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Introduction: Recurring viral outbreaks have a significant negative impact on society. This creates a need to develop novel strategies to complement the existing antiviral approaches. There is a need for safe and sustainable antiviral solutions derived from nature. Objective: This study aimed to investigate the antiviral potential of willow (Salix spp.) bark hot water extracts against coronaviruses and enteroviruses. Willow bark has long been recognized for its medicinal properties and has been used in traditional medicines. However, its potential as a broad-spectrum antiviral agent remains relatively unexplored. Methods: Cytopathic effect inhibition assay and virucidal and qPCR-based assays were used to evaluate the antiviral potential of the bark extracts. Themechanismof action was investigated using time-of-addition assay, confocal microscopy, TEM, thermal, and binding assays. Extracts were fractionated and screened for their chemical composition using high-resolution LC-MS. Results: The native Salix samples demonstrated their excellent antiviral potential against the non-enveloped enteroviruses even at roomtemperature and after 45 s. They were equally effective against the seasonal and pandemic coronaviruses. Confocal microscopy verified the loss of infection capacity by negligible staining of the newly synthesized capsid or spike proteins. Time-of-addition studies demonstrated that Salix bark extract had a direct effect on the virus particles but not through cellular targets. Negative stain TEM and thermal assay showed that antiviral action on enteroviruses was based on the added stability of the virions. In contrast, Salix bark extract caused visible changes in the coronavirus structure, which was demonstrated by the negative stain TEM. However, the binding to the cells was not affected, as verified by the qPCR study. Furthermore, coronavirus accumulated in the cellular endosomes and did not proceed after this stage, based on the confocal studies. None of the tested commercial reference samples, such as salicin, salicylic acid, picein, and triandrin, had any antiviral activity. Fractionation of the extract and subsequentMS analysis revealed thatmost of the separated fractions were very effective against enteroviruses and contained several different chemical groups such as hydroxycinnamic acid derivatives, flavonoids, and procyanidins. Conclusion: Salix spp. bark extracts contain several virucidal agents that are likely to act synergistically and directly on the viruses. [ABSTRACT FROM AUTHOR]

Tannins from Norway spruce (Picea abies [L.] Karst.) and Scots pine (Pinus sylvestris L.) bark were extracted with water at different temperatures (60–140 °C) in an ASE-350 system in order to optimize yield. In addition, the effect of chemicals such as urea, sodium bisulfite (NaHSO 3), sodium carbonate (Na 2 CO 3), and sodium benzoate on the yield was also investigated. Bark from debarking processes at both a sawmill and a pulp mill were included. The highest overall yield expressed as total dissolved solids (TDS) was obtained with hot water extraction of spruce bark at 140 °C. The TDS was 117 mg/g and it contained 47 mg/g tannins. With an increase in extraction temperature over 100 °C, the proportion of tannins decreased, whereas the proportion of carbohydrates increased. The addition of sodium carbonate improved yield within a 60–90 °C temperature range compared with pure water. Other chemicals did not improve the yield. Pine bark showed similar extraction yields to spruce bark but the proportion of tannins was lower in spruce than in pine. Pure water at 110 °C was chosen to be used for piloting in larger scale 300-liter extraction vessel. Based on the results, a machine-learning approach was applied using seemingly unrelated regression models (SUR). The models were able to predict the extracted tannin yields of spruce and pine bark when extractions were scaled up to 2 liters and then to 300 liters. [Display omitted] • Industrial Norway spruce and Scots pine bark was extracted in three different reactor scales with water and chemical additions. • Extraction conditions for tannin yield were optimised in laboratory scale. • Usability of tannin containing extract in adhesives were assessed with Stiasny number. • Machine learning model was created to predict scaling up results based on laboratory scale extractions. [ABSTRACT FROM AUTHOR]

Birch sawdust was extracted with a pressurized hot water (PHW) flow- through system. The pH of the extract was controlled during extraction by the addition of acetic acid/sodium acetate buffer. Three different pH levels, 4.0, 4.2, and 4.6, were used. Extraction temperatures were 160, 170, and 180 °C, with a constant 4 mL/min flow rate through the 50 mL extraction vessel. During PHW extraction with plain water, the end pH of the extract dropped from 5 to below 3. Buffers kept the pH of the extracts constant during the first 30 min of extraction. Compared to plain water, the use of buffers resulted in a lower yield of xylans during the 170 °C extraction. However, with the buffered system it was possible to obtain xylans from sawdust with a higher molar mass than plain water extraction. Acetic acid/sodium acetate buffer enabled control of the hydrolysis rate of xylans during extraction. [ABSTRACT FROM AUTHOR]

Pressurized hot water extraction with a flow-through system was used to extract hemicelluloses and lignin from birch sawdust. The structure of the extraction residue was studied on various levels. Molecular mass distributions were determined with gel permeation chromatography and the crystal structure of cellulose was characterized using wide-angle X-ray scattering (WAXS). Information on the short-range order of cellulose microfibrils and on the nanoscale pore structure was obtained with small-angle X-ray scattering (SAXS), and the micrometre scale cellular morphology was imaged with X-ray microtomography. The pressurized hot water treatment was observed to increase the lateral width of cellulose crystallites, determined with WAXS, whereas a possible small decrease in the crystallinity of cellulose compared to native wood was detected. The molecular mass of cellulose remained at a relatively high level. According to the SAXS results, a tighter lateral association of cellulose microfibrils was observed in the extracted samples, which possibly led to opening of pores between bundles of microfibrils, as indicated by an increased specific surface area. A reduction in the thickness of the fibre cell walls was evidenced by X-ray microtomography. [ABSTRACT FROM AUTHOR]

Softwood bark is an important by-product of forest industry. Currently, bark is under-utilized and mainly directed for energy production, although it can be extracted with hot water to obtain compounds for value-added use. In Norway spruce (Picea abies [L.] Karst.) bark, condensed tannins and stilbene glycosides are among the compounds that comprise majority of the antioxidative extractives. For developing feasible production chain for softwood bark extractives, knowledge on raw material quality is critical. This study examined the fate of spruce bark tannins and stilbenes during storage treatment with two seasonal replications (i.e., during winter and summer). In the experiment, mature logs were harvested and stored outside. During six-month-storage periods, samples were periodically collected for chemical analysis from both inner and outer bark layers. Additionally, bark extractives were analyzed for antioxidative activities by FRAP, ORAC, and H2O2 scavenging assays. According to the results, stilbenes rapidly degraded during storage, whereas tannins were more stable: only 5–7% of the original stilbene amount and ca. 30–50% of the original amount of condensed tannins were found after 24-week-storage. Summer conditions led to the faster modification of bark chemistry than winter conditions. Changes in antioxidative activity were less pronounced than those of analyzed chemical compounds, indicating that the derivatives of the compounds contribute to the antioxidative activity. The results of the assays showed that, on average, ca. 27% of the original antioxidative capacity remained 24 weeks after the onset of the storage treatment, while a large variation (2–95% of the original capacity remaining) was found between assays, seasons, and bark layers. Inner bark preserved its activities longer than outer bark, and intact bark attached to timber is expected to maintain its activities longer than a debarked one. Thus, to ensure prolonged quality, no debarking before storage is suggested: outer bark protects the inner bark, and debarking enhances the degradation. [ABSTRACT FROM AUTHOR]

Bark of Norway spruce and Scots pine trees contain large amounts of condensed tannins. Tannins extracted with hot water could be used in different applications as they possess antioxidative and antimicrobial activities. The use of bark tannins as e.g., food preservatives calls for increases in our knowledge of their antioxidative activities when applied in foodstuffs. To assess the ability of bark tannins to prevent lipid oxidation, hot water extracts were evaluated in a liposome model. Isolated tannins were also applied in dry-cured, salty meat snacks either as liquid extracts or in dry-powder form. Consumer acceptance of the snacks was tested by a sensory evaluation panel where outlook, odor, taste, and structure of the snacks were evaluated and compared to a commercial product without tannin ingredients. Our results show that conifer bark tannin-rich extracts have high capacity to prevent lipid oxidation in the liposome model. The efficacies of pine and spruce bark extracts were ten to hundred folds higher, respectively, than those of phenolic berry extracts. The bark extracts did not significantly influence the odor or taste of the meat snacks. The findings indicate that bark extracts may be used as sustainable food ingredients. However, more research is needed to verify their safety. [ABSTRACT FROM AUTHOR]

• Softwood bark can be refined into valuable compounds. • HWE, pyrolysis and AD were combined as cascade process. • With cascade processing, no waste streams were produced. • The most important development schemes were defined. A process model based on hot water extraction (HWE), slow pyrolysis and anaerobic digestion (AD) were used for pine and spruce bark utilisation. First tannins (32 mg/g and 11.8 mg/g, respectively) and polyphenols were recovered via HWE. Then, the residue was pyrolysed to produce biochar (marketable quality), gas (energy source) and liquid fractions. The liquid fraction was further separated into aqueous acidic fraction and to tar fraction. Bark, extracted bark residue and acidic liquid fraction from pyrolysis were treated in AD to produce biomethane and digestate. The methane yields from pine and spruce bark and extracted bark residue were low (from 42 to 96 mLCH4/gVSadded) and showed only small differences. In conclusion, cascade processing can improve the performance of subsequent single processes and utilise biomass sources with higher efficiency. The best processing chain may vary in different cases and the overall energy balance of processing needs further research. [ABSTRACT FROM AUTHOR]