Bioassay-Guided Fractionation of a Leaf Extract from Combretum mucronatum with Anthelmintic Activity: Oligomeric Procyanidins as the Active Principle.
Combretum mucronatum Schumach. &amp;amp; Thonn. is a medicinal plant widely used in West African traditional medicine for wound healing and the treatment of helminth infections. The present study aimed at a phytochemical characterization of a hydroalcoholic leaf extract of this plant and the identification of the anthelmintic compounds by bioassay-guided fractionation. An EtOH-H2O (1:1) extract from defatted leaves was partitioned between EtOAc and H2O. Further fractionation was performed by fast centrifugal partition chromatography, RP18-MPLC and HPLC. Epicatechin (1), oligomeric proanthocyanidins (OPC) 2 to 10 (mainly procyanidins) and flavonoids 11 to 13 were identified as main components of the extract. The hydroalcoholic extract, fractions and purified compounds were tested in vitro for their anthelmintic activity using the model nematode Caenorhabditis elegans. The bioassay-guided fractionation led to the identification of OPCs as the active compounds with a dose-dependent anthelmintic activity ranging from 1 to 1000 μM. Using OPC-clusters with a defined degree of polymerization (DP) revealed that a DP ≥ 3 is necessary for an anthelmintic activity, whereas a DP > 4 does not lead to a further increased inhibitory effect against the helminths. In summary, the findings rationalize the traditional use of C. mucronatum and provide further insight into the anthelmintic activity of condensed tannins.
Institute for Pharmaceutical Biology and Phytochemistry, University of Münster, Schlossplatz 2, D-48149 Münster, Germany. verena.spiegler@uni-muenster.de.
Verena
V
Spiegler
Institute for Pharmaceutical Biology and Phytochemistry, University of Münster, Schlossplatz 2, D-48149 Münster, Germany. jandirk.sendker@uni-muenster.de.
Jandirk
J
Sendker
Institute for Pharmaceutical Biology and Phytochemistry, University of Münster, Schlossplatz 2, D-48149 Münster, Germany. frank.petereit@uni-muenster.de.
Frank
F
Petereit
Institute for Zoophysiology, University of Münster, Schlossplatz 8, D-48143 Münster, Germany. liebaue@uni-muenster.de.
Eva
E
Liebau
Institute for Pharmaceutical Biology and Phytochemistry, University of Münster, Schlossplatz 2, D-48149 Münster, Germany. ahensel@uni-muenster.de.
Andreas
A
Hensel
D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D044946:Biflavonoids / Q000737:chemistry / Q000494:pharmacology*; D001681:Biological Assay / Q000379:methods*; D017173:Caenorhabditis elegans / Q000187:drug effects; D002392:Catechin / Q000737:chemistry / Q000494:pharmacology*; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D029765:Combretum / Q000737:chemistry*; D000431:Ethanol; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry*; D058105:Polymerization; D044945:Proanthocyanidins / Q000737:chemistry / Q000494:pharmacology*; D014867:Water
D000871:Anthelmintics; D044946:Biflavonoids; D010936:Plant Extracts; D044945:Proanthocyanidins; D014867:Water; D000431:Ethanol; C017674:procyanidin; D002392:Catechin
Caenorhabditis elegans; Combretum mucronatum; anthelmintic; flavonoids; proanthocyanidins; structure-activity; tannins