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Medicinal plants from Guinea-Bissau
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Antimicrobial, Antitumor and Antileishmania Screening of Medicinal Plants from Guinea-Bissau, P.M. Abreu, E.S. Martins, O. Kayser, K.-U. Bindseil, K. Siems, A. Seemann and J. Frevert, Phytomedicine, 6, 187 (1999). |
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Abstract: Following an ethnobotanical search carried out in Guinea-Bissau, eighteen extracts derived from sixteen medicinal species have been screened for antimicrobial, antitumor and antileishmania activity. Significant antitumor activity was found for Holarrhena floribunda against KB (squamous carcinoma), SK-Mel 28 (melanoma), A 549 (lung carcinoma) and MDA-MB 231 (mamma carcinoma) cell lines, with corresponding IC50 values of 7.9, 9.0, 3.4 and 9.9 mg/ml. Khaya senegalensis and Anthostema senegalense exhibited a significant activity against Leishmania donovani with IC50 values of 9.8 and 9.1 mg/ml, respectively. Most of the extracts showed week or moderate antibacterial and antifungal activity, with MIC values in the range 0.25-1.0 mg/ml. Active extracts were submitted to bioassay-guided fractionation, and the IC50 and MIC of the active fractions were determined.
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LPLC
and HPLC reversed phase isolation of meliacins from Khaya
senegalensis,
Pedro Abreu, Abstracts of the 14th Annual Congress of the Portuguese
Chemical Society, Aveiro, 1994. |
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Khaya senegalensis
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Chemical constituents of Parkia biglobosa, M.E.M.Araújo, F.M.S.B.Palma, A.T.Moutinho, P.M.Abreu, Fitoterapia, 5, 468 (1995). |
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Constituents of Tephrosia uniflora, Pedro M.Abreu and Maria H.Luis, Natural Product Letters, 9, 81 (1996). |
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Abstract: Elongatin (1), 12a-hydroxyrotenone (2), Praecansone A (3) b-sitosterol and stigmasterol have been isolated and identified from the stems and leaves of Tephrosia uniflora, collected at the Cap Verde Islands.
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Phytochemical analysis and antimicrobial evaluation of Detarium microcarpum bark extracts, Abreu PM, Rosa VS, Araújo EM, Canda AB, Kayser O, Bindseil K-U, Siems K, Seeman A, Pharma. Pharmacol. Lett. 8, 107 (1998). |
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Abstract: Sitosterol-3b-O-[6'-O-palmitoyl-2',3',4'-O-triacetyl-b-D-glucopyranoside] (1), lupeol, lup-20(29)-en-2a,3b-diol, b-sitosterol, stigmasterol and campesterol were isolated from the bark of Detarium microcarpum. The ethanol extract of D. microcarpum showed antimicrobial activity against Pseudomonas aeuruginosa, Klebsiella pneumoniae, Citrobacter freundii, Staphylococcus aureus, and Listeria monocytogenes.
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Carbohydrates from Detarium microcarpum bark extract, Pedro Abreu and Angela Relva, Carbohydrate Research, 337, 1663 (2002). |
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Abstract: The bark extract of the medicinal plant Detarium microcarpum was analysed for its carbohydrate content by GLC-CIMS. Preparative HPLC of the benzoylated carbohydrate fraction led to the isolation of γ-quinide, (–)-bornesitol, D-pinitol, myo-inositol, sucrose, D-glucose, and D-fructose benzoates, which were characterised by extensive NMR experiments.
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Volatile constituents of the rhizomes of Aframomum alboviolaceum (Ridley) K.Schum. from Guinea-Bissau, Pedro M.Abreu and Rita G.Noronha, Flavour and Fragrance Journal, 12, 79 (1997). |
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Abstract: The volatile components of the rhizomes of Aframomum alboviolaceum (Ridley) K. Schum. were extracted with hexane and analysed by GC-MS. The main constituents are (E)-labda-8(17),12-diene-15,16-dial 1 (33.1%), (+)-intermedeol 2 (24.1%), carotol (8.3%), spathulenol (5.8%), a-eudesmol (2.3%), (z)-b-farnesene (2%), 10-epi-g-eudesmol (1.8%), b-biotol (1.5%) and kongol (1.2%). The diterpene (E)-labda-8(17),12-diene-15,16-dial and the sesquiterpene (+)-intermedeol were isolated and fully characterized by mass spectra, 1H-NMR and 13C-NMR spectra.
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A new indole alkaloid from Sarcocephalus latifolius, Pedro Abreu and António Pereira, Heterocycles, 48, 885 (1998). |
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Abstract: A new indole alkaloid, 19-O-ethylangustoline (1), as well as the known alkaloids angustoline, angustine, angustidine and nauclefine were isolated from the stem bark of Sarcocephalus latifolius (Smith) Bruce and characterised by spectral methods. The absolute stereochemistry at C-19 of angustoline and 19-O-ethylangustoline was determined by Horeau’s method and optical rotatory dispersion.
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Two indole alkaloids from Sarcocephalus latifolius, Pedro M. Abreu and António Pereira, Nat. Prod. Letters, 15, 43 (2001). |
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Abstract: Phytochemical investigation of the root extract of Sarcocephalus latifolius has led to the isolation of the new indole alkaloids 21-O-methylstrictosamide aglycone and 21-O-ethylstrictosamide aglycone, together with strictosamide, angustine, nauclefine, angustidine, angustoline, 19-O-ethylangustoline, naucleidinal, 19-epi-naucleidinal, quinovic acid-3b-O-b-D-fucopyranoside, quinovic acid-3b-O-a-L-rhamnopyranoside, scopoletin, and b-sitosterol. Strictosamide displayed moderate antiplasmodial activity against Plasmodium falciparum.
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| Sarcocephallus latifolius | |||
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Characterisation of a sugar fraction from Sarcocephalus latifolius stem bark extract, P. Abreu, A. Relva and A. Pereira, Carbohydrate Polymers, 45, 155 (2001). |
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Abstract: The stem bark extract of the medicinal plant Sarcocephalus latifolius was analysed for its qualitative and quantitative carbohydrate content. Preparative high-performance liquid chromatography (HPLC) of the benzoylated sugar fraction, led to the isolation of the D-fructose derivatives 1,2,3,4,6-penta-O-benzoyl-a-D-fructofuranose, 1,2,3,4,6-penta-O-benzoyl-b-D-fructofuranose, 1,2,3,4,5-penta-O-benzoyl-b-D-fructopyranose, and 1,3,4,5-tetra-O-benzoyl-b-D-fructopyranose, in addition to the a- and b-D-pyranose forms of glucose, xylose, and arabinose perbenzoates, glycerol and D-erythriol perbenzoates, and an inseparable mixture of methyl 1,3,4,6-tetra-O-benzoyl-a,b-D-fructofuranoside whose occurrence had never been previously reported from a natural source. The corresponding structures and conformations were fully characterised by extensive one and two dimensional nuclear magnetic resonance (NMR) experiments. Quantification of the natural free sugars in the extract was achieved by HPLC using refractive-index detection.
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New trichothecenes from Holarrhena floribunda, Ali Loukaci, Oliver Kayser, K.-U. Bindseil, Karsten Siems, J. Frevert and Pedro M. Abreu, J. Nat. Prod,. 63, 52 (2000). |
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Abstract: Bioassay-guided fractionation of an extract of Holarrhena floribunda stem, has led to the isolation of the new trichothecenes 8-dihydrotrichothecinol A (1), loukacinol A (2), and loukacinol B (3), and the known compounds trichothecolone (4), trichothecin (5), trichothecinol-A (6), rosenonolactone (7), 6b-hydroxyrosenonolactone (8), and rosololactone (9). The structures were determined by spectral and chemical methods, and absolute configurations were established by a modified Horeau's method using HPLC. Compounds 1 and 6 exhibited significant cytotoxicity against several human tumor cell lines, whereas compound 8 showed moderate and weak antileishmanial activity towards extracellular and intracellular Leishmania donovani, respectively.
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| Holarrhena floribunda | |||
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Antileishmanial and immunostimulating activities of two dimeric proanthocyanidins from Khaya senegalensis, O. Kayser and P.M. Abreu, Pharmaceutical Biology, 39, 284 (2001). |
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Abstract: Bioassay-guided fractionation of the bark of Khaya senegalensis (Desr.) A. Jus. (Meliaceae), led to the isolation of two dimeric proanthocyanidins, catechin-(4a,6)-catechin (1) and catechin-(4a,8)-catechin) (2), with immunostimulating activities. Their structures were determined by chromatographic and spectroscopic methods (EIMS, 1H-NMR). Anti-Leishmania screening of extracts and pure compounds was conducted against Leishmania donovani, L. major, L. infantum promastigotes and retested against L. donovani amastigotes persisting in RAW macrophages as host cells. Their cytotoxicity was checked against three mammilian cell lines (RAW, A549 and KB). Isolated compounds (1) and (2) were not active against promastigotes (EC50 > 25.0 µg/ml), but exhibited significant effects when tested against amastigotes indicating an indirect immunostimulating principle (EC50= 3.85 and 3.98 µg/ml, respectively) with no cytotoxicity. |
Leishmaniasis
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Sandfly From Peter and Gilles (Color Atlas of Tropical Medicine and Parasitology) |
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Long Chain Alkyl and Alkenyl Phenols from the Roots of Ozoroa insignis, Yonghong Liu and Pedro J.M. Abreu, J. Braz. Chem. Soc., 17, 527 (2006). |
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Abstract: Bioassay-guided fractionation of the ethanolic root extract of Ozoroa insignis, collected in Guinea-Bissau, led to the isolation of a 41-member library of alkyl and alkenylphenols, whose structures were determined by 1H and 13C NMR, and GCMS. Determination of double-bond positions in the side chains of alkenylphenols were established by methylthiolation-GCMS. |
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Tirucallane triterpenes from the roots of Ozoroa insignis, Yonghong Liu and Pedro J.M. Abreu, Phytochemistry, 67, 1309 (2006). |
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Abstract: Eight new tirucallane triterpenes, methyl 24(S)-3a,24-dihydroxy-tirucalla-8,25(27)-dien-21-oate, methyl 3a-hydroxy-tirucalla-8,25(27)-dien-24-one-21-oate, methyl 3a-hydroxy-tirucalla-8-ene-24-al-25,26,27-trisnor-21-oate, 3a,25,32-trihydroxy-tirucalla-8-ene-24-ethyl-21-oic acid, 24(S)- and 24(R)-3a,24,25-trihydroxy-tirucalla-8-ene-21-oic acid, 3a,25-dihydroxy-tirucalla-8-ene-21-oic acid, and methyl 3a,25-dihydroxy-tirucalla-8-ene-21-oate, together with a-elemolic acid methyl ester, were isolated from the roots of Ozoroa insignis. Their structures were elucidated on the basis of spectroscopic evidence.
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Ozoroalide, a new orsellinic acid type macrolide from Ozoroa insignis, Yonghong Liu and Pedro Abreu, Fitoterapia, 78, 388 (2007). |
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Abstract: From the roots of
Ozoroa insignis a new orsellinic acid type macrolide, named as
ozoroalide (1), and anacardic acid methyl ester (2), were
isolated and identified on the basis of spectroscopic methods.
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