Phytochemistry and Biological Profile of Gaultheria procumbens L. and Wintergreen Essential Oil: From Traditional Application to Molecular Mechanisms and Therapeutic Targets.

Gaultheria procumbens L. is a medicinal plant whose aerial parts (leaves, stems, and fruits) and methyl salicylate-rich essential oil (wintergreen oil) are used in phytotherapy to treat inflammation, muscular pain, and infection-related disorders. This overview summarises the current knowledge about ethnobotany, phytochemistry, pharmacology, molecular mechanisms, biocompatibility, and traditional use of G. procumbens and the wintergreen oil distilled from different plant organs. Over 70 hydrophilic compounds, including methyl salicylate glycosides, flavonoids, procyanidins, free catechins, caffeoylquinic acids, and simple phenolic acids, have been identified in G. procumbens plant parts. Moreover, aliphatic compounds, triterpene acids, and sterols have been revealed in lipophilic fractions. Furthermore, over 130 volatile compounds have been detected in wintergreen oil with dominating methyl salicylate (96.9-100%). The accumulated research indicates that mainly hydrophilic non-volatiles are responsible for the pharmacological effects of G. procumbens, primarily its potent anti-inflammatory, antioxidant, and photoprotective activity, with mechanisms verified in vitro and ex vivo in cellular and cell-free assays. The biological effectiveness of the dominant methyl salicylate glycoside-gaultherin-has also been confirmed in animals. Wintergreen oil is reported as a potent anti-inflammatory agent exhibiting moderate antioxidant and antimicrobial activity in vitro and significant insecticidal and larvicidal capacity. Together, G. procumbens accumulate a diverse fraction of polyphenols, triterpenes, and volatiles with validated in vitro and ex vivo biological activity but with the absence of in vivo studies, especially clinical trials concerning effective dose determination and toxicological verification and technological research, including drug formulation.

Valorisation of the Inhibitory Potential of Fresh and Dried Fruit Extracts of Prunus spinosa L. towards Carbohydrate Hydrolysing Enzymes, Protein Glycation, Multiple Oxidants and Oxidative Stress-Induced Changes in Human Plasma Constituents.

Prunus spinosa fruits (sloes), both fresh and dried, are underexplored dietary components and ethno-phytotherapeutic remedies applied to treat chronic oxidative-stress-related diseases, including diabetes. The present study aimed to evaluate drying-related changes in the antidiabetic potential of sloe extracts and some bioactivity mechanisms, which might be connected with their traditional application. The polyphenol-enriched extracts, prepared by fractionated extraction and phytochemically standardised, i.a., by LC-MS/MS, were tested in vitro using a set of biological and chemical models. The experiments revealed the significant extracts' ability to counteract the generation of advanced glycation end products (AGEs) and inhibit the activity of key glycolytic enzymes, i.e., α-glucosidase and α-amylase. Moreover, they were proved to effectively scavenge multiple oxidants of physiological importance (O2•-, HO•, H2O2, NO•, HOCl), increase the non-enzymatic antioxidant capacity of human plasma (NEAC) under oxidative stress conditions induced by peroxynitrite, and protect plasma proteins and lipids against peroxidation and nitration at in vivo-relevant levels (1-50 µg/mL, equivalent to 0.03-6.32 µg polyphenols/mL). In most cases, the activity of fresh fruit extracts surpassed that of dried-based products. The correlation studies and tests on model compounds proved polyphenols as dominant contributors to the observed effects. Furthermore, the co-occurring representatives of various polyphenolic classes were found to contribute to the biological activity of sloes through additive and synergistic effects. Considering the extraction yield and activity parameters, especially the superior outcomes compared to anti-diabetic drugs aminoguanidine and acarbose in the anti-glycation and α-glucosidase inhibition tests, the methanol-water (75:25, v/v) extract of fresh fruits and its phenolic-enriched fractions revealed the most advantageous potential for functional application.

Fruits of Hippophaë rhamnoides in human leukocytes and Caco-2 cell monolayer models-A question about their preventive role in lipopolysaccharide leakage and cytokine secretion in endotoxemia.

Preparations from Hippophaë rhamnoides L. (sea buckthorn) have been traditionally used in the treatment of skin and digestive disorders, such as gastritis, gastric and duodenal ulcers, uterine erosions, as well as oral, rectal, and vaginal mucositis, in particular in the Himalayan and Eurasian regions. An influence of an aqueous extract from the fruits of H. rhamnoides (HR) on leakage of lipopolysaccharide (LPS) from Escherichia coli through gut epithelium developed from the human colorectal adenocarcinoma (Caco-2) monolayer in vitro and glucose transporter 2 (GLUT2) translocation were the principal objectives of the study. Additionally, the effect of HR on the production of pro- and anti-inflammatory cytokines (interleukins: IL-8, IL-1ß, IL-10, IL-6; tumor necrosis factor: TNF-α) by the Caco-2 cell line, human neutrophils (PMN), and peripheral blood mononuclear cells (PBMC) was evaluated. The concentration of LPS on the apical and basolateral sides of the Caco-2 monolayer was evaluated with a Limulus Amebocyte Lysate (LAL) assay. GLUT2 translocation was evaluated using an immunostaining assay, whereas secretion of cytokines by cell cultures was established with an enzyme-linked immunosorbent (ELISA) assay. HR (500 µg/ml) significantly inhibited LPS leakage through epithelial monolayer in vitro in comparison with non-treated control. The treatment of Caco-2 cells with HR (50-100 µg/ml) showed GLUT2 expression similar to the non-treated control. HR decreased the secretion of most pro-inflammatory cytokines in all tested models. HR might prevent low-grade chronic inflammation caused by metabolic endotoxemia through the prevention of the absorption of LPS and decrease of chemotactic factors released by immune and epithelial cells, which support its use in metabolic disorders in traditional medicine.

The Effect of Standardised Leaf Extracts of Gaultheria procumbens on Multiple Oxidants, Inflammation-Related Enzymes, and Pro-Oxidant and Pro-Inflammatory Functions of Human Neutrophils.

The leaves of Gaultheria procumbens are polyphenol-rich traditional medicines used to treat inflammation-related diseases. The present study aimed to optimise the solvent for the effective recovery of active leaf components through simple direct extraction and verify the biological effects of the selected extract in a model of human neutrophils ex vivo. The extracts were comprehensively standardised, and forty-one individual polyphenols, representing salicylates, catechins, procyanidins, phenolic acids, and flavonoids, were identified by UHPLC-PDA-ESI-MS3. The chosen methanol-water (75:25, v/v) extract (ME) was obtained with the highest extraction yield and total phenolic levels (397.9 mg/g extract's dw), including 98.9 mg/g salicylates and 299.0 mg/g non-salicylate polyphenols. In biological tests, ME revealed a significant and dose-dependent ability to modulate pro-oxidant and pro-inflammatory functions of human neutrophils: it strongly reduced the ROS level and downregulated the release of pro-inflammatory cytokines and tissue remodelling enzymes, especially IL-1ß and elastase 2, in cells stimulated by fMLP, LPS, or fMLP + cytochalasin B. The extracts were also potent direct scavengers of in vivo relevant oxidants (O2•-, •OH, and H2O2) and inhibitors of pro-inflammatory enzymes (cyclooxygenase-2, hyaluronidase, and lipoxygenase). The statistically significant correlations between the tested variables revealed the synergic contribution of individual polyphenols to the observed effects and indicated them as useful active markers for the standardisation of the extract/plant material. Moreover, the safety of ME was confirmed in cytotoxicity tests. The obtained results might partially explain the ethnomedicinal application of G. procumbens leaves and support the usage of the standardised leaf extract in the adjuvant treatment of oxidative stress and inflammation-related chronic diseases.

Screening for the Active Anti-Inflammatory and Antioxidant Polyphenols of Gaultheria procumbens and Their Application for Standardisation: From Identification through Cellular Studies to Quantitative Determination.

Aerial parts, leaves, and stems of Gaultheria procumbens are polyphenol-rich herbal medicines with anti-inflammatory and antioxidant effects. The present study focused on identifying active markers of the G. procumbens extracts in an integrated approach combining phytochemical and biological capacity tests. The target compounds, representing all classes of Gaultheria polyphenols, were pre-selected by LC-ESI-PDA-MS/MS. For unambiguous identification, the key analytes, including a rare procyanidin trimer (cinnamtannin B-1), miquelianin potassium salt, and two new natural products: quercetin and kaempferol 3-O-ß-d-xylopyranosyl-(1→2)-ß-d-glucuronopyranosides, were isolated by preparative HPLC and investigated by spectroscopy (HR-ESI-MS, UV-vis, CD, 1D- and 2D-NMR), thiolysis, flame photometry, optical rotation experiments, and absolute configuration studies. The significant contribution of the pre-selected compounds to the biological effects of the extracts was confirmed in vitro: the analytes significantly and in a dose-dependent manner down-regulated the pro-oxidant and pro-inflammatory functions of human neutrophils ex vivo (inhibited the release of reactive oxygen species, IL-1ß, TNF-α, and neutrophils elastase, ELA-2), inhibited two key pro-inflammatory enzymes (cyclooxygenase, COX-2, and hyaluronidase), and most of them, except gaultherin, exerted potent direct antioxidant activity (ferric reducing antioxidant power and superoxide anion scavenging capacity). Moreover, cellular safety was confirmed for all compounds by flow cytometry. Eventually, as these mechanisms have been connected to the health benefits of G. procumbens, 11 polyphenols were accepted as active markers, and a simple, accurate, reproducible, and fully validated RP-HPLC-PDA method for standardisation of the target extracts was proposed.

Lipophilic extracts from leaves, inflorescences and fruits of Prunus padus L. as potential sources of corosolic, ursolic and oleanolic acids with anti-inflammatory activity.

Chloroform extracts from leaves, inflorescences and fruits of Prunus padus were analysed for anti-inflammatory activity and accumulation of corosolic (CA), ursolic (UA) and oleanolic (OA) acids. The analytes were identified and quantified by GC-MS and UHPLC-PDA. Their total levels depend on plant material type and harvesting time, and varied from 0.25 mg/g DW in fruits, through 0.76-1.09 mg/g DW in flowers, to 1.41-4.54 mg/g DW in leaves. Significant variation in the leaf analytes contents was observed during vegetation with the peak amounts in autumn, which indicated the optimal harvesting season. The plant extracts inhibited pro-inflammatory enzymes (lipoxygenase and hyaluronidase) in a concentration-dependent manner, and their activity parameters correlated with the levels and activity of pure triterpene acids, especially CA and UA. The results of the comparison with the positive controls (heparin, indomethacin, dexamethasone) might partly support the application of P. padus in anti-inflammatory therapies, reported by traditional medicine.

Biological and chemical insight into Gaultheria procumbens fruits: a rich source of anti-inflammatory and antioxidant salicylate glycosides and procyanidins for food and functional application.

The fruits of Gaultheria procumbens are traditionally used for culinary and healing purposes as anti-inflammatory agents. In the present work, the active components of the fruits were identified (UHPLC-PDA-ESI-MS3, preparative HPLC isolation, and NMR structural studies), and their biological capacity was evaluated in vitro in cell-based and non-cellular models. The fruits were revealed to be the richest known dietary source of salicylates (38.5 mg per g fruit dw). They are also rich in procyanidins (28.5 mg per g fruit dw). Among five tested solvents, acetone was the most efficient in concentrating the phenolic matrix (39 identified compounds; 191.3 mg g-1, 121.7 mg g-1, and 50.9 mg g-1 dry extract for total phenolics, salicylates, and procyanidins, respectively). In comparison to positive controls (dexamethasone, indomethacin, and quercetin), the extract (AE) and pure salicylates exhibited strong inhibitory activity towards pro-inflammatory enzymes (cyclooxygenase-2 and hyaluronidase). The analytes were found to be non-cytotoxic (flow cytometry) towards human neutrophils ex vivo. Moreover, they significantly, in a dose-dependent manner, downregulated the release of ROS, TNF-α, IL-1ß, and elastase-2 and slightly inhibited the secretion of IL-8 and metalloproteinase-9 in the cells. The observed effects might support the usage of G. procumbens fruits as functional components of an anti-inflammatory diet and indicate the potential of AE for use in adjuvant treatment of inflammatory disorders cross-linked with oxidative stress and associated with the excessive production of TNF-α, IL-1ß, and elastase-2.

Salicylate and Procyanidin-Rich Stem Extracts of Gaultheria procumbens L. Inhibit Pro-Inflammatory Enzymes and Suppress Pro-Inflammatory and Pro-Oxidant Functions of Human Neutrophils Ex Vivo.

Salicylate-rich plants are an attractive alternative to synthetic anti-inflammatory drugs due to a better safety profile and the advantage of complementary anti-inflammatory and antioxidant effects of the co-occurring non-salicylate phytochemicals. Here, the phytochemical value and biological effects in vitro and ex vivo of the stems of one of such plants, Gaultheria procumbens L., were evaluated. The best extrahent for effective recovery of the active stem molecules was established in comparative studies of five extracts. The UHPLC-PDA-ESI-MS³, HPLC-PDA, and UV-photometric assays revealed that the selected acetone extract (AE) accumulates a rich polyphenolic fraction (35 identified constituents; total content 427.2 mg/g dw), mainly flavanols (catechins and proanthocyanidins; 201.3 mg/g dw) and methyl salicylate glycosides (199.9 mg/g dw). The extract and its model components were effective cyclooxygenase-2, lipoxygenase, and hyaluronidase inhibitors; exhibited strong antioxidant capacity in six non-cellular in vitro models (AE and procyanidins); and also significantly and dose-dependently reduced the levels of reactive oxygen species (ROS), and the release of cytokines (IL-1ß, IL-8, TNF-α) and proteinases (elastase-2, metalloproteinase-9) in human neutrophils stimulated ex vivo by lipopolysaccharide (LPS) and N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). The cellular safety of AE was demonstrated by flow cytometry. The results support the application of the plant in traditional medicine and encourage the use of AE for development of new therapeutic agents.

The Effect of Standardised Flower Extracts of Sorbus aucuparia L. on Proinflammatory Enzymes, Multiple Oxidants, and Oxidative/Nitrative Damage of Human Plasma Components In Vitro.

Polyphenol-rich plant extracts might alleviate the negative impact of oxidative stress and inflammation, but careful phytochemical standardisation and evaluation of various mechanisms are required to fully understand their effects. In this context, flower extracts of Sorbus aucuparia L.-a traditional medicinal plant-were investigated in the present work. The LC-MS/MS profiling of the extracts, obtained by fractionated extraction, led to the identification of 66 constituents, mostly flavonols (quercetin and sexangularetin glycosides with dominating isoquercitrin), pseudodepsides of quinic and shikimic acids (prevailing isomers of chlorogenic acid and cynarin), and flavanols (catechins and proanthocyanidins). Minor extract components of possible chemotaxonomic value were flavalignans (cinchonain I isomers) and phenylamides (spermidine derivatives). As assessed by HPLC-PDA and UV-spectrophotometric studies, the extracts were polyphenol-abundant, with the contents up to 597.6 mg/g dry weight (dw), 333.9 mg/g dw, 382.0 mg/g dw, and 169.0 mg/g dw of total phenolics, flavonoids, proanthocyanidins, and caffeoylquinic acids, respectively. Their biological in vitro effects were phenolic-dependent and the strongest for diethyl ether, ethyl acetate, and n-butanol fractions of the methanol-water (7 : 3, v/v) extract. The extracts showed significant, concentration-dependent ability to scavenge in vivo-relevant radical/oxidant agents (O2 ∙-, OH∙, H2O2, ONOO-, NO∙, and HClO) with the strongest effects towards OH∙, ONOO-, HClO, and O2 ∙- (compared to ascorbic acid). Moreover, the extracts efficiently inhibited lipoxygenase and hyaluronidase (compared to indomethacin) but were inactive towards xanthine oxidase. At in vivo-relevant levels (1-5 µg/mL), they also effectively protected human plasma components (proteins and lipids) against ONOO--induced oxidative damage (reduced the levels of 3-nitrotyrosine, lipid hydroperoxides, and thiobarbituric acid-reactive substances) and normalised/enhanced the total nonenzymatic antioxidant capacity of plasma. In cytotoxicity tests, the extracts did not affect the viability of human PBMCs and might be regarded as safe. The results support the application of the extracts in the treatment of oxidative stress-related pathologies cross-linked with inflammatory changes.

Nigella damascena L. essential oil and its main constituents, damascenine and ß-elemene modulate inflammatory response of human neutrophils ex vivo.

Nigella damascena L belongs to Ranunculaceae family and is mentioned in Eastern traditional medicine for the treatment of high temperatures, regulation of menstruation or catarrhal affections. The anti-inflammatory activity of compounds present in the essential oil obtained from seeds of this plant can be found in literature, however no studies on immunomodulatory activity are provided. Hence, in this work anti-inflammatory activity of N. damascena seed essential oil as well as damascenine and main compound ß-elemene was evaluated on ex-vivo lipopolysaccharide (LPS)-stimulated human neutrophils. For isolation of damascenine fast and efficient protocol was elaborated using high performance countercurrent chromatography technique for the first time. Also detailed spectroscopic characteristic of damascenine was provided for the first time. Damascenine was separated from the essential oil in a mixture of petroleum ether/acetonitrile/acetone (2:1.5:0.5 v/v/v) in reversed phase mode in 12 min with 99.47% purity. Essential oil, damascenine and ß-elemene presented immunomodulatory activity evaluated in LPS-stimulated neutrophils ex vivo. All studied samples significantly inhibited release of interleukin 1 beta (IL-1ß) and interleukin 8 (IL-8). What is more, damascenine and ß-elemene decreased matrix metallopeptidase 9 (MMP-9) production similar to dexamethasone. The release of tumor necrosis factor (TNF-α) was also inhibited in all range of concentrations, however the activity was weaker then activity of dexametasone. The previously reported anti-inflammatory activity of damascenine and ß-elemene investigated in murine models was confirmed in our study on human neuthrophils suggesting their possible strong inhibitory effect on inflammatory response progression.

Metabolite Profiling of Eastern Teaberry (Gaultheria procumbens L.) Lipophilic Leaf Extracts with Hyaluronidase and Lipoxygenase Inhibitory Activity.

The phytochemical profile and anti-inflammatory activity of Gaultheria procumbens dry lipophilic leaf extracts were evaluated. Forty compounds were identified by GC-MS, representing 86.36% and 81.97% of the petroleum ether (PE) and chloroform (CHE) extracts, respectively, with ursolic acid (28.82%), oleanolic acid (10.11%), methyl benzoate (10.03%), and methyl salicylate (6.88%) dominating in CHE, and methyl benzoate (21.59%), docosane (18.86%), and octacosane (11.72%) prevailing in PE. Three components of CHE were fully identified after flash chromatography isolation and spectroscopic studies as (6S,9R)-vomifoliol (4.35%), 8-demethyl-latifolin (1.13%), and 8-demethylsideroxylin (2.25%). Hyaluronidase and lipoxygenase inhibitory activity was tested for CHE (IC50 = 282.15 ± 10.38 µg/mL and 899.97 ± 31.17 µg/mL, respectively), PE (IC50 = 401.82 ± 16.12 µg/mL and 738.49 ± 15.92 µg/mL), and nine of the main constituents versus heparin (IC50 = 366.24 ± 14.72 µg/mL) and indomethacin (IC50 = 92.60 ± 3.71 µg/mL) as positive controls. With the best activity/concentration relationships, ursolic and oleanolic acids were recommended as analytical markers for the extracts and plant material. Seasonal variation of both markers following foliar development was investigated by UHPLC-PDA. The highest levels of ursolic (5.36-5.87 mg/g DW of the leaves) and oleanolic (1.14-1.26 mg/g DW) acids were observed between August and October, indicating the optimal season for harvesting.

Phenolic Profile and Antioxidant Potential of Leaves from Selected Cotoneaster Medik. Species.

The antioxidant efficiency of 70% aqueous methanolic extracts from the leaves of twelve selected Cotoneaster Medik. species was evaluated using four complementary in vitro tests based on SET- (single electron transfer) and HAT-type (hydrogen atom transfer) mechanisms (DPPH, FRAP, O2(•-) and H2O2 scavenging assays). The samples exhibited the dose-dependent responses in all assays with activity parameters of EC50 = 18.5-34.5 µg/mL for DPPH; 0.9-3.8 mmol Fe(2+)/g for FRAP; SC50 = 27.7-74.8 µg/mL for O2(•-); and SC50 = 29.0-91.3 µg/mL for H2O2. Significant linear correlations (|r| = 0.76-0.97, p < 0.01) between activity parameters and total contents of phenolics (5.2%-15.4% GAE) and proanthocyanidins (2.1%-15.0% CYE), with weak or no effects for chlorogenic acid isomers (0.69%-2.93%) and total flavonoids (0.28%-1.40%) suggested that among the listed polyphenols, proanthocyanidins are the most important determinants of the tested activity. UHPLC-PDA-ESI-QTOF-MS analyses led to detection of 34 polyphenols, of which 10 B-type procyanidins, 5 caffeoylquinic acids and 14 flavonoids were identified. After cluster analysis of the data matrix, the leaves of Cotoneaster zabelii, C. splendens, C. bullatus, C. divaricatus, C. hjelmqvistii and C. lucidus were selected as the most promising sources of natural antioxidants, exhibiting the highest phenolic levels and antioxidant capacities, and therefore the greatest potential for pharmaceutical applications.

Polyphenolic Profile, Antioxidant and Anti-Inflammatory Activity of Eastern Teaberry (Gaultheria procumbens L.) Leaf Extracts.

Dry leaf extracts of eastern teaberry (Gaultheria procumbens L.) were evaluated as a source of bioactive phytocompounds through systematic activity testing and phytochemical profiling. The antioxidant efficiency was tested using five complementary in vitro models (DPPH; FRAP; linoleic acid (LA) peroxidation assay; O2•- and H2O2 scavenging tests) in parallel with standard antioxidants. The 75% methanol extract and its diethyl ether, ethyl acetate (EAF), n-butanol and water fractions exhibited the dose-dependent responses in all assays, with the highest capacities found for EAF (DPPH EC50 = 2.9 µg/mL; FRAP = 12.8 mmol Fe2+/g; IC50 for LA-peroxidation = 123.9 µg/mL; O2•- SC50 = 3.9 µg/mL; H2O2 SC50 = 7.2 µg/mL). The EAF had also the highest anti-inflammatory activity in the inhibition tests of lipoxygenase and hyaluronidase (60.14% and 21.83% effects, respectively, at the concentration of 100 µg/mL). Activity parameters of the extracts correlated strongly with the levels of total phenolics (72.4-270.7 mg GAE/g), procyanidins, and phenolic acids, whereas for flavonoids only moderate effects were observed. Comprehensive UHPLC-PDA-ESI-MS3 and HPLC-PDA studies led to the identification of 35 polyphenols with a procyanidin A-type trimer, quercetin 3-O-glucuronide, isomers of caffeoylquinic acids, and (‒)-epicatechin being the dominant components. Significant activity levels, high phenolic contents and high extraction yields (39.4%-42.5% DW for defatted and crude methanol extracts, respectively) indicate the value of eastern teaberry leaves as bioactive products.

Profiling of phenolic compounds and antioxidant activity of dry extracts from the selected Sorbus species.

The antioxidant efficiency of dry extracts from inflorescences and/or leaves of seven Sorbus species was studied using four in vitro tests of SET (single electron transfer) and HAT-type (hydrogen atom transfer) mechanisms. The 70% methanol extracts and its diethyl ether, ethyl acetate, n-butanol and water fractions were tested in parallel with the phenolic standards, e.g., caffeic acid, quercetin, BHA, BHT, and Trolox. The SET-type activity of the extracts depended primarily on the extraction solvent. The most valuable extracts were n-butanol and ethyl acetate ones, which activity was high in the DPPH (EC(50) = 3.2-5.2 µg/mL), TEAC (2.8-4.0 mmol Trolox/g), and FRAP (9.8-13.7 mmol Fe2+/g) tests, and strongly correlated with the total phenolic levels (39.6-58.2% of gallic acid equivalents). The HPLC-PDA analysis of the extracts led to the identification of chlorogenic acid, isoquercitrin, hyperoside, rutin, quercetin 3-O-sophoroside, and sexangularetin 3-O-ß-D-glucopyranoside as the main components. Apart from flavonoids and hydroxycinnamic acids, proanthocyanidins have also a significant impact on the SET-type activity. The HAT-reactivity of the extracts in the linoleic acid peroxidation test (IC(50) = 36.9-228.3 µg/mL) depended more strongly on the plant tissue than on the extraction solvent, and its correlation with the phenolic content was weak. Both SET and HAT-type activity of the most potent Sorbus extracts was comparable with the activity of the standards, indicating their great potential as effective sources for health products.

Activity-guided isolation and identification of free radical-scavenging components from various leaf extracts of Sorbus aria (L.) Crantz.

Nine phenolics were obtained from the leaves of Sorbus aria (L.) Crantz by activity-directed isolation: isorhamnetin 3-O-ß-glucopyranoside (1), astragalin (2), isoquercitrin (3), hyperoside (4), kaempferol 3-O-ß-glucopyranoside-7-O-α-rhamnopyranoside (5), quercetin 3-O-ß-glucopyranoside-7-O-α-rhamnopyranoside (6), rutin (7), chlorogenic acid (8) and neochlorogenic acid (9). The isolates were identified by spectral methods (UV, (1)H- and (13)C-NMR, COSY, HMQC and HMBC), and their free radical-scavenging activity was tested using the l,l-diphenyl-2-picrylhydrazyl (DPPH) method. The antioxidant potential of the different extracts obtained in the fractionation process was evaluated using the DPPH test in relation to the HPLC contents of the isolates 1-9, total phenolics and total proanthocyanidins. Among the analytes tested, superior activity was expressed by isoquercitrin (3, EC(50) = 2.76 mg L(-1)) and the ethyl acetate extract (EC(50) = 2.99 mg L(-1)). Five strongly active isolates 3, 6, 7, 8 and 9 were found to be major components and to be principally responsible for the radical-scavenging activity of S. aria extracts.

Assessment of the content of phenolics and antioxidant action of inflorescences and leaves of selected species from the genus Sorbus sensu stricto.

In order to find new sources of natural antioxidants, the antioxidant potential of 70% methanolic extracts from the inflorescences and leaves of 16 species from the genus Sorbus s.s. was evaluated using two complementary in vitro test systems: the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging assay and the AAPH [2,2¢-azobis-(2-amidinopropane)dihydrochloride]-induced linoleic acid (LA) peroxidation test. The radical-scavenging capacities of the extracts towards the DPPH radical were in the range of 0.25-0.86 millimolar Trolox® equivalents/g dry weight. They were significantly correlated (r=-0.8089, p<0.001) with the results of the LA-peroxidation test, indicating the Sorbus extracts to be universal antioxidants. Significant linear correlations were also found between the different antioxidant potentials and total phenolic contents as estimated by the Folin-Ciocalteu method and further verified by serial determinations of proanthocyanidins, chlorogenic acid isomers and flavonoids (çrêin the range of 0.71-0.95, p<0.001). Cluster analysis of the data matrix identified the ten samples (inflorescences of S. aucuparia, S. pohuashanensis, S. decora, S. koehneana, S. commixta, S. gracilis, and S. sitchensis, and the leaves of S. wilfordii, S. pogonopetala, and S. gracilis) exhibiting the highest antioxidant activity and total phenolic levels and therefore the greatest potential as effective sources for natural health products.

Antioxidant activity of inflorescences, leaves and fruits of three Sorbus species in relation to their polyphenolic composition.

The antioxidant potential of 70% methanolic extracts from the inflorescences, leaves and fruits of Sorbus aucuparia, S. aria and S. intermedia was evaluated using three in vitro test systems (DPPH: 2,2-diphenyl-1-picryl hydrazyl; TEAC: trolox equivalent antioxidant capacity and FRAP: ferric reducing/antioxidant power). High activities found were expressed as micromoles trolox equivalents per gram dry weight and were in the range of 86.9-956.2 for the DPPH test, 65.3-577.2 for the TEAC assay and 221.1-1915.2 for the FRAP method. Significant linear correlations (R(2) in the range of 0.75-0.98) between these values and the contents of total phenolics, total flavonoids, total proanthocyanidins and chlorogenic acid isomers showed that the listed phenolic compounds are determinants of the antioxidant capacity tested. As the superior activity and the highest phenolic levels (11.83% of total phenolics calculated as gallic acid equivalents, 4.35% of chlorogenic acid isomers, 5.01% of proanthocyanidins and 1.28% of flavonoid aglycones) were found for S. aucuparia inflorescence, this plant material has the greatest potential as a source for natural health products.