Antibacterial activity and mechanism of luteolin isolated from Lophatherum gracile Brongn. against multidrug-resistant Escherichia coli.

Infections caused by multidrug-resistant (MDR) bacteria have become a major challenge for global healthcare systems. The search for antibacterial compounds from plants has received increasing attention in the fight against MDR bacteria. As a medicinal and edible plant, Lophatherum gracile Brongn. (L. gracile) has favorable antibacterial effect. However, the main antibacterial active compound and its antimicrobial mechanism are not clear. Here, our study first identified the key active compound from L. gracile as luteolin. Meanwhile, the antibacterial effect of luteolin was detected by using the broth microdilution method and time-kill curve analysis. Luteolin can also cause morphological structure degeneration and content leakage, cell wall/membrane damage, ATP synthesis reduction, and downregulation of mRNA expression levels of sulfonamide and quinolones resistance genes in multidrug-resistant Escherichia coli (MDR E. coli). Furthermore, untargeted UPLC/Q-TOF-MS-based metabolomics analysis of the bacterial metabolites revealed that luteolin significantly changed riboflavin energy metabolism, bacterial chemotaxis cell process and glycerophospholipid metabolism of MDR E. coli. This study suggests that luteolin could be a potential new food additive or preservative for controlling MDR E. coli infection and spread.

The Application of Lophatherum Gracile Brongn Flavonoids in Wheat Flour Products: Effects on the Structural and Functional Characteristics of Wheat Dough.

The effects of lophatherum gracile brongn flavonoids on the multiscale structure and functional properties of wheat dough were investigated. Wheat dough samples with varying contents of lophatherum gracile brongn flavonoids were analyzed to assess changes in thermal-mechanical rheological properties, microstructure, chemical interactions, water distribution, and macropolymer formation by Mixolab mixer, fluorescence microscopy, and low-field nuclear magnetic resonance (LF-NMR). The findings revealed that lophatherum gracile brongn flavonoids disrupted the three-dimensional network of gluten proteins in the wheat dough, leading to decreased water-binding capacity and reduced gluten protein crosslinking while enhancing thermal stability and inhibiting the starch retrogradation of the dough. This study provided important insights into the interaction mechanisms between lophatherum gracile brongn flavonoids and the proteins/starch in wheat dough, offering theoretical guidance for the development of novel wheat-based products for industrialization and practical production.

Spectrum-effect relationship between ultra-high-performance liquid chromatography fingerprints and antioxidant activities of Lophatherum gracile Brongn.

Lophatherum gracile Brongn. is a medicinal and edible plant resource as well as a natural additive in the functional food market. To better understand its characteristics and efficacy, a method combining chromatographic fingerprints and antioxidant activity was proposed. A total of 21 common peaks were confirmed from liquid chromatography fingerprints and were identified as 14 flavonoids and 7 phenolic acids by ultra-high-performance liquid chromatography (UHPLC) coupled with quadrupole Orbitrap mass spectrometry (Q-Orbitrap/MS). Their antioxidant activities were evaluated by 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH), 2,2'-diazide-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP) assay. The results showed that all of the test samples had moderate to high antioxidant effects, with IC50 values ranging from 5.2 to 16.1 mg/ml and 1.2 to 2.8 mg/ml for DPPH and ABTS assays, and the FeSO4 concentrations of 1.84-4.20 mmol/L for the FRAP assay. The spectrum-effect relationship between UHPLC fingerprints and antioxidant activity was investigated through Pearson correlation analysis and Grey relational analysis (GRA) to identify the antioxidant constitutes in Lophatherum gracile Brongn. The results showed that 11 compounds were greatly associated with the antioxidant activity with a correlation degree >0.80, which can be used as the quality marker of Lophatherum gracile Brongn.

Lophatherum gracile Brongn. attenuates neutrophilic inflammation through inhibition of JNK and calcium.

ETHNOPHARMACOLOGICAL RELEVANCE: Lophatherum gracile Brongn. (L. gracile) has been long used in traditional herbal medicine to clinically clear heat, disinhibit dampness, and treat inflammation. However, the effect of L. gracile on the activation of human neutrophils remains unclear. AIM OF THE STUDY: The aim of current study is to investigate the anti-inflammatory properties of L. gracile extract (LGE) in N-formyl-methionyl-leucyl-phenylalanine (fMLF)-induced activation of human neutrophils. MATERIALS AND METHODS: Superoxide anion generation and elastase release were estimated by spectrophotometry. A series of signaling pathways including mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt), as well as calcium mobilization were studied by Western blot analysis and spectrofluorometry. RESULTS: Our experimental results indicated that the nontoxic dosage of LGE does-dependently inhibited the fMLF-induced superoxide anion (O2•-) generation, elastase release, CD11b expression, adhesion, and chemotactic migration in human neutrophils. LGE selectively inhibited the fMLF-induced phosphorylation of JNK but not p38, ERK, or Akt in human neutrophils. LGE also decreased the intracellular Ca2+ levels ([Ca2+]i) in fMLF-activated human neutrophils. However, a specific JNK inhibitor inhibited the fMLF-induced O2•- generation and CD11b expression, but it had no effect on [Ca2+]i in human neutrophils. CONCLUSIONS: LGE exhibited anti-inflammatory activities in fMLF-activated human neutrophils. The pharmacological mechanisms of LGE-repressed neutrophilic inflammation were through two independent pathways, JNK signaling and calcium mobilization. Our results suggested that LGE holds the potential to be developed as an anti-inflammatory botanical medicine.

Effects of pretreatment, NaOH concentration, and extraction temperature on the cellulose from Lophatherum gracile Brongn.

Lophatherum gracile Brongn. (LGB), a homology material of medicine and food, has plentiful cellulose. Aiming to investigate the physiochemical characteristic differences of LGB cellulose extracted by various pretreatment methods and extraction conditions, the effect of dry crushing and wet beating, and the alkaline solution concentration and temperature were compared. Results showed that the extracted cellulose after dry crushing pretreatment had higher purity and lower non-cellulosic components such as hemicellulose, lignin and ash than those obtained by wet beating pretreatment. Furthermore, the impurities were more thoroughly removed by the alkaline solution at high concentration and temperature. Structural characterization revealed that the cellulose obtained by wet beating pretreatment had more fibrillation and smaller particle size, while destroyed crystallinity resulting in bad thermal stability. The alkaline solution temperature had no effect on the morphology and particle size, but high alkaline solution temperature (90 °C) improved crystallinity and thermal stability. Furtherly, the cellulose II produced by at high alkaline solution concentration (18 wt%) exhibited denser surface, smaller particle size and higher thermal stability than the cellulose I extracted at low alkaline solution concentration (4 wt%). Especially, the crystallinity of cellulose II was higher than that of cellulose I with dry crushing pretreatment, while the cellulose obtained by wet beating displayed an opposite trend. Hydration properties indicated that the water holding capacity, oil binding capacity and swelling capacity of the cellulose pretreated by dry crushing were higher than those of the cellulose pretreated by wet beating, and the cellulose I exhibited higher hydration properties compared to the cellulose II, which may depend on its loose network structure. This study suggested that dry crushing pretreatment and high alkaline solution temperature could effectively improve functional properties of LGB cellulose I and II, which promoted its use in food applications.

High-throughput and sensitive screening of compounds with deoxyribonucleic acid-binding activity by a high-performance liquid chromatography-tandem mass spectrometry-fluorescence detection technique using palmatine as a fluorescence probe.

A high-throughput biochemical detection method based on the combination of high-performance liquid chromatography (HPLC), multiple-stage mass spectrometry (MS(n)) and DNA-binding activity assay was developed and validated for the simultaneous screening and identification of DNA-binding compounds in complex samples. Palmatine was used as a sensitive, nontoxic and environmentally friendly DNA fluorescence probe. HPLC fingerprints, ultraviolet absorption spectra, MS(n) fragments of components, and DNA-binding activity profiles could be simultaneously recorded during real-time analysis. Using the proposed method, 25 compounds were identified from Lophatherum gracile Brongn extracts, of which 18 were novel compounds first identified in these extracts. Nineteen compounds showed DNA-binding activity, most of which were flavone glycosides, with distinct dose-effect and structure-activity relationships. The method was validated and was proven to have a good linearity in the range of concentrations used in the study. The limit of detection was 0.2020nmol. Our study indicated that the proposed method was sensitive, accurate, precise and reliable to be used for simultaneous screening and identification of DNA-binding compounds in complex samples.

Study on Extraction Process of Total Flavonoids in Lophatherum Gracile Brongn / 中国中医药信息杂志

Objective To study the optimum ethanol extraction process of total flavonoids in Lophatherun gracile Brongn. Methods The extraction of total flavonoids was choosen as the assessment index. Ethanol volumn extracting time and times were the studing factors. The optimum ethanol extraction process was selected with the orthogonal design. Results The optimum ethanol extracting process conditions were as follows:adding 18 fold of 75% ethanol,extracting for 1.0 h and one in all. Ethanol dosage was the predominant influencing factor. Conclusion This optimum extradion process of total flavonoids in Lophatherum gracle Brongn is reliable.