasion of his 100th birthday     

An Old Yellow Enzyme Gene Controls the Branch Point between Aspergillus fumigatus and Claviceps purpurea Ergot Alkaloid Pathways

Ergot fungi in the genus Claviceps and several related fungal groups in the family Clavicipitaceae produce toxic ergot alkaloids. These fungi produce a variety of ergot alkaloids, including clavines as well as lysergic acid derivatives. Ergot alkaloids are also produced by the distantly related, opportunistic human pathogen Aspergillus fumigatus. However, this fungus produces festuclavine and fumigaclavines A, B, and C, which collectively differ from clavines of clavicipitaceous fungi in saturation of the last assembled of four rings in the ergoline ring structure. The two lineages are hypothesized to share early steps of the ergot alkaloid pathway before diverging at some point after the synthesis of the tricyclic intermediate chanoclavine-I. Disruption of easA, a gene predicted to encode a flavin-dependent oxidoreductase of the old yellow enzyme class, in A. fumigatus led to accumulation of chanoclavine-I and chanoclavine-I-aldehyde. Complementation of the A. fumigatus easA mutant with a wild-type allele from the same fungus restored the wild-type profile of ergot alkaloids. These data demonstrate that the product of A. fumigatus easA is required for incorporation of chanoclavine-I-aldehyde into more-complex ergot alkaloids, presumably by reducing the double bond conjugated to the aldehyde group, thus facilitating ring closure. Augmentation of the A. fumigatus easA mutant with a homologue of easA from Claviceps purpurea resulted in accumulation of ergot alkaloids typical of clavicipitaceous fungi (agroclavine, setoclavine, and its diastereoisomer isosetoclavine). These data indicate that functional differences in the easA-encoded old yellow enzymes of A. fumigatus and C. purpurea result in divergence of their respective ergot alkaloid pathways.Different classes of ergot alkaloids are produced by members of two distinct fungal lineages. Clavicipitaceous species, which include Claviceps spp. and Neotyphodium spp., are in the order Hypocreales and typically synthesize lysergic acid derivatives (13, 16, 18). These alkaloids have a double bond in the last assembled of four rings (D ring) of the tetracyclic ergoline ring structure. Ergot alkaloids are also produced by the distantly related opportunistic human pathogen Aspergillus fumigatus, a member of the order Eurotiales (8, 14, 16, 18). Ergot alkaloids of A. fumigatus are of the clavine class and differ from the more complex profile of Claviceps purpurea and Neotyphodium spp. One important distinction between the ergot alkaloids produced by these different fungi is the saturation of the fourth ring of the ergoline structure in A. fumigatus (Fig. ​(Fig.11).Open in a separate windowFIG. 1.Structures and relationships of relevant ergot alkaloids. (A) Chanoclavine-I is oxidized to its aldehyde form before being incorporated into festuclavine (and downstream alkaloids) in A. fumigatus or agroclavine (and downstream alkaloids) in C. purpurea. (B) Conventional ring labeling and atom numbering referred to in the text.Several genes involved in the ergot alkaloid pathways of A. fumigatus and clavicipitaceous fungi are found clustered together in the genome of each species (3, 4, 6, 18, 23). These distantly related fungi are hypothesized to share several early pathway steps, after which the pathways diverge to yield distinct sets of ergot alkaloids (3, 13, 16). The gene dmaW, which encodes dimethylallyltryptophan (DMAT) synthase, catalyzes the prenylation of tryptophan that initiates the ergot alkaloid pathway in clavicipitaceous fungi (22, 25) and functions similarly in A. fumigatus (3, 24). The region surrounding this gene in A. fumigatus contains homologues of genes also found in Neotyphodium lolii and C. purpurea ergot alkaloid gene clusters (3, 4, 6). One of the shared genes, easA, is predicted to encode a member of the old yellow enzyme (OYE) family of oxidoreductases. Old yellow enzymes are flavin-containing oxidoreductases initially found in the brewer''s bottom yeast Saccharomyces carlsbergensis (26). Enzymes in this family use a reduced flavin cofactor and an active-site tyrosine residue to reduce the carbon-carbon double bond in an α/β-unsaturated aldehyde or ketone (7, 10). Subsequently, the enzymes require NADPH to restore the flavin cofactor to its reduced state. OYEs catalyze multiple reactions useful for both biotechnological and pharmaceutical applications; however, physiological roles and natural substrates for many of these enzymes presently are unknown (26). On the basis of the apparent need in the ergot alkaloid pathway of A. fumigatus for reduction of a carbon-carbon double bond in the intermediate chanoclavine-I-aldehyde, we hypothesized that the OYE-encoding gene easA is required for ergot alkaloid biosynthesis (3, 16). In this study, easA in A. fumigatus was disrupted and complemented to ascertain the role of its gene product in ergot alkaloid biosynthesis.     

Elimination of ergoline alkaloids following treatment of<Emphasis Type="Italic"> Ipomoea asarifolia</Emphasis> (Convolvulaceae) with fungicides

Ergoline alkaloids are constituents of Clavicipitaceous fungi living on Poaceae plants. Ergoline alkaloids as well as volatile oil are also present in Ipomoea asarifolia Roem. & Schult (Convolvulaceae). Treatment of this plant with two fungicides (Folicur, Pronto Plus) eliminates the ergoline alkaloids but not the volatile oil. Elimination of ergoline alkaloids occurs concomitantly with loss of fungal hyphae associated with secretory glands on the upper leaf surface of the Ipomoea plant. Our observations suggest that accumulation of ergoline alkaloids in the Convolvulaceae may depend on the presence of a plant-associated fungus.Dedicated to Wolfgang Steglich, München, on the occasion of his 70th birthday     

Composition and stereochemistry of ephedrine alkaloids accumulation in Ephedra sinica Stapf

Ephedra sinica Stapf (Ephedraceae) is a widely used Chinese medicinal plant (Chinese name: Ma Huang). The main active constituents of E. sinica are the unique and taxonomically restricted adrenergic agonists phenylpropylamino alkaloids, also known as ephedrine alkaloids: (1R,2S)-norephedrine (1S,2S)-norpseudoephedrine, (1R,2S)-ephedrine, (1S,2S)-pseudoephedrine, (1R,2S)-N-methylephedrine and (1S,2S)-N-methylpseudoephedrine. GC–MS analysis of freshly picked young E. sinica stems enabled the detection of 1-phenylpropane-1,2-dione and (S)-cathinone, the first two putative committed biosynthetic precursors to the ephedrine alkaloids. These metabolites are only present in young E. sinica stems and not in mature stems or roots. The related Ephedra foemina and Ephedra foliata also lack ephedrine alkaloids and their metabolic precursors in their aerial parts. A marked diversity in the ephedrine alkaloids content and stereochemical composition in 16 different E. sinica accessions growing under the same environmental conditions was revealed, indicating genetic control of these traits. The accessions can be classified into two groups according to the stereochemistry of the products accumulated: a group that displayed only 1R stereoisomers, and a group that displayed both 1S and 1R stereoisomers. (S)-cathinone reductase activities were detected in E. sinica stems capable of reducing (S)-cathinone to (1R,2S)-norephedrine and (1S,2S)-norpseudoephedrine in the presence of NADH. The proportion of the diastereoisomers formed varied according to the accession tested. A (1R,2S)-norephedrine N-methyltransferase capable of converting (1R,2S)-norephedrine to (1R,2S)-ephedrine in the presence of S-adenosylmethionine (SAM) was also detected in E. sinica stems. Our studies further support the notion that 1-phenylpropane-1,2-dione and (S)-cathinone are biosynthetic precursors of the ephedrine alkaloids in E. sinica stems and that the activity of (S)-cathinone reductases directs and determines the stereochemical branching of the pathway. Further methylations are likely due to N-methyltransferase activities.     

Biosynthesis and accumulation of ergoline alkaloids in a mutualistic association between Ipomoea asarifolia (Convolvulaceae) and a clavicipitalean fungus

Ergoline alkaloids occur in taxonomically unrelated taxa, such as fungi, belonging to the phylum Ascomycetes and higher plants of the family Convolvulaceae. The disjointed occurrence can be explained by the observation that plant-associated epibiotic clavicipitalean fungi capable of synthesizing ergoline alkaloids colonize the adaxial leaf surface of certain Convolvulaceae plant species. The fungi are seed transmitted. Their capacity to synthesize ergoline alkaloids depends on the presence of an intact differentiated host plant (e.g. Ipomoea asarifolia or Turbina corymbosa [Convolvulaceae]). Here, we present independent proof that these fungi are equipped with genetic material responsible for ergoline alkaloid biosynthesis. The gene (dmaW) for the determinant step in ergoline alkaloid biosynthesis was shown to be part of a cluster involved in ergoline alkaloid formation. The dmaW gene was overexpressed in Saccharomyces cerevisiae, the encoded DmaW protein purified to homogeneity, and characterized. Neither the gene nor the biosynthetic capacity, however, was detectable in the intact I. asarifolia or the taxonomically related T. corymbosa host plants. Both plants, however, contained the ergoline alkaloids almost exclusively, whereas alkaloids are not detectable in the associated epibiotic fungi. This indicates that a transport system may exist translocating the alkaloids from the epibiotic fungus into the plant. The association between the fungus and the plant very likely is a symbiotum in which ergoline alkaloids play an essential role.     

On the Mechanism for the Formation of Indole Alkaloids in Penicillium concavo-rugulosum

Experiments on the biosynthesis and microbiological conversion of indole alkaloids in Pénicillium concavo-rugulosum were carried out with the growing and resting mycelia, respectively, of a selected strain of the same mold. The former experiments were performed by the use of dl-tryptophan-3-¹⁴C or dl-mevalonic acid-2-¹⁴C-lactone as a precursor, while the latter experiments by the use of rugulovasine A–³H, dihydrorugulovasine A–³H, 4-[γ, γ-dimethylallyl]-tryptophan-³H, chanoclavine-[I]–³H or the other tritilated ergoline alkaloids. The results of these experiments suggested that in the Penicillium mold employed there exist the following biosynthetic route: tryptophan + mevalonic acid→4-[γ, γ-dimethylallyl]-tryptophan→rugulovasine A→dihydrorugulovasine A→dihydrorugulovasine A-lactam.     

Physiological status of submergedClaviceps during enzymic assembly of ergot alkaloids

Ergot alkaloids are formed only for arelatively brief time during the lifespan of the culture and under conditions of reduced proliferation. They cannot be taken for waste products of general metabolism. Ergot strains are capable of carrying out all the simple steps of the anthranilic acid—tryptophan cycles. Alkaloids influence activities of certain enzymes of primary metabolism in the ergot mycelium,e.g. tryptophan synthetase, acetyl-CoA carboxylase, citrate synthase, isocitrate lyase, and malate synthase. Ergot alkaloids do not belong to a group of physiologically inert secondary metabolites. A tentative scheme of the enzymic assembly of the ergoline nucleus is presented. The increased yield of ergoline alkaloids may be attributed to the following points: (1) Unbalnced growth of the culture. (2) Support of competition of fatty acids and alkaloid biosynthesis for acetyl-CoA. (3) Decreased activities of tricarboxylic acid and glyoxylate cycles. (4) Positive association between the rate of protein turnover and alkaloid formation. (5) Stimulation of both tryptophan synthesis and degradation via kynurenine—anthranilate. (6) Regulation of tryptophan-histidine cross-pathway. (7) Continuous control of the alkaloid level during fermentation.     

Abundant Respirable Ergot Alkaloids from the Common Airborne Fungus Aspergillus fumigatus

Ergot alkaloids are mycotoxins that interact with several monoamine receptors, negatively affecting cardiovascular, nervous, reproductive, and immune systems of exposed humans and animals. Aspergillus fumigatus, a common airborne fungus and opportunistic human pathogen, can produce ergot alkaloids in broth culture. The objectives of this study were to determine if A. fumigatus accumulates ergot alkaloids in a respirable form in or on its conidia, to quantify ergot alkaloids associated with conidia produced on several different substrates, and to measure relevant physical properties of the conidia. We found at least four ergot alkaloids, fumigaclavine C, festuclavine, fumigaclavine A, and fumigaclavine B (in order of abundance), associated with conidia of A. fumigatus. Under environmentally relevant conditions, the total mass of ergot alkaloids often constituted >1% of the mass of the conidium. Ergot alkaloids were extracted from conidia produced on all media tested, and the greatest quantities were observed when the fungus was cultured on latex paint or cultured maize seedlings. The values for physical properties of conidia likely to affect their respirability (i.e., diameter, mass, and specific gravity) were significantly lower for A. fumigatus than for Aspergillus nidulans, Aspergillus niger, and Stachybotrys chartarum. The demonstration of relatively high concentrations of ergot alkaloids associated with conidia of A. fumigatus presents opportunities for investigations of potential contributions of the toxins to adverse health effects associated with the fungus and to aspects of the biology of the fungus that contribute to its success.     

Screening for Ergot Alkaloid Producers among Microscopic Fungi by Means of the Polymerase Chain Reaction

The potential of the polymerase chain reaction for the detection of ergot alkaloid producers among microscopic fungi of the generaPenicilliumand Clavicepswas evaluated. Twenty-three strains of various species of fungi with a previously studied capacity for alkaloid production were used. The internal fragment of the gene encoding 4-dimethylallyltryptophan synthase, the enzyme catalyzing the first step in the biosynthesis of ergot alkaloids, was amplified using degenerate primers. This approach revealed an about 1.2-kb specific DNA fragment in micromycetes synthesizing ergot alkaloids with complete tetracyclic ergoline system. Microorganisms that produce alkaloids with modified C or D ergoline rings, as well as -cyclopiazonic acid, did not yield the PCR fragment of the expected size. This fragment was also not found in fungi incapable of ergot alkaloid production.     

Lumi-ergometrine – structural identification and occurrence in sclerotia

The fungus Claviceps purpurea grows on grasses and cereal grains and produces six predominant ergot alkaloids. These toxic substances undergo different transformation reactions during storage and cereal processing. One of these reactions is the addition of water to a double bond in the ergoline skeleton. Since light is required for this process, the substances formed were named lumi-ergot alkaloids. From these, a new asymmetric carbon and consequently two epimers with different polarities are formed. For investigations of lumi-ergot alkaloids, ergometrine was used exemplarily as it represents one of the six ergot alkaloids predominantly formed by Claviceps purpurea. The main reaction product, the less polar compound of the two lumi-ergometrine epimers, was separated by HPLC and unambiguously identified as 10-(S)-lumi-ergometrine using X-ray structural analysis. A HPLC-MS/MS method was developed for the detection of this substance in sclerotia extracts. Using this method, the existence of both epimeric forms of lumi-ergometrine could be proved in the sclerotia. This is the first time that the existence of a lumi-transformation product of ergot alkaloids was proved in naturally grown samples.     

Monoterpenoid indole alkaloids from Kopsia hainanensis Tsiang

A phytochemical investigation on the twigs and leaves of Kopsia hainanensis Tsiang resulted in the isolation and identification of 18 alkaloids, including two sarpagine type alkaloids (1 and 2), five eburnane type alkaloids (3–7), three aspidofractinine type alkaloids (8–10), one vincadine type alkaloid (11), three akuammiline type alkaloids (12–13 and 15), one corynanthean type alkaloid (14), two ajmalicine-like type alkaloids (16 and 17), and one aspidospermine type alkaloid (18). The new structure of compound 1 was elucidated by means of spectroscopic analysis, including HRESIMS, and 1D and 2D NMR experiments. Compounds 1–2, 4–5, 7, and 10–17 are herein reported for the first time from this plant, while the compounds 1, 2, 7, and 12–17 have not been previously recorded in the Kopsia genus. The chemotaxonomic significance and distribution of these monoterpenoid indole alkaloids in Kopsia genus are discussed.     

The Fungus Penicillium citrinum Thom 1910 VKM FW-800 Isolated from Ancient Permafrost Sediments As a Producer of the Ergot Alkaloids Agroclavine-1 and Epoxyagroclavine-1

The study of the secondary metabolites of the relict strain Penicillium citrinum VKM FW-800 isolated from ancient Arctic permafrost sediments showed that this fungus produces agroclavine-1 and epoxyagroclavine-1, which are rare ergot alkaloids with the 5R,10S configuration of the tetracyclic ergoline ring system. The production of the alkaloids by the fungus showed a biphasic behavior, being intense in the phase of active growth and slowing down in the adaptive lag phase and in the stationary growth phase. The addition of zinc ions to the incubation medium led to a fivefold increase in the yield of the alkaloids. The alkaloid-producing Penicillium fungi isolated from different regions exhibited the same tendencies of growth and alkaloid production.     

Alkaloid secretion inhibited by antibiotics in Aphaenogaster ants

Although alkaloids are frequent in the poison glands of ants of the genus Aphaenogaster, this is not the case for A. iberica. Hypothesizing that in the genus Aphaenogaster, alkaloids are produced by symbiotic bacteria, except for A. iberica, we treated an experimental lot of both A. iberica and a ‘classical’ Aphaenogaster species, A. senilis, with an antibiotic. Compared to workers from a control lot, this treatment reduced considerably alkaloid production in A. senilis, whereas A. iberica did not react to the treatment. Furthermore, the treatment induced an increase in cuticular hydrocarbon quantities in A. senilis, but not in A. iberica. An analysis of the ant microbiota will be the next step to confirm our hypothesis.     

Concomitant occurrence of pyrrolizidine and quinolizidine alkaloids in the hemiparasite Osyris alba L. (Santalaceae)

The investigation of the alkaloid extracts of the hemiparasitic plant Osyris alba, collected from three different localities in southern France, revealed the concomitant presence of both pyrrolizidine (PA) and quinolizidine (QA) alkaloids in the samples from two of these localities. The sample from the third locality contained only PAs. The eight QAs identified were sparteine, N-methylcytisine, cytisine, methyl-12-cytisine acetate, hydroxy-N-methylcytisine, N-acetylcytisine, lupanine, and anagyrine. Of the eleven detected PAs, eight were identified as chysin A, chysin B, 1-carboxypyrrolizidine-7-olide, senecionine, integerrimine, retrorsine, senecivernine and a new alkaloid janfestine (7R-hydroxychysin A or 1R-carbomethoxy-7R-hydroxypyrrolizidine). PAs were mainly present as their N-oxides This is, to our knowledge, the first report demonstrating the simultaneous presence of two classes of alkaloids, quinolizidine and pyrrolizidine alkaloids, in a single parasitic plant. As these alkaloids do not occur in the same host plant, the results indicate that Osyris must have tapped more than one host plant concomitantly. Since both quinolizidine and pyrrolizidine alkaloids serve as defence compounds against herbivores, affecting different molecular targets, the simultaneous acquisition of the two types of alkaloids by a single plant could provide a novel mode of defence of hemiparasites against herbivores.     

Two new steroidal alkaloids from the mature fruits of Solanum nigrum

Two previously undescribed steroidal alkaloids, compounds 1–2, were isolated from the ripe fruits of Solanum nigrum, along with seven known metabolites (3–9). Based on spectroscopic and chemical evidence, including IR, NMR, and HR-ESI-MS analyses, the structures of the isolated compounds were elucidated as 12β-hydroxy-(3β,22α,25R)-spirosol-5-en-27-acid-3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→3)]-β-D-galacopyranoside and 12β-hydroxy-(3β,22α,25R)-spirosol-5-en-27-acid-3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside. Four steroidal alkaloids (compounds 1–2 and 4–5) were tested for their anti-proliferative effects against the HT-29, A549, and Lewis cell lines. Both of the previously isolated compounds inhibited the proliferation of these three cell lines in a dose-dependent manner, with the most significant effect being in the A549 cells, but neither reached IC₅₀ at 50 μM. These results revealed that S. nigrum had weak cytotoxicity, indicating its clinical safety as a traditional anti-tumor herbal medicine.     

Chemical constituents of Melodinus hemsleyanus diels

Phytochemical investigation on the aerial parts of Melodinus hemsleyanus diels (Jahrb, Syst, 1995) led to the isolation and identification of 27 compounds, including fifteen aspidosperma-type alkaloids (1–15), four quinoline-type alkaloids (16–19), three quebrachamine-type alkaloids (20–22), and five eburna-type alkaloids (23–27). The structure of compound 1 was elucidated by means of spectroscopic analysis, including HRESIMS, and 1D and 2D NMR experiments. Compounds 1–2, 6, 10, 12, 13, 15, 16 and 20–27 are herein reported for the first time from the studied plant, while the compounds 1–2 and 21 have not previously been recorded in the genus Melodinus. The aspidosperma-type monoterpenoid indole alkaloids in M. hemsleyanus could serve as chemotaxonomic markers.     

Chemical constituents from the leaves and branches of Annona coriacea Mart. (Annonaceae)

The phytochemical investigation of the leaves and branches of Annona coriacea Mart. (Annonaceae) led to the isolation and characterization of eight compounds: five isoquinoline-derived alkaloids, including pukateine (1), liriodenine (4), anonaine (5), obovanine (6), and norisocorydine (7); one terpene lactone known as loliolide (3); one benzoic acid derivative, 2-methoxybenzoic acid (2), and 3,4,5-trimethoxyphenol (8). All compounds, except liriodenine, are being described for the first time in the species A. coriacea, and their chemophenetics relationships were discussed. The structures were elucidated by extensive analyses of 1D and 2D NMR (COSY, HSQC, and HMBC) spectroscopy in combination with MS, and the data were compared with literature values. The NMR dataset of pukateine and obovanine was reviewed. Our results showed that A. coriacea is a typical species of the Annonaceae family and an important source of aporphine alkaloids with chemophenetic relationships with Xylopia, Duguetia, Guatteria, Artabotrys, and Goniothalamus genera.