Isolation and structure of gustastatin from the Brazilian nut tree Gustavia hexapetala

Stereoselective synthesis of the pyran subunit of portentol

An efficient strategy for the stereoselective synthesis of a fully elaborated pyran fragment of portentol was developed. The final route eventually proceeds through nine steps with an overall yield of 20% and key transformations include a Paterson anti-aldol reaction, selective lactol formation and a concise diastereoselective Corey-Winter elimination. The resulting pyran adopts a chair-type conformation with all methyl bearing centers in equatorial positions, facilitating a top-side attack on the olefin, which is crucial for the projected total synthesis of portentol.

Xanthones: Biosynthesis and Trafficking in Plants, Fungi and Lichens

Xanthones are a class of secondary metabolites produced by plant organisms. They are characterized by a wide structural variety and numerous biological activities that make them valuable metabolites for use in the pharmaceutical field. This review shows the current knowledge of the xanthone biosynthetic pathway with a focus on the precursors and the enzymes involved, as well as on the cellular and organ localization of xanthones in plants. Xanthone biosynthesis in plants involves the shikimate and the acetate pathways which originate in plastids and endoplasmic reticulum, respectively. The pathway continues following three alternative routes, two phenylalanine-dependent and one phenylalanine-independent. All three routes lead to the biosynthesis of 2,3',4,6-tetrahydroxybenzophenone, which is the central intermediate. Unlike plants, the xanthone core in fungi and lichens is wholly derived from polyketide. Although organs and tissues synthesizing and accumulating xanthones are known in plants, no information is yet available on their subcellular and cellular localization in fungi and lichens. This review highlights the studies published to date on xanthone biosynthesis and trafficking in plant organisms, from which it emerges that the mechanisms underlying their synthesis need to be further investigated in order to exploit them for application purposes.

Biological properties of aqueous extract and pyranocoumarins obtained from the bark of Brosimum alicastrum tree

ETHNOPHARMACOLOGICAL RELEVANCE

Brosimum alicastrum is a tree used in Mexican traditional medicine for the treatment of several diseases, including uterine cancer.

AIM OF THE STUDY

In this study, the cytotoxic activity of aqueous extract of B. alicastrum bark and isolated compounds xanthyletin (1), luvangetin (2), and 8-hydroxyxanthyletin (3) on three human cancer cell lines was determined. Moreover, the biological effects of 8-hydroxyxanthyletin (3) were investigated.

MATERIALS AND METHODS

The aqueous extract was prepared according to the ethnomedical information reported from the bark. The compounds were purified using chromatographic methods and their structures were elucidated by spectroscopic techniques. The antiproliferative effect of aqueous extract and isolates was determined in three human tumor cell lines: HeLa, A2780, and MSTO-211H, and evaluated by trypan blue exclusion assay. The cell cycle and the mitochondrial transmembrane potential (ΔΨ) were measured by flow cytometry, while Reactive Oxygen Species (ROS) levels were determined using 2',7'-dichlorofluorescein diacetate (DCFH-DA) probe. The effect on the relaxation activity, mediated by topoisomerase I and II, was evaluated by electrophoresis, and docking studies were performed using Autodock 4.2 to analyze the interactions.

RESULTS

Aqueous extract of B. alicastrum bark showed significant antiproliferative effect on the evaluated cancer cell lines (IC₅₀ = 1.6, 8.5, and 21.4 μg/ml). Four coumarins were identified in the extract and three of them were also evaluated. A2780 cell line exhibited higher sensitivity against pyranocoumarins with IC₅₀ values ranging from 32 to 47 μmol/l. 8-hydroxyxanthyletin (3) exerts an interesting effect on human topoisomerases I and II, by inhibiting the enzymes at concentrations comparable to those obtained in antiproliferative assay. Moreover, 8-hydroxyxanthyletin (3) arrests the cell cycle at G₀/G₁ phase and induces in A2780 cells a concentration-dependent increase in ROS levels. The results of molecular docking suggest the participation of the hydroxyl group in the interaction between 8-hydroxyxanthyletin (3) and topoisomerase I and II.

CONCLUSION

This is the first report that demonstrates the cytotoxic activity of the aqueous extract of B. alicastrum bark, and determines the main metabolites.

Phytochemical profile and ethnopharmacological applications of Lecythidaceae: An overview

ETHNOPHARMACOLOGICAL RELEVANCE

The family Lecythidaceae has about 25 genera and 400 identified species, which are distributed especially in the pantropical region, mostly found in the tropics of Central and South America, Southeast Asia and Africa. The third most abundant family in Amazonian forests and the genus Eschweilera, with the large number of species in Lecythidaceae.

AIM OF THE REVIEW

The present review compiles information since the 1934s about of ethnopharmacology, and chemical constituents of species of Lecythidaceae, as well as a summary of the bioactivities shown by the extracts, fractions, and secondary metabolites.

MATERIALS AND METHODS

All relevant information on ethnopharmacology, and chemical constituents of species of Lecythidaceae were gathered from electronic databases including Web of Science, Science Direct, Elsevier, ResearchGate, and Google Scholar. Information was also obtained from local books, PhD. and MSc. Dissertations.

RESULTS

The phytochemical diversity of the family was demonstrated with 180 different metabolites that have been reported from 25 species, most of them being triterpenes or flavonoids. The pharmacological studies carried out with the extracts, fractions and compounds showed promising antibacterial, antifungal, anti-inflammatory, antinociceptive, cytotoxic and antioxidant activities.

CONCLUSION

The present review provides an insight into ethnopharmacology, phytochemistry and pharmacology of species of Lecythidaceae. Based on the pharmacological studies it has been found that different plant species of Lecythidaceae possess a wide range of bioactivities such as anti-arthritic, anti-inflammatory, antileishmanial, antibacterial and antifungal. These activities are due to the presence of bioactive compounds including triterpenoids and their glycosides derivatives, flavonoids, steroids, sesquiterpenoids, alkaloids, and other compounds. However, there are many plants, which have not been assessed pharmacologically and hence warrant further studies.

Antiprotozoal activity of medicinal plants used by Iquitos-Nauta road communities in Loreto (Peru)

ETHNOPHARMACOLOGICAL RELEVANCE

In the Peruvian Amazon, the use of medicinal plants is a common practice. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point for this work was a set of interviews of people living in rural communities from the Peruvian Amazon about their uses of plants. Protozoan diseases are a public health issue in the Amazonian communities, who partly cope with it by using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help identify new antiprotozoal compounds.

AIMS OF STUDY

to inventory and validate the use of medicinal plants by rural people of Loreto region.

MATERIALS AND METHODS

Rural mestizos were interviewed about traditional medication of parasite infections with medicinal plants. Ethnopharmacological surveys were undertaken in two villages along Iquitos-Nauta road (Loreto region, Peru), namely 13 de Febrero and El Dorado communities. Forty-six plants were collected according to their traditional use for the treatment of parasitic diseases, 50 ethanolic extracts (different parts for some of the plants) were tested in vitro on Plasmodium falciparum (3D7 sensitive strain and W2 chloroquine resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Cytotoxic assessment (HUVEC cells) of the active extracts was performed. Two of the most active plants were submitted to preliminary bioguided fractionation to ascertain and explore their activities.

RESULTS

From the initial plants list, 10 were found to be active on P. falciparum, 15 on L. donovani and 2 on the three parasites. The ethanolic extract from Costus curvibracteatus (Costaceae) leaves and Grias neuberthii (Lecythidaceae) bark showed strong in vitro activity on P. falciparum (sensitive and resistant strain) and L. donovani and moderate activity on T. brucei gambiense.

CONCLUSIONS

The Amazonian forest communities in Peru represents a source of knowledge on the use of medicinal plants. In this work, several extracts with antiprotozoal activity were identified. This work contributes to validate some traditional uses and opens subsequent investigations on active compounds isolation and identification.

A Highly Convergent and Biomimetic Total Synthesis of Portentol

An efficient total synthesis of the unusual polyketide portentol is reported. Three boron aldol reactions were used to assemble the linear carbon chain of the natural product, which contains two challenging anti-anti stereotriads. A biomimetic double cyclization cascade, triggered by an oxidation, then afforded portentol and its known dehydration product, anhydroportentol. The biosynthesis of portentol and the biosynthetic relevance of our key step are discussed.

Qualitative and spatial metabolite profiling of lichens by a LC-MS approach combined with optimised extraction

INTRODUCTION

Lichens are self-sustaining partnerships comprising fungi as shape-forming partners for their enclosed symbiotic algae. They produce a tremendous diversity of metabolites (1050 metabolites described so far).

OBJECTIVES

A comparison of metabolic profiles in nine lichen species belonging to three genera (Lichina, Collema and Roccella) by using an optimised extraction protocol, determination of the fragmentation pathway and the in situ localisation for major compounds in Roccella species.

METHODS

Chemical analysis was performed using a complementary study combining a Taguchi experimental design with qualitative analysis by high-performance liquid chromatography coupled with mass spectrometry techniques.

RESULTS

Optimal conditions to obtain the best total extraction yield were determined as follows: mortar grinding to a fine powder, two successive extractions, solid:liquid ratio (2:60) and 700 rpm stirring. Qualitative analysis of the metabolite profiling of these nine species extracted with the optimised method was corroborated using MS and MS/MS approaches. Nine main compounds were identified: 1 β-orcinol, 2 orsellinic acid, 3 putative choline sulphate, 4 roccellic acid, 5 montagnetol, 6 lecanoric acid, 7 erythrin, 8 lepraric acid and 9 acetylportentol, and several other compounds were reported. Identification was performed using the m/z ratio, fragmentation pathway and/or after isolation by NMR analysis. The variation of the metabolite profile in differently organised parts of two Roccella species suggests a specific role of major compounds in developmental stages of this symbiotic association.

CONCLUSION

Metabolic profiles represent specific chemical species and depend on the extraction conditions, the kind of the photobiont partner and the in situ localisation of major compounds.

Amazonian Brazilian medicinal plants described by C.F.P. von Martius in the 19th century

ETHNOPHARMACOLOGICAL RELEVANCE

Information regarding the use of beneficial, native Brazilian plants was compiled by European naturalists during the 19th century. The German botanist C.F.P. von Martius was one of the most prominent naturalists and described the use of several Brazilian plants.

AIM OF THE STUDY

To present data on Amazonian medicinal plants documented by von Martius in his books.

MATERIALS AND METHODS

Data on Amazonian medicinal plants were obtained from three books published by von Martius. Traditional information about these plants was translated from Latin and the cited plant species reorganised according to current taxonomic criteria. Correlated pharmacological studies were obtained from different scientific databases.

RESULTS

A total of 92 native medicinal species from the Amazon were recorded in von Martius' books. These accounts described 117 different medical uses for these plants. Several parts of the plants were used, including many exudates. The principal use of the species recorded was the treatment of dermatological problems, followed by gastro-intestinal, urinary and respiratory disorders. Few species were recorded as purgatives and febrifuges, a result that differs from the observations of other naturalists. The efficacy of the recorded traditional uses has been confirmed for the few species that have been subjected to laboratory studies.

CONCLUSION

The data recorded by the German naturalist von Martius represent a rich, unexplored source of information about the traditional uses of Brazilian plants.

Anti-inflammatory activity of ethanol extract and fractions from Couroupita guianensis Aublet leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Couroupita guianensis Aublet, 'macacarecuia', 'abricó-de-macaco', 'castanha-de-macaco' and 'amêndoa-dos-andes', is found in tropical regions and is widely used in the treatment of tumors, pain, and inflammatory processes.

AIM OF THE STUDY

Ethanol extract and hexane and ethyl acetate fractions were evaluated in models of inflammatory pain (formalin-induced licking) and acute inflammation (carrageenan-induced peritonitis).

MATERIALS AND METHODS

Ethanol extract, hexane and ethyl acetate fractions (10, 30 or 100 mg/kg, p.o.) and the reference drugs dexamethasone (5 mg/kg), morphine (5 mg/kg, s.c.), and acetylsalicylic acid (100 mg/kg, p.o.) were tested in formalin-induced licking response and carrageenan-induced peritonitis.

RESULTS

All three doses from Couroupita guianensis fractions significantly reduced the time that the animal spent licking the formalin-injected paw in first and second phases. However, only higher doses (30 and 100 mg/kg) were able to inhibit the leukocyte migration into the peritoneal cavity after carrageenan injection. In this model, the 100 mg/kg dose almost abolished the cell migration. It was also observed that protein concentration resulted from extravasation to the peritoneum and nitric oxide (NO) productions were significantly reduced. Cytokines production was differently affected by the treatment. TNF-α production was reduced after ethanol extract and ethyl acetate fraction pre-treatment whereas hexane fraction had effect only with 100 mg/kg dose. IL-1β production was inhibited only after hexane fraction pre-treatment. The inhibitory effect observed was not due to a direct cytotoxic effect on cells nor to a NO-scavenger activity. The effect was due to a direct inhibition on NO production by the cells.

CONCLUSIONS

The results show that Couroupita guianensis fractions have anti-inflammatory effect, partly due to a reduction on cell migration and a inhibition on cytokines and inflammatory mediators production.

Antiparasitic compounds from Cupania cinerea with activities against Plasmodium falciparum and Trypanosoma brucei rhodesiense

In a survey of plants from Ecuador with antiprotozoal activity, Cupania cinerea was found to show significant in vitro activity against the Plasmodium falciparum K1 strain and Trypanosoma brucei rhodesiense. Subsequently, activity-guided isolation of the n-hexane and dichloromethane extracts from the bark of C. cinerea afforded two diterpene glycosides (1 and 2), named cupacinoside and 6'-de-O-acetylcupacinoside, and a lactonized triterpene bearing an oxepin moiety named cupacinoxepin (3), together with the known compounds scopoletin (4), caryophyllene oxide (5), two bisabolane sesquiterpenes (6 and 7), lichexanthone (8), gustastatin (9), lupenone (10), betulone (11), 17β,21β-epoxyhopan-3-one (12), taraxerol (13), and taraxerone (14). For compound 3, X-ray crystallography was employed to elucidate the relative configuration. For cupacinosides (1) and (2) and cupacinoxepin (3), in vitro activities against the P. falciparum K1 strain (IC(50)1, 1.3; 2, 1.8; and 3, 8.7 μM) and T. b. rhodesiense (IC(50)1, 4.5; 2, 15.8; and 3, 71.6 μM) were found. Cytotoxicity toward L-6 cells is discussed for all the compounds isolated.

Antineoplastic agents. 558. Ampelocissus sp. cancer cell growth inhibitory constituents

An investigation of the Phillippine Ampelocissus sp. roots for cancer cell growth inhibitory components led to the isolation of a new acetogenin characterized as 22-epicalamistrin (1) employing primarily 2D NMR and high-resolution mass spectral analysis. Two other antineoplastic constituents proved to be the known acetogenin uvaribonin (2) and chalcone 3. Constituents 1-3 were all found to show significant cancer cell growth inhibitory activity against a panel of human cancer cell lines.

The apoptosis effect of hispolon from Phellinus linteus (Berkeley & Curtis) Teng on human epidermoid KB cells

Phellinus linteus (Berkeley & Curtis) Teng, a well-known fungus of the genus Phellinus in the family of Hymenochaetaceae, is being increasingly used to treat a wide variety of disease processes such as oral ulcer, gastroenteric disorder, inflammation, lymphatic disease, and various cancers. However, the mechanism underlying its anti-oral cancer effect is poorly understood. In the present study, we prepared the ethanol extract of Phellinus linteus as a crude drug, and then obtained the active component hispolon by bioassay-guided isolation. Hispolon showed a dose-dependent inhibition of human epidermoid KB cell proliferation with IC50 of 4.62+/-0.16 microg/ml. Furthermore, it was revealed that hispolon could induce human epidermoid KB cell apoptosis with the characteristic of a DNA ladder, and with a significant increase of sub-G1. This process was accompanied by the collapse of mitochondrial membrane potential, the release of cytochrome c and the activation of Caspase-3. These results demonstrated that hispolon induced the death of KB cells through a mitochondria mediated apoptotic pathway. We propose that Phellinus linteus and its effective components could be used as an anti-oral cancer drug for future studies.