Pinus Pinaster Bark Research Articles

The Chemical Characterisation of the Maritime Pine Bark Cultivated in Northern Portugal

Maritime pine, scientifically known as Pinus pinaster, holds a vital role in Iberian Peninsula forests, primarily as a source of wood for panels, paper, and cellulose production. Recently, there has been a growing interest in utilising agroforestry by-products to yield valuable chemicals for applications in various sectors, including the food, pharmaceutical, and bioenergy industries. This study aimed to assess the value of the primary by-product of Pinus pinaster from the Minho region of northwestern Portugal, i.e., the bark. The research extensively examined the bark’s chemical and thermal characteristics, including ash content, extractives, lignin, cellulose, hemicellulose, fatty acids, and mineral composition. Additionally, various analytical techniques like FTIR, SEM, DSC, DTG, and XRD were used to observe chemical structure differences. The results reveal that the Pinus pinaster bark primarily consists of lignin (51.15%) and holocellulose (46.09%), with extractives mainly soluble in toluene–ethanol, followed by water, and a small amount of them are soluble in ethanol. The bark contained around 0.44% ash, and heavy metals such as Cd and Pb were not found. During degradation, Pinus pinaster experienced a 10% mass loss at 140 °C. In terms of crystallinity, holocellulose and cellulose showed similar percentages at approximately 25.5%, while α-cellulose displayed the highest crystallinity index at 41%.

Biosorption of methylene blue and malachite green from single and binary solutions by Pinus pinaster bark

Aiming to develop a sustainable separation process reducing the water pollution, in this work Pinus pinaster (cluster pine) bark from a wood veneer industry was used for methylene blue and malachite green removal from aqueous systems. For single adsorption, the influence of time (up 8 h), adsorbent dose (2,5 - 5 - 10 g·L-1), temperature (25 ºC - 40 ºC - 60 ºC), pH (2 - 4 - 6) and particle size (0,1 mm - 0,5 mm, 0,5 mm - 1 mm and 1,6 mm - 2 mm) on adsorption was investigated. To study the initial concentration effect on binary adsorption, different concentrations (0 - 5 - 25 - 50 mg·L-1) were used at 25 ºC, natural pH and a dose of 5 g·L-1. High efficiency was obtained at pH = 4 (natural pH), dose of 5 g·L-1 and particle size of 0,5 - 1 mm. Adsorption percentages higher than 70 % were reached in less than one hour, with removal almost complete at equilibrium in single systems, without temperature influence. Methylene blue was slightly better adsorbed by bark. In binary systems, dyes exhibited competitive adsorption, decreasing their removal, especially increasing the initial concentration of the other dye. Dyes adsorption followed the pseudo-second order kinetic model, whereas the Langmuir isotherm explained adsorption equilibria in mono-component systems. High adsorption capacities (41,7 mg·g-1 for malachite green and 50,0 mg·g-1 for methylene blue) were obtained at 40 ºC and natural pH indicating that pine bark can be effectively used as biosorbent.

Efficacy of a topical serum containing L-ascorbic acid, neohesperidin, pycnogenol, tocopherol, and hyaluronic acid in relation to skin aging signs.

Skin aging is a process regulated by chronological aging and amplified by exposome factors including chronic UV exposure and pollution, which both induce reactive oxygen species. Topical antioxidants have the potential to counteract this process and to improve skin aging signs, including wrinkles and hyperpigmentation. To evaluate the efficacy of a topical antioxidant serum containing 15% L-ascorbic acid, neohesperidin, Pinus pinaster bark, tocopherol, and hyaluronic acid (HA) ex vivo on air pollution-induced pigmentation and gene expression, as well as in vivo on skin aging signs in Brazilian volunteers, after 90days of use. Ex vivo human skin samples were repetitively exposed to Diesel Exhaust Particles (DEP) and subsequently analyzed for changes in pigmentation and gene expression. Clinical efficacy was evaluated in 40healthy adult females with phototype II to IV and visible photoaging signs, including facial hyperpigmentation, through dermatological evaluation and instrumental analysis including Reflectance Confocal Microscopy. Ex vivo, the topical antioxidant serum significantly reduced DEP-induced skin pigmentation and expression of proinflammatory genes. A significant improvement of skin aging signs was observed after 90days. Local tolerance was good. The tested serum is effective in protecting human skin ex vivo against air pollution-induced skin pigmentation/aging and reduced in vivo skin aging signs, with a good safety profile after 90days of daily use.

Tannins extraction from Pinus pinaster and Acacia dealbata bark with applications in the industry

The use of wood waste is considered a valuable resource and a market opportunity for new products that society and industry can employ. In this context, it seems important to consider the use of the bark of two species that are found in large quantities within the extensive forest area of Galicia (north-western Spain). These species are widely used in industrial processes in which a large amount of waste is generated, mainly bark. In this work, we extracted the tannins from the bark of Pinus pinaster and Acacia dealbata, and we studied the yields obtained according to three variables: the extraction method applied, soxhlet and in natural conditions with temperature and agitation; the particle size of the samples; and the two solvents used, ethanol and distilled water. The chemical properties of the extracts were also analysed. The yields obtained ranged from 3.6 to 25.8 wt% for P. pinaster, and from 5.2 to 29.5 wt% for A. dealbata. Phenol and anthocyanin content ranged from 217.8 to 873. 2 mg/g extract for P. pinaster, and from 77.3 to 820 mg/g extract for A. dealbata. Our results demonstrate that the differences in the extracts content depending on the method and particle size show different features of the antioxidant capacity.

Uptake and Recovery of Gold from Simulated Hydrometallurgical Liquors by Adsorption on Pine Bark Tannin Resin

The recovery of critical and precious metals from waste electrical and electronic equipment (WEEE) is an environmental and economic imperative. Biosorption has been considered a key technology for the selective extraction of gold from hydrometallurgical liquors obtained in the chemical leaching of e-waste. In this work, the potential of tannin resins prepared from Pinus pinaster bark to sequester and recover gold(III) from hydrochloric acid and aqua regia solutions was assessed. Equilibrium isotherms were experimentally determined and maximum adsorption capacities of 343 ± 38 and 270 ± 19 mg g−1 were found for Au uptake from HCl and HCl/HNO3 (3:1 v/v) solutions containing 1.0 mol L−1 H+. Higher levels of acidity (and chloride ligands) significantly impaired the adsorption of gold from both kinds of leaching solutions, especially in the aqua regia system, in which the adsorbent underperformed. Pseudo-first and pseudo-second order models successfully described the kinetic data. The adsorbent presented high selectivity towards gold. Actually, in simulated aqua regia WEEE liquors, Au(III) was extensively adsorbed, compared to Cu(II), Fe(III), Ni(II), Pd(II), and Zn(II). In three adsorption–desorption cycles, the adsorption capacity of the regenerated adsorbent moderately decreased (19%), although the gold elution in acidic thiourea solution had been quite limited. Future research is needed to examine more closely the elution of gold from the exhausted adsorbents. The results obtained in this work show good perspectives as regards the application of pine bark tannin resins for the selective extraction of Au from electronic waste leach liquors.

Removal of arsenic from water by an iron-loaded resin prepared from Pinus pinaster bark tannins

Arsenic is a toxic and carcinogenic metalloid naturally present in water bodies. However, its concentration can be exacerbated by anthropogenic activities (e.g. mining, industry, agriculture). Thus, removal of arsenic from contaminated waters is a crucially important goal. Tannins are ubiquitous and inexpensive natural biopolymers that are easy to extract and convert into insoluble matrices. The aim of this work was to assess the potential of Pinus pinaster bark tannin resins to take up arsenic from aqueous solutions. Methods of tannin extraction and polymerization, oxidation and iron-loading were optimized. An extraction efficiency of 24.2 ± 0.1% was achieved and 166 ± 2 mg of formaldehyde-condensable phenols were extracted per gram of bark used. Polymerization of tannins, under the best conditions, presented an efficiency around 80%. Oxidation and iron loading yielded a tannin resin with an iron content of approx. 20 mg g–1. Adsorption of As(V) was optimal at pH 3 with a removal of approx. 90% from an initial solution containing 5 mg L–1. Adsorption assays with As(III) presented negligible results. As(V) adsorption was somewhat fast, with equilibrium being achieved in 1–4 h. Equilibrium data obtained for As(V) adsorption showed a maximum adsorption capacity of 0.72 ± 0.03 mg g–1 (pH 3, smaller than 150 µm). Iron leaching was high at low pH but could be drastically reduced by limiting the contact time. This work attempts to show that a forest residue, usually undervalued, can be converted into an adsorbent and can help in dealing with arsenic-contaminated waters, which is an environmental problem affecting many countries in the world.

Unravelling the Biological Potential of Pinus pinaster Bark Extracts.

Natural compounds from agro-food by-products have fostered interest in food industries. The aim of this study was to unravel potential uses for Pinus pinaster bark extracts (PBE). As functional features of this type of extracts are usually attributed to phenolic compounds, the extraction process was studied. Different PBEs were achieved, with high content in phenolic compounds, using different water/ethanol combinations as a solvent. These PBEs were chemically characterized, and their bioactivity and in vitro cell viability were evaluated. Extracts obtained with hydroethanolic solvents had higher content in phenolic and flavonoid compounds. All the PBEs presented high antioxidant, antibacterial and antihyperglycemic activities. Moreover, PBEs have low cytotoxicity and a selective activity against cancer cells as these were negatively affected. These features may allow the extracts to be used in food formulation and processing (as preservatives, antioxidants or bioactive ingredients), but they showed also potential for the pharmaceutical or nutraceutical sectors.

Adsorption of an anionic dye (Congo red) from aqueous solutions by pine bark

Pinus pinaster bark, an abundant by-product from the timber industry, has been studied as a potential low-cost adsorbent for the removal of Congo red (CR) dye from wastewaters. Surface morphological and physico-chemical characteristics of pine bark were analysed using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), determination of the point of zero charge (pHPZC) and elemental analysis. Assays were performed to determine the wavelength for the maximum absorbance and the stability with time of CR solutions depending on concentration and/or pH, which resulted to be a very significant parameter. Adsorption studies were conducted on batch mode to study the effect of contact time (till 7 days), pH (2–9), adsorbent dosage (1–10 g L−1) and temperature (25–60 °C). The bark adsorption capacity at equilibrium varied between 0.3 and 1.6 mg g−1 and the equilibrium adsorption percentage between 23.4 and 100% depending on adsorbent dosage, temperature and pH at an initial CR concentration of 5 mg L−1. Kinetic data for the removal of CR by pine bark were best fitted by the pseudo-second-order kinetic model. The equilibrium data fitted well with the Freundlich model. Thermodynamic analysis indicated that the adsorption process is exothermic and spontaneous.

Efficacy and Safety of an Oral Nutritional (Dietary) Supplement Containing Pinus pinaster Bark Extract and Grape Seed Extract in Combination with a High SPF Sunscreen in the Treatment of Mild-to-Moderate Melasma: A Prospective Clinical Study

Background: Melasma is a common hyperpigmentation disorder, characterized by light-to-dark brown patches, usually distributed on sun-exposed areas of the body. The objective of this study was to evaluate the efficacy and tolerability of an oral nutritional supplement containing Pinus pinaster and Grape seed extract, vitamins and minerals, used concomitantly with a high SPF sunscreen in 30 women with mild-to-moderate facial melasma. Methods: Efficacy was assessed by measurement of the Melasma Area and Severity Index (MASI), instrumental analysis of the lesions (Mexameter®, VISIA®)) and Patient’s and Physician’s Global Assessment (PGA). Results: The MASI score decreased significantly compared with baseline at days 28, 56, and 84. Mexameter® analysis showed a significant decrease of ∆M (difference in the melanin index between melasma and adjacent area). VISIA® results also showed a reduction in the number and areas of UV pigmented spots and in the areas of melasma overtime. Both the Patient’s and Physician’s Global Assessment showed that the product led to an improvement of the lesions in terms of depigmentation and had positive cosmetic features without adverse events. Conclusion: The oral supplement subject of this study in combination with high SPF sunscreen was effective and well-tolerated for treatment of mild to moderate facial melasma.

Plant-derived medicines for treatment of endometriosis: A comprehensive review of molecular mechanisms

Endometriosis is an estrogen-dependent disease with inflammatory lesions at extra-uterine sites, causing pelvic pain and fertility reduction. Conventional therapies primarily focus on reducing systemic levels of estrogens; however, they do not have desirable effectiveness and possess considerable side effects. Therefore, there is a growing interest in the use of herbal medicine for the treatment of endometriosis. In this paper, electronic databases including PubMed, Scopus, Cochrane library and Google Scholar were searched to obtain any studies evaluating any herbal products in the management of endometriosis. Data were collected from 1980 to 2018. Most of studies investigating the effect of herbal medicines in endometriosis were in vitro and animal and only three clinical trials were found; one on Pinus pinaster bark extract (Pycnogenol) and two on Chinese herbal formulas. The studies on phytochemicals had mostly focused on polyphenolic compounds (epigallocatechin-3-gallate, genistein) and sesquiterpenes (β-caryophyllene, parthenolide). Various molecular mechanisms of action have been involved in beneficial effects of herbal medicines and phytochemicals including anti-inflammatory (via reduction of proinflammatory cytokines such as interleukin -1, interleukin -6, interleukin -8, transforming growth factor-beta, tumor necrosis factor-α, nuclear factor-kappa B, growth factors, monocyte chemoattractant protein-1), antioxidant (through downregulation of hydrogen peroxide, malondialdehyde, reactive oxygen species and upregulation of superoxide dismutase), anti-proliferative and apoptotic (via enhancing Bcl-2-associated X protein/ B-cell lymphoma-2 and caspase3, 8 and 9 activity), anti-angiogenic (by downregulation of vascular endothelial growth factor receptors/ vascular endothelial growth factor), anti-invasive (via decreasing expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and matrix metalloproteinases), immunomodulatory, and estrogen modulating activities. So, medicinal plants seem to be a valuable source for identifying new drugs for treatment of endometriosis; however, since most of studies are preclinical, further clinical trials are required to achieve more conclusive results.

Recovery and valorization of tannins from a forest waste as an adsorbent for antimony uptake

Abstract In the current context, it is imperative to seek for a sustainable management and an efficient use of natural resources. Pinus pinaster bark is a forest and industrial waste whose chemical richness is commonly ignored. In this work, tannins were extracted from P. pinaster bark and converted into adsorbents through polymerization. Aqueous (alkaline) extraction yielded more formaldehyde-condensable phenols than an organic extraction using ethanol (Soxhlet) (53 ± 8 vs. 13 ± 4 mg of gallic acid equivalents per g of bark). The polymerization reaction was optimized and higher amounts of adsorbent were produced using 6.0 mL of 0.25 mol L−1 sodium hydroxide solution and 0.40 mL of formaldehyde (36 % wt) per g of extract. The performance of the produced adsorbent was assessed on the sequestration of Sb(III) and Sb(V) species from water. The adsorbent was effective for both species, in diluted and heavily-contaminated waters, providing maximum adsorption capacities (Langmuir model) of 24 ± 3 mg g−1 (pH 6) and 27 ± 7 mg g−1 (pH 2), respectively for Sb(III) and Sb(V). No significant effect was observed due to the presence of arsenic, chloride, nitrate, sulfate or phosphate and little influence was obtained when a tailings water from a mine site was used as aqueous matrix. Electrostatic attraction and Sb(III) and Sb(V) complexation with polyol groups of tannin-adsorbents were the suggested adsorption mechanisms. Moreover, tannin-adsorbents were stable at different pH (no color leaching; total dissolved carbon ≤16 mg L−1) and their production does not require high energy or expensive chemicals.

Influence of solvent additives on the aqueous extraction of tannins from pine bark: potential extracts for leather tanning

AbstractBACKGROUNDPine bark, which represents approximately 10 to 20% in weight of the tree trunk, is an abundant and low cost agro‐industrial waste. In order to obtain condensed tannin‐rich pine bark extracts (for future application in leather tanning/retanning processes), conventional aqueous extractions were performed, varying the type and amount of the solvent additive: sodium hydroxide (0.5, 1.0 and 1.5%, w/v), formic acid (0.5, 1.0 and 1.5%, v/v) and ethanol (5, 10 and 15%, v/v). Extractions were performed with and without the addition of sodium sulfite (1.0%, w/v).RESULTSThe most favorable solvent additive in terms of total phenolics and condensed tannins was ethanol: extracts achieved 34.8% of gallic acid equivalents and 62.8% of catechin monohydrate equivalents. Moreover, the favorable pH values (∼3.5) of the resultant aqueous solutions and their relatively low viscosities are suitable for subsequent tanning applications.CONCLUSIONSThe results of this study suggest that the high added‐value aqueous extracts of Pinus pinaster bark, which were achieved with small amounts of ethanol, have appropriate characteristics for leather tanning, and therefore they may be used as eco‐friendly tanning agents to partially replace chromium salts, thus reducing some of the environmental impacts typically associated with the leather industry. © 2017 Society of Chemical Industry

Pycnogenol Cytotoxicity in Pancreatic INS-1E β cells Induced by Calcium Dysregulation.

Natural standardized flavonoid extract from the bark of Pinus pinaster, Pycnogenol (Pyc), was recently found to decrease intensively the activity of sarcoplasmic reticulum Ca2+ -ATPase of rabbit skeletal muscle (SERCA1). On the basis of this inhibitory effect in a cell-free system and similarities of SERCA1 to its other isoforms, proapoptotic properties of Pyc may be expected in cellular systems. Pycnogenol (40-100μg/mL) induced a concentration-dependent decrease of the viability of pancreatic INS-1E β cells associated with induction of apoptosis. In addition, intracellular Ca2+ level increase was found along with reduction of protein expression level of SERCA2b and impairment of insulin secretion by β cells. These facts indicate that Pyc may induce apoptosis by impairment of calcium homeostasis. Copyright © 2017 John Wiley & Sons, Ltd.

Development, Optimization and Validation of an HPLC-PDA Method for Quantification of Taxifolin in the Bark Extract ofPinus pinaster

The aqueous extract of the bark of Pinus pinaster has a high concentration of polyphenols represented by a mixture of procyanidins, besides taxifolin, phenolic acids, cinnamic acids and their glycosides. Its quality control is specified in the United States Pharmacopeia, and the assay test is performed by determination of the total procyanidins content. However, determining the individual polyphenol content may represent an additional quality parameter for this extract. In this sense, the present study aimed to develop and optimize a method of high performance liquid chromatography with photodiode array detection (HPLC-PDA) for quantification of taxifolin in the bark extract of P. pinaster, using a 33 Box-Behnken factorial design. The proposed method was validated for specificity, linearity, limits of detection and quantification, precision, accuracy and robustness and it has shown that taxifolin may be used as a chemical marker for quality control of the bark extract of P. pinaster.

UV protection effects of phenolic extracts from chestnut fruit and forest industries residues

Extracts from different lignocellulosic sources were applied in the wood veneer dyeing process with the aim of preventing colour changes caused by ultraviolet (UV) degradation. Chestnut (Castanea sativa) fruit shell and bur, and barks from Pinus pinaster, Eucalyptus globulus and Quercus frainetto extracted using water or aqueous solutions of sodium sulphite and/or sodium hydroxide were used. Wood veneers from ash (Fraxinus excelsior), koto (Pterygota bequaertii) and lime (Tilia cordata) were dyed, treated with extracts and subjected to accelerated exposure to UV light for variable lengths of time. The colour degradation was measured and the results were studied using cluster analysis. Pinus pinaster bark extracts were the best protectors for dyed veneers. Chemical changes due to UV exposure were analyzed by X-ray photoelectron spectroscopy. The degraded untreated wood increased its functional groups rich in oxygen, that is, photo-oxidation occurred. Nevertheless chemical bonding of wood treated with extracts hardly underwent changes.

Hydroxypropyl tannin from Pinus pinaster bark as polyol source in urethane chemistry

Novel thermosetting polyphenol-based polyurethane (PU) films were prepared using condensed tannin (CTs) and hydroxypropyl tannin derivatives (HPTs) from Pinus pinaster bark and diisocyanates. Four HPTs with a degree of substitution (DS) rising stepwise from 1 to 4 were crosslinked with either an aromatic (polymeric methylene diphenyl diisocyanate (pMDI)) or an aliphatic isocyanate (hexamethylene diisocyanate (HDI)). Chemical structure, moisture sorption, thermal, and morphological properties of the films were studied. Properties varies with NCO:OH ratio (0.5–4.0), DS, diisocyanate type, and cross-link density (CD). Partial tannin hydroxypropylation (DS 2, 3) based/films showed a flexible-type character in term of Young’s modulus, elongation and tensile strain. Significant relationships were established between CD and physicochemical properties. HPTs constitute suitable macro building-block polyols for urethane chemistry.

Antibacterial Activity of Pinus pinaster Bark Extract and its Components Against Multidrug-resistant Clinical Isolates of Acinetobacter baumannii

The aim of this research was to test the antibacterial activity of Pinus pinaster aqueous bark ex- tract (PABE) and its basic components against multidrug-resistant isolates of Acinetobacter baumannii belonging to European clone I and II, isolated previously from the clinical outbreaks. The minimum bactericidal concentration of PABE against both clones of A. baumannii was 200 mg ml -1 , while lower concentrations showed high antibacterial activity. After 24 h of treatment with 100, 50 or 10 mg ml -1 of extract, the reduction in the number of A. baumannii isolates belonging to European clone I and II was 85.8 ± 2.5 %, 78.5 ± 1.1 %, 66.3 ± 2.5 % and 90.2 ± 1.7 %, 78.6 ± 1.2 %, 69.8 ± 0.7 %, respectively. Sev- eral basic components: caffeic acid, catechin, epicatechin, gallic acid and vanillin, detected in the extract by high performance liquid chromatography, contributed to the antibacterial activity of the extract against both clones of A. baumannii. However, the antibacterial activity of extract was higher than that of each tested basic component suggesting that proanthocyanidins, which were present in quite a large amount in the extract, might have also contributed to the activity of the extract. Antibacterial activity of PABE against A. baumannii reveals that complex and inexpensive natural product might be useful in combat against natu- rally competent bacteria that easily acquire resistance against antibiotics.

Substitution pattern elucidation of hydroxypropyl Pinus pinaster (Ait.) bark polyflavonoid derivatives by ESI(-)-MS/MS.

The structure of condensed tannins (CTs) from Pinus pinaster bark extract and their hydroxypropylated derivatives with four degrees of substitution (DS 1, 2, 3 and 4) has been characterized for the first time using negative-ion mode electrospray ionization tandem mass spectrometry (ESI(-)-MS/MS). The results showed that P. pinaster bark CTs possess structural homogeneity in terms of monomeric units (C(15), catechin). The oligomer sizes were detected to be dimers to heptamers. The derivatives showed typical phenyl-propyl ether mass fragmentation by substituent elimination (58 amu) and inherent C(15) flavonoid fissions. The relative abundance of the product ions revealed a preferential triple, tetra-/penta- and octa- hydroxypropylation substitution pattern in the monomer, dimer and trimer derivatives, respectively. A defined order of -OH reactivity towards propylene oxide was established by means of multistage experiments (A-ring ≥ B-ring > C-ring). A high structural heterogeneity of the modified oligomers was detected.

Skin-lightening and anti-ageing effect of a food supplement containing Pinus pinaster extract

Oligomeric proanthocyanidins extracted from the bark of the French maritime pine Pinus pinaster (FMPBE) have been studied for a long time and demonstrated various phytopharmaceutical applications. The objectives of this study were to assess the cutaneous lightening and anti-ageing effects of FMPBE after 56 days of consumption, in healthy Asian women. The cosmetic efficacy of the product was assessed through various biometrological evaluations. This randomized, double-blind, placebo-controlled and cross-over study evidenced the safety and efficacy of the 100 mg FMPBE supplementation from 28 days of intake: in comparison to placebo, the skin on pigmentary spots became significantly lighter and less red, skin on the face was more firm and its surface was less wrinkled. After 56 days of consumption, the skin was additionally significantly more elastic and the yellow constituent of the skin decreased on the normal skin.

Synthesis and physicochemical properties of hydroxypropyl tannins from maritime pine bark (Pinus pinaster Ait.)

Abstract Simple derivatives of condensed tannins are described, which allow the tailoring of gelation (with aldehydes) and thermal degradation behaviors that have been obstacles to the commercial utilization of this abundant bioresource. Hydroxypropyl tannin (HPT) derivatives from bark of Pinus pinaster with varying degrees of substitution (DS 0.1–4.7) were analyzed with regard to molecular and physical characteristics, such as structure, molecular weight, thermal behavior, solubility and gelation. The modification reaction of tannin proceeds stoichiometrically to a mixture of oligomeric derivatives, mostly to trimers and tetramers, as demonstrated by 1H-nuclear magnetic resonance, elemental analysis, and gel permeation chromatography. The derivatives have an improved solubility in organic solvents and increased thermal stability. The glass transition temperature (Tg) was reduced by up to 37°C over unmodified tannin. At DS ≥1.0, the HPT lost the capacity to produce gel with formaldehyde. A structure-property relationship was established by means of multivariate analysis, and the derivatives could be grouped according to their physicochemical profile. HPTs are promising biomacromolecular building blocks for tannin-derived materials.