Rapid identification and characterization of antioxidants from Ligularia fischeri

Identification of drought-responsive phenolic compounds and their biosynthetic regulation under drought stress in Ligularia fischeri

Ligularia fischeri, a leafy edible plant found in damp shady regions, has been used as an herbal medicine and is also consumed as a horticultural crop. In this study, we investigated the physiological and transcriptomic changes, especially those involved in phenylpropanoid biosynthesis, induced by severe drought stress in L. fischeri plants. A distinguishing characteristic of L. fischeri is a color change from green to purple due to anthocyanin biosynthesis. We chromatographically isolated and identified two anthocyanins and two flavones upregulated by drought stress using liquid chromatography-mass spectrometry and nuclear magnetic resonance analyses in this plant for the first time. In contrast, all types of caffeoylquinic acids (CQAs) and flavonol contents were decreased under drought stress. Further, we performed RNA sequencing to examine the molecular changes in these phenolic compounds at the transcriptome level. In an overview of drought-inducible responses, we identified 2,105 hits for 516 distinct transcripts as drought-responsive genes. Moreover, differentially expressed genes (DEGs) associated with phenylpropanoid biosynthesis accounted for the greatest number of both up- and downregulated DEGs by Kyoto Encyclopedia of Genes and Genomes enrichment analysis. We identified 24 meaningful DEGs based on the regulation of phenylpropanoid biosynthetic genes. Potential drought-responsive genes included upregulated flavone synthase (LfFNS, TRINITY DN31661 c0 g1 i1) and anthocyanin 5-O-glucosyltransferase (LfA5GT1, TRINITY DN782 c0 g1 i1), which could contribute to the high levels of flavones and anthocyanins under drought stress in L. fischeri. In addition, the downregulated shikimate O-hydroxycinnamolytransferase (LfHCT, TRINITY DN31661 c0 g1 i1) and hydroxycinnamoyl-CoA quinate/shikimate transferase (LfHQT4, TRINITY DN15180 c0 g1 i1) genes led to a reduction in CQAs. Only one or two BLASTP hits for LfHCT were obtained for six different Asteraceae species. It is possible that the HCT gene plays a crucial role in CQAs biosynthesis in these species. These findings expand our knowledge of the response mechanisms to drought stress, particularly regarding the regulation of key phenylpropanoid biosynthetic genes in L. fischeri.

Systematic Identification, Fragmentation Pattern, And Metabolic Pathways of Hyperoside in Rat Plasma, Urine, And Feces by UPLC-Q-Exactive Orbitrap MS

Hyperoside is a natural flavonol glycoside, which has antioxidation, antitumor, and anticancer activities together with other healthy effects like improving cardiovascular function, protecting the liver, and regulating the immune system. It is a popular compound used in the traditional Chinese medicine and different studies on hyperoside are present in the literature. However, studies on the metabolism of hyperoside in vivo were not comprehensive. In this study, UPLC-Q-Exactive Orbitrap MS technology was used to establish a rapid and comprehensive analysis strategy to explore the metabolites and metabolic process of hyperoside in rats. The metabolites of hyperoside were systematically identified in rat plasma, urine, and feces. According to the hyperoside standard substance and relevant works of literature, a total of 33 metabolites were identified, including 16 in plasma, 31 in urine, and 14 in feces. Among them, the metabolites quercetin and dihydroquercetin were unambiguously confirmed by comparison with standard substances. In addition, 13 metabolites had not been reported in hyperoside metabolism-related articles at present. The metabolic reactions of hyperoside in vivo were further explored, including phase I metabolism (hydroxylation, dehydroxylation, glycoside hydrolysis, hydrogenation, and hydration) and phase II metabolism (methylation, acetylation, sulfation, and glucuronide conjugation). The fragment ions of hyperoside and its metabolites were usually produced by glucoside bond hydrolysis, the neutral loss of (CO + OH), COH, CO, O, and Retro-Diels Alder (RDA) cleavage. In conclusion, this study comprehensively characterized the metabolism of hyperoside in rats, providing a basis for exploring its various biological activities.

Laxative Metabolites from the Leaves of Moringa oleifera

Three new flavonoids, quercetin-3-O-6-[methyl-(S)-3-hydroxy-3-methylglutaroyl(1→6]-β-d-glucopyranoside (1), kaempferol-3-O-[methyl-(S)-3-hydroxy-3-methylglutaroyl(1→6)]-β-d-glucopyranoside (2), and quercetin-3-O-6-[(E)-4-methoxy-5-methylhexa-2,4-dienoatyl(1→6)]-β-d-glucopyranoside (3), and two new alkaloids, 5-dehydroxymethyl-pyrrolemarumine 4″-O-α-l-rhamnopyranoside (4) and N¹-methyl-N²-((4-O-α-l-rhamnopyranoside)benzyl) oxalamide (5), together with 45 known compounds (6-50) were isolated from the leaves of Moringa oleifera Lam. Among those compounds, 1-octacosanol (50), a straight-chain 28-carbon alcohol, exhibited good activity against diphenoxylate-induced constipation in mice, which is obtained as a laxative constituent from the plant for the first time. In order to have an accurate understanding of the content of compound 50, a quantification with gas chromatography-tandem mass spectrometry (GC-MS/MS) was carried out. The anti-inflammatory and α-glucosidase inhibitory activity of some compounds also was assessed.

Development and application of a rapid HPLC method for simultaneous determination of hyperoside, isoquercitrin and eleutheroside E in Apocynum venetum L. and Eleutherococcus senticosus

Apocynum venetum L. and Eleutherococcus senticosus have been used for hundreds of years to treat hypertension in China. In previous research, there was not a suitable quality control of method for the formulas of Apocynum venetum L. and Eleutherococcus senticosus. It is urgent and essential to develop modern analytical methods for Apocynum venetum L. and Eleutherococcus senticosus to ensure the quality of the formulas. A rapid approach for simultaneous determination of hyperoside, isoquercitrin and eleutheroside E in Apocynum venetum L. and Eleutherococcus senticosus by high-performance liquid chromatography with a diode array detector was described and validated. The full method validation, including the linearity, limits of detection and quantification, precision, repeatability, stability and recovery, was examined. All target components, including isomers of hyperoside and isoquercitrin, were baseline separated in 35 min. The developed method was sensitive, reliable and feasible. With this method, the optimal decoction conditions of Apocynum venetum L. and Eleutherococcus senticosus were selected, and their quality analysis was carried out. Furthermore, an herbal compatibility study of Apocynum venetum L. and Eleutherococcus senticosus based on detecting variations in the content of their active ingredients was performed by the developed HPLC method. It could be an alternative for the quantitative analysis of herbs that contain hyperoside, isoquercitrin or (and) eleutheroside E in the future.

Antihyperlipidemic Activity of Ligularia fischeri Extract in Mice Fed a High-Carbohydrate Diet

Ligularia fischeri, indigenous to eastern Asia, has been used as a traditional herbal medicine. Ligularia fischeri reportedly possesses a number of biological activities such as antimutagenic, antioxidant, antigenotoxic, and anti-inflammation. This study demonstrated the effects of ethanol extracts of Ligularia fischeri (ELF) on a high-carbohydrate diet (HCD)-induced hyperlipidemia in C57BL/6 mice. The mice were divided into six groups (n = 7/group) as follows: normal diet, HCD, or HCD+ELF (100, 200, 400, and 800 mg/kg/day), which were orally administered daily for 12 weeks. Various lipid parameters and histological changes in liver and fat tissue were compared among the treatment and control groups. ELF remarkably reduced body weight gain and attenuated hyperlipidemia by improving the plasma levels of total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, atherogenic index, and cardiac risk factor. Moreover, ELF decreased the HCD-induced hepatic accumulation of lipid droplets and adipocyte hypertrophy. These regulatory effects of ELF appeared to be mediated through the phosphorylation of AMP-activated protein kinase, acetyl-CoA carboxylase, sterol regulatory element-binding protein-1c, and expression of fatty acid synthase. Taken together, these findings indicate a functional role for ELF in the regulation of HCD-induced obesity and hyperlipidemia.

4,5-Di-O-Caffeoylquinic Acid from Ligularia fischeri Suppresses Inflammatory Responses Through TRPV1 Activation

Ligularia fischeri (Ledeb.) Turcz., a perennial plant native to northeastern Asia, has long been used as folk remedies for the alleviation of inflammatory symptoms. We investigated whether the extract of L. fischeri (LFEx) and caffeoylquinic acid (CQA) derivatives, the pharmacologically active ingredients identified from L. fischeri, regulate inflammation via a transient receptor potential vanilloid 1 (TRPV1)-mediated pathway. Changes in intracellular Ca²⁺ levels to the LFEx and trans-5-O-CQA, 3,4-di-O-CQA, 3,5-di-O-CQA, and 4,5-di-O-CQA were monitored in TRPV1-expressing human embryonic kidney cell HEK 293T. LFEx and 4,5-di-O-CQA (EC₅₀  = 69.34 ± 1.12 μM) activated TRPV1, and these activations were significantly inhibited by ruthenium red, a general blocker of TRP channels, and capsazepine, a specific antagonist of TRPV1. 4,5-Di-O-CQA has been determined having antiinflammatory effect under hypoxic conditions by detecting the expression of cyclooxygenase-2 (COX-2), a representative inflammatory marker, and cellular migration in human pulmonary epithelial A549 cells. 4,5-Di-O-CQA suppressed COX-2 expression and cell migration, and this inhibition was countered by co-treatment with capsazepine. This study provides evidence that L. fischeri is selective to inflammatory responses via a TRPV1-mediated pathway, and 4,5-di-O-CQA might play a key role to create these effects. Copyright © 2017 John Wiley & Sons, Ltd.

Preventive effect of Ligularia fischerion inhibition of nitric oxide in lipopolysaccharide-stimulated RAW 264.7 macrophages depending on cooking method

BACKGROUND

Ligularia fischeri (common name Gomchwi) is known for its pharmaceutical properties and used in the treatment of jaundice, scarlet-fever, rheumatoidal arthritis, and hepatic diseases; however, little is known about its anti-inflammatory effect. In this study the influence of blanching and pan-frying on the anti-inflammatory activity of Ligularia fischeri (LF) was evaluated.

RESULTS

Fresh LF and cooked LF showed no significant effect on the viability of macrophages after 24 h incubation. Fresh LF was found to be the most potent inhibitor of nitric oxide (NO) production at 100 μg/ml, while pan-fried LF showed little inhibitory effect on lipoloysaccharide (LPS) stimulated murine machrophage RAW264.7 cells. In contrast with its effect on NO production, pan-fried LF showed significant attenuation of the expression of inducible nitiric oxide synthase (iNOS) compared with fresh LF. In the cooking method of LF, PGE2 production was not affected in the LPS-induced RAW 264.7 cells. In LPS-induced RAW 264.7 cells, pretreatment by fresh and cooked LF increased COX2 mRNA expression. The 3-O-caffeoylquinic acid content of blanching and pan-frying LF increased by 4.92 and 9.7 fold with blanching and pan-frying respectively in comparison with uncooked LF.

CONCLUSIONS

Regardless of the cooking method, Ligularia fischeri exhibited potent inhibition of NO production through expression of iNOS in LPS-induced RAW264.7 cells.

Evaluation of the Antioxidant Activity of Cooked Gomchwi (Ligularia fischeri) Using the Myoglobin Methods

This study evaluated the influence of cooking methods (blanching, pan-frying, and microwaving) on the antioxidant activity of Ligularia fischeri (LF) using myoglobin methods against five different reactive oxygen species (ROS) (i.e., 2,2-diphenyl-1-picrylhydrazyl (DPPH), hypochlorite ions, hydroxyl radicals, peroxyl radicals, and peroxynitrite ions). With respect to DPPH scavenging activity, the antioxidant activities of blanched LF and pan-fried LF were significantly higher (P<0.05) than that of fresh LF for all cooking times. Pan-fried LF and microwaved LF showed higher antioxidant activities against hydroxyl radicals and peroxyl radicals than uncooked LF, while the protective effect of blanched LF was low, except for the at the 3 min cooking time point. Microwaved LF showed high antioxidant activity against all ROS at the 2 min cooking time point. Interestingly, LF that had been microwaved for 2 min and 3 min had high antioxidant values, whereas blanched LF and pan-fried LF had low antioxidant values. The activities of cooked LF against five different ROS were characterized comprehensively by 5-axe cobweb charts.

Antioxidant activity and characterization of phenolic compounds from bacaba (Oenocarpus bacaba Mart.) fruit by HPLC-DAD-MS(n)

The phytochemicals in fruits have been shown to be major bioactive compounds with regard to health benefits. Bacaba (Oenocarpus bacaba Mart.) is a native palm fruit from the Brazilian savannah and Amazon rainforest that plays an important role in the diet of rural communities and is also a source of income for poor people. This paper reports the characterization and analyses of phenolics from bacaba fruit extract. The total phenolic content of bacaba fruit amounted to 1759.27 ± 1.01 mg GAE/100 g, the flavonoid content was 1134.32 ± 0.03 mg CTE/100 g, and the anthocyanin content was 34.69 ± 0.00 mg cyn-3-glc/100 g. The antioxidant activity was evaluated through different assays [ORAC, FRAP, DPPH, TEAC, and cellular antioxidant assay (CAA) assays] and revealed a significant antioxidant capacity for bacaba in comparison to the data available in the literature. The assignment of the phenolic compounds using HPLC-DAD-MS(n) was based on the evaluation of their UV-vis absorption maxima (λ(max)) and mass spectral analyses, and 14 compounds were tentatively identified. The results suggest that bacaba fruits are a promising source of phenolics.

Content of antioxidative caffeoylquinic acid derivatives in field-grown Ligularia fischeri (Ledeb.) Turcz and responses to sunlight

Ligularia fischeri (Ledeb.) Turcz, a commercial leafy vegetable, contains caffeoylquinic acid derivatives (CQAs) as major phenolic constituents. The HPLC chromatograms of leaf extracts collected from different areas in Korea showed a significant variation in CQA amount, and two tri-O-caffeoylquinic acids (triCQAs) were purified and structurally identified by NMR and MS from this plant. Radical scavenging activities among CQAs were found to be increased in proportion to the number of caffeoyl groups. Since this plant prefers damp and shady growth conditions, the effects of sunlight were investigated by growing plantlets in sunlight and shade for four weeks. Greater leaf thickness and higher phenolic contents were found for leaves grown in sunlight than in shade. Four major CQAs-5-mono-O-caffeoylquinic acid (5-monoCQA), and 3,4-, 3,5-, and 4,5-di-O-caffeoylquinic acid (diCQA)-were induced by solar irradiation, whereas the content of these compounds decreased steadily in shade leaves. The leaves of L. fischeri clearly showed adaptation responses to sunlight, and these characteristics can be exploited for cultivation of this plant for potential use as a nutraceutical and functional food.

Comparison of the phenolic content and antioxidant activities of Apocynum venetum L. (Luo-Bu-Ma) and two of its alternative species

The leaves of Apocynum venetum L. (AV), a native Chinese plant, have been used as folk medicine in China and Japan. This study evaluated the content of the active antioxidant component and antioxidant activities of AV, and its two alternative species, Poacynum pictum (Schrenk) Baill. (PP) and Poacynum hendersonii (Hook.f.) Woodson (PH). The total phenolic and total flavonoid contents were determined. In addition, the quantitative analysis of two major flavonoid compounds (hyperoside and isoquercitrin) was carried out by HPLC. The antioxidant activities were investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity method, the reducing power test and the chelating ability of ferrous ions. The highest total phenolic and flavonoid contents were observed in the AV methanolic extract, followed by the PP and PH methanolic extracts. HPLC analysis indicated that isoquercitrin was one of the major components in all three species, however, hyperoside was only detected in AV at high levels. All the antioxidant assays we performed demonstrated that the AV extract was markedly superior to those of the other two species.