@phdthesis{orgprints49877,
           month = {April},
           title = {The impact of bark extracts from Norway spruce
and Scots pine on gastrointestinal parasites in
ruminants},
          author = {Berit Marie Blomstrand},
           pages = {1--175},
          school = {University of Copenhagen, Faculty of health and medical sciences},
            year = {2023},
        abstract = {Gastrointestinal parasite infections cause a decrease in animal health and welfare, productivity, and farm profitability worldwide. The development of parasite resistance towards current antiparasitic pharmaceuticals stresses the importance of finding alternative approaches to reducing the impact of parasitism on the hosts. Exploring the antiparasitic traits of bioactive plants, i.e. a plant which has the ability to interact with compounds of the living tissue of animals by presenting a wide range of probable effects, may be a way to contribute to this. Coniferous bark is rich on condensed tannins and other plant secondary metabolites (PSM). Norway has a large forestry industry with bark as an under-exploited by-product. The overall aim of this project was to explore the antiparasitic effects of bark extracts from Norway spruce and Scots pine harvested in Norway as a novel bioactive agent against parasites in ruminants. Bark from Norway spruce and Scots pine was harvested at two seasons (winter and summer) at processing plants using two different debarking methods (ring and drum debarking). The bark was extracted with three different solvents (acetone, methanol, and water), which produced 18 different bark extracts.
In Paper I, we investigated the ability of the bark extracts to inhibit the development of Cryptosporidium parvum in HCT-8 cell cultures. We found that pine bark extracts extracted with methanol and acetone as solvents inhibited C. parvum development in a sigmoid, dosedependent manner. We did not see any parasite inhibition of the water extracts at the tested concentrations. 
To assess the anthelmintic activity of spruce and pine bark, 18 different extracts were tested against two important gastrointestinal nematodes in sheep (Paper II). The extracts were tested on the abomasal parasite Teladorsagia circumcincta and the intestinal parasite Trichostrongylus colubriformis at two life stages (egg hatching and 3rd stage larvae). For the egg hatch assay (EHA), the half maximum inhibitory concentration (IC50) was estimated for all extracts. For the larval motility assay, the motility of L3 treated with bark extract was measured with a real time cell analyser and compared to the motility of the dead larvae. The bark extracts were analysed for the content of condensed tannins (CT) as well as for other possible antiparasitic compounds. Putative annotations of identified masses were procured, and the abundance of CT and of the masses were correlated with the EHA IC50. We found that several of the tested extracts inhibited the egg hatching up to 100\%. The intestinal parasite was more susceptible to treatment compared to the abomasal parasite, pine bark, winter bark, and bark extracted with organic solvents (acetone or methanol) inhibited the parasites to a larger extent compared to spruce bark, summer 10 bark, and water extracts. CT was negatively correlated to EHA IC50 for T. colubriformis but not for T. circumcincta, and several putative annotations were obtained, suggesting the identity of novel antiparasitic masses. 
In Paper III we explored the anticoccidial properties of water extracted spruce bark. Young preruminant lambs infected with ovine Eimeria spp. were treated with spruce bark extract. The bark extract treated lambs exhibited a lower Eimeria oocyst count and lower rate and severity of
diarrhoea compared to the untreated lambs. Simultaneously, the treated lambs experienced detrimental effects like reduced milk intake with a subsequent lower growth during the treatment period, which subsided after discontinuing the treatment. 
When assessing acetone extracted pine bark harvested during the winter using Heligmosomoides bakeri infected mice as a model (Paper IV), we found no significant effects in parasitological parameters, though the bark extract treatment increased the body weight and carcass weight and reduced the feed intake-bodyweight ratio in the most susceptible group only: the infected slow responder mice (C57BL/6). Furthermore, the treatment reduced the tolerance to the parasite of the more resistant, fast responder mice (BALB/c). These results indicate that the host responses to PSM may be sensitive to variation in the genetic susceptibility to the parasite.
In conclusion, the results obtained in this project have provided new and essential knowledge to the antiparasitic efficacy of bark extracts from P. abies and P. sylvestris against a wide range of gastrointestinal parasite infections in various host species. There was a negative correlation between CT content of the extracts and EHA IC50 of T. colubriformis, and several novel compounds with a significant negative correlation with EHA IC50 were putatively annotated. However, investigations of the chemical compounds in the bark extracts responsible for the antiparasitic effects has only begun. Thus, it is of importance to gain further knowledge into the identification of the actual antiparasitic compounds, their concentrations, and their effect against various parasites, alone or synergistically.},
             url = {https://orgprints.org/id/eprint/49877/},
        keywords = {BarkCure, ruminants, parasites, bark extracts, spruce, pine, plant secondary metabolites, barkeekstrakt, parasitter,}
}