DHBA Research Articles

Corn distiller’s dried grains with solubles as a target for fermentation to improve bioactive functionality for animal feed and as a source for a novel microorganism with antibacterial activity

Plant-based bioenergy by-products such as corn distillers’ dried grains with solubles (DDGS) are widely utilized as animal feed sources and feed ingredients due to their balanced nutritional profile and animal health protective functional qualities. Bioprocessing of this bioenergy by-product using beneficial lactic acid bacteria (LAB)-based fermentation strategy to improve animal-health targeted functional qualities has wider relevance for animal feed applications. In this study, liquid extracts of corn DDGS were fermented with Lactiplantibacillus plantarum and Lactobacillus helveticus. The unfermented and fermented extracts were then analyzed (at 0, 24, 48 and 72-h) for their total soluble phenolic content (TSP), phenolic profile, antioxidant activity via ABTS and DPPH radical scavenging activity, and antimicrobial activity against the gut pathogen Helicobacter pylori using in vitro assay models. Statistical differences in antioxidant activity and phenolic content were observed among the unfermented and fermented extracts. The major phenolic compounds detected in corn DDGS were gallic, dihydroxybenzoic, p-coumaric, caffeic and ferulic acid, and catechin. Antimicrobial activity against H. pylori was observed for the unfermented extracts and the antimicrobial activity was attributed to the growth of a corn DDGS-endemic culture. The culture was isolated, sequenced, and identified as Bacillus amyloliquefaciens. Results of this study indicated that processing strategies of by-products such as LAB- based fermentation of corn DDGS could affect its bioactive-linked functional qualities due to microbial interaction with the phytochemicals. Furthermore, plant by-products can serve as novel sources of beneficial microflora that have relevance in wider agriculture, food safety, and therapeutic applications.

Phytochemical screening and antioxidative property evaluation of lipid-producing fungi

The increased demands for natural bioactive compounds have induced the search for unusual sources. Microorganisms, especially fungi are a potent source of secondary metabolites, which could act mainly as antioxidant compounds to prevent oxidative stress. In the present study three soil-isolated fungi Aspergillus niger, Aspergillus heteromorphus and Aspergillus fumigatus, were screened for their oleaginous property as well as their potential for the production of bioactive compounds. Fungal biomasses were freeze dried and extracted with methanol using a cold percolation process for the production of intracellular metabolites and the fungal culture media after fermentation were examined for extracellular metabolites. Intracellular and extracellular extracts of the isolated fungi along with the single-cell oils extracted from those fungi were screened for phytochemicals, which showed the presence of alkaloids, flavonoides, glycosides, phenols, saponins and terpenoids. All strains showed potent antioxidant activity, determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) activity. Extracellular extract and single-cell oil of A. heteromorphus showed the highest antioxidant activity with maximum ABTS radical scavenging activity and reducing potential. Highest content of phenolic and flavonoid compounds within the isolated fungi was found to be 37.58mg gallic acid equivalent (GAE)/g and 62.07mg catechine equivalent (CE)/g, respectively. Chromatographic analysis of the intracellular and extracellular extracts of the fungi showed the presence of gallic acid, di-hydroxy benzoic acid, ferulic acid, quercetin, epigerin, kampferol, trans cinnamic acid, chlorogenic acid and rutin, which made them biologically important and beneficial for human health.

Effective ammonia separation by non-chloride deep eutectic solvents composed of dihydroxybenzoic acids and ethylene glycol through multiple-site interaction

The effective separation of ammonia (NH3) has important implication for the conversion improvement and pollution control during the synthesis of NH3. In the present work, a novel kind of non-chloride deep eutectic solvents (DESs) were constructed from dihydroxybenzoic acids (DHBAs) and ethylene glycol (EG). The DHBA + EG DESs exhibit several weak acidic sites and hydrogen-bond sites, thus were proposed for NH3 separation. We found that the amounts of NH3 absorbed by DHBA + EG DESs are quite impressive, particularly at reduced pressures. The capacities can reach 5.64 and 11.69 mol/kg at 0.1 and 1 bar respectively, when the temperature of 298.2 K is considered. Besides, after five absorption–desorption cycles, the DHBA + EG DESs can preserve the excellent NH3 absorption performance. The DHAB + EG DESs can also selectively absorb NH3 from N2 and H2 in the mixed gas. The NH3 absorption mechanism of DHBA + EG DESs was further deeply illustrated by spectroscopic techniques and theoretical calculations.

Stability and Antibiotic Potency Improvement of Levofloxacin by Producing New Salts with 2,6- and 3,5-Dihydroxybenzoic Acid and Their Comprehensive Structural Study

Recently, solid-state engineering has become a promising approach to improving the stability and potency of antibiotics. Levofloxacin (LF) is a broad-spectrum fluoroquinolone antibiotic marketed in solid and solution dosage forms. However, this substance forms solid hydrates under ambient conditions and degrades due to lighting, which may change its solid properties and dose. In addition, resistance cases have been reported due to long-time antibiotic usage. This research aims to allow LF to react with antioxidant dihydroxybenzoic acid (DHBA), which has low antimicrobial activity, to produce a more stable compound under water and lighting conditions and improve LF's potency. The experiment begins with a screening to select potential DHBA isomers that can react with LF and predict the stoichiometric ratio using phase diagrams, which show that 2,6-DHBA and 3,5-DHBA are prospective antioxidants that can react with LF in a (1:1) molar ratio. Multicomponent systems are prepared by dissolving the LF-DHBA mixture in (1:1) ethanol-methanol (95% grade) and evaporating it. Then, the new solid phase formation is confirmed by thermal analysis and powder X-ray diffractometry. Next, infrared spectrophotometry and neutron magnetic resonance analyses are used to identify the LF-DHBA's interactions. Finally, single-crystal X-ray diffractometry is used to solve the three-dimensional structure of the multicomponent system. We then conduct a hygroscopicity and stability test followed by a lighting and potency test using the microdilution method. Our data reveal that both reactions produce salts, which are named LF-26 and LF-35, respectively. Structurally, LF-26 is found in an anhydrous form with a triclinic crystal packing, while LF-35 is a hemihydrate in a monoclinic system. Afterward, both salts are proven more stable regarding water adsorption and UV lighting than LF. Finally, both multicomponent systems have an approximately two-fold higher antibiotic potency than LF. LF-26 and LF-35 are suitable for further development in solid and liquid dosage formulations, especially LF-35, which has superior stability compared with LF-26.

Amaranth Seeds and Sprouts as Functional Ingredients for the Development of Dietary Fiber, Betalains, and Polyphenol-Enriched Minced Tilapia Meat Gels

There is an increasing interest in the development of meat processed products enriched with antioxidant dietary fiber to augment the consumption of these health beneficial compounds. This study aimed to evaluate the nutritional, nutraceutical, and antioxidant potential, as well as the physicochemical properties of minced tilapia fillets (meat) gels with added amaranth seed or sprout flours (0%, 2%, 4%, 8%, and 10% w/w). Dietary fiber content was significantly increased with the addition of amaranth seed (1.25-1.75-fold) and sprout flours (1.99-3.21-fold). Tilapia gels with added 10% amaranth seed flour showed a high content of extractable dihydroxybenzoic acid and cinnamic acid, whereas the addition of 10% amaranth sprout flour provided a high and wide variety of bioactive compounds, mainly amaranthine and bound ferulic acid. The addition of amaranth seed and sprout flours increased hardness (1.01-1.73-fold) without affecting springiness, decreased luminosity (1.05-1.15-fold), and increased redness and yellowness. Therefore, amaranth seed and sprout flours could be used as functional ingredients for the development of fish products rich in bioactive compounds.

Anticholinesterase Activity of Selected Medicinal Plants from Navarra Region of Spain and a Detailed Phytochemical Investigation of Origanum vulgare L. ssp. vulgare.

Alzheimer’s disease is a neurodegenerative disease characterized by progressive memory loss and cognitive impairment due to a severe loss of cholinergic neurons in specific brain areas. It is the most common type of dementia in the aging population. Although many anti-acetylcholinesterase (AChE) drugs are already available on the market, their performance sometimes yields unexpected results. For this reason, research works are ongoing to find potential anti-AChE agents both from natural and synthetic sources. In this study, 90 extracts from 30 native and naturalized medicinal plants are tested by TLC and Ellman’s colorimetric assay at 250, 125 and 62.5 μg/mL in order to determine the inhibitory effect on AChE. In total, 21 out of 90 extracts show high anti-AChE activity (75–100% inhibition) in a dose-dependent manner. Among them, ethanolic extract from aerial parts of O. vulgare ssp. vulgare shows an IC50 value 7.7 times lower than galantamine. This research also establishes the chemical profile of oregano extract by TLC, HPLC-DAD and LC-MS, and twenty-three compounds are identified and quantified. Dihydroxycinnamic acids and flavonoids are the most abundant ones (56.90 and 25.94%, respectively). Finally, total phenolic compounds and antioxidant properties are quantified by colorimetric methods. The total phenolic content is 207.64 ± 0.69 µg/mg of extract. The antioxidant activity is measured against two radicals, DPPH and ABTS. In both assays, the oregano extract shows high activity. The Pearson correlation matrix shows the relationship between syringic acids, a type of dihydroxybenzoic acid, and anti-AChE (r2 = −0.9864) and antioxidant activity (r2 = 0.9409 and 0.9976). In conclusion, the results of this study demonstrate promising potential new uses of these medicinal herbs for the treatment of Alzheimer’s. Origanum vulgare ssp. vulgare and syringic acids, which have anti-AChE activity and beneficial antioxidant capacity, can be highlighted as potential candidates for the development of drugs for the treatment of Alzheimer’s disease and other diseases characterized by a cholinergic deficit.

Ameliorating substance accessibility for microorganisms to amplify toluene degradation and power generation of microbial fuel cell by using activated carbon anode

Limited access to the hydrophobic organic compounds by microorganisms impedes the improvement of performance of bioreactor processing contaminant degradation. Here, we assembled activated carbon in the anode chamber of the microbial fuel cell (MFC) to serve as a reservoir for toluene molecular and exoelectrogens. The adsorption of toluene by activated carbon facilitated the substrate accessible by exoelectrogens and was beneficial for toluene biodegradation. Rapid degradation of toluene was achieved by MFC assembled with active carbon anode (AC-MFC) in 36 h, which was shorter than that (∼60 h) for MFC with carbon felt anode (CF-MFC). In addition, significant decrease of gaseous toluene released from anolyte into headspace as the introduction of activated carbon. The model EABs Geobacter anodicances was enriched on activated carbon, which brought out the elevated performance of AC-MFC for toluene degradation and power generation. Polarized curves revealed that the maximum power density of AC-MFC was 3328 mW/m3, which was 2.6 times higher than that of CF-MFC (1267 mW/m3). Analysis of anolyte revealed that benzoic acid, dihydroxybenzoic acid and β-carboxy-cis-cis-muconate were the main intermediate products during toluene degradation. This work provides an effective strategy for improving biodegradation efficiency of hydrophobic organic compounds accompany with power generation.

Screening the extraction process of phenolic compounds from pressed grape seed residue: Towards an integrated and sustainable management of viticultural waste

The integrated valorisation of waste from the food chain to obtain value-added compounds with biological functionality will facilitate the transition to the era of a sustainable bioeconomy. To this end, an efficient matrix solid-phase dispersion (MSPD) extraction method was developed and optimized, using experimental factorial design and response surface methodology, for polyphenols recovery from pressed grape seeds obtained after the extraction of essential oils by cold pressing. Gallic, dihydroxybenzoic, p-coumaric and trans-ferulic acid, naringin, resveratrol, quercetin and kaempferol were quantified at 2.1–295 μg g−1 by capillary liquid chromatography coupled to a diode array detector and a mass analyser (cLC-DAD-MS). Furthermore, total antioxidant activity, free radical scavenging and lipid peroxidation suppression, together with the inhibition of beta-amyloid (Αβ42) protein aggregation, considered one of the main pathological effects of Alzheimer's disease, were evaluated. Potent lipid peroxidation inhibition (IC50 0.238 ± 0.003 ng g−1) was observed, along with the reduction of Αβ42 fibril width (9.4–54.8%) and aggregation. The results presented proved that the MSPD extraction method could be considered as an efficient and sustainable methodology to produce phenolic-rich extracts that may serve as an alternative antioxidant and neuroprotective ingredient for the food or pharmaceutical formulations, leading to the cascade valorisation of winery by-products.

Anti-inflammatory activity and metabolites profiling of aqueous stem bark extract of Ficus vogelii (Moraceae) in rats

IntroductionFicus vogelii is a terrestrial tree, used in Cameroonian pharmacopeia to treat various inflammatory diseases such as rheumatism. Accordingly, the present work aimed at evaluating anti-inflammatory potential of Ficus vogelii aqueous extract and identified phytochemicals of interest. MethodsThe characterization of the phytochemicals was carried out by HPLC-ESI-MSn. The anti-inflammatory potential of the aqueous extract of Ficus vogelii (100, 200, 400 and 600 mg/kg) was investigated using acute inflammatory models induced by chemicals, and chronic inflammatory models induced by formalin and Complete Freund Adjuvant (CFA) in rats. ResultsFicus vogelii significantly (p < 0.001) inhibited carrageenan-induced rat paw edema with maximum inhibitions of 75.86% (0.5 h), 82.41% (3 h) and 90.18% (6 h) at 100 mg/kg. This extract significantly (p < 0.001) reduced paw edema induced by histamine (54.10%), serotonin (54.06%), dextran (38.90%) and arachidonic acid (56.95%) respectively up to 1 h. Similarly, the extract significantly (p < 0.001) inhibited edema formation on the left paws of rats from day 2 up to 7 days post formalin injection, and significantly (p < 0.001) decreased paw edema of CFA-treated rats with the highest effect of 67.85% and 77.07% obtained on day 13 and day 21. Furthermore, the extract showed an antioxidant potential by improving the tissue levels of malondialdehyde, nitrites, superoxide dismutase and catalase. Phytochemicals analysis showed several compounds with isocitric acid (19%), trihydroxy-octadecenoic acid (18%), followed by dihydroxybenzoic acid, chlorogenic acid and vicenin-2 (8–9%). Oxylipins represented approximately 25% of the extract, thus being some of the compounds responsible for the observed activity. ConclusionThese results suggest that Ficus vogelii have anti-inflammatory effects on acute and chronic inflammation conditions.

Inhibition studies of the protozoan α-carbonic anhydrase from Trypanosoma cruzi with phenols

The α-class carbonic anhydrase (CA, EC 4.2.1.1) from the protozoan pathogen Trypanosoma cruzi, TcCA, was investigated earlier for its inhibition with anions, sulphonamides, thiols and hydroxamates, well-known classes of CA inhibitors (CAIs). Here we present the first inhibition study of this enzyme with phenols, which possess a diverse CA inhibition mechanism compared to the previously investigated compounds, which are all zinc binders. Indeed, phenols are known to anchor to the zinc coordinated water molecule within the enzyme active site. In a series of 22 diversely substituted phenols, the best inhibitors were simple phenol, pyrocatechol, salicylic acid, 3,5-difluorophenol, 3,4-dihydroxy-benzoic acid, 3,6- dihydroxy-benzoic acid, caffeic acid and its des-hydroxy analog, with KIs of 1.8 − 7.3 µM. The least effective TcCA inhibitor was 3-chloro-4-amino-phenol (KI of 47.9 µM). Although it is not yet clear whether TcCA can be considered as an anti-Chagas disease drug target, as no animal model for investigating the antiprotozoan effects is available so far, finding effective in vitro inhibitors may be a first relevant step towards new antiprotozoal agents.

Abstract 5949: Aspirins metabolites inhibit human colon cancer cell growth: Potential role in colorectal cancer prevention

Abstract Aspirin’s role in colorectal cancer (CRC) prevention is evidential from several epidemiological data. Numerous theories and targets have been proposed, a consensus has not been reached regarding its mechanism of action. One of the unexplored area in aspirin’s CRC prevention is the role of Dihydroxy benzoic acids (DHBAs), which are generated from aspirin’s metabolism by gut microflora and cytochrome P450 (CYP450). Out of the screened DHBAs, 2,3-DHBA and 2,5-DHBA showed concentration dependent inhibition of CDK1, CDK2, CDK4 and CDK6 enzyme activity in-vitro. We demonstrated that 2,3-DHBA and 2,5-DHBA inhibits CDK-1 enzyme activity beginning at 500 µM, while CDK2 and CDK4 activity was inhibited only at higher concentrations (&amp;gt;750 µM). 2,3-DHBA inhibited CDK6 enzyme activity from 250 µM, while 2,5-DHBA inhibited its activity &amp;gt;750 µM. Using colony formation assays, we further demonstrated the role of 2,3-DHBA and 2,5-DHBA in cancer cell cycle inhibition in 3 different cancer cell lines. Out of the 2 DHBAs, 2,5-DHBA was highly effective in inhibiting clonal formation in HCT-116 and HT-29 CRC cell lines (250-500 µM), and in the MDA-MB-231 breast cancer cell line (~100 µM); whereas both aspirin and salicylic acid failed to inhibit all four CDKs and colony formation. Based on the present results, it is suggested that 2,3-DHBA and 2,5-DHBA may contribute to the chemopreventive properties of aspirin, possibly through the inhibition of CDKs. The present data and the proposed mechanisms should open new areas for future investigations. Citation Format: Poojitha Tummala, Ranjini Sankaranarayanan, Rakesh Dachineni, Jayarama Gunaje Bhat. Aspirins metabolites inhibit human colon cancer cell growth: Potential role in colorectal cancer prevention [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5949.

Evaluation of the in vitro bioaccessibility of phenolic compounds of black cumin (BARI‐1cumin) methanolic extract

AbstractThis study aims to evaluate the phenolic contents, chemical composition, mineral amount as well as antioxidant activity of methanolic extracts from dried black cumin (Nigella sativa L; family: Ranunculaceae) seed powder. We also performed an in vitro gastrointestinal digestion process to understand the effect on phenolic components and their antioxidant activity after gastrointestinal digestion. Black cumin showed high amounts of total phenolic and flavonoid contents, such as dihydroxybenzoic acid and ferulic acid, through high‐performance liquid chromatography analysis. Six mineral elements (Ca, Cu, Fe, K, Se, and Zn) were determined by using coupled plasma mass spectrometry, while 25 fatty acids (13 saturated, 7 unsaturated, and 5 unsaturated omega fatty acids) were also identified by gas chromatography, with linoleic acid the most present. In addition, black cumin extract presented high antioxidant capacity measured by DPPH, FRAP, and TEAC. Additionally, dried black cumin powder was evaluated after gastrointestinal digestion: phenolic compounds (1.81‐fold), flavonoids (1.03‐fold), and antioxidant capacity (up to 2.1‐fold) increased in gastric fraction compared to the undigested methanolic extract. Moreover, a higher amount (p &lt; 0.05) of total phenolic content and flavonoids, as well as higher total antioxidant capacity, were found in the gastric and elimination fraction than in the bioaccessible fraction. Our results demonstrated that there were a significant decrease in the quantity of phenolic compounds (68%) and flavonoids (95.53%) after gastrointestinal digestion in the bioaccessible fraction as well as a reduced the antioxidant activity (10.79%–94.84%), suggesting that phenolic compounds are responsible for antioxidant activity.

Ontogenetic changes in phenolic contents and volatile composition of Hypericum androsaemum and Hypericumxylosteifolium

We described the ontogenetic changes in phenolic contents and volatile composition of Hypericum androsaemum L. and Hypericum xylosteifolium (Spach) N. Robson from Turkish flora for the first time. 30 randomly selected plants were gathered in each of six phenological stages for H. androsaemum (vegetative, floral budding, full flowering, green capsule, red capsule and black capsule) and each of seven phenological stages for H. xylosteifolium (vegetative, floral budding, %10 flowering, %50 flowering, full flowering, green capsule and brown capsule). After dried at room temperature, the plant materials were assayed for phenolic and volatile ingredients by detailed chemical analyses. The accumulations of several phenolics followed a consistent manner but, hyperforin, quercetin, rutin, 2,4 dihydroxybenzoic acid, quercitrin, hyperoside, biapigenin, (+)-catechin and (−)-epicatechin were accumulated at higher levels during floral development depending on species. Germacrene B (31.50%), α-zingiberene (22.75%), α-curcumene (15.21%) β-caryophyllene (14.34%) and naphtalene (11.87%) in H. androsaemum and daucol (23.36%), naphtalene (14.17%) and aromadendrene (10.36%) in H. xylosteifolium were recorded as major volatile components depending on phenophases. Floral budding and flowering phases were characterized by higher accumulation levels of majority of phenolic and volatile compounds in both species indicating these phases as the appropriate harvesting times. These findings can guide the suppliers of Hyperici herba to obtain the raw material that have the highest content of desirable compounds and the most suited chemical composition to the demands of relevant industries. As a remarkable conclusion of this work, H. androsaemum and, especially, H. xylosteifolium can be introduced as new sources of bioactive secondary metabolites.

A new strategy to design isostructural salts: The case of the antitumor drug dimethylaminomicheliolide

Isostructural multicomponent crystals provide a promising way for fine-tuning physicochemical properties, whereas their design remains quite challenging. The purpose of this work was to provide a new strategy for obtaining isostructural multicomponent crystals by introducing coformers with functional group positional isomerism. Five isostructural salts of an antitumor drug dimethylaminomicheliolide (DMAMCL) were reported and designed with a series of dihydroxybenzoic acid regioisomers for the first time, which were identified by power and single-crystal X-ray diffractions. Similar lattice parameters suggested these obtained salts may have the same crystal packing mode. The quantitative similarity parameters via XPac, CrystalCMP and Mercury program further proved these crystal structures are 3D isostructural. Hirshfeld surface maps and 2D fingerprint plots show that the isostructural salts have similar intermolecular interactions. Compared with DMAMCL, obvious improvement was observed in the thermal stability, hygroscopicity, and solubility of these isostructural salts. Meanwhile, isostructural crystals may have different physicochemical properties, even though the shape and molecular size are similar and the packing of crystal structures is equally matched.

Antimicrobial, Antibiofilm, and Antioxidant Properties of Boletus edulis and Neoboletus luridiformis Against Multidrug-Resistant ESKAPE Pathogens.

Multidrug-resistant ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) has become the most recurrent global cause of skin and soft-tissue infections, belonging to the WHO priority pathogens list. Successful therapy remains challenging and entails the assessment of novel and successful antibiotics. In this study, mushrooms are considered a valuable and unique source of natural antimicrobial compounds. Therefore, this study aimed to evaluate the antimicrobial and antibiofilm properties of Boletus edulis (B. edulis) and Neoboletus luridiformis (N. luridiformis) aqueous and methanolic extracts against ESKAPE isolates from clinical wound infections. Disk diffusion and microdilution methods were used to assess the antimicrobial activity. Phytochemical characterization was achieved by analysis of total phenols, orthodiphenols content, and antioxidant activity as well as by high-performance liquid chromatography-diode array detector (HPLC-DAD). Human foreskin fibroblasts-1 (HFF-1) cell viability was performed by the MTT assay. Aqueous and methanolic extracts of B. edulis and N. luridiformis showed antimicrobial and antibiofilm properties against multidrug-resistant bacteria, although with different efficacy rates. The results showed that there is a convincing relation between the content of phenolic compounds, antioxidant activity, and antimicrobial activity suggesting that the presence of phenolic compounds may explain the biological effects. HPLC analysis revealed high levels of protocatechuic acid, homogentisic acid, pyrogallol, gallic acid, p-catechin, and dihydroxybenzoic acid in the aqueous extract of B. edulis, explaining the highest antimicrobial and antibiofilm properties. Importantly, the mushrooms extracts were non-cytotoxic at all the tested concentrations. Overall, the tested mushrooms extracts are good candidates to further explore its use in the prevention of wound infection, particularly by multidrug-resistant pathogens.

Effect of Hydroxybenzoic Acids on Caffeine Detection Using Taste Sensor with Lipid/Polymer Membranes.

A taste sensor with lipid/polymer membranes can objectively evaluate taste. As previously reported, caffeine can be detected electrically using lipid/polymer membranes modified with hydroxybenzoic acids (HBAs). However, a systematic understanding of how HBAs contribute to caffeine detection is still lacking. In this study, we used various HBAs such as 2,6–dihydroxybenzoic acid (2,6–DHBA) to modify lipid/polymer membranes, and we detected caffeine using a taste sensor with the modified membranes. The effect of the concentrations of the HBAs on caffeine detection was also discussed. The results of the caffeine detection indicated that the response to caffeine and the reference potential measured in a reference solution were affected by the log P and pKa of HBAs. Furthermore, the taste sensor displayed high sensitivity to caffeine when the reference potential was adjusted to an appropriate range by modification with 2,6–DHBA, where the slope of the change in reference potential with increasing 2,6–DHBA concentration was steep. This is helpful in order to improve the sensitivity of taste sensors to other taste substances, such as theophylline and theobromine, in the future.

Structure-Antioxidant Capacity Relationships of the Dihydroxy Derivatives of Benzaldehyde and Benzoic Acid

In this paper, the antioxidant capacities (AOC) of the dihydroxybenzaldehyes (DHB) and dihydroxybenzoic acids (DHBA) are determined by two single electron transfer (SET) assays, namely CUPRAC and e-CUPRAC (CUPric Reducing Antioxidant Capacity), and a SET + hydrogen atom transfer (HAT) assay: 2,2-diphenyl-1-picrylhydrazyl (DPPH). It is found that the oxidation potential (EOX) determined by voltammetry can be used as a structural parameter in the same way as the HOMO energy. From the dependencies of the AOC with EOX, it follows that only the electrondonor derivatives of DHB and DHBA exhibit antioxidant activity, which means that the number of hydroxyl groups, two for all molecules, is not the only factor related to the AOC. A relationship between the position of the hydroxyl groups and the AOC is shown. Moreover, the value of the AOC also has a contribution of dissociation of the hydroxyl groups.

Ciprofloxacin salt and salt co-crystal with di-hydroxy-benzoic acids.

The crystal structure of two multi-component crystals of ciprofloxacin [systematic name: 1-cyclo-propyl-6-fluoro-4-oxo-7-(piperazin-1-yl)quinoline-3-carb--oxy-lic acid], a fluoro-quinolone anti-biotic, namely, ciprofloxacin 2,6-di-hydroxy-benzoate salt, C17H19FN3O3 +·C7H5O4 -, (I), and ciprofloxacin hydro-chloride-3,5-di-hydroxy-benzoic-water (1/1/1), C17H19FN3O3 +·Cl-·C7H6O4·H2O, (II), were determined. In (I) and (II), the ciprofloxacin cations are connected via head-to-tail N-H⋯O hydrogen bonding. Both structures show an alternating layered arrangement between ciprofloxacin and di-hydroxy-benzoic acid.

Computational Investigation of the Antioxidant Activity of Dihydroxybenzoic Acids in Aqueous and Lipid Media

Reactive free radicals have both beneficial and destructive effects. Indeed, at physiological levels, free radicals help to preserve homeostasis by acting as signal transducers. However, excessive generation of free radicals can harm and damage membranes, proteins, and DNA, among other cell structures. Dihydroxybenzoic acids (DHBAs) have proven their antioxidant capacity against a large variety of free radicals, as well as their ability to inhibit or restrict reactive species overproduction. In this paper, a computational analysis of the antioxidant activity of a series of DHBAs in polar and nonpolar media was carried out at the DFT/M06-2X/6-[Formula: see text] level of theory. The implicit SMD solvation model was used in order to rationalize the experimental findings and to investigate the solvent effect on the mechanism and the radical scavenging ability. The obtained results put in evidence that HAT is the predominant mechanism in nonpolar media, whereas SPLET is more favored in polar environment. The BDE[Formula: see text], [Formula: see text], and [Formula: see text] descriptors are used to predict the most reactive hydroxyl groups and the antioxidant activity order of the studied DHBAs. Our results are in total agreement with experimental findings (inhibition of lipid peroxidation and scavenging of hydrogen peroxide). Moreover, this study shows that the substitution of the hydrogen atom by strong electron-donating groups, namely NMe2, in the ortho positions of the best experimental DHBAs leads to a significant enhancement of their antioxidant activity.

Pseudomonas spp. Mediate defense response in sugarcane through differential exudation of root phenolics

Pseudomonas spp., a ubiquitous biocontrol agent, protects the plants from phytopathogens by suppressing them directly by reinforcing the plant’s intrinsic defense mechanism. Root exudated phenolics play an important role in establishing the rhizobacteria population and cross the host boundaries in beneficial plant–microbe interaction. In this study, Pseudomonas spp. HU-8 & HU-9 antagonized the sugarcane red rot pathogen (C. falcatum) and showed a positive chemotactic response against different concentrations (10–30 µM) of synthetic phenolic acids like p-coumaric, vanillic, and 3,4 di-hydroxybenzoic acid. In a pot experiment, they effectively colonized the sugarcane rhizosphere and mediated defense response in sugarcane plants challenged with red rot pathogen C. falcatum by regulating the exudation of root phenolics under hydroponic conditions. They significantly induced the activity of the antioxidant enzymes CAT (1.24–1.64 fold), PO (0.78–1.61 fold), PAL (0.77–0.97 fold), and PPO (3.67–3.73 fold) over untreated plants in sugarcane. They also induced the total phenolic contents (TPC) in sugarcane in the presence (6.56–10.29 mg/g GAE) and absence (2.89–4.16 mg/g GAE) of the pathogen quantified through the Folin-Ciocalteu (FC) method. However, their effect was lower than that of the pathogen (4.34–8 mg/g GAE). The Pseudomonas spp. significantly colonized the sugarcane rhizosphere by maintaining a cell population of (1.0E + 07–1.3E + 08 CFU/mL). A significant positive Pearson’s correlation was observed between the root exudated total phenolic contents, antioxidant enzymatic activities, and rhizospheric population of inoculated bacteria. The 16S rRNA and rpoD gene analysis showed sequence conservation (C: 0.707), average number of nucleotide differences (k: 199.816), nucleotide diversity, (Pi): 0.09819), average number of informative nucleotide sites per site (Psi: 0.01275), GC content (0.57), and polymorphic sites (n = 656). These diverse Pseudomonas spp. could be an ideal bio-inoculants for a broad range of hosts especially graminaceous crops.