Extracts of pine bark (Pinus sylvestris) inhibit Cryptosporidium parvum growth in cell culture

Condensed tannins, novel compounds and sources of variation determine the antiparasitic activity of Nordic conifer bark against gastrointestinal nematodes

The antiparasitic potential of plants could offer a vital solution to alleviating the costs of gastrointestinal nematode (GIN) infections in ruminant production globally. Leveraging known bioactive molecules, however, is complex, where plant species, extraction processes and seasonality impact bioavailability and efficacy. This study assessed the impact of a comprehensive set of factors on the antiparasitic activity of Norwegian conifers to identify bark compounds specific against GIN. Antiparasitic activity was determined using in vitro assays targeting morphologically distinct life stages of ovine GIN: the egg hatch assay and larval motility assay. In depth characterisation of the chemical composition of the bark extracts was carried out using chromatographic separation, UV-absorbance, and molecular mass profiles to identify compounds implicated in the activity. Three key findings emerged: (1) the activity of bark extracts varied markedly from 0 to 100% antiparasitic efficacy, owing to tree species, extraction solvent and seasonality; (2) the GIN exhibited species-and stage-specific susceptibility to the bark extracts; (3) the presence of condensed tannins, amongst other compounds, was associated with anthelmintic activity. These findings add new insights into urgently needed alternative parasite control strategies in livestock.

Silver Nanoparticles Synthesized from Abies alba and Pinus sylvestris Bark Extracts: Characterization, Antioxidant, Cytotoxic, and Antibacterial Effects

In recent years, phytofunctionalized AgNPs have attracted great interest due to their remarkable biological activities. In the present study, AgNPs were synthesized using Abies alba and Pinus sylvestris bark extracts. The chemical profile of these bark extracts was analyzed by LC-HRMS/MS. As a first step, the synthesis parameters (pH, AgNO₃ concentration, ratio of bark extract and AgNO₃, temperature, and reaction time) were optimized. The synthesized AgNPs were characterized by ATR-FTIR spectroscopy, DLS, SEM, EDX, and TEM. Their antioxidant, cytotoxic, and antibacterial properties were evaluated by the DPPH, ABTS, MTT, and broth microdilution assays, respectively. Abies alba and Pinus sylvestris bark extract-derived AgNPs were well-dispersed, spherical, small (average particle size of 9.92 and 24.49 nm, respectively), stable (zeta potential values of -10.9 and -10.8 mV, respectively), and cytotoxic to A-375 human malignant melanoma cells (IC₅₀ = 2.40 ± 0.21 and 6.02 ± 0.61 μg/mL, respectively). The phytosynthesized AgNPs also showed antioxidant and antibacterial effects.

Effects of selected condensed tannins on Cryptosporidium parvum growth and proliferation in HCT-8 cell cultures

Infections with Cryptosporidium spp. constitute a substantial public health burden and are responsible for widespread production losses in cattle herds. Reducing disease and shedding of Cryptosporidium spp. oocysts is an important One Health goal. There are very few therapeutic options available to treat cryptosporidiosis. Interest in plant bioactive compounds to mitigate the spread of anthelmintic resistance in ruminants has led to investigation of these phytocompounds against other parasitic taxa. Condensed tannins (CTs) are plant secondary metabolites that have shown potential against nematodes in vitro and in vivo but their applicability to Cryptosporidium spp. is comparatively under-explored. Cryptosporidium parvum infected human ileocecal colorectal adenocarcinoma (HCT)-8 cell cultures were treated with escalating doses of highly purified and well-characterized CTs from five plant species, big trefoil (Lotus pedunculatus), black currant (Ribes nigrum), sainfoin (Onobrychis viciifolia), white clover (Trifolium repens) and grapeseed (Vitis vinifera) for 44 h. Quantitative-PCR (qPCR) analysis revealed that none of the CTs examined demonstrated inhibitory potential against the parasite. Substantial inhibition of C. parvum by paromomycin was observed in positive controls in all assays (76.94-90.72% inhibition), proving the validity of the assay. Despite the lack of inhibition, these results represent an important step towards identifying alternative treatment options against this parasite.

Administration of spruce bark (Picea abies) extracts in young lambs exhibits anticoccidial effects but reduces milk intake and body weight gain

Background

Eimeria spp. are widespread apicomplexan parasites known to cause coccidiosis in livestock, resulting in reduced animal welfare and productivity, particularly in sheep. The treatment options are limited, and there is an emerging development of resistance against registered pharmaceuticals. Spruce bark is rich in plant secondary metabolites (PSM), such as condensed tannins, which are bioactive compounds previously shown to have antiparasitic activity. Here, we examined the anticoccidial properties of bark extract of Norway spruce (Picea abies) against a field isolate of ovine Eimeria spp. by treating Eimeria-infected pre-ruminant lambs with water-extracted bark daily for 12 days. We hypothesised that the bark extract would reduce the faecal oocyst excretion and, consequently, the severity of diarrhoea.

Results

Oral administration of spruce bark extract significantly reduced the excretion of Eimeria oocysts in milk-fed lambs post treatment till the end of the trial 22 days post infection. This difference in oocyst excretion between the treated and the untreated infected animals increased with time.

Compared to the untreated and the sham-infected control group, the group treated with bark extract had softer faeces and reduced milk intake during the treatment period. After discontinuing the treatment, the treated animals got a more solid and formed faeces compared to that of the untreated control group, and the milk intake increased to the level of the sham-infected, untreated control group. The bark extract treated animals had a lower body weight and a lower mean daily body weight gain throughout the whole duration of the experiment.

Conclusions

Bark extract from Norway spruce showed marked anticoccidial properties by reducing the faecal oocyst count and associated diarrhoea in young lambs. Simultaneously we experienced detrimental effects of the treatment, displayed as reduced feed intake and daily body weight gain. Therefore, we suggest conducting similar studies with lower bark extract dosage to explore the possibilities of a better trade-off to reduce the negative impact while maintaining the antiparasitic effect.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13028-022-00629-y.

Use of agro-industrial by-products containing tannins for the integrated control of gastrointestinal nematodes in ruminants

Previous studies have illustrated that different bioactive legume fodders containing condensed tannins might represent one of the options for integrated sustainable control of gastrointestinal nematodes (GIN) in ruminants, which may help address the worldwide development of resistance to synthetic anthelmintics. More recently, impetus has been given to assess the potential antiparasitic activity of less conventional resources, represented by different agro-industrial by-products (AIBPs). This review presents in vitro and in vivo results obtained with a range of tannin-containing AIBPs of various geographical and botanical origins, namely AIBP of nuts, temperate and tropical barks, carob, coffee and cocoa. They tend to confirm the “proof of concept” for their antiparasitic effects and also for other aspects of ruminant production in an agro-ecological context. Socio-economic aspects of the exploitation of such non-conventional resources are also discussed as potential models of the circular economy, by using waste. The different modes of use of these resources are presented in this review, as well as strengths, weaknesses, opportunities, and threats (SWOT) analyses to illustrate the advantages and limitations of on-farm use.