The Health-Promoting Potential of Salix spp. Bark Polar Extracts: Key Insights on Phenolic Composition and In Vitro Bioactivity and Biocompatibility

Abstract

Salix spp. have been exploited for energy generation, along with folk medicine use of bark extracts for antipyretic and analgesic benefits. Bark phenolic components, rather than salicin, have demonstrated interesting bioactivities, which may ensure the sustainable bioprospection of Salix bark. Therefore, this study highlights the detailed phenolic characterization, as well as the in vitro antioxidant, anti-hypertensive, Staphylococcus aureus growth inhibitory effects, and biocompatibility of Salix atrocinerea Brot., Salix fragilis L., and Salix viminalis L. bark polar extracts. Fifteen phenolic compounds were characterized by ultra-high-performance liquid chromatography-ultraviolet detection-mass spectrometry analysis, from which two flavan-3-ols, an acetophenone, five flavanones, and a flavonol were detected, for the first time, as their bark components. Salix bark extracts demonstrated strong free radical scavenging activity (5.58-23.62 µg mL −1 IC 50 range), effective inhibition on angiotensin-I converting enzyme (58-84%), and S. aureus bactericidal action at 1250-2500 µg mL −1 (6-8 log CFU mL −1 reduction range). All tested Salix bark extracts did not show cytotoxic potential against Caco-2 cells, as well as S. atrocinerea Brot. and S. fragilis L. extracts at 625 and 1250 µg mL −1 against HaCaT and L929 cells. These valuable findings can pave innovative and safer food, nutraceutical, and/or cosmetic applications of Salix bark phenolic-containing fractions.

Identification and Accumulation of Phenolic Compounds in the Leaves and Bark of Salix alba (L.) and Their Biological Potential

“…Among other Salix species, S. atrocinerea and S. viminalis bark extracts exhibited similar activities in the DPPH test (EC 50 = 10.98 and 14.06 μg/mL, respectively) as in the present study. On the other hand, the bark extract of S. fragilis demonstrated lower activity (EC 50 = 23.62 μg/mL) [ 42 ]. The results of the ABTS assay are comparable with those achieved earlier for other willow species, including S. purpurea barks (EC 50 = 20 μg/mL) [ 43 ].…”

“…In earlier studies, S. alba bark extract has demonstrated cytotoxic and genotoxic potential against different cell lines, for example the human leukemia (HL-60) cell line [ 6 ], human peripheral leukocyte cells and the human hepatoma cell line, with doses from 50 and 200 µg/mL [ 44 ]. However, other extracts from bark of S. atrocinerea and S. fragilis did not exert a cytotoxic effect (at 625 and 1250 µg/mL) against immortalized human keratinocytes (HaCaT) and mouse fibroblast (L929) cells [ 42 ]. The differences between cytotoxicity dose could be connected with differences in the solvent or cell line model.…”

Heat Stress in Broiler Chickens and the Effect of Dietary Polyphenols, with Special Reference to Willow (Salix spp.) Bark Supplements—A Review

“…Willow bark is listed in the European Pharmacopoeia [ 26 ] and due to its salicin content (precursor of aspirin), it has been traditionally used for treating fever, pain, and inflammation in humans. The bioactive phytomolecules, medicinal values, and nutritional properties of this plant have been extensively studied by previous researchers [ 27 , 28 , 29 , 30 ]. Salix bark is a rich and inexpensive source of phenolic glycosides [ 31 ] and polyphenols, such as flavonoids and condensed tannins [ 32 ].…”

“…Salix bark is a rich and inexpensive source of phenolic glycosides [ 31 ] and polyphenols, such as flavonoids and condensed tannins [ 32 ]. These constituents are reported to possess antirheumatic, antipyretic, anti-inflammatory, hypoglycemic [ 33 ], antibacterial [ 34 ], and antioxidant activities [ 30 , 35 ]. Although willow has been extensively studied in vitro and its undeniable beneficial properties have been proven, few studies are found on its applications in animal nutrition.…”

Heat Stress in Broiler Chickens and the Effect of Dietary Polyphenols, with Special Reference to Willow (Salix spp.) Bark Supplements - A Review

“…Willow bark is listed in the European Pharmacopoeia [26] and due to its salicin content (precursor of aspirin), it has been traditionally used for treating fever, pain, and inflammation in humans. The bioactive phytomolecules, medicinal values, and nutritional properties of this plant have been extensively studied by previous researchers [27][28][29][30]. Salix bark is a rich and inexpensive source of phenolic glycosides [31] and polyphenols, such as flavonoids and condensed tannins [32].…”