| 1. |
- Arévalo-Lopéz, Diandra, et al.
(author)
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Leishmanicidal and cytotoxic activity from plants used in Tacana traditional medicine (Bolivia)
- 2018
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In: Journal of Ethnopharmacology. - : Elsevier BV. - 0378-8741. ; 216, s. 120-133
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Journal article (peer-reviewed)abstract
- Etnopharmacological relevance: Thirty-eight Tacana medicinal plant species used to treat skin problems, including leishmania ulcers, skin infections, inflammation and wound healing, were collected in the community of Buena Vista, Bolivia, with the Tacana people. Twenty two species are documented for the first time as medicinal plants for this ethnic group living in the northern area of the Department of La Paz. Aim of the study: To evaluate the leishmanicidal effect (IC50) and cytotoxicity (LD50) of the selected plants. To carry out bioguided studies on the active extracts. To assess the potential of Bolivian plant biodiversity associated with traditional knowledge in the discovery of alternative sources to fight leishmaniasis. Materials and methods: Seventy three ethanol extracts were prepared from 38 species by maceration and were evaluated in vitro against promastigotes of Leishmania amazonensis and L. braziliensis. Active extracts (IC50 ≤ 50 μg/mL) were fractionated by chromatography on Silica gel column and the fractions were assessed against the two Leishmania strains. The most active fractions and the crude extracts were evaluated against reference strains of L. amazonensis, L. braziliensis, L. aethiopica, two native strains (L. Lainsoni and L. braziliensis) and for cytotoxicity against HeLa cells. The chromatographic profile of the active fractions was obtained by reverse phase chromatography using HPLC. Results: From the 73 extracts, 39 extracts (53.4%) were inactive and 34 showed activity. Thirteen species were sselected for bioguided studies. The crude extracts and their 36 fractions were evaluated against two Leishmania strains. The most active fraction were tested in a panel of five leishmania strains and for cytotoxicity. The Selective Index (SI = LD50/IC50) was calculated, and were generally low. Retention time and UV spectra were recorded for the active fractions by HPLC-DAD using a reverse phase column. Profiles were very different from each other, showing the presence of different compounds. Conclusion: Bolivian traditional knowledge from the Tacanba was useful to identify plants with effect on Leishmania promastigotes. Chromatographic bioguided studies showed stronger leishmanicidal and cytotoxic activity for the medium polar fraction. HPLC analysis showed different chromatographic profiles of the active fractions.
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| 2. |
- Gonzales-Ramirez, Mariela, et al.
(author)
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Trichilones A–E: New Limonoids from Trichilia adolfi
- 2021
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In: Molecules. - : MDPI AG. - 1420-3049. ; 26:11
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Journal article (peer-reviewed)abstract
- In addition to the trichilianones A–D recently reported from Trichilia adolfi, a continuing investigation of the chemical constituents of the ethanol extract of the bark of this medicinal plant yielded the five new limonoids 1–5. They are characterized by having four fused rings and are new examples of prieurianin-type limonoids, having a ε-lactone which in 4 and 5 is α, β- unsaturated. The structures of the isolated metabolites were determined by high field NMR spectroscopy and HR mass spectrometry. The new metabolites were shown to have the ε-lactone fused with a tetrahydrofuran ring which is connected to an oxidized hexane ring joined with a cyclo-pentanone having a 3-furanyl substituent. As the crude extract possesses antileishmanial activity, the compounds were assayed for cytotoxic and antiparasitic activities in vitro in murine macrophage cells (raw 264.7 cells) and in Leishmania amazoniensis as well as L. braziliensis promastigotes. Metabolites 1–3 and 5 showed moderate cytotoxicity (between 30–94 μg/mL) but are not responsible for the antileishmanial effect of the extract.
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| 3. |
- Limachi, Ivan, et al.
(author)
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Antiparasitic metabolites from hyptis brevipes, a tacana medicinal plant
- 2019
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In: Natural Product Communications. - 1934-578X. ; 14:1, s. 55-58
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Journal article (peer-reviewed)abstract
- A bioassay screening against protozoa parasites of several Tacana medicinal plants gave Hyptis brevipes (Id'ene eidhue), traditionally used as decoction for intestinal parasites, as the most active extract. In this work we did a bioguided isolation of active constituents found in leaves. Structure elucidation was carried out by NMR spectroscopy and MS spectrometry analyses. Active constituents showed differentiated activity towards Giardia lamblia, Trypanosoma cruzi, several Leishmania strains, Plasmodium falciparum and cytotoxicity against HeLa cells. Brevipolide H (1) was the less cytotoxic and best antiparasitic, while the catechol derivative (2) the most active and cytotoxic.
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| 4. |
- Limachi, Ivan
(author)
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Antiparasitic metabolites from plants used in the Tacana Bolivian native tribe : Traditional medicine, an overview of natural products with medicinal interest.
- 2019
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Doctoral thesis (other academic/artistic)abstract
- The thesis aims to contribute to the preservation of traditional medicinal knowledge of the Tacana Bolivian native tribe, as well as to the isolation and characterization of antiparasitic metabolites from plants used for the treatment of endemic diseases. A selection of medicinal plants, made in collaboration with the Tacana communities who decided which plants have a specific medicinal propose, were collected and identified by the national herbarium of Bolivia, and confirmed by healers from the most representative communities. From the screened plants the most active species were selected, using as selection criteria the in vitro antiparasitic activity in Leishmania strains. These species were subjected to chemical analysis that includes the chromatographic isolation of their major metabolites and structural elucidation of these by spectroscopic techniques. The main metabolites identified were evaluated in a broad battery of parasite assays, besides the cytotoxicity, to determine the potency as well asselectivity to obtain a better understanding of the medicinal properties of the medicinal plants.In the first chapter, a general description about Tacana native tribe is given in order to understand the intimate connection that this people have with their environment. A cooperation project between the Tacana people, La Paz university and international organizations, facilitated the collection and taxonomical identification of 38 plants with medicinal uses to be added to the ethnobotany list of Tacana traditional medicine.In the second chapter, the laboratory work that was carried out to prepare ethanolic extracts of the plants collected is described, and the antiparasitic activity against leishmania promastigotes of each extract was evaluated in vitro besides the cytotoxicity in HeLa cells. This gave the selectivity index (SI),. Thus, three vegetable species were selected as the most active antiparasitic plants, identified as Hyptis mutabilis, Hyptis brevipes and Tessaria integrifolia. Additionally, two species were selected due to the extended use among Tacana people: Renealmia breviscapa and Trichilia adolfi. The last chapter is concentrated on the chemical exploration of selected plants. The ethanolic extracts of H. brevipes and H. mutabilis, both belonging to the same family, afforded the isolation of nine metabolites with diverse antiparasitic activity, some of them part of the brevipolide chemical family. The most active compound was found in H. mutabilis and identified as olguine. Super critical fluid extraction technique was applied to extract the chemical content of T. integrifolia, and eleven metabolites were isolated. Seven of them were identified as eremophilane-type sesquiterpenoids, the remaining were flavonoids and terpenoids. The relative chemical contents were compared in the crude extract and fractions using LC-MS techniques. The ethanolic extract of T. adolfi afforded nine new tetranortriterpenoids, and an extensive spectroscopic analysis was necessary to elucidate their complex structures. The trivial name trichilianone-type was proposed for compounds that possess a bicyclo-cyclopropane-hexanesystem as part of the terpenoic skeleton. The antiparasitic activity and cytotoxicity was reported together with a short analysis of the hypothetical biosynthetic pathway.
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| 5. |
- Limachi, Ivan, et al.
(author)
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Trichilianones A-D, Novel Cyclopropane-Type Limonoids from Trichilia adolfi
- 2021
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In: Molecules (Basel, Switzerland). - : MDPI AG. - 1420-3049. ; 26:4
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Journal article (peer-reviewed)abstract
- The fractionation of an ethanol extract of the bark of Trichilia adolfi yielded four novel limonoids (trichilinones A-D, 1-4), with five fused rings and related to the hortiolide-type limonoids. Starting with an ε-lactone, which is α,β-unsaturated in trichilinones A and D (1 and 4), attached to a tetrahydrofuran ring that is connected to an unusual bicyclo [5.1.0] hexane system, joined with a cyclopentanone with a 3-furanyl substituent [(2-oxo)-furan-(5H)-3-yl in trichilinone D (4)], the four compounds isolated display a new 7/5/3/5/5 limonoid ring system. Their structures were established based on extensive analysis of NMR spectroscopic data. As the crude extract possessed anti-leishmanial properties, the compounds were assayed for cytotoxic and anti-parasitic activities in vitro in murine macrophages cells (Raw 264.7) and leishmania promastigotes (L. amazoniensis and L. braziliensis), respectively. The compounds showed moderate cytotoxicity (approximately 70 μg/mL), but are not responsible for the leishmanicidal effect of the extract.
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