Anthelmintic activity of trans-cinnamaldehyde and A- and B-type proanthocyanidins derived from cinnamon (Cinnamomum verum)

Cinnamon (Cinnamomum verum) has been shown to have anti-inflammatory and antimicrobial properties, but effects on parasitic worms of the intestine have not been investigated. Here, extracts of cinnamon bark were shown to have potent in vitro anthelmintic properties against the swine nematode Ascaris suum. Analysis of the extract revealed high concentrations of proanthocyanidins (PAC) and trans-cinnamaldehyde (CA). The PAC were subjected to thiolysis and HPLC-MS analysis which demonstrated that they were exclusively procyanidins, had a mean degree of polymerization of 5.2 and 21% of their inter-flavan-3-ol links were A-type linkages. Purification of the PAC revealed that whilst they had activity against A. suum, most of the potency of the extract derived from CA. Trichuris suis and Oesophagostomum dentatum larvae were similarly susceptible to CA. To test whether CA could reduce A. suum infection in pigs in vivo, CA was administered daily in the diet or as a targeted, encapsulated dose. However, infection was not significantly reduced. It is proposed that the rapid absorption or metabolism of CA in vivo may prevent it from being present in sufficient concentrations in situ to exert efficacy. Therefore, further work should focus on whether formulation of CA can enhance its activity against internal parasites.