Antibacterial phenolic components from Eriocaulon buergerianum

Ethnomedicinal Importance of Patuletin in Medicine: Pharmacological Activities and Analytical Aspects

BACKGROUND

Plant-derived bioactive molecules have been a major source of therapeutic agents for human and veterinarian purposes. Different traditional medicine system across the globe had relied on natural resources to meet their demand of healthcare. Still in modern world, pharmaceutical industries look for phytochemicals to develop new drugs. The current review explores patuletin, a flavonoid for its diverse reported pharmacological activities along with its analytical techniques.

METHODS

Scientific data published on patuletin was collected from Scopus, Science Direct, Pubmed, Google, and Google Scholar. The collected data were analyzed and arranged as per specific pharmacological activities performed using in-vitro or in-vivo methods. Analytical methods of patuletin have been presented next to pharmacological activities Results: Available scientific literature indicates patuletin has anti-inflammatory, cytotoxic, genotoxic, hepatoprotective, antiproliferative, antiplatelet, antinociceptive, and antioxidant activity. In addition to these activities, its biological potential on breast cancer, rheumatoid arthritis, aldose reductase, and different types of microorganisms has been also presented in this work. Analytical data on patuletin signified the importance of patuletin for the standardization of herbal products and derived medicine.

CONCLUSION

It may be concluded that patuletin with its diverse biological activities and readily available analytical methods, holds the potential to be translated into a new drug entity.

Three new feruloyl glucuronopyranosyl glycerols from Eriocaulon buergerianum with their anti-fibrotic effects on hepatic stellate cells

Three new feruloyl glucuronopyranosyl glycerols, 1-O-α-D-(2'-feruloyl) glucuronopyranosyl glycerol (1), 1-O-α-D-(3'-feruloyl) glucuronopyranosyl glycerol (2), and 1-O-α-D-(4'-feruloyl) glucuronopyranosyl glycerol (3) were isolated and purified from the capitulum of Eriocaulon buergerianum Koern. Their structures were identified by spectroscopic and chemical methods. Molecular docking study showed that 1 is a potential inhibitor of TGF-β1 receptor. Bioassay results revealed that 1 exhibited strong inhibitory activity against the TGF-β-induced expression of α-smooth muscle actin (α-SMA) and fibronectin in human hepatic stellate LX-2 cells. The results in this study indicated that the new feruloyl glucuronopyranosyl glycerol 1 has preventive and therapeutic potentials against hepatic fibrosis.

Xanthones and Xanthone O-β-D-glucosides from the Roots of Polygala azizsancarii Dönmez

Nine xanthone derivatives (1-9) were isolated from the roots of Polygala azizsancarii, which is a narrow endemic species for the flora of Türkiye. Based on all of the evidence, the structures of 1-9 were established as two previously undescribed xanthone O-glucosides, 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,5,7-trimethoxyxanthone (1), 3-O-β-D-glucopyranosyloxy-1,6-dihydroxy-2,7-dimethoxyxanthone (2), and seven previously described xanthones, 1,3,6-trihydroxy-2,5,7-trimethoxyxanthone (3), 1,3,6-trihydroxy-2,7-dimethoxyxanthone (4), 1,2,3,4,7-pentamethoxyxanthone (5), 1,3-dihydroxy-2,5,6,7-tetramethoxyxanthone (6), 1,3-dihydroxy-4,7-dimethoxyxanthone (7), 1,7-dihydroxy-3-methoxyxanthone (8), 1,7-dihydroxy-2,3-methylenedioxy-xanthone (9). The structures of the compounds were determined by spectroscopic methods, including 1D-NMR (1H NMR, 13C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC, INADEQUATE), and HRMS. The solid-state structures of 1-4, including the absolute configurations of the stereogenic carbons of the sugar moiety in 1 and 2, were established by X-ray crystal-structure analyses. For the newly described compounds, the trivial names sancarosides A (1) and B (2) are proposed.

The potential effects and mechanisms of hispidulin in the treatment of diabetic retinopathy based on network pharmacology

Background

Diabetic retinopathy (DR), one of the most common and severe microvascular complication of diabetes mellitus (DM), is mainly caused by diabetic metabolic disorder. So far, there is no effective treatment for DR. Eriocauli Flos, a traditional Chinese herb, has been used in treating the ophthalmic diseases including DR. However, the active ingredients and molecular mechanisms of Eriocauli Flos to treat diabetic retinopathy remain elusive.

Methods

Here, the systems pharmacology model was developed via constructing network approach. 8 active components which were screened by oral bioavailability (OB ≥ 30%) and drug-likeness (DL ≥ 0.18) and 154 targets were selected from Eriocauli Flos through TCMSP database. Another 3593 targets related to DR were obtained from Genecards, OMIM, TTD, and Drugbank databases. The 103 intersecting targets of DR and Eriocauli Flos were obtained by Draw Venn Diagram. In addition, protein-protein interaction network was established from STRING database and the compound-target network was constructed by Cytoscape which screened top 12 core targets with cytoNCA module. Then the overlapping targets were analyzed by GO and KEGG enrichment. Moreover, two core targets were selected to perform molecular docking simulation. Subsequently, CCK8 assay, RT-PCR and Western blotting were applied to further reveal the mechanism of new candidate active component from Eriocauli Flos in high glucose-induced HRECs.

Results

The results showed that the overlapping targets by GO analysis were enriched in cellular response to chemical stress, response to oxidative stress, response to reactive oxygen species, reactive oxygen species metabolic process and so on. Besides, the overlapping targets principally regulated pathways such as AGE-RAGE signaling pathway in diabetic complications, lipid atherosclerosis, fluid shear stress and atherosclerosis, and PI3K-Akt signaling pathway. Molecular docking exhibited that VEGFA and TNF-α, had good bindings to the great majority of compounds, especially the compound hispidulin. In vitro, hispidulin ameliorated high-glucose induced proliferation by down-regulating the expression of p-ERK, p-Akt, and VEGFA; meanwhile inhibited the mRNA levels of TNF-α.

Conclusions

In this study, through network pharmacology analysis and experimental validation, we found that hispidulin maybe has a potential targeted therapy effect for DR by decreasing the expression of p-Akt, p-ERK, and VEGFA, which resulted in ameliorating the proliferation in HRECs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03593-2.

Diversity of O-Glycosyltransferases Contributes to the Biosynthesis of Flavonoid and Triterpenoid Glycosides in Glycyrrhiza uralensis

Licorice (Glycyrrhiza uralensis) is a popular medicinal plant containing more than 70 flavonoid and triterpenoid glycosides. Thus far, only a few reports are available on the glycosylation enzymes involved in their biosynthesis. In this work, we mined the transcriptome data of G. uralensis and discovered 43 candidate genes for O-glycosyltransferase (O-GT). Among them, 17 genes could be expressed in E. coli, and functions of the enzymes were analyzed by catalyzing eight native substrates. As a result, we characterized 11 O-GTs, including isoflavone 7-O-GTs, flavonol 3-O-GTs, and promiscuous O-GTs catalyzing flavones, chalcones, and triterpenoids. They could efficiently synthesize key licorice compounds such as liquiritin, isoliquiritin, ononin, and 3-O-β-d-glucuronosyl glycyrrhetinic acid. The diversity of O-GTs contributes to the biosynthesis of various glycosides in licorice. These enzymes could also be used as biocatalytic tools to synthesize other bioactive O-glycosides.

Patuletin induces apoptosis of human breast cancer SK-BR-3 cell line via inhibiting fatty acid synthase gene expression and activity

Fatty acid synthase (FASN) is a key enzyme involved in fatty acid biosynthesis and serves an important role in breast cancer development. The aim of the present study was to investigate the effects of patuletin on the gene expression and activity of FASN in the human breast cancer SK-BR-3 cell line, and the apoptotic effects of patuletin to breast cancer cells. Quantitative reverse transcription polymerase chain reaction, western blotting and intracellular FASN activity assays were used to evaluate FASN gene expression, protein expression and activity in patuletin-treated SK-BR-3 cells. MTT assays and flow cytometry were used to measure cell growth and cell apoptosis, respectively, following patuletin treatment. As a result, it was demonstrated that patuletin dose-dependently reduces FASN expression and intracellular activity in human breast cancer cells, and induces apoptosis in FASN over-expressing SK-BR-3 cells. Notably, apoptosis is associated with the reduction of intracellular FASN activity. The present study demonstrates that patuletin may be considered as a novel natural inhibitor of FASN, may induce anti-proliferative and pro-apoptotic effects in certain human breast cancer cells and may be useful for preventing and/or treating human breast cancer.

Morphological and chemical analyses of Eriocauli Flos sold in Taiwan markets

Eriocauli Flos (Gujingcao; EF), the dried capitulum with the peduncle of Eriocaulon buergerianum Koern. (Eriocaulaceae), is a Chinese herbal medicine for treating eye diseases and inflammation. However, several species of the Eriocaulon genus are used as substitutes in different areas. To examine the species of EF used in Taiwan and to establish the quality control platform, morphological and chemical analyses have been performed. Ten major compounds, including apigenin (7) and its 7-O-β-D-glucopyranoside (1) and 7-O-(6-O-E-coumaroyl)-β-D-glucopyranoside (6), hispidulin (8) and its 7-O-β-D-glucopyranoside (2) and 7-O-(6-O-E-coumaroyl)-β-D-glucopyranoside (5), jaceosidin (9) and its 7-O-β-D-glucopyr-anoside (3), and toralactone (10) and its 9-O-β-D-glucopyranosyl(1→6)-β-D-glucopyranoside (4), were isolated and identified from commercially available EF. Morphological investigation showed that two kinds of EFs and most of the EFs sold in Taiwan herbal markets are capitulum without the peduncle. A simultaneous high performance liquid chromatography and ultra performance liquid chromatography analyses of multiple components (1–10) in commercially available EFs, collected from different areas of Taiwan, was conducted. Results showed wide variations in morphology and chemical profiles between capitulum with and without the peduncle. In comparison with an authentic E. buergerianum, we found not only the morphology but also the chemical profile was different from both collected samples. In terms of the morphological examination, the samples without peduncle are closer to the authentic one. To ensure the correct EF materia medica is used in Taiwan so as to guarantee their therapeutic efficacy in clinical practice, further monitoring is necessary.

Ferulic Acid and Naturally Occurring Compounds Bearing a Feruloyl Moiety: A Review on Their Structures, Occurrence, and Potential Health Benefits

The ubiquitous compound 4-hydroxy-3-methoxycinnamic acid, also known as ferulic acid (FA), constitutes a bioactive ingredient of many foods that may offer beneficial effects against disorders related to oxidative stress, including cancer, diabetes, and neurodegenerative diseases. This review discusses the antioxidant properties of FA, establishing relationships to several biological activities already described for this natural product. Next, 387 naturally occurring compounds, all isolated from plants and published between 1990 and 2015, the structures of which bear 1 or more feruloyl moieties, are covered in this review along with their structural formulas, botanical sources, and bioactivities. The compounds' distribution, structural patterns, bioactivities, and perspectives on food research are also succinctly discussed.

First asymmetric total synthesis of aspergillide D

The first asymmetric total synthesis of aspergillide D was achieved in a longest linear sequence of 18 steps following Sharpless resolution, Yamaguchi esterification, RCM reaction and Shiina macrolactonization.

Bioactive compounds of Eriocaulon sieboldianum blocking proliferation and inducing apoptosis of HepG2 cells might be involved in Aurora kinase inhibition

Eriocaulon sieboldianum (Sieb. & Zucc. ex Steud.) is an edible and medicinal plant used in traditional Chinese medicine. Often in combination with other herbs, it is processed into healthcare beverages for expelling wind-heat, protecting eyes, and reducing blood lipids. Besides, its water decoction together with other herbs has been utilized to treat cancer in China. However, the active ingredients and the precise cellular mechanisms of E. sieboldianum remain to be elucidated. The Aurora kinase family plays critical roles in the regulation of cell division and has attracted great attention to the identification of small-molecule Aurora kinase inhibitors for potential treatment of cancer. A molecular docking study was employed for docking of the most bioactive compounds. Hispidulin (HPDL) and quercetin-3-O-(6''-O-galloyl)-β-D-galactopyranoside (QGGP) were singled out as potent inhibitors of Aurora kinase. Their inhibitory activity towards Aurora kinase was further confirmed by the obvious decrease in autophosphorylation of Aurora-A (Thr288) and Aurora-B (Thr232). Moreover, the induction of cell cycle arrest in HepG2 cells and the suppressed phosphorylation of histone H3 were also consistent with the inhibition of Aurora kinase. The data indicate that the E. sieboldianum extract and its two active compounds, HPDL and QGGP, could effectively induce apoptosis via p53, MAPKs and the mitochondrial apoptotic pathways. These findings could improve the understanding and enhance the development of drugs based on E. sieboldianum and raise its application value in anticancer therapy or prevention. In addition, our results indicated that Aurora kinase might be a novel target of HPDL and QGGP.

Naphthopyranones--isolation, bioactivity, biosynthesis and synthesis

The 1H-naphtho[2,3-c]pyran-1-one (naphthopyranone) moiety forms the structural framework of a group of secondary metabolites that have been isolated from a range of organisms including fungi, bacteria, lichen and plants. This review documents the known naturally occurring naphthopyranones - their isolation, biosynthesis and biological activity. A survey of methods reported for the synthesis of naphthopyranone natural products is presented.

Low energy induced homolytic fragmentation of flavonol 3-O-glycosides by negative electrospray ionization tandem mass spectrometry

RATIONALE

Negative ESI-QIT-MS of several subtypes of flavonoid O-glycosides is known to produce deprotonated molecular ions which undergo homolytic fragmentation at the glycosidic bond upon collision-induced dissociation (CID). However, these subtypes have never been simultaneously compared under unified MS conditions.

METHODS

The (-)-ESI-MS(n) fragmentations of 69 flavonoid O-glycosides, involving eight subtypes, were analyzed using a quadrupole ion-trap mass spectrometer with collision energies varying from 18-44%. Factors influencing the homolytic glycosidic bond fragmentation, such as collision energy, hydroxylation of aglycone, and glycosylation pattern, were comprehensively studied.

RESULTS

Under the unified CID-QIT-MS(2) conditions, the precursor deprotonated molecular ions [M-H](-) for 3-O-glycosyl, 3,7-di-O-glycosyl and 3,6,7-tri-O-glycosyl flavonols experienced homolytic fragmentation at the glycosidic bond and generated the radical aglycone ion [Y0-H](-•). This gas-phase CID fragmentation behavior was not observed for the other subtypes. A general trend was found that hydroxyl substitution at C-6, glycosylation at C-6/C-7, and acetylation of the saccharide moiety remarkably suppressed this fragmentation. In addition, flavonol 3-O-diglycosides (disaccharides) possessing a 1 → 2 glycosidic bond generated more abundant [Y0-H](-•) product ions than those with a 1 → 3 or 1 → 6 bond. The terminal sugar triggered the homolytic fragmentation in the order Rha > Xyl > Glc. Moreover, new counterexamples were found for previously reported fragmentation rules.

CONCLUSIONS

The low-energy CID homolytic fragmentation was diagnostic for structural identification of flavonol 3-O-glycosides. We have summarized key factors affecting this fragmentation. The results could be useful for rapid characterization of flavonoid O-glycosides in complicated herbal extracts.

Flavonoids from the capitula of Eriocaulon australe

A flavan, eriocaulin A (1), and three flavone acyl glucosides, eriocaulosides A-C (2-4) were isolated from the capitula of Eriocaulon australe R. Br. (Eriocaulaceae), a Chinese medicine and an herb for health care beverages, together with seven known flavones and three isoflavones (5-14). The new flavonoids were elucidated as (2S)-3',4'-methylenedioxy-5-methoxy-7-hydroxyflavan (1), hispidulin 7-O-β-D-(6-O-cinnamoyl)glucopyranoside (2), jaceosidin 7-O-β-D-(6-O-p-coumaroyl)glucopyranoside (3), jaceosidin 7-O-β-D-(6-O-p-hydroxybenzoyl)glucopyranoside (4) based on their spectroscopic data. All the 14 flavonoids were obtained from this species for the first time. The in vitro cytotoxicity of compounds 1-14 against human lung adenocarcinoma A549, human breast adenocarcinoma MCF-7, and human cervical carcinoma HeLa cell lines was evaluated using the MTT colourimetric assay. Compounds 1, 7, and 9 were cytotoxic to A549, compounds 1, 2, 7, 9, 12, and 14 to MCF-7, and compounds 7, 9, and 14 to HeLa cells, with IC50 values ranging from 7.17 to 29.57 μg/ml, while the others were inactive (IC50>50 μg/ml).

Anticancer potential of emodin

Traditional Chinese Medicine (TCM) is widely used in clinical research due to its low toxicity, low number of side effects, and low cost. Many components of common fruits and vegetables play well-documented roles as chemopreventive or chemotherapeutic agents that suppress tumorigenesis. Anthraquinones are commonly extracted from the Polygonaceae family of plants, e.g., Rheum palmatum and Rheum officinale. Some of the major chemical components of anthraquinone and its derivatives, such as aloe-emodin, danthron, emodin, chrysophanol, physcion, and rhein, have demonstrated potential anticancer properties. This review evaluates the pharmacological effects of emodin, a major component of Aloe vera. In particular, emodin demonstrates anti-neoplastic, anti-inflammatory, anti-angiogenesis, and toxicological potential for use in pharmacology, both in vitro and in vivo. Emodin demonstrates cytotoxic effects (e.g., cell death) through the arrest of the cell cycle and the induction of apoptosis in cancer cells. The overall molecular mechanisms of emodin include cell cycle arrest, apoptosis, and the promotion of the expression of hypoxia-inducible factor 1α, glutathione S-transferase P, N-acetyltransferase, and glutathione phase I and II detoxification enzymes while inhibiting angiogenesis, invasion, migration, chemical-induced carcinogen-DNA adduct formation, HER2/neu, CKII kinase, and p34cdc2 kinase in human cancer cells. Hopefully, this summary will provide information regarding the actions of emodin in cancer cells and broaden the application potential of chemotherapy to additional cancer patients in the future.

Chemical constituents of the methanolic extract of leaves of Leiothrix spiralis Ruhland and their antimicrobial activity

Chemical fractionation of the methanolic extract of leaves of Leiothrix spiralis Ruhland afforded the flavonoids luteolin-6-C-β-D-glucopyranoside (1), 7-methoxyluteolin-6-C-β-D-glucopyranoside (2), 7-methoxyluteolin-8-C-β-D-glucopyranoside (3), 4′-methoxyluteolin-6-C-β-D-glucopyranoside (4), and 6-hydroxy-7-methoxyluteolin (5), and the xanthones 8-carboxymethyl-1,5,6-trihydroxy-3-methoxyxanthone (6), 8-carboxy-methyl-1,3,5,6-tetrahydroxyxanthone (7). Methanolic extract, fractions, and isolated compounds of the leaves of L. spiralis were assayed against Gram-positive (Staphylococcus aureus, Bacillus subtilis and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella setubal and Helicobacter pylori) and fungi (the yeasts Candida albicans, C. tropicalis, C. krusei and C. parapsilosis). We observed the best minimum inhibitory concentration values for the methanolic extract against Candida parapsilosis, for the fraction 5 + 6 against Gram-negative bacteria E. coli and P. aeruginosa, and compound 7 against all tested Candida strains. The methanolic extract contents suggest that this species may be a promising source of compounds to produce natural phytomedicines.

Eriocaulon buergerianum extract protects PC12 cells and neurons in zebrafish against 6-hydroxydopamine-induced damage

Background

Ericaulon buergerianum (Gujingcao) is an ophthalmic, anti-inflammatory and antimicrobial Chinese medicinal herb. This study aims to investigate the neuroprotective effects of Ericaulon buergerianum ethanol extract (EBE) and to elucidate its underlying action mechanism.

Methods

The viability of dopaminergic (DA) neuron in zebrafish was examined by anti-tyrosine hydroxylase (TH) immunostaining. The locomotor activity of zebrafish was assessed with a digital video tracking system. The viability and cellular damage of the PC12 cells were determined by MTT and LDH assays respectively. The nuclear morphological changes in apoptotic cells were evaluated with DNA staining by Hoechst 33342 dye. Intracellular nitric oxide (NO) was quantified by DAF-FM diacetate staining. The expression of inducible nitric oxide synthase (iNOS) was determined by Western blot.

Results

EBE inhibited the 6-OHDA-induced decrease in total distance of movement in zebrafish. Pretreatments of EBE (25, 50, 100 and 200 μg/ml) increased the viability of 6-OHDA-damaged PC12 cells in a dose dependent manner. Protection against 6-OHDA-induced nuclear fragmentation and accumulation of apoptotic bodies was also observed in EBE pretreated cells. Anti-oxidative (inhibition of NO production and iNOS expression in PC12 cells in vitro) activities of EBE are related to its neuroprotective effects in 6-OHDA-induced DA neuron damage.

Conclusion

EBE exhibited significant neuroprotective activities in zebrafish, including recovery of dopaminergic neuron loss caused by 6-OHDA in a dose-dependent manner in vivo, inhibition of 6-OHDA-induced decrease of total distance in movement in zebrafish. The iNOS-NO pathway may be involved.

Characterization of Flavonoid and Naphthopyranone Derivatives from Eriocaulon ligulatum using Liquid Chromatography Tandem Mass Spectrometry

Liquid chromatography-electrospray ionization multistage ion trap mass spectrometry (LC-ESI-IT-MSn) was used to analyze the secondary metabolites in the methanol extract of the capitulae of Eriocaulon ligulatum. The major components were mono-and diglycosides of flavonoids and naphthopyranones. Eleven compounds, including four new flavonol glycosides, were identified based on their fragmentation patterns in MS experiments and on NMR analysis of the isolated compounds. The described data may contribute to a better understanding of the taxonomic classification of the Eriocaulaceae family.