Adaptive growth and acidogenic fermentation performance of haloalkaliphilic bacterial communities enriched from biofilms colonising strongly alkaline and saline bauxite residue.

The present study aimed to characterise the adaptive growth and acidogenic fermentation performance of haloalkaliphilic bacteria sourced from field biofilms colonising seawater-treated bauxite residue, under moderate and extremely alkaline pH conditions (8.5 to 10.8) and coupled saline (EC ≈ 50 mS/cm) conditions. The haloalkaliphilic bacterial communities demonstrated strong adaptiveness to the increasing pH from 8.5 to 10.8. The dominant groups were Exiguobacterales and Bacillales at pH 8.5 and 10, but Lactobacillales and Bacillales at pH 10.8. The exposure to pH 10.8 initially delayed bacterial growth in the first 24 h, but which rapidly recovered to a peak rate at 48 h similar to that in the pH 10 treatment. Correspondingly, lactic acid concentration at pH 10.8 rapidly rose to as high as >2000 mg/L at 48 h. Bacterial growth and organic acid production were positively related to carbohydrate supply. Overall, these bacterial groups fermented glucose to produce mainly lactic acid (>80 %) and other acids (such as acetic acid, formic acid, and succinic acid), leading to 0.5-2.0 units of pH reduction, despite the strong buffering capacity in the culture solution. The bacteria could up-regulate their phosphatase activity to mineralise the organic P in the basal nutrient broth, but increasing soluble phosphate-P at a 1:10 of glucose-C was beneficial. The biofilm-sourced bacteria communities contained redundant fermentative haloalkaliphilic groups which were adaptive to strongly alkaline pH and saline conditions.

The mobility of thorium, uranium and rare earth elements from Mid Ordovician black shales to acid waters and its removal by goethite and schwertmannite.

Previous studies have addressed the occurrence of Acid Rock Drainage (ARD) affecting La Silva stream due to the generation of large dumps of Middle Ordovician black shales during the construction of a highway close to El Bierzo (León, Spain). This ARD was characterized by sulphated acid waters with high concentration of heavy metals and anomalies in dissolved thorium (Th) and uranium (U). In the present study, we analyse in depth black shales and water, streambed sediments and precipitates of La Silva stream and its tributaries using different petrographic, mineralogical and geochemical approaches. Black shales, with average Th and U contents of 20 and 3 µg/g respectively contain disseminated detritic micro-grains of high weathering-resistant minerals, such as monazite and xenotime, that present smaller amounts of yttrium and rare earth elements (REY) and other elements as Ca, U, Th, Si and F. Results of the affected waters by ARD show an enrichment in dissolved Th, U and REY of several orders of magnitude with respect to natural waters. Sampled precipitates were mainly schwertmannite (Fe8O8(OH)8-2x (SO4)xO16•nH2O) and goethite (α-Fe3+O(OH)) that showed an enrichment of Th (up to 798 µg/g) and REY, due to the presence of dissolved anionic species (e.g. [Formula: see text] , [Formula: see text] ) that enables their adsorption. Furthermore, these black shales show a clear enrichment in REE (Rare Earth Elements) with respect to NASC (North American Shales Composite) normalized REE patterns. Likewise, normalized REE patterns of stream waters and precipitates clearly show convex curvatures in middle-REE (MREE) with respect to light- and something less than heavy-REE, indicating the trend towards MREE enrichment. These findings are essential to evaluate the impact of ARD of Mid Ordovician shales in the surrounding environment, and to start considering these site as potential source of REE and critical raw materials, activating a Circular Economy.

Construction and carbon source optimization of a microbial-plant coupled reactor for treating acid mine drainage.

Acid mine drainage (AMD) is recognized as one of the most serious contamination sources in the nonferrous metal mining industry. In this study, aerobic strains VCZ02 and VCZ09, which were identified as Leclercia adecarboxylata and Klebsiella aerogenes, were screened from 11 strains of copper-zinc-resistant bacteria in the soil of the Dexing copper mine with Cu2+/Zn2+ removal rates of 46.32%/41.03% and 57.96%/67.05%, respectively. The composition of extracellular polymers plays an important role in the removal of heavy metals by these two strains. A mixed community consisting of VCZ02 and VCZ09 was coupled with Sagittaria trifolia L.var.sinensis (Sims) Mak to construct a microbial-plant coupled reactor to remediate AMD. Under the optimal condition of sodium acetate as carbon source, the pH of AMD increased from less than 5 to above 6.5, showing Cu2+/Zn2+ removal rates of 70-80% and above 30%, respectively. SEM-EDS results showed that VZC02 and VZC09 in the coupled reactor also helped with resisting the toxicity of heavy metals to plants by forming biofilms on the root surface and increasing the content of heavy metals on the surface of roots, thus improving the treatment effect of plants. This study provides a theoretical basis for the bioremediation of AMD and its application.

Acid mine drainage treatment using zero-valent iron nanoparticles in biochemical passive reactors.

Acid mine drainage (AMD) is the major effluent generated from metal and coal mines, causing serious ecological risks and degradation of aquatic habitats and surrounding soil quality. Biochemical passive reactors (BPRs) are an option for improving AMD affected water. This study investigates the effect of the size and concentration of zerovalent iron nanoparticles (nZVI) on the efficiency of batch BPRs during AMD remediation. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were also used as complementary techniques for the investigation of the changes in microbial cells and nZVI properties after the AMD remediation. The results from the batch experiment showed that the concentration of nZVI increases the pH and decreases ORP during AMD treatment, thus favouring the removal of metals. The results also suggest that metal sulfide precipitation occurred in all the batch with reactive mixture but was greater in reactors amended with nZVI of larger size. This study revealed that the presence of nZVI in the BPR leads to metal removal as well as the inhibition of sulfate-reducing bacteria (SRB) activity. Microscopy study indicated that the addition of nZVI creates a morphological change on certain microorganisms in which the cellular membrane was fully covered with nZVI, inducing cell lysis process. These results show that nZVI is a promising reactive material for the treatment of AMD in BPR systems.

In Silico Evaluation of Natural Compounds for an Acidic Extracellular Environment in Human Breast Cancer.

The survival rates for breast cancer (BC) have improved in recent years, but resistance, metastasis, and recurrence still remain major therapeutic challenges for BC. The acidic tumor microenvironment (TME) has attracted attention because of its association with tumorigenesis, metastasis, drug resistance, and immune surveillance. In this study, we evaluated natural compounds from traditional herbal medicine used to treat cancer that selectively target genes regulated by extracellular acidosis. We integrated four transcriptomic data including BC prognostic data from The Cancer Genome Atlas database, gene expression profiles of MCF-7 cells treated with 102 natural compounds, patterns of gene profiles by acidic condition, and single-cell RNA-sequencing from BC patient samples. Bruceine D (BD) was predicted as having the highest therapeutic potential, having an information gain (IG) score of 0.24, to regulate reprogrammed genes driven by acidosis affecting the survival of BC patients. BD showed the highest IG on EMT (IG score: 0.11) and invasion (IG score: 0.1) compared to the other phenotypes with the CancerSEA database. BD also demonstrated therapeutic potential by interfering with the tumor cell-TME interactions by reducing the amyloid beta precursor protein and CD44 expression. Therefore, BD is a potential candidate to target the acidic TME induced metastatic process in BC.

Effect of Continuous and Discontinuous Microwave-Assisted Heating on Starch-Derived Dietary Fiber Production.

Dietary fiber can be obtained by dextrinization, which occurs while heating starch in the presence of acids. During dextrinization, depolymerization, transglycosylation, and repolymerization occur, leading to structural changes responsible for increasing resistance to starch enzymatic digestion. The conventional dextrinization time can be decreased by using microwave-assisted heating. The main objective of this study was to obtain dietary fiber from acidified potato starch using continuous and discontinuous microwave-assisted heating and to investigate the structure and physicochemical properties of the resulting dextrins. Dextrins were characterized by water solubility, dextrose equivalent, and color parameters (L* a* b*). Total dietary fiber content was measured according to the AOAC 2009.01 method. Structural and morphological changes were determined by means of SEM, XRD, DSC, and GC-MS analyses. Microwave-assisted dextrinization of potato starch led to light yellow to brownish products with increased solubility in water and diminished crystallinity and gelatinization enthalpy. Dextrinization products contained glycosidic linkages and branched residues not present in native starch, indicative of its conversion into dietary fiber. Thus, microwave-assisted heating can induce structural changes in potato starch, originating products with a high level of dietary fiber content.

Effect of cranberry juice deacidification on its antibacterial activity against periodontal pathogens and its anti-inflammatory properties in an oral epithelial cell model.

Cranberries are widely recognized as a functional food that can promote oral health. However, the high concentration of organic acids in cranberry juice can cause tooth enamel erosion. Electrodialysis with bipolar membrane (EDBM) is a process used for the deacidification of cranberry juice. The present study investigated whether the removal of organic acids (0%, 19%, 42%, 60%, and 79%) from cranberry juice by EDBM affects its antibacterial activity against major periodontopathogens as well as its anti-inflammatory properties in an oral epithelial cell model. A deacidification rate ≥60% attenuated the bactericidal effect against planktonic and biofilm-embedded Aggregatibacter actinomycetemcomitans but had no impact on Porphyromonas gingivalis and Fusobacterium nucleatum. Cranberry juice increased the adherence of A. actinomycetemcomitans and P. gingivalis to oral epithelial cells, but reduced the adherence of F. nucleatum by half regardless of the deacidification rate. F. nucleatum produced more hydrogen sulfide when it was exposed to deacidified cranberry juice with a deacidification rate ≥42% compared to the raw beverage. Interestingly, the removal of organic acids from cranberry juice lowered the cytotoxicity of the beverage for oral epithelial cells. Deacidification attenuated the anti-inflammatory effect of cranberry juice in an in vitro oral epithelial cell model. The secretion of IL-6 by lipopolysaccharide (LPS)-stimulated oral epithelial cells exposed to cranberry juice increased proportionally with the deacidification rate. No such effect was observed with respect to the production of IL-8. This study provided evidence that organic acids, just like phenolic compounds, might contribute to the health benefits of cranberry juice against periodontitis.

Cross-pollination affects fruit colour, acidity, firmness and shelf life of self-compatible strawberry.

Cross-pollination affects the fruit characteristics of many crops but the effects of cross-pollination on fruit quality of strawberry (Fragaria × ananassa Duch.) are poorly known. This study determined how cross-pollination affects fruit quality of the strawberry cultivar, Redlands Joy, under controlled environment conditions. Plants were allocated to one of four treatments, with all flowers on each plant receiving either: (1) unassisted self-pollination (Autogamy); (2) hand-pollination with Redlands Joy pollen (Self); (3) hand-pollination with cross-pollen from a small-fruited cultivar (Sugarbaby); or (4) hand-pollination with cross-pollen from a large-fruited cultivar (Rubygem). Cross-pollination did not significantly affect plant yield or fruit mass, size, shape, firmness or shelf life. However, cross-pollination affected fruit colour and taste attributes. Cross-pollinated fruit were 3%-5% darker than self-pollinated fruit. They also had 26%-34% lower acidity and 43%-58% higher Brix:acid ratio. Cross-pollination by Sugarbaby increased fruit P, K, Ca, Fe and Mn, but decreased B, Cu and Zn, concentrations. Cross-pollination by Rubygem increased fruit Mn, but decreased K and Na, concentrations and reduced shelf life. Fruit mass, length, diameter and firmness within all treatments increased with increasing numbers of fertilized seeds per fruit. Hand self-pollinated fruit had a higher percentage of fertilized seeds than fruit arising from autogamy and they were also darker, redder, firmer, and had a longer shelf life, higher protein concentration, and lower Al and Na concentrations. The results indicate that strawberry fruit quality can be affected by both the source of pollen and the number of stigmas pollinated.

Impact of ocean warming and ocean acidification on asexual reproduction and statolith formation of the symbiotic jellyfish Cotylorhiza tuberculata.

Ocean acidification and warming are challenging marine organisms and ecosystems around the world. The synergetic effects of these two climate change stressors on jellyfish remain still understudied. Here, we examine the independent and combined effects of these two environmental variables on polyp population dynamics of the Mediterranean jellyfish Cotylorhiza tuberculata. An experiment was conducted to examine asexual reproduction by budding and strobilation considering current and ca. 2100 winter (Trial 1, 36 days) and summer (Trial 2, 36 days) conditions under the RCP8.5 (IPCC 2013). In Trial 1, a temperature of 18°C and two pH levels (current: 7.9 and, reduced: 7.7) were tested. Trial 2 considered two temperature levels 24°C and 30°C, under current and reduced acidification conditions (8.0 and 7.7, respectively). Ephyrae size and statolith formation of released ephyrae from polyps exposed to summer temperatures under both acidification treatment was also analyzed. Zooxanthellae density inside the polyps throughout the experiment was measured. C. tuberculata polyps could cope with the conditions mimicked in all experimental treatments and no significant effect of pH, temperature, or the combination of both variables on the abundance of polyps was observed. At 18°C, strobilation was reduced under high PCO2 conditions. Under summer treatments (24°C and 30°C), percentage strobilation was very low and several released ephyrae suffered malformations and reduced size, as a consequence of reduced pH and elevated temperatures, separately. The number of statoliths was not affected by pH or temperature, however, bigger statoliths were formed at elevated temperatures (30°C). Finally, zooxanthellae density was not affected by experimental conditions, even if, the duration of the experiment significantly affected symbiont concentration. Our results show that even though polyps of C. tuberculata would thrive the future worst scenario predicted for the Mediterranean Sea, their capacity to undergo a proper strobilation and to produce healthy ephyrae will be more vulnerable to climate induced environmental conditions, thereby affecting medusae recruitment and, therefore, population dynamics of the species.

Plant Uptake of Lactate-Bound Metals: A Sustainable Alternative to Metal Chlorides.

Global agricultural intensification has prompted investigations into biostimulants to enhance plant nutrition and soil ecosystem processes. Metal lactates are an understudied class of organic micronutrient supplement that provide both a labile carbon source and mineral nutrition for plant and microbial growth. To gain a fundamental understanding of plant responses to metal lactates, we employed a series of sterile culture-vessel experiments to compare the uptake and toxicity of five metals (Zn, Mn, Cu, Ni, and Co) supplied in lactate and chloride salt form. Additionally, primary root growth in plate-grown Arabidopsis thaliana seedlings was used to determine optimal concentrations of each metal lactate. Our results suggest that uptake and utilization of metals in wheat (Triticum aestivum L.) when supplied in lactate form is comparable to that of metal chlorides. Metal lactates also have promotional growth effects on A. thaliana seedlings with optimal concentrations identified for Zn (0.5-1.0 µM), Mn (0.5-1.0 µM), Cu (0.5 µM), Ni (1.0 µM), and Co (0.5 µM) lactate. These findings present foundational evidence to support the use of metal lactates as potential crop biostimulants due to their ability to both supply nutrients and stimulate plant growth.

Chitosan-silica with hops ß-acids added films as prospective food packaging materials: Preparation, characterization, and properties.

In this study, silica (SiO2) and ß-acids were added to the chitosan films in order to improve the film's properties. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD) were used to explore the structure of film. The results of mechanical test indicated that the film containing SiO2 (0.3%) and ß-acids (0.3%) could obtain a significant tensile strength (10.04 MPa). The complex films possessed a good inhibitory effect on three types of bacteria, and good antioxidant activity (>56%, DPPH). The release mechanism of ß-acids from the films exhibited Fickian diffusion (n < 0.45). During the storage of soybean oil, the films could well control the changes of the peroxide value, acid value and thiobarbituric acid reactant content. Overall, the biofilms not only possess good physical and chemical properties, but also prolongs the time of food storage.

Synthesis, characterization, and utilization of potato starch nanoparticles as a filler in nanocomposite films.

The nanoparticles for the preparation of nanocomposite starch films were synthesized from potato starch using the acid hydrolysis method. The films were prepared by incorporating starch nanoparticles into the film formulation at 0.5, 1, 2, 5, and 10% level of total starch. The control starch film was prepared without the incorporation of starch nanoparticles (SNPs) in film formulation. The starch and SNPs were analyzed for physicochemical and morphological properties. The absorption capacity of SNPs for water and oil was significantly (p < 0.05) lower as compared to native starch. Whereas, the swelling power and solubility of SNPs were significantly (p < 0.05) higher than the swelling power and solubility of starch, respectively. The starch granules were oval and spherical with regular surfaces whereas the SNPs had irregular cracked exteriors spaces. The water vapor transmission rate (WVTR) from nanocomposite starch films was significantly (p < 0.05) lower than the control starch film. The burst strength of films was increased significantly (p < 0.05) with an increased level of SNPs incorporation in film formulation. The incorporation of SNPs increased film thickness and biodegradability. Thus, the present study revealed that the incorporation of SNPs in film formulation resulted in improved film properties.

Mass spectrometry-based quantification and spatial localization of small organic acid exudates in plant roots under phosphorus deficiency and aluminum toxicity.

Low-molecular-weight organic acid (OA) extrusion by plant roots is critical for plant nutrition, tolerance to cations toxicity, and plant-microbe interactions. Therefore, methodologies for the rapid and precise quantification of OAs are necessary to be incorporated in the analysis of roots and their exudates. The spatial location of root exudates is also important to understand the molecular mechanisms directing OA production and release into the rhizosphere. Here, we report the development of two complementary methodologies for OA determination, which were employed to evaluate the effect of inorganic ortho-phosphate (Pi) deficiency and aluminum toxicity on OA excretion by Arabidopsis roots. OA exudation by roots is considered a core response to different types of abiotic stress and for the interaction of roots with soil microbes, and for decades has been a target trait to produce plant varieties with increased capacities of Pi uptake and Al tolerance. Using targeted ultra-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC-HRMS/MS), we achieved the quantification of six OAs in root exudates at sub-micromolar detection limits with an analysis time of less than 5 min per sample. We also employed targeted (MS/MS) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) to detect the spatial location of citric and malic acid with high specificity in roots and exudates. Using these methods, we studied OA exudation in response to Al toxicity and Pi deficiency in Arabidopsis seedlings overexpressing genes involved in OA excretion. Finally, we show the transferability of the MALDI-MSI method by analyzing OA excretion in Marchantia polymorpha gemmalings subjected to Pi deficiency.

A purified acidic polysaccharide from Sarcandra glabra as vaccine adjuvant to enhance anti-tumor effect of cancer vaccine.

Immunological adjuvants are an important part of tumor vaccines and are critical for stimulating anti-tumor immune responses. However, the clinical needs of strong adjuvants have not been met. In this work, we found that the purified acidic polysaccharide from Sarcandra glabra, named p-SGP, is an ideal adjuvant for tumor vaccines. Cancer vaccines could induce stronger humoral and cellular immune responses when they are adjuvanted with p-SGP. Compared with CpG, a well-studied adjuvant, p-SGP significantly augmented the anti-tumor immunity of various cancer vaccines, which is leading to noticeable inhibition of tumor growth and metastasis in tumor-bearing mice. Moreover, p-SGP promoted dendritic cells (DCs) maturation and Th1-polarized immune response. Toll-like receptor 4 (TLR4) inhibitor TAK-242 could significantly inhibit the expression of mature molecules on the surface of DCs stimulated by p-SGP, suggesting that p-SGP could play the role of activating DCs through the TLR4 receptor. Results of RNA-seq showed that the Delta-like ligand 4 (DLL4) gene in the pathway Th1 and Th2 cell differentiation was significantly up-regulated in the DCs treated with p-SGP, suggesting that p-SGP has a unique mechanism of enhancing anti-tumor immunity.

Structural characterization and antioxidant activities of one neutral polysaccharide and three acid polysaccharides from Ziziphus jujuba cv. Hamidazao: A comparison.

A neutral polysaccharide (HJP-1a) and three acid polysaccharides (HJP-2, HJP-3 and HJP-4) were obtained from Z. jujuba cv. Hamidazao. HJP-1a was mainly composed of arabinose and galactose in a ratio of 56.9:20.0, with an average molecular weight of 3.115 × 104 g/mol. HJP-2, HJP-3 and HJP-4 were homogeneous heteropolysaccharides mainly containing galacturonic acid, arabinose and galactose, with average molecular weights of 4.590 × 104, 6.986 × 104 and 1.951 × 105 g/mol, respectively. Structural characterization indicated that the backbone of HJP-3 appeared to be mainly composed of →4)-α-d-GalpA (1→ and →2,4)-α-l-Rhap (1→ residues with some branches consisting of →5)-α-l-Araf (1→ residues and terminals of T-α-l-Araf (1→ and T-ß-d-Galp residues. The four purified fractions displayed dose-dependent radical scavenging activity on ABTS+ radicals and reducing capacity, as well as excellent protective effect on H2O2-induced HepG2 cells and metronidazole-damaged zebrafish embryos, especially HJP-2 in vitro and HJP-1a in vivo. Therefore, the polysaccharides from Z. jujuba cv. Hamidazao could be used as a potential antioxidant in functional foods.

Formation and structural evolution of starch nanocrystals from waxy maize starch and waxy potato starch.

The formation and structural evolution of starch nanocrystals from waxy maize starch (WMS) and waxy potato starch (WPS) by acid hydrolysis were studied. The relative crystallinity, the short-range molecular order, and the double-helix content of WMS and WPS increased significantly during the initial stage of acid hydrolysis, indicating that acid preferentially eroded the amorphous regions of starch granules. With time, there was increased destruction of lamellar structures, causing the granules to completely disintegrate to form nanocrystals. WMS and WPS displayed different hydrolysis mechanisms. WPS was more susceptible to acid hydrolysis than WMS, and WMS exhibited an endo-corrosion pattern and WPS showed an exo-corrosion pattern. WMS nanocrystals had a parallelepiped shape, and WPS nanocrystals were round. This difference in shape is likely due to the different packing configuration of double helices in native starches.

Natural pentacyclic triterpenoid acids potentially useful as biocompatible nanocarriers.

The importance of natural raw materials has grown recently because of their ready availability, renewable nature, biocompatibility and controllable degradability. One such group of plant-derived substances includes the triterpenoid acids, terpenic compounds consisting of six isoprene units, a carboxyl group and other functional groups producing various isomers. Most can be easily extracted from different parts of the plant and modified successfully. By themselves or as aglycones (genins) of triterpene saponins, they have potentially useful pharmaceutical activity. This review focuses on the supramolecular properties of triterpenoid acids with regard to their subsequent use as biocompatible nanocarriers. The review also considers the current list of pentacyclic triterpene acids for which molecular self-assembly has been confirmed without the need for structural modification.

Content of Phenolic Compounds in Meadow Vegetation and Soil Depending on the Isolation Method.

The aim of this paper was to determine the effect of the hydrolysis method on the amounts of phenolic compounds in the plant material in soil and, as a consequence, on the parameters to determine the degree of lignins transformation in soils. The study included the plant material (hay, sward, and roots) and soil-Albic Brunic Arenosol (horizon A, AE, and Bsv) samples. Phenolic compounds were isolated at two stages by applying acid hydrolysis followed by alkaline re-hydrolysis. The quantitative and qualitative analysis of phenolic compounds was performed with high-performance liquid chromatography with a DAD. The content of phenolic compounds in the extracts depended on the hydrolysis method and it was determined by the type of the research material. The amounts of phenolic compounds contained in the alkaline hydrolysates accounted for 55.7% (soil, horizon Bsv)-454% (roots) of their content in acid hydrolysates. In the extracts from acid hydrolysates, chlorogenic and p-hydroxybenzoic acids were dominant. In the alkaline extracts from the plant material, the highest content was recorded for p-coumaric and ferulic acids, and in the extracts from soil, ferulic and chlorogenic acids. A combination of acid and alkaline hydrolysis ensures the best extraction efficiency of insoluble-bound forms of polyphenols from plant and soil material.

Physicochemical and Antioxidative Characteristics of Potato Protein Isolate Hydrolysate.

This study investigated the physicochemical characteristics of potato protein isolate hydrolysate (PPIH) and its antioxidant activity. Potato protein isolate (PPI) was hydrolyzed into PPIH by the proteases bromelain, Neutrase, and Flavourzyme. Compared with PPI, the resulting PPIH had a lower molecular weight (MW, from 103.5 to 422.7 Da) and smaller particle size (<50 nm), as well as a higher solubility rate (>70%) under acidic conditions (pH 3-6). PPIH presented good solubility (73%) across the tested pH range of 3-6. As the pH was increased, the zeta potential of PPIH decreased from -7.4 to -21.6. Using the 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical-scavenging assay, we determined that the half-maximal effective concentration (EC50) values of ascorbic acid, PPIH, and PPI were 0.01, 0.89, and >2.33 mg/mL, respectively. Furthermore, PPIH (50 µg/mL) protected C2C12 cells from H2O2 oxidation significantly better than PPI (10.5% higher viability rate; p < 0.01). These findings demonstrated the possible use of PPIH as an antioxidant in medical applications.

Ethanol Extract of Campsis grandiflora Flower and Its Organic Acid Components Have Inhibitory Effects on Autoinducer Type 1 Quorum Sensing.

Chinese herbs are a useful resource bank for natural drug development, and have attracted considerable attention to exploit quorum sensing inhibitors (QSIs). This study was designed to screen QSIs from raw Chinese herb materials. Of the 38 common herbs examined, the ethanol extract of Campsis grandiflora flower had the strongest QSI activity. The C. grandiflora flower ethanol extract (CFEE) was purified by HPD600, and the QSI activities were examined in further detail. CFEE inhibited violacein production of Chromobacterium violaceum 026 in a dose-dependent manner, and inhibit the swarming abilities of Escherichia coli K-12 and Pseudomonas aeruginosa PAO1. Furthermore, CFEE could inhibited biofilm formation and destroyed mature biofilms of E. coli K-12 and P. aeruginosa PAO1. The composition of CFEE was determined by UPLC-MS/MS to distinguish active QSI compounds, and 21 compounds were identified. In addition to gallic acid and caffeic acid, two organic acids, malic acid and succinic acid, were confirmed for the first time to have autoinducer type 1 QSI activities. Therefore, CFEE is a potential QSI that could be used as a novel antimicrobial agent and should be considered for medicinal development.