Salix spp. Bark Hot Water Extracts Show Antiviral, Antibacterial, and Antioxidant Activities—The Bioactive Properties of 16 Clones

Abstract

Earlier studies have shown that the bark of Salix L. species (Salicaceae family) is rich in extractives, such as diverse bioactive phenolic compounds. However, we lack knowledge on the bioactive properties of the bark of willow species and clones adapted to the harsh climate conditions of the cool temperate zone. Therefore, the present study aimed to obtain information on the functional profiles of northern willow clones for the use of value-added bioactive solutions. Of the 16 willow clones studied here, 12 were examples of widely distributed native Finnish willow species, including dark-leaved willow (S. myrsinifolia Salisb.) and tea-leaved willow (S. phylicifolia L.) (3 + 4 clones, respectively) and their natural and artificial hybrids (3 + 2 clones, respectively). The four remaining clones were commercial willow varieties from the Swedish willow breeding program. Hot water extraction of bark under mild conditions was carried out. Bioactivity assays were used to screen antiviral, antibacterial, antifungal, yeasticidal, and antioxidant activities, as well as the total phenolic content of the extracts. Additionally, we introduce a fast and less labor-intensive steam-debarking method for Salix spp. feedstocks. Clonal variation was observed in the antioxidant properties of the bark extracts of the 16 Salix spp. clones. High antiviral activity against a non-enveloped enterovirus, coxsackievirus A9, was found, with no marked differences in efficacy between the native clones. All the clones also showed antibacterial activity against Staphylococcus aureus and Escherichia coli, whereas no antifungal (Aspergillus brasiliensis) or yeasticidal (Candida albicans) efficacy was detected. When grouping the clone extract results into Salix myrsinifolia, Salix phylicifolia, native hybrid, artificial hybrid, and commercial clones, there was a significant difference in the activities between S. phylicifolia clone extracts and commercial clone extracts in the favor of S. phylicifolia in the antibacterial and antioxidant tests. In some antioxidant tests, S. phylicifolia clone extracts were also significantly more active than artificial clone extracts. Additionally, S. myrsinifolia clone extracts showed significantly higher activities in some antioxidant tests than commercial clone extracts and artificial clone extracts. Nevertheless, the bark extracts of native Finnish willow clones showed high bioactivity. The obtained knowledge paves the way towards developing high value-added biochemicals and other functional solutions based on willow biorefinery approaches.

Inspired by nature: Fiber networks functionalized with tannic acid and condensed tannin-rich extracts of Norway spruce bark show antimicrobial efficacy

“…This study provides baseline knowledge and proof-of-concept for the further development of antimicrobial, biobased functional coatings, and protective materials by valorizing the side streams of forestry industries, focusing on the condensed tannin-rich extract of Norway spruce bark as a case study. Similar value-added phenolics can also be obtained from other wood species or plant biomasses, such as willows, as shown in our earlier study ( Tienaho et al, 2021 ) and those by ( Lohtander et al, 2020 ; Lohtander et al, 2021 )…”

“…Tests were conducted according to the procedure described earlier ( Tienaho et al, 2021 ). In brief, the constitutively luminescent light signal emitting bacterial biosensor strains E. coli K12+pcGLS11 and S. aureus RN4220+pAT19 were used.…”

“…bark is annually produced in round wood processing, providing a potential source for high-value extracts ( Statistics Finland OSF, 2021 ). Naturally, bioactive biopolymers with antibacterial and antiviral properties ( Välimaa et al, 2020 ; Reshamwala et al, 2021 ; Tienaho et al, 2021 ) can be obtained from bark by applying extraction and fractionation processes of green chemistry ( Kilpeläinen et al, 2014 ; Rasi et al, 2019 ). The isolated biopolymers, fibers, and extracts can be used as such or further chemically modified and used as building blocks for functionalized consumer products, such as hygienic products, protective equipment, and packaging, or even in medical care equipment ( Baranwal et al, 2022 ).…”

Antibacterial and Oxidative Stress-Protective Effects of Five Monoterpenes from Softwood

“…These strains have been constructed to produce a constant luminescent light signal and antibacterial effects can be observed as a loss of emitted light signal intensity. The storage, cultivation, and test protocol has been previously described [36,44]. In brief, the strains were stored at −80 • C and awoken by approximately 16 h cultivation at 30 • C (for E. coli) and 37 • C (for S. aureus) in lysogeny agar plates (tryptone 10 g/L; yeast extract 5 g/L; NaCl 10 g/L; and agar 15 g/L).…”

Chemical composition and bioactivity of hemp, reed canary grass and common reed grown on boreal marginal lands

“…29 Notably, secondary metabolites found in such biomass are known for their multifaceted properties, encompassing antioxidant, antibacterial, antiviral, antihyperglycemic, antihypertensive and antiproliferative properties. [30][31][32] Given the extant evidence on the health and technological benets of ingredients and natural preservatives, biorenery potential and alternative valorisation techniques have been explored to replace synthetic antioxidants with plant-derived bioactive compounds. Evidence has shown that hemp fractions can provide natural antioxidants and anti-inammatory nutritional support.…”