Investigation of the flavan-3-ol patterns in willow species during one growing-season

Effects of leaf herbivory and autumn seasonality on plant secondary metabolites: A meta-analysis

Plant secondary metabolites (PSMs) are produced by plants to overcome environmental challenges, both biotic and abiotic. We were interested in characterizing how autumn seasonality in temperate and subtropical climates affects overall PSM production in comparison to herbivory. Herbivory is commonly measured between spring to summer when plants have high resource availability and prioritize growth and reproduction. However, autumn seasonality also challenges plants as they cope with limited resources and prepare survival for winter. This suggests a potential gap in our understanding of how herbivory affects PSM production in autumn compared to spring/summer. Using meta-analysis, we recorded overall production of 22 different PSM subgroups from 58 published papers to calculate effect sizes from herbivory studies (absence to presence) and temperate to subtropical seasonal studies (summer to autumn), while considering other variables (e.g., plant type, increase in time since herbivory, temperature, and precipitation). We also compared production of five phenolic PSM subgroups - hydroxybenzoic acids, flavan-3-ols, flavonols, hydrolysable tannins, and condensed tannins. We wanted to detect a shared response across all PSMs and found that herbivory increased overall PSM production in herbaceous plants. Herbivory was also found to have a positive effect on individual PSM subgroups, such as flavonol production, while autumn seasonality was found to have a positive effect on flavan-3-ol and condensed tannin production. We discuss how these responses might stem from plants producing some PSMs constitutively, whereas others are induced only after herbivory, and how plants produce metabolites with higher costs only during seasons when other resources for growth and reproduction are less available, while other phenolic PSM subgroups serve more than one function for plants and such functions can be season dependent. The outcome of our meta-analysis is that autumn seasonality changes some PSM production differently from herbivory, and we see value in further investigating seasonality-herbivory interactions with plant chemical defense.

Bassia longifolia (= Madhuca longifolia): Isolation of flavan-3-ols and their contribution to the antibacterial and antidiabetic activity in vitro

Bassia longifoliaKOENIG (= Madhuca longifolia (L.) is an evergreen tree that is widely distributed throughout Nepal, India, and Sri Lanka. The bark has various traditional uses: as a paste in the treatment of cuts and wounds or internally as a decoction that is given to diabetic patients. Chemical-analytical and pharmacological investigations regarding the bark are not sufficiently available. We focused on the isolation of flavan-3-ols from the methanolic extract and their contribution to the described traditional uses in wound healing and diabetes treatment. Therefore, an antibacterial assay and an α-glucosidase assay were performed. The isolation process was performed by a combination of Sephadex®-, MCI®-Gel-, and RP-18 chromatography. The structures of the isolated compounds were elucidated by 1H- and 13C-NMR-spectroscopy including COSY, ROESY, HSQC, and HMBC methods. Optical characterization was performed by polarimetry and circular dichroism. Two monomeric, seven dimeric, six trimeric, and one tetrameric flavan-3-ols were found including one dimer and three trimers with rare epiafzelechin units. Two compounds were isolated for the first time. A fraction containing higher oligomeric and polymeric proanthocyanidins (PAs) was examined by 13C NMR spectroscopy and revealed an average degree of polymerization of 8-9. PA with cis-configurated subunits predominated at 90 % and the presence of further monohydroxylated flavan-3-ols was revealed. Minimal inhibitory concentrations (MICs) were investigated by the serial microdilution broth assay with Staphylococcus aureus. The bacterial suspension was inoculated on agar plates for determining the MICs. The α-glucosidase assay was performed in 96 well plates with α-glucosidase from Bacillus stearothermophilus. For the detection of enzyme inhibition, p-nitrophenyl-α-d-glucopyranoside was used as a substrate and after incubation absorbance was measured at 405 nm. Antibacterial effects were only found for fractions enriched with PAs or containing higher oligomeric and polymeric flavan-3-ols. All tested substances showed high α-glucosidase inhibition. Whereby 4β→8 conjugated dimers and the monomers showed the lowest inhibition, procyanidin (PC) B5 as 4β→6 conjugated and cinnamtannin A2 as tetrameric flavan-3-ol showed the highest. PAs with epiafzelechin units are rarely found in nature but their reoccurring appearance in B. longifolia could be characteristic of this plant. For its traditional uses, the antibacterial activity of the PA-enriched fractions could contribute to the wound healing process when applied to the injured skin. Moreover, all tested substances and fractions showed α-glucosidase inhibition, which could also explain the use of a decoction in the treatment of diabetes. In conclusion, pharmacological investigations could provide scientific evidence for traditional uses of B. longifolia.

Comparative study of three plant-derived extracts as new management strategies against Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

Finding innovative eco-friendly agents for pest control may be aided by investigating the plant-derived extracts' properties on economic pests. Therefore, the insecticidal, behavioral, biological and biochemical effects of Magnolia grandiflora (Magnoliaceae) leaf water and methanol extracts, Schinus terebinthifolius (Anacardiaceae) wood methanol extract, and Salix babylonica (Salicaceae) leaf methanol extract in comparison with a reference insecticide novaluron against S. littoralis were evaluated. The extracts were analyzed by High-Performance Liquid Chromatography (HPLC). The most abundant phenolic compounds were 4-hydroxybenzoic acid (7.16 mg/mL) and ferulic acid (6.34 mg/mL) in M. grandiflora leaf water extract; catechol (13.05 mg/mL), ferulic acid (11.87 mg/mL), and chlorogenic acid (10.33 mg/mL) in M. grandiflora leaf methanol extract; ferulic acid (14.81 mg/mL), caffeic acid (5.61 mg/mL), and gallic acid (5.07 mg/mL) In the S. terebinthifolius extract; cinnamic acid (11.36 mg/mL), and protocatechuic acid (10.33 mg/mL) In the methanol extract from S. babylonica extract. S. terebinthifolius extract had a highly toxic effect against second larvae after 96 h and eggs with LC50 values of 0.89 and 0.94 mg/L, respectively. Despite M. grandiflora extracts didn't show any toxicity against S. littoralis stages, they had an attractant effect on fourth- and second larvae, with feeding deterrence values of - 2.7% and - 6.7%, respectively, at 10 mg/L. S. terebinthifolius extract significantly reduced the percentage of pupation, adult emergence, hatchability, and fecundity, with values of 60.2%, 56.7%, 35.3%, and 105.4 eggs/female, respectively. Novaluron and S. terebinthifolius extract drastically inhibited the activities of α-amylase and total proteases to 1.16 and 0.52, and 1.47 and 0.65 ΔOD/mg protein/min, respectively. In the semi-field experiment, the residual toxicity of tested extracts on S. littoralis gradually decreased over time compared to novaluron. These findings indicate that extract from S. terebinthifolius is a promising insecticidal agent against S. littoralis.

Willow (Salix babylonica) Extracts Can Act as Biostimulants for Enhancing Salinity Tolerance of Maize Grown in Soilless Culture

Salinity negatively affects agricultural production by reducing crop growth and yield. Botanical biostimulants can be used as innovative and sustainable tools to cope with abiotic stress. In this study, salicylic acid (SA) (25 µM) and willow leaf (WL) (0.1 and 0.2%) and bark (WB) (0.1 and 0.2%) extracts were applied as plant-based biostimulants to hydroponically grown maize in the absence and presence of salinity stress (60 mM NaCl). The hormone-like activity and mineral composition of willow extracts were analyzed, and the effects of willow extracts on growth parameters, chlorophyll content, antioxidative enzyme activities, protein levels and mineral nutrient concentrations of maize plants were measured. Within the tested biostimulant applications, 0.2% WB, 0.1% WL and 0.2% WL gave the most promising results, considering the stress alleviating effects. The shoot biomass was increased up to 50% with 0.1% WL treatment and Na⁺ uptake was reduced with biostimulant applications under saline conditions. Under stress, the protein concentrations of maize leaves were enhanced by 50% and 80% with high doses of WB and WL applications, respectively. Results indicate that willow tree prunings can be valuable bio-economy resources, and aqueous extracts prepared from their leaves and barks can be used as effective and eco-friendly biostimulants.

Factors Associated with White Fat Browning: New Regulators of Lipid Metabolism

Mammalian adipose tissue can be divided into white and brown adipose tissue based on its colour, location, and cellular structure. Certain conditions, such as sympathetic nerve excitement, can induce the white adipose adipocytes into a new type of adipocytes, known as beige adipocytes. The process, leading to the conversion of white adipocytes into beige adipocytes, is called white fat browning. The dynamic balance between white and beige adipocytes is closely related to the body’s metabolic homeostasis. Studying the signal transduction pathways of the white fat browning might provide novel ideas for the treatment of obesity and alleviation of obesity-related glucose and lipid metabolism disorders. This article aimed to provide an overview of recent advances in understanding white fat browning and the role of BAT in lipid metabolism.

Seed Treatment with Biostimulants Extracted from Weeping Willow (Salix babylonica) Enhances Early Maize Growth

Biostimulants can be used as innovative and promising agents to address current needs of sustainable agriculture. Weeping willow tree (Salix babylonica) extracts are rich in many bioactive compounds, including, but not limited, to salicylates and phenolics. In this study, the potential of willow bark (WB) and willow leaf (WL) extracts is evaluated as plant-based biostimulants to improve the early growth of maize (Zea mays) under control and salinity stress conditions. In 3 days, seed treatment with salicylic acid and willow extract increased the shoot FW of maize seedlings 130% and 225%, respectively. The root area was, on average, enhanced by 43% with SA and 87% with willow extract applications. Moreover, these extracts increased the leaf protein concentration and reduced the negative effects of salinity during early growth. Reductions in lipid peroxidation and specific activities of antioxidative enzymes by seed treatments with willow extracts suggests a mitigation of salinity-induced oxidative stress. For most reported traits, WL applications were at least as effective as WB applications. Results indicate that aqueous extracts of weeping willow leaves, as well as bark, can be used as seed treatment agents with biostimulant activity to improve seedling growth and establishment under control and stress conditions.

Seasonal dynamics of the phenolic constituents of the cones and leaves of oriental Thuja (Platycladus orientalis L.) reveal their anti-inflammatory biomarkers

In this study, the seasonal dynamics of the flavonoids in the cones and leaves of oriental Thuja (Platycladus orientalis L. Franco) as well as the in vitro anti-inflammatory activity of their extracts were investigated. The important chemical markers of the studied extracts were determined using untargeted HPTLC profiling, which was further utilized to assess the seasonality effect on the composition of these metabolites over three seasonal cycles. A quantitative HPTLC method was developed and validated for the identified chemical markers of oriental Thuja: hyperoside, quercetrin, isoscutellarein-7-O-β-xyloside, cupressuflavone, hinokiflavone, sotetsuflavone and isoscutellarein-8-methyl ether. The highest amounts of flavonoids were observed during the summer and winter seasons, where the leaves possessed higher contents of flavonoids compared to cones. Flavone glycosides are a major class of flavones encountered in leaves, while the cones mainly accumulated biflavones. The results showed that the effect of seasonal variation on the accumulation of flavonoids within the cones was less pronounced than in the leaves. The summer leaves showed a remarkable reduction in the levels of INF-γ, where the value decreased to 80.7 ± 1.25 pg mL-1, a significantly lower level than that obtained with piroxicam (180 ± 1.47 pg mL-1); this suggests a noteworthy anti-inflammatory potential. OPLS (orthogonal projection to latent structures) models showed that flavonoidal glycosides, quercetrin, hyperoside and isoscutellarein-7-O-β-xyloside were the most contributing biomarkers to the reduction in pro-inflammatory mediators in LPS-stimulated WBCs. The results obtained in the study can thus be exploited to establish the best organs as well as the optimal periods of the year for collecting and obtaining certain biomarkers at high concentrations to guarantee the efficacy of the obtained extracts.

Identification and accumulation of phenolic compounds in the leaves and bark of Salix alba (L.) and their biological potential

The study examines the phenolic compounds in hydromethanolic extracts of Salix alba (L.) leaves and bark as well as their antioxidant activity and cytotoxic potential. UPLC-PDA-Q/TOF-MS analysis showed a total of 29 phenolic compounds in leaves and 34 in bark. Total phenolic compound content was 5575.96 mg/100 g of dry weight (DW) in leaves and 2330.31 mg/100 g DW in bark. The compounds were identified as derivatives of phenolic acids (seven in leaves and five in bark), flavanols and procyanidins (eight in leaves and 26 in bark) and flavonols (14 in leaves and three in bark). Both extracts exhibited strong antioxidant potential, assessed by radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), but the bark extract was even stronger than the ascorbic acid used as a standard. The cytotoxicity of both extracts was evaluated against human skin fibroblasts and human epidermal keratinocytes cell lines using the Presto Blue cell viability assay. The keratinocytes were more resistant to tested extracts than fibroblasts. The leaf and bark extracts at concentrations which exhibited antioxidant activity were also not toxic against the keratinocyte cell line. Thus, S. alba extracts, especially the leaf extract, offer promise as a nontoxic natural antioxidant, in cosmetic products or herbal medicines, and as a source of bioactive secondary metabolites.

Sulfated flavanones and dihydroflavonols from willow

Phytochemical profiling of a hybrid species of willow, Salix × alberti L. (S. integra Thunb. × Salix suchowensis W.C. Cheng ex G.Zhu) revealed four sulfated flavonoids, which were then isolated from young stem tissue. The structures of dihydroflavonols (flavanonols) taxifolin-7-sulfate (1) and dihydrokaempferol-7-sulfate (2) and flavanones, eridictyol-7-sulfate (3) and naringenin-7-sulfate (4) were elucidated through NMR spectroscopy and high-resolution mass spectrometry. The identified sulfated flavanones and dihydroflavonols have not been previously seen in plants, but the former have been partially characterised as metabolites in mammalian metabolism of dietary flavonoids. In addition to providing full spectroscopic characterisation of these metabolites for the first time, we also compared the in vitro antioxidant properties, via the DPPH radical scavenging assay, of the parent and sulfated flavanones, which showed that 7-sulfation of taxifolin and eriodictyol attenuates but does not remove anti-oxidant activity.