Diderot Tchamo Noungoue

Isoflavone Dimers and Other Bioactive Constituents from the Figs of Ficus mucuso

Phytochemical investigation of the figs of Ficus mucuso led to the isolation of three new isoflavone dimer derivatives, mucusisoflavones A-C (1-3), together with 16 known compounds. Some of the isolates were tested in vitro for their inhibitory properties toward β-glucuronidase and Plasmodium falciparum enoyl-ACP reductase (PfENR) enzymes. Compound 1 (IC₅₀) 0.68 μM) showed inhibitory activity on β-glucuronidase enzyme, while 3 (IC₅₀) 7.69 μM) exhibited a weak inhibitory activity against P. falciparum enoyl-ACP reductase (PfENR).

Antiplasmodial sesquiterpenes from the seeds of Salacia longipes var. camerunensis

Phytochemical investigation of the seeds of Salacia longipes var. camerunensis led to the isolation of four sesquiterpenoid derivatives, salaterpene A (1) (1α,2β,8β-triacetoxy-6β,9β-dibenzoyloxy-4β-hydroxy-dihydro-β-agarofuran), salaterpene B (2) (1α,2β,8β-triacetoxy-9β-benzoyloxy-6β-cinnamoyloxy-4β-hydroxy-dihydro-β-agarofuran), salaterpene C (3) (1α,2β-diacetoxy-6β,9β-dibenzoyloxy-4β-hydroxy-dihydro-β-agarofuran) and salaterpene D (4) (2β-acetoxy-1α,6β-dibenzoyloxy-4β-hydroxy-9β-nicotinoyloxy-dihydro-β-agarofuran) together with two known compounds (5 and 6). The structures of the compounds were established by means of NMR spectroscopy. Compounds 1-4 and 6 were tested in vitro for their antiplasmodial activity against Plasmodium falciparum chloroquine-resistant strain W2. All the tested compounds exhibited a moderate potency with IC50 below 2.7 μM.

Antimalarial compounds from the stem bark of Vismia laurentii.

A phytochemical study of the stem bark of Vismia laurentii resulted in the isolation of a tetracyclic triterpene, tirucalla-7,24-dien-3-one (1), and seven other known compounds: 3-geranyloxyemodin (2), vismiaquinone A (3), vismiaquinone B (4), bivismiaquinone (5), epifriedelinol (6), betulinic acid (7) and stigmasta-7,22-dien-3-ol (8). The structure of all these compounds was elucidated by spectroscopic means. The stem bark extract and compounds 1 and 3 showed good antimalarial activity against the W2 strain of Plasmodium falciparum.

(1R*,5R*,7R*,8S*)‐3‐(3,4‐Dihydroxy­benzo­yl)‐4‐hydr­oxy‐8‐methyl‐1,5,7‐tris­(3‐methyl‐2‐buten­yl)‐8‐(4‐methyl‐3‐penten­yl)bicyclo­[3.3.1]non‐3‐ene‐2,9‐dione

The title compound, C38H50O6, also known as guttiferone A, was isolated from the medicinal plant Symphonia globulifera. It is a benzophenone derivative where one aryl group is derivatized to give a bicyclic system which has two prenyl groups attached to the bridgehead. One of the cyclohexane rings in the bicyclic system is in a chair form, while the other has a distorted half-chair conformation. In addition to an intramolecular O-H center dot center dot center dot O hydrogen bond, intermolecular O-H center dot center dot center dot O hydrogen bonds link molecules into one-dimensional chains.

Pobeguinine: a monoterpene indole alkaloid and other bioactive constituents from the stem bark of Nauclea pobeguinii

Abstract Phytochemical investigation of dichloromethane neutral phase of stem bark of Nauclea pobeguinii led to the isolation of a new monoterpene indole alkaloid, pobeguinine 1 along with 14 known compounds including (−)-naucleofficine D (2a), (+)-naucleofficine D (2b), naucleidinal (3), quafrinoic acid (4), betulinic acid (5), ursolic acid (6), quinovic acid (7), quinovic acid 3-O-α-L-rhamnopyranoside (8a), quinovic acid 3-O-β-D-fucopyranoside (8b), β-sitosterol (9), β-sitosterol 3-O-β-D-glucopyranoside (10), benzoic acid (11), lacceroic acid (12) and n-heptacosane (13). The structure of compound 1 was unambiguously assigned on the basis of single-crystal X-ray diffraction technique. The Hirshfeld surface analysis was further carried out to quantitatively analyze the role of various types of hydrogen bonding in crystal stability. These structures were elucidated using spectroscopic methods. The isolates were evaluated for their radical scavenging properties as well as inhibitory activities against urease and tyrosinase enzymes with IC50 values ranging from 13.4 to 58.9, 46.0 to 86.7 and 39.4 to 87.1 μg/mL, respectively. Compound 6 exhibited maximum radical scavenging activity with IC50 13.4 μg/mL, while compound 4 exhibited maximum tyrosinase with IC50 39.4 μg/mL. All the isolates showed moderate urease inhibition.

Salacetal, an Oleanane-type Triterpene from Salacia longipes var. camerunensis

Phytochemical investigation of the roots of Salacia longipes var. camerunensis led to the isolation of a new triterpenoid, salacetal (1), together with the known compounds mangiferin, 2-hydroxy- 3-oxo-D:A-friedooleanan-29-oic acid, β -sitosterol, and stigmasterol. The structure of the new compound as well as those of the known compounds were established by means of spectroscopic methods and by comparison with reported data. Graphical Abstract Salacetal, an Oleanane-type Triterpene from Salacia longipes var. camerunensis