Coumarins and anthelmintic A-type procyanidins from the roots of Paullinia pinnata L.

Extracts from the roots of Paullinia pinnata L. are used in West Africa as traditional remedies for a variety of diseases including infestations with soil-transmitted helminths [1]. Based on the results of an ethnopharmacological survey in Ghana [2] an aqueous acetone (70%) extract was investigated in this study for its anthelmintic and phytochemical properties. The crude extract showed lethal effects against the free-living nematode Caenorhabditis elegans (LC₅₀ 2.5 mg/mL after 72h of incubation; positive control: Levamisole-HCl 40 mM, negative control: DMSO 1%) and bioassay-guided fractionation using Sephadex^® LH-20 followed by preparative HPLC lead to oligomeric procyanidins (OPC) as the predominant class of active compounds. Structure elucidation by LC-MS and NMR revealed cinnamtannin B1 (epicatechin-(2β→O→7,4β→8)-epicatechin-(4β→8)-epicatechin), parameritannin A1 (epicatechin-(2β→O→7,4β→8)-[epicatechin-(4β→8)]-epicatechin-(4β→8)-epicatechin), epicatechin-(4β→8)-epicatechin-(2β→O→7,4β→8)-epicatechin-(4β→8)-epicatechin and epicatechin-(2β→O→7,4β→8)-ent-catechin-(4β→8)-epicatechin as the major OPCs in the extract. The anthelmintic activity of OPCs is well known [3], however suprisingly, the A-type trimer cinnamtannin B1 caused a significantly higher mortality in C. elegans than the structurally related B-type trimer procyanidin C1 (86 % vs. 47 % at 1 mM respectively).

In addition to the OPCs, a glucosyloxy-4-methyl-2(5H)-furanone along with several coumarins, including cleomiscosins A-D and the novel isofraxidin-7-O-β-D-glucopyranosyl-(1′′→6′)-α-L-rhamnopyranoside, were isolated. None of these compounds contributed to the anthelmintic activity, however, the presence of coumarins has not been described previously for Paullinia species.

In summary, this study provides an insight into the composition of phenolic compounds in the root extract from P. pinnata and is one of the first investigations of A-type proanthocyanidins against nematodes, supporting the traditional use as an anthelmintic remedy.

• References

• 1 Okpekon T, Yolou S, Gleye C, Roblot F, Loiseau P, Bories C, Grellier P, Frappier F, Laurens A, Hocquemiller R. Antiparasitic activities of medicinal plants used in Ivory Coast. J Ethnopharmacol 2004; 90: 91-97
• 2 Agyare C, Spiegler V, Sarkodie H, Asase A, Liebau E, Hensel A. An ethnopharmacological survey and in vitro confirmation of the ethnopharmacological use of medicinal plants as anthelmintic remedies in the Ashanti region, in the central part of Ghana. J Ethnopharmacol 2014; 158PA: 255-263
• 3 Spiegler V, Liebau E, Hensel A. Medicinal plant extracts and plant-derived polyphenols with anthelmintic activity against intestinal nematodes. Nat Prod Rep 2017; 34: 627-643