A new procyanidin B from <i>Campylospermum zenkeri</i> (Ochnaceae) and antiplasmodial activity of two derivatives of (±)-serotobenine

<p>Phytochemical investigation of the stem bark of <i>Campylospermum zenkeri</i> led to the isolation of five known compounds: (<i>Z,Z</i>)-9,12-octadecadienoic acid (<b>1),</b> serotobenine (<b>2</b>), agathisflavone (<b>3</b>), lophirone A (<b>4</b>) and lophirone F (<b>5</b>), together with a new derivative of procyanidin B, a catechin dimer named zenkerinol (<b>6</b>). Serotobenine (<b>2</b>) is structurally related to decursivine which shows moderate activity against D6 and W2 strains of <i>Plasmodium falciparum</i>. For a better understanding of structure-activity relationships, three new semi-synthetic derivatives of serotobenine (<b>2</b>) have been prepared. These are: serotobenine monopropionate (<b>2a</b>), serotobenine monopivalate (<b>2b</b>) and serotobenine cyclohexyl ether (<b>2c</b>) respectively. Two of them (<b>2a)</b> and <b>(2b)</b>, were evaluated for their antiplasmodial activity against <i>P. falciparum</i> 3D7 strain in a parasite lactate-dehydrogenase (pLDH) assay. Compound <b>2b</b> was more active than compound <b>2a</b> based on their IC₅₀ values (36.6 and 123 μM, respectively).</p

Secondary metabolites from <i>Triclisia gilletii</i> (De Wild) Staner (Menispermaceae) with antimycobacterial activity against <i>Mycobacterium tuberculosis</i>

<p>Triclisinone (<b>2</b>), a new ochnaflavone derivative, was isolated from the aerial parts of <i>Triclisia gilletii</i>, along with known drypemolundein B (<b>1</b>) and eight other known compounds. The chemical shifts of drypemolundein B (<b>1</b>) have been partially revised based on reinterpretation of NMR spectroscopic data. The eight other secondary metabolites are composed of: (+)-nonacosan-10-ol (<b>3</b>); stigmasterol (<b>4</b>), 3-<i>O</i>-β-D-glucopyranosylsitosterol (<b>5</b>), 3-<i>O</i>-β-D-glucopyranosylstigmasterol (<b>6</b>); oleanic acid (<b>7</b>); myricetin (<b>8</b>), quercetin (<b>9</b>) and 3-methoxyquercetin (<b>10</b>). Their structures were elucidated using IR, MS, NMR 1D and 2D, ¹H and ¹³C and comparison with literature data. Furthermore, compounds <b>1</b>, <b>2</b>, <b>5, 6, 8, 9</b> and the crude extract were tested against <i>Mycobacterium tuberculosis</i>. Compounds <b>1, 2, 8</b> and <b>9</b> displayed moderate to very good activity against resistant strain (codified AC 45) of <i>M. tuberculosis</i> with minimum inhibitory concentrations MICs ranging from 3.90 to 62.5 μg/mL<i>.</i></p