| 1. |
- Bergum, Sartaz, et al.
(författare)
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Bioactivities of extracts, debromolaurinterol and fucosterol from macroalgae species
- 2018
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Ingår i: Tanzania Journal of Science. - Dar es Salaam. - 0856-1761 .- 2507-7961. ; 44:2, s. 104-116
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Tidskriftsartikel (refereegranskat)abstract
- Parasitic diseases including malaria, and other numerous microbial infections and physiological diseases are threatening the global population. Tanzanian coast shores are endowed with a variety of macroalgae (seaweeds), hitherto unsystematically explored to establish their biomedical potentials. Thus, antiplasmodial activity using malarial imaging assay, antimicrobial activity using microplate dilution technique, antioxidant activity using DPPH radical scavenging method and cytotoxicity using brine shrimp test were carried out on crude extracts from the selected species of algae (Acanthophora spicifera, Cystoseira myrica, Cystoseira trinodis, Laurencia filiformis, Padina boryana, Sargassum oligocystum, Turbinaria crateriformis, Ulva fasciata and Ulva reticulata) occurring along the coast of Tanzania. The extracts showed antimicrobial activities with MIC ranging from 0.3- 5.0 µg/mL against Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Cryptococcus neoformans; DPPH radical scavenging activity at EC50 1.0- 100 µg/mL and cytotoxicity on brine shrimp larvae with LC50 value ranging from20 - 1000 µg/mL. The extracts from C. myrica and P. boryana inhibited growth of Plasmodium falciparum (3D7 strain) by 80 and 71%, respectively at 40 µg/mL while a sesquiterpene debromolaurinterol (1) which was chromatographically isolated from C. myrica exhibited antiplasmodial activity with IC50 20 µM whereas a sterol fucosterol (2) from P. boryana showed weak activity at 40 µM. Bioactivities portrayed by the investigated extracts indicate their ingredients as potential sources of bioactive agents that warrant further explorations.
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| 2. |
- Hernández, Guiomar, et al.
(författare)
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Do non-coordinating polymers function as host materials for solid polymer electrolytes? : The case of PVdF-HFP
- 2023
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:28, s. 15329-15335
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Tidskriftsartikel (refereegranskat)abstract
- In the search for novel solid polymer electrolytes (SPEs), primarily targeting battery applications, a range of different polymers is currently being explored. In this context, the non-coordinating poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer is a frequently utilized system. Considering that PVdF-HFP should be a poor solvent for cation salts, it is counterintuitive that this is a functional host material for SPEs. Here, we do an in-depth study of the salt dissolution properties and ionic conductivity of PVdF-HFP-based electrolytes, using two different fabrication methods and also employing a low-molecular-weight solvent analogue. It is seen that PVdF-HFP is remarkably poor as an SPE host, despite its comparatively high dielectric constant, and that the salt dissolution properties instead are controlled by fluorophilic interactions of the anion with the polymer.
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| 3. |
- Irungu, Beatrice N., et al.
(författare)
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Antiplasmodial and cytotoxic activities of the constituents of Turraea robusta and Turraea nilotica
- 2015
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Ingår i: Journal of Ethnopharmacology. - : Elsevier Ireland Ltd. - 0378-8741 .- 1872-7573. ; 174, s. 419-425
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Tidskriftsartikel (refereegranskat)abstract
- Ethnopharmacological relevance: Turraea robusta and Turraea nilotica are African medicinal plants used for the treatment of a wide variety of diseases, including malaria. The genus Turraea is rich in limonoids and other triterpenoids known to possess various biological activities. Materials and methods: From the stem bark of T. robusta six compounds, and from various parts of T. nilotica eleven compounds were isolated by the use of a combination of chromatographic techniques. The structures of the isolated compounds were elucidated using NMR and MS, whilst the relative configuration of one of the isolated compounds, toonapubesin F, was established by X-ray crystallography. The antiplasmodial activities of the crude extracts and the isolated constituents against the D6 and W2 strains of Plasmodium falciparum were determined using the semiautomated micro dilution technique that measures the ability of the extracts to inhibit the incorporation of (G-3H, where G is guanine) hypoxanthine into the malaria parasite. The cytotoxicity of the crude extracts and their isolated constituents was evaluated against the mammalian cell lines African monkey kidney (vero), mouse breast cancer (4T1) and human larynx carcinoma (HEp2). Results: The extracts showed good to moderate antiplasmodial activities, where the extract of the stem bark of T. robusta was also cytotoxic against the 4T1 and the HEp2 cells (IC50<10 μg/ml). The compounds isolated from these extracts were characterized as limonoids, protolimonoids and phytosterol glucosides. These compounds showed good to moderate activities with the most active one being azadironolide, IC50 2.4±0.03 μM and 1.1±0.01 μM against the D6 and W2 strains of Plasmodium falciparum, respectively; all other compounds possessed IC50 14.4-40.5 μM. None of the compounds showed significant cytotoxicity against vero cells, yet four of them were toxic against the 4T1 and HEp2 cancer cell lines with piscidinol A having IC50 8.0±0.03 and 8.4 ±0.01 μM against the 4T1 and HEp2 cells, respectively. Diacetylation of piscidinol A resulted in reduced cytotoxicity. Conclusion: From the medicinal plants T. robusta and T. nilotica, twelve compounds were isolated and characterized; two of the isolated compounds, namely 11-epi-toonacilin and azadironolide showed good antiplasmodial activity with the highest selectivity indices. © 2015 The Authors. Published by Elsevier Ireland Ltd.
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| 4. |
- Mabeyo, P. E., et al.
(författare)
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Selenium Accumulating Leafy Vegetables Are a Potential Source of Functional Foods
- 2015
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Ingår i: International Journal of Food Science. - : Hindawi Limited. - 2356-7015 .- 2314-5765. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- Selenium deficiency in humans has been associated with various diseases, the risks of which can be reduced through dietary supplementation. Selenium accumulating plants may provide a beneficial nutrient for avoiding such illnesses. Thus, leafy vegetables such as Amaranthus hybridus, Amaranthus sp., Cucurbita maxima, Ipomoea batatas, Solanum villosum, Solanum scabrum, and Vigna unguiculata were explored for their capabilities to accumulate selenium when grown on selenium enriched soil and for use as a potential source of selenium enriched functional foods. Their selenium contents were determined by spectrophotometry using the complex of 3,3′-diaminobenzidine hydrochloride (DABH) as a chromogen. The mean concentrations in the leaves were found to range from to μg/g dry weight (DW), with C. maxima accumulating the most selenium. In stems, the accumulated selenium content ranged from μg/g in Amaranthus sp. to μg/g DW in C. maxima and was hence significantly different (). The cancer cell line MDA-MB-231 was used in cytotoxicity assays to determine the anticancer potential of these extracts. With exception of S. scabrum and S. villosum, no cytotoxicity was detected for the selenium enriched vegetable extracts up to 100μg/mL concentration. Hence, following careful evaluation the studied vegetables may be considered as selenium enriched functional foods.
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| 5. |
- Maeda, Gasper, et al.
(författare)
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A Meroisoprenoid, Heptenolides, and C-Benzylated Flavonoids from Sphaerocoryne gracilis ssp. gracilis
- 2020
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Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 83:2, s. 316-322
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Tidskriftsartikel (refereegranskat)abstract
- A new meroisoprenoid (1), two heptenolides (2 and 3), two C-benzylated flavonoids (4 and 5), and 11 known compounds (6-16) were isolated from leaf, stem bark, and root bark extracts of Sphaerocoryne gracilis ssp. gracilis by chromatographic separation. The structures of the new metabolites 1-5 were established by NMR, IR, and UV spectroscopic and mass spectrometric data analysis. (Z)-Sphaerodiol (7), (Z)-acetylmelodorinol (8), 7-hydroxy-6-hydromelodienone (10), and dichamanetin (15) inhibited the proliferation of Plasmodium falciparum (3D7, Dd2) with IC50 values of 1.4-10.5 mu M, although these compounds also showed cytotoxicity against human embryonic kidney HEK-293 cells. None of the compounds exhibited significant disruption in protein translation when assayed in vitro.
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| 6. |
- Nyandoro, Stephen S., 1975, et al.
(författare)
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A New Benzopyranyl Cadenane Sesquiterpene and Other Antiplasmodial and Cytotoxic Metabolites from Cleistochlamys kirkii
- 2019
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Ingår i: Molecules. - : MDPI AG. - 1420-3049 .- 1431-5157. ; 24:15
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Tidskriftsartikel (refereegranskat)abstract
- Phytochemical investigations of ethanol root bark and stem bark extracts of Cleistochlamys kirkii (Benth.) Oliv. (Annonaceae) yielded a new benzopyranyl cadinane-type sesquiterpene (cleistonol, 1) alongside 12 known compounds (2-13). The structures of the isolated compounds were established from NMR spectroscopic and mass spectrometric analyses. Structures of compounds 5 and 10 were further confirmed by single crystal X-ray crystallographic analyses, which also established their absolute stereochemical configuration. The ethanolic crude extract of C. kirkii root bark gave 72% inhibition against the chloroquine-sensitive 3D7-strain malaria parasite Plasmodium falciparum at 0.01 mu g/mL. The isolated metabolites dichamanetin, (E)-acetylmelodorinol, and cleistenolide showed IC50 = 9.3, 7.6 and 15.2 mu M, respectively, against P. falciparum 3D7. Both the crude extract and the isolated compounds exhibited cytotoxicity against the triple-negative, aggressive breast cancer cell line, MDA-MB-231, with IC50 = 42.0 mu g/mL (crude extract) and 9.6-30.7 mu M (isolated compounds). Our findings demonstrate the potential applicability of C. kirkii as a source of antimalarial and anticancer agents.
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| 7. |
- Nyandoro, Stephen S., 1975, et al.
(författare)
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Flavonoids from Erythrina schliebenii
- 2017
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Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 80:2, s. 377-383
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Tidskriftsartikel (refereegranskat)abstract
- Prenylated and O-methylflavonoids including one new pterocarpan (1), three new isoflavones (2-4), and nineteen known natural products (5-23) were isolated and identified from the root, stem bark, and leaf extracts of Erythrina schliebenii. The crude extracts and their constituents were evaluated for antitubercular activity against Mycobacterium tuberculosis (H37Rv strain), showing MICs of 32-64 mu g mL(-1) and 36.9-101.8 mu M, respectively. Evaluation of their toxicity against the aggressive human breast cancer cell line MDA-MB-231 indicated EC50 values of 13.0-290.6 mu M (pure compounds) and 38.3 to >100 mu g mL(-1) (crude extracts). RAMSON D, 1973, PHYTOCHEMISTRY, V12, P2211
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| 8. |
- Nyandoro, Stephen S., 1975, et al.
(författare)
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N-Cinnamoyltetraketide Derivatives from the Leaves of Toussaintia orientalis
- 2015
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Ingår i: Journal of natural products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 78:8, s. 2045-2050
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Tidskriftsartikel (refereegranskat)abstract
- Seven N-cinnamoyltetraketides (1–7), including the new Z-toussaintine E (2), toussaintine F (6), and toussaintine G (7), were isolated from the methanol extract of the leaves of Toussaintia orientalis using column chromatography and HPLC. The configurations of E-toussaintine E (1) and toussaintines A (3) and D (5) are revised based on single-crystal X-ray diffraction data from racemic crystals. Both the crude methanol extract and the isolated constituents exhibit antimycobacterial activities (MIC 83.3–107.7 μM) against the H37Rv strain of Mycobacterium tuberculosis. Compounds 1, 3, 4, and 5 are cytotoxic (ED50 15.3–105.7 μM) against the MDA-MB-231 triple negative aggressive breast cancer cell line.
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| 9. |
- Nyandoro, Stephen S., 1975, et al.
(författare)
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Polyoxygenated Cyclohexenes and Other Constituents of Cleistochlamys kirkii Leaves
- 2017
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Ingår i: Journal of natural products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 80:1, s. 114-125
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Tidskriftsartikel (refereegranskat)abstract
- Thirteen new metabolites, including the polyoxygenated cyclohexene derivatives cleistodiendiol (1), cleistodienol B (3), cleistenechlorohydrins A (4) and B (5), cleistenediols A–F (6–11), cleistenonal (12), and the butenolide cleistanolate (13), 2,5-dihydroxybenzyl benzoate (cleistophenolide, 14), and eight known compounds (2, 15–21) were isolated from a MeOH extract of the leaves of Cleistochlamys kirkii. The purified metabolites were identified by NMR spectroscopic and mass spectrometric analyses, whereas the absolute configurations of compounds 1, 17, and 19 were established by single-crystal X-ray diffraction. The configuration of the exocyclic double bond of compound 2 was revised based on comparison of its NMR spectroscopic features and optical rotation to those of 1, for which the configuration was determined by X-ray diffraction. Observation of the co-occurrence of cyclohexenoids and heptenolides in C. kirkii is of biogenetic and chemotaxonomic significance. Some of the isolated compounds showed activity against Plasmodium falciparum (3D7, Dd2), with IC50 values of 0.2–40 μM, and against HEK293 mammalian cells (IC50 2.7–3.6 μM). While the crude extract was inactive at 100 μg/mL against the MDA-MB-231 triple-negative breast cancer cell line, some of its isolated constituents demonstrated cytotoxic activity with IC50 values ranging from 0.03–8.2 μM. Compound 1 showed the most potent antiplasmodial (IC50 0.2 μM) and cytotoxic (IC50 0.03 μM, MDA-MB-231 cell line) activities. None of the compounds investigated exhibited translational inhibitory activity in vitro at 20 μM.
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| 10. |
- Abdissa, Negera, et al.
(författare)
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Cytotoxic Quinones from the roots of Aloe dawei
- 2014
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Ingår i: Molecules. - : MDPI AG. - 1420-3049 .- 1431-5157. ; 19:3, s. 3264-3273
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Tidskriftsartikel (refereegranskat)abstract
- Seven naphthoquinones and nine anthraquinones were isolated from the roots of Aloe dawei by chromatographic separation. The purified metabolites were identified by NMR and MS analyses. Out of the sixteen quinones, 6-hydroxy-3,5-dimethoxy-2-methyl-1,4-naphthoquinone is a new compound. Two of the isolates, 5,8-dihydroxy-3-methoxy-2-methylnaphthalene-1,4-dione and 1-hydroxy-8-methoxy-3-methylanthraquinone showed high cytotoxic activity (IC50 1.15 and 4.85 µM) on MCF-7 breast cancer cells, whereas the others showed moderate to low cytotoxic activity against MDA-MB-231 (ER Negative) and MCF-7 (ER Positive) cancer cells.
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