Two new phenolic compounds from the leaves of Alnus sibirica Fisch. ex Turcz

3-Pentanol glycosides from root nodules of the actinorhizal plant Alnus cremastogyne

Alnus cremastogyne Burkill (Betulaceae), an actinorhizal plant, can enter a mutualistic symbiosis with Frankia species that leads to the formation of nitrogen fixing root nodules. Some primary metabolites (carbohydrates, dicarboxylic acids, amino acids, citrulline and amides) involved in carbon and nitrogen metabolism in actinorhizal nodules have been identified, while specialized metabolites in A. cremastogyne root nodules are yet to be characterized. In this study, we isolated and identified three undescribed 3-pentanol glycosides, i.e., 3-pentyl α-l-arabinofuranosyl-(1''→6')-β-d-glucopyranoside, 3-pentyl α-l-rhamnopyranosyl-(1''→6')-β-d-glucopyranoside, and 3-pentyl 6'-(3-hydroxy3-methylglutaryl)-β-d-glucopyranoside, as well as seventeen known compounds from A. cremastogyne root nodules. 3-Pentanol glycosides are abundantly distributed in root nodules, while they are distributed in stems, roots, leaves and fruits at low/zero levels. A. cremastogyne plants treated by root nodule suspension emit 3-pentanol. This study enriches the knowledge about specialized metabolites in the actinorhizal host, and provides preliminarily information on the signal exchange in the actinorhizal symbiosis between A. cremastogyne and Frankia.

Antiacne and Anti-Inflammatory Effects of Phenolic Compounds from Quercus acutissima Carruth. Leaves

Quercus plants are widely distributed in Korea and have been used for their antiallergic and anti-inflammatory properties to treat dermatitis. The phenolic compounds of Quercus acutissima Carruth (QA) are estimated to have antioxidant and anti-inflammatory activities, based on the results of previous studies with Quercus mongilica, Quercus stenophylla, Quercus gilva Blame., and Quercus acuta Thunb. We yield QA extract and the isolated phenolic compounds (hyperoside (1), astragalin (2), kaempferol 3-O-(6″- galloyl)-β-D-glucopyranoside (KGG) (3), quercetin 3-O-(6″-O-galloyl)-β-D-glucopyranoside (QGG) (4), pedunculagin (5), and casuarinin (6)) and were identified using NMR. Among them, KGG (3) and QGG (4) were isolated for the first time from QA. QA extract and the isolated phenolic compounds demonstrated antioxidative, anti-inflammatory, and antiacne activities in RAW 264.7 mouse macrophage cells in vitro. 3-6 demonstrated strong inhibitory activities in the DPPH scavenging and NO production assay and anti-inflammatory and antiacne activities through western blotting (NLRP3, IL-1β, and 5α-reductase). The most outstanding activity in all experiments was casuarinin (6). The study findings suggest potential therapeutic candidates for acne.

Isolation and characterization of secondary metabolites from Gaultheria tenuifolia berries

Gaultheria berries (Ericaceae) are consumed as food or used in folk medicine throughout the world. In the present study, Gaultheria tenuifolia berries were studied to describe their polyphenol and iridoid composition, aroma volatiles, and cytoprotective effects. In total, 14 metabolites were isolated using a combination of countercurrent chromatography and Sephadex LH-20, namely, cyanidin-3-O-β-galactoside, cyanidin-3-O-β-arabinoside, 3-O-caffeoylquinic acid, 5-O-caffeoylshikimic acid, quercetin, quercetin-3-O-β-glucuronide, quercetin-3-O-β-rutinoside, quercetin-3-O-β-glucoside, quercetin-3-O-β-arabinoside, quercetin-3-O-β-rhamnoside, 6α-hydroxydihydromonotropein-10-trans-cinnamate, monotropein-10-trans-cinnamate, and an (epi)-catechin dimer and trimer. Other flavan-3-ols, proanthocyanidins, and iridoids were tentatively identified by spectroscopic and spectrometric means in the fruit extracts. The tentative volatile organic compound characterization pointed to methyl salicylate as responsible for the aroma of this species. The extracts showed significant cytoprotective effects in an oxidative stress model in human gastric epithelial cells. This is the first report on the isolation, characterization, and potential biological activity of secondary metabolites from G. tenuifolia berries and insights on its possible application as a functional food. PRACTICAL APPLICATION: Berries are desirable fruit species because of their phytochemical composition and pleasant taste. Gaultheria berries are special due to their high content of iridoids and the presence of salicylic acid derivatives. Aroma of native berries is relevant for the development of new products reflecting the local identity and use of fruits. The present work involves cooperation of academia and industry on the constituents of the native products. The results provided in this article could be useful for the introduction of this species in the food and nutraceutical industries.

Assessing specialized metabolite diversity of Alnus species by a digitized LC-MS/MS data analysis workflow

Alnus spp. (Betulaceae) have been used for treatments of hemorrhage, burn injuries, antipyretic fever, diarrhea, and alcoholism in traditional medicines. In this study, a digitized LC-MS/MS data analysis workflow was applied to provide an overview on chemical diversity of 15 Alnus extracts prepared from bark, twigs, leaves, and fruits of A. japonica, A. firma, A. hirsuta, and A. hirsuta var. sibirica. Most of the MS/MS spectra could be putatively annotated based on library matching, in silico fragmentation, and substructural topic modeling. The putative annotation allowed us to discriminate the extracts into three chemotypes based on dominant chemical scaffolds: diarylheptanoids, flavonoids or tannins. This high-throughput chemical annotation was correlated with α-glucosidase inhibition data of extracts, and it allowed us to identify gallic acid as the major active compound of A. firma.

Alnus Sibirica Extracts Suppress the Expression of Inflammatory Cytokines Induced by Lipopolysaccharides, Tumor Necrosis Factor-α, and Interferon-γ in Human Dermal Fibroblasts

The effects of Alnus sibirica (AS) extracts on cytokine expression induced by inflammatory stimulants were examined in human dermal fibroblasts (HDFs) and RAW264.7 cells. The anti-oxidative effect and effect on cell viability of AS extracts were evaluated, and four extracts with the highest anti-oxidative effects were selected. HDFs and RAW264.7 cells were treated with inflammatory stimulants, and the expression of cytokines involved in acute (IL-6 and IL-10) and chronic (IL-18) inflammation, the initiation of the immune response (IL-33), and non-specific immune responses (IL-1β, IL-8, and TNF-α) were determined using a reverse-transcription polymerase chain reaction. LPS increased the expression of all the cytokines, except for IL-18; however, AS extracts, particularly AS2 and AS4, reduced this increase, and TNF-α treatment markedly increased the expression of cytokines related to non-specific immune responses. IFN-γ treatment induced no significant changes, except for increased IL-33 expression in HDFs. AS extracts inhibited the increase in the expression of IL-33 and other cytokines in HDFs. Thus, the exposure of HDFs and RAW264.7 cells to inflammatory stimulants increased the expression of cytokines related to all the inflammatory processes. HDFs are involved not only in simple tissue regeneration but also in inflammatory reactions in the skin. AS2 and AS4 may offer effective therapy for related conditions.

Determination of phenolic compounds, in vitro antioxidant activity and characterization of secondary metabolites in different parts of Passiflora cincinnata by HPLC-DAD-MS/MS analysis

Ethanol extracts of different parts of Passiflora cincinnata were obtained by maceration. The total phenolic and flavonoid contents were evaluated. The antioxidant activities were determined by β-carotene-linoleic acid bleaching test, 2,2-diphenyl-1-picrylhydrazil (DPPH), and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging. The crude ethanol stem extract showed the highest amount of total polyphenols (45.53 mg gallic acid equivalent/g) while the highest total flavonoid contents (1.42 mg of quercetin equivalent/g) were observed in the leaf extract. The lowest IC₅₀ (25.65 μg/ml) by the DPPH method was observed for the stem extract. The ABTS method showed a significant antioxidant activity for all investigated extracts. The secondary metabolite composition of ethanol extracts was assessed by HPLC-DAD-MS/MS analysis, leading to the identification of fourteen secondary metabolites in P. cincinnata extracts. These results showed the potentiality of this species as a source of phenolic compounds and antioxidants.

Inhibitory Activity of Allergic Contact Dermatitis and Atopic Dermatitis-Like Skin in BALB/c Mouse through Oral Administration of Fermented Barks of Alnus sibirica

Phytochemical isolation of fermented Alnus sibirica (FAS) which was produced by using Lactobacillus plantarum subsp. argentoratensis, exhibited multiple and different composition compared with the original plant. Anti-allergic contact dermatitis (anti-ACD)/anti-atopic dermatitis (anti-AD) activities (visual observation and regulation of Th₁/Th₂ cytokines and IgE in blood) of FAS and the barks of Alnus sibirica extract (AS) and the two diarylheptanoids, hirsutenone (1) and muricarpon B (2), which are major components of FAS, were measured in vitro and in vivo. FAS, AS and the two compounds showed potent anti-oxidative, anti-inflammatory, anti-ACD and anti-AD activity. In particular, FAS showed more potent biological activity than AS. Thus, fermentation might be a prominent way to enhance the biological activity compared with the original plant. In addition, compounds (1) and (2) might be developed as functional materials or herbal medicines for ACD and AD.

Characterization of diarylheptanoids: An emerging class of bioactive natural products

Diarylheptanoids are a class of secondary plant metabolites with a wide variety of bioactivity. Research on their phytochemistry and phytoanalysis is rapidly growing and the number of identified structures bearing the aryl-C₇-aryl skeleton is at present approaching 500. Historically, the yellow pigment curcumin has been characterized as the first diarylheptanoid and the extensive research on naturally occurring analogues is still ongoing. In this review, studies dealing with the characterization of linear and cyclic derivatives are discussed from the phytoanalytical point of view. Isolation, fractionation and purification strategies from natural sources along with their chromatographic behavior and structural characteristics are discussed. The role of various techniques used for the extraction (such as Soxhlet extraction, sonication, maceration/percolation, microwave-assisted extraction, supercritical carbon dioxide extraction); isolation (liquid-liquid extraction, column chromatographic techniques, preparative thin-layer and high-performance liquid chromatography, centrifugal partition chromatography, counter-current chromatography); separation (thin-layer chromatography, high-performance liquid chromatography, gas chromatography, capillary electrophoresis) and structural characterization (UV/Vis spectroscopy, infrared spectroscopy, X-ray crystallography, mass spectrometry, nuclear magnetic resonance spectroscopy and circular dichroism spectroscopy) are critically reviewed.

Anti-Inflammatory and Anti-Oxidative Activities of Phenolic Compounds from Alnus sibirica Stems Fermented by Lactobacillus plantarum subsp. argentoratensis

Fermentation of Alnus sibirica (AS) stems using Lactobacillus plantarum subsp. argentoratensis was conducted and three compounds isolated from the Alnus species were identified for the first time, 7-(3,4-dihydroxyphenyl)-1-(4-hydroxyphenyl)-heptan-3-one, 1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptan-3-one and 4-(3,4-dihydroxyphenyl)-butan-2-one, along with 14 known compounds. The anti-oxidative and anti-inflammatory abilities of AS and fermented AS (FAS) as well as the isolated phenolic compounds from FAS were investigated. FAS showed stronger anti-oxidative and anti-inflammatory activities than non-fermented AS.

Cytotoxicity, In vitro anti-Leishmanial and fingerprint HPLC- photodiode array analysis of the roots of Trillium govanianum

Trillium govanianum Wall. ex D. Don (Melanthiaceae alt. Trilliaceae), commonly known as 'nagchhatry' or 'teen patra', distributed from Pakistan to Bhutan about 2500-3800 m altitude is indigenous to Himalayas region. In folk medicine the plant has been reported for the treatment of wound healing, sepsis and in various sexual disorders. This paper reports, for the first time, to evaluate the cytotoxicity, in vitro anti-leishmanial (promastigotes) and fingerprint HPLC-photodiode array analysis of the MeOH extract of the roots of T. govanianum and its solid phase extraction fractions. Reverse phase HPLC-PDA based quantification revealed the presence of significant amount of quercetin, myrecetin and kaemferol ranging from 0.221to 0.528 μg/mg DW. MeOH extract revealed distinguishable protein kinase inhibitory activity against Streptomyces 85E strain with 18 mm bald phenotype. The remarkable toxicity profile against brine shrimps and leishmanial was manifested by MeOH extract with LC₅₀ 10 and 38.5 μg/mL, respectively.