Pedro M. Abreu

Antimicrobial, antitumor and antileishmania screening of medicinal plants from Guinea-Bissau.

Following an ethnobotanical search carried out in Guinea-Bissau, eighteen extracts derived from sixteen medicinal species were 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 micrograms/ml. Khaya senegalensis and Anthostema senegalense exhibited a significant activity against Leishmania donovani with IC50 values of 9.8 and 9.1 micrograms/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.

New indole alkaloids from Sarcocephalus latifolius.

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-3β-O-β-D-fucopyranoside, quinovic acid-3β-O-α-L-rhamnopyranoside, scopoletin, and β-sitosterol. Strictosamide displayed moderate antiplasmodial activity against Plasmodium falciparum.

Heterocyclic terpenes: linear furano- and pyrroloterpenoids

Covering: January 1970 to December 2005 The emphasis of this review is on linear furano- and pyrroloterpenoids, together with their relevant biological activities, source organisms and country of origin. First total syntheses that lead to the revision of structures or stereochemistries have been included, and 206 references are cited.

Antileishmanial activity of piceatannol isolated from Euphorbia lagascae seeds

In the search for biologically active compounds from Euphorbia lagascae Spreng, an herbaceous plant native to southeast of Iberic Peninsula, a stilbene, two coumarins and two 12‐deoxyphorbol diterpene esters were isolated by chromatographic methods, from the methanol extracts of its defatted seeds. The structures of these compounds were elucidated by a combination of physical and spectral data (IR, MS and high‐resolution 1H‐NMR and 13C‐NMR spectroscopy utilizing COSY, HMBC, HMQC and NOESY experiments). The stilbene, piceatannol, was screened for its antileishmanial activity against promastigotes as an extracellular form of Leishmania donovani, Leishmania infantum and Leishmania major, and amastigotes of Leishmania donovani as an intracellular form. Pentostan® (sodium stibogluconate), the first line clinical drug, was used as a standard reference. Piceatannol was moderately active against the extracellular forms of the three tested Leishmania species, and more active than the reference compound against the intracellular form of Leishmania donovani. Copyright

Antimalarial Flavonol Glycosides from Euphorbia hirta.

Abstract Bioassay-guided fractionation of the MeOH extracts of Euphorbia hirta. Linn (Euphorbiaceae) aerial parts led to the isolation of flavonol glycosides afzelin (1), quercitrin (2), and myricitrin (3), whose structures were established by MS and NMR analysis. Compounds 1–3 showed proliferation inhibition of Plasmodium falciparum., with IC50 values of 1.1, 4.1, 5.4 µg/mL, repectively. On the other hand, they exhibited little cytotoxic property against human epidermoid carcinoma KB 3-1 cells.

Volatile constituents of the rhizomes of Aframomum alboviolaceum (Ridley) K. Schum. from Guinea-Bissau

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 (26, 33.1%), (+)-intermedeol (21, 24.1%), carotol (13, 8.3%), spathulenol (11, 5.8%), α-eudesmol (19, 2.3%), (Z)-β-farnesene (2, 2%), 10-epi-γ-eudesmol (15, 1.8%), β-biotol (14, 1.5%) and kongol (20, 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.

Carbohydrates from Detarium microcarpum bark extract.

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 L-quino-1,5-lactone, D-(-)-bornesitol, D-pinitol, myo-inositol, sucrose, D-glucose, and D-fructose benzoates, which were characterised by NMR spectroscopy experiments.

Effects of strictosamide on mouse brain and kidney Na+,K+-ATPase and Mg2+-ATPase activities

Present study reports on the general bioactivity of strictosamide and on its effects on Na(+),K(+)-ATPase and Mg(2+)-ATPase activities of Charles River male mouse. Strictosamide is the main glycoalkaloid of Sarcocephalus latifolius (Rubiaceae) leaves and roots, used as medicinal plant in folk medicine. In this work, we studied the in vitro effects of various concentrations of strictosamide (0.25, 0.5, 1 or 2 mg/mL) and the in vivo effects of single doses (50, 100 or 200 mg/kg, i.p.) of this compound on kidney and brain Na(+),K(+)-ATPase and Mg(2+)-ATPase activities. Results of general study showed that strictosamide is slightly toxic to Charles River mouse (LD(50)=723.17 mg/kg), producing CNS depression and kidney toxicity, but the exact mechanism of these effects could not be defined. Strictosamide inhibited the in vitro and in vivo Mg(2+)-ATPase activity on kidney but had nonsignificant effect on brain. Furthermore, strictosamide had nonsignificant in vitro and in vivo effect on kidney Na(+),K(+)-ATPase activity but produced an in vivo increase of Na(+),K(+)-ATPase activity of brain, these findings suggesting that strictosamine may be related to the induction of alpha(2) isoform of Na(+),K(+)-ATPase and may account for the folk use of Sarcocephalus latifolius root infusion on hypertension.

Long chain alkyl and alkenyl phenols from the roots of Ozoroa insignis

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 H-1 and C-13 NMR, and GCMS. Determination of double-bond positions in the side chains of alkenylphenols were established by methylthiolation-GCMS.

New ceramides from Rantherium suaveolens

A mixture of five new ceramides was isolated from the aerial parts of Rantherium suaveolens and characterized by spectroscopic and chemical methods. Their structures were elucidated by spectroscopic and chemical methods as (2S, 3S, 4R, 2′R, 14E)-2-(2′-hydroxydocosanoylamino)-14-octadecene-1,3,4-triol (1), (2S,3S,4R,2′R, 14F)-2-(2′-hydroxytricosanoylamino)-14-octadecene-1,3,4-triol (2), (2S,3S,4R,2′R,14F)-2-(2′-hydroxytetracosanoylamino)-14-octadecene-1,3,4-triol (3), (2S,3S,4R,2′R,14E)-2-(2′-hydroxypentacosanoylamino)-14-octadecene-1,3,4-triol (4), and (2S,3S,4R,2′R,14E)-2-(2′-hydroxyhexacosanoylamino)-14-octadecene-1,3,4-triol (5).