The antiplasmodial agents of the stem bark of <i>Entandrophragma angolense</i> (Meliaceae).

Abstract

In the search of active principles from the stem bark of Entandrophragma angolense, we submitted the compounds isolated from the dichloromethane-methanol (1:1) extract of the stem bark to antimalarial test against chloroquine resistant strain W2 of Plasmodium falciparum malaria parasite. Only 7α-obacunyl acetate and a cycloartane derivative exhibited a good activity, with IC 50 s of 2 and 5.4 µg/ml respectively. Other compounds were moderately active.

Cameroonian medicinal plants: a bioactivity versus ethnobotanical survey and chemotaxonomic classification

“…The activities of the selected metabolites are anti-malarial, estrogenic, antisalmonellal, hepatoprotective, antifungal, antioxidant, antidermatophytic, vasorelaxant, anticancer, antileishmanial, antimicrobial and α-glucosidase inhibition. The antimalarials with significant antiparasitic activity, which have been isolated from plants used in anti-malarial or anti-fever preparations include: betulinic acid (49), 2,2’,5,6’-tetrahydroxybenzophenone (50), 5-hydroxy-3-methoxyxanthone (51) and 3-hydroxy-5-methoxyxanthone (52) [62]; bazouanthrone (54), ferruginin A (55), harunganin (56), harunganol A (57) and harunganol B (58) [63]; isoxanthochymol (59), which exhibited an anti-malarial activity against the NF54 strain with a 50% inhibitory concentration (IC 50 ) of 2.21 μM [64]; gaboxanthone (65), symphonin (66), globuliferin (67) and guttiferone A (68) [65]; garcinone E (70), with an IC 50 of 0.20 μM, which was isolated from Pentadesma butyracea , concurrently with other potent anti-malarials pentadexanthone, cratoxylone and α-mangostin [66]; the limonoid 7α-obacunyl acetate (80) [67]; the homogentisic acid derivatives methyl 2-(1’β-geranyl-5’β-hydroxy-2’-oxocyclohex-3’-enyl) acetate (87) and 2-(1’β-geranyl-5’β-hydroxy-2’-oxocyclohex-3’-enyl)acetic acid (88) and the alkaloid liriodenine (89) isolated from Glossocalyx brevipes [66]; the flavonoids artocarpesin (90), Kushenol E (91), and the arylbenzofuran derivative mulberrofuran F (92) isolated from Morus mesozygia [68]; the chalcones bartericin A (97) and 4-hydroxylonchocarpin (100) [69]; 3- O -betulinic acid p -coumarate (112) isolated from Baillonella toxisperma , with an IC 50 of 1.65 μM [70]; the labdane 3-deoxyaulacocarpin A (115) from Aframomum zambesiacum [71]; and the sesquiterpenoids oplodiol (118), 5 E ,10(14)-germacradien-1β,4β-diol (119) and 1(10) E ,5 E -germacradien-4α-ol (120) with respective IC 50 values of 4.17, 1.63 and 1.54 μM [72]. In all cases, antiplasmodial activity was measured by inhibition of the chloroquine-resistant W2 P .…”

Phytochemistry and pharmacology of the genusEntandrophragmaover the 50 years from 1967 to 2018: a ‘golden’ overview

“…The cleavage of the rings A and D can be explained as previously mentioned by a Baeyer–Villiger‐type oxidation of C‐3 and C‐16 carbonyl functions of the azadirone‐class limonoids. From E. angolense , previous chemical investigations led to the isolation of 7α‐acetoxydihydronomilin ( 20 ) and 7α‐obacunyl acetate ( 21 ) (Figure ) . Later in 2013, in attempting to fathom the structure relationship in the antiplasmodial assay of these two naturally produced limonoids, Tchouya ( et al .)…”

“…Some fatty acids and methyl ester derivatives ( 159 – 164 ) were isolated during chemical investigations of E. angolense …”

“…Bickii and coworkers reported an IC 50 of 18.8 μg/ml for the dichloromethane–methanol (1 : 1) extract of the stem bark of E. angolense against P. falciparum W2. The observed results on this extract pushed them to its chemical investigations which led to isolation of several compounds including the most active characterized as 7α‐obacunyl acetate ( 21 ) with an IC 50 of 2 μg/ml . The extracts of bark of E. palustre showed a moderate antiplasmodial activity against two strains of P. falciparum (3D7 and W2) compared to the used standards chloroquine and artemisinin.…”

“…Despite the increasing number of phytochemical and pharmaceutical investigations carried out on medicinal plants, only about 1% of the actual medicines used in traditional medications have thus far been scientifically investigated . In Africa, plants from the genus Entandrophragma are extensively used for the treatment of several diseases including malaria, rheumatism, joint pains, or wounds . The first chemical investigations of the genus Entandrophragma took place earlier in 1960 with the isolation of gedunin ( 12 ) from E. angolense .…”