Acid Reagent Research Articles

Quantitative monitoring of galactolipid hydrolysis by pancreatic lipase-related protein 2 using thin layer chromatography and thymol-sulfuric acid derivatization

Galactolipids are the most abundant lipids on earth where they are mainly found in photosynthetic membranes of plant, algae, and cyanobacteria. Pancreatic lipase-related protein 2 (PLRP2) is an enzyme with galactolipase activity allowing mammals, especially herbivores, to digest this important source of fatty acids. We present a method for the quantitative analysis of galactolipids and galactosylated products resulting from their digestion by guinea pig PLRP2 (GPLRP2), using thin-layer-chromatography (TLC), thymol-sulfuric acid as derivatization reagent and scanning densitometry for detection. Thymol-sulfuric acid reagent has been used for the colorimetric detection of carbohydrates. It is shown here that the derivatization of galactosyl group from galactolipids by this reagent is not affected by the bound acyl glycerol, acyl chains length and number of galactose residues in the polar head. This allowed quantifying simultaneously the initial substrate and all galactosylated products generated upon the hydrolysis of monogalactosyl di-octanoylglycerol (C8-MGDG) by GPLRP2 using a single calibration with C8-MGDG as reference standard. The reaction products, monogalactosyl monooctanoyl glycerol (C8-MGMG) and monogalactosyl glycerol (MGG), were identified and quantified, MGG being recovered from the aqueous phase and analyzed by a separate TLC analysis. This method is therefore suitable to quantify the products resulting from the release of both fatty acids present in MGDG and thereby shows that PLRP2 can contribute to the complete digestion of galactolipids and further intestinal absorption of their fatty acids.

Amelanotic B16-F10 Melanoma Compatible with Advanced Three-Dimensional Imaging Modalities

Amelanotic B16-F10 Melanoma Compatible with Advanced Three-Dimensional Imaging Modalities

Pistacia atlantica Desf. roots extract: LC-ESI-MS Analysis, antioxidant activity and gastroprotective effect on experimentally-induced ultrastructural gastric ulcers in mice

ABSTRACT Pistacia atlantica Desf. (Atlas Pistachio) is an Anacardiaceae tree traditionally used in Tunisia for the treatment of ophthalmic, stomatitis, and digestive tract diseases. In the present study, the Pistacia atlantica Desf. roots extract (PR) was phytochemically analyzed, for the first time, by LC-ESI-MS for phenolic and flavonoid contents, in vitro tested for its potential antioxidant activity based on the 2.2-diphenyl-1-picrylhydrazyl (DPPH) and the reduced power essays (FRAP), and in vivo tested for its ability to shield against ethanol-induced gastric ulcer in mice. The LC-ESI-MS analysis proved the identification of 12 compounds, including Quinic, Gallic, and Protocatechuic, as major phenolic acids and high levels of flavonoids, such as Catechin, Epicatechin, and Cirsiliol. PR also exhibited a mild in vitro antioxidant activity when compared with ascorbic acid. In vivo pretreatment of ethanol-ulcerated mice with PR doses 50 mg/kg and 100 mg/kg body weight (b.w) significantly reduced (P< .05) gastric lesions at a rate of 20.10% and a rate of 40.90%, respectively, when compared with 60.70% rate of sucralfate (50 mg/kg b.w) evidenced by a dose-dependent manner increase in the gastric mucosa enzymatic (SOD, CAT, GPx) antioxidant levels, the decline of the lipid peroxidation, and the preservation of normal gastric superficial epithelium. The underlying mechanism of PR antiulcerogenic activity could be due to a synergistic effect of phenolic acids and flavonoid contents which enhances the gastric antioxidant defense system. Abbreviations: BHT: butylated hydroxytoluene, b.w: body weight, CAT: catalase, DPPH:1-Diphenyl-2-picrylhydrazyl, DW: dry weight, EtOH: ethanol, FRAP: Ferric reducing antioxidant power, GAE: gallic acid equivalents, GPx: Glutathione peroxidase, QE: quercetin equivalents, LC-ESI-MS: Liquid chromatography-Electrospray Ionization-Tandem Mass Spectrometry, MDA: malondialdehyde, PR: Pistacia root, TBA: thiobarbituric acid reagent, TBARS: thiobarbituric acid reactive substances, TCA: trichloroacetic acid, SOD: Superoxide dismutase.

Enhancement of fine flavour cocoa attributes under a controlled postharvest process

Despite the importance of fermentation for cocoa quality, process parameters are not controlled under spontaneous conditions at farms. This study evaluates the influence of spontaneous fermentation and processing under laboratory-controlled conditions using the acidic reagents acetic and lactic acids on the cocoa quality of two cultivars, FEAR 5 and CCN 51, at the sensory and metabolomic levels. Under spontaneous conditions, cocoa differs in flavour quality. While FEAR 5 produces chocolate with good global quality, chocolate made with CCN 51 does not have outstanding quality attributes. Transformation under controlled conditions with acidic reagents increases the perception of fine aromatic notes such as fruity, nutty and floral attributes in chocolates made from both cultivars of cocoa. Metabolomic profiles allowed grouping of cocoa samples as a function of postharvest treatment. Twenty-five differential metabolites were identified during the postharvest processes, and these metabolites may be related to the expression of fine sensory attributes; however, more research is needed.

Suggestions for global coagulation assays for the assessment of COVID-19 associated hypercoagulability

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection is associated with a clear prothrombotic phenotype. Although the exact pathophysiological mechanisms are not yet fully understood, thrombosis is clearly a highly important in the prognosis and outcome of COVID-19. As such, there is a need for diagnostic analysis and quantification of the coagulation potential in these patients, both at diagnosis and follow-up. Global coagulation assays like thrombin generation (TG) and rotational thromboelastometry (ROTEM) might be suitable in estimating COVID-19 associated coagulopathy and thrombosis risk. Therefore, we aimed at validating both assays for samples with high levels of fibrinogen and in the presence of anticoagulant heparins, such as commonly observed for COVID-19 ICU patients. Materials and methodsCalibrated Automated Thrombography (CAT) was optimized to assess plasma thrombin generation in the presence of heparins. The final conditions with either 10 μg/mL Ellagic acid (EA) or PPP Reagent HIGH (high tissue factor; HPPH) were validated according to the EP5 protocol for within-run and between-run variability. Overall variability was well below 10%. To estimate the influences of heparins and high fibrinogen levels, CAT was performed on spiked plasma aliquots from 13 healthy volunteers. Comparable to the CAT method, tPA-ROTEM was used to validate the effect of high fibrinogen and heparins on clotting time, clot firmness and clot lysis parameters. ResultsOur adjusted COVID-19 assay showed a heparin dose dependent decrease in peak height and endogenous thrombin potential (ETP) for both EA and HPPH triggered variants. High fibrinogen did not alter the inhibitory effect of either LMWH or UFH, nor did it influence the peak height or ETP in any of the conditions. The tPA-ROTEM showed a significant prolongation in clotting time with the additions of heparin, which normalized with the addition of high fibrinogen. MCF was markedly increased in all hyperfibrinogenemic conditions. A trend towards increased lysis time and, thus, decreased fibrinolysis was observed. ConclusionThrombin generation and tPA-ROTEM protocols for measurements in the COVID-19 populations were adjusted and validated. The adjusted thrombin generation assay shows good sensitivity for measurements in heparin spiked plasma. High levels of fibrinogen did not alter the assay or the effectiveness of heparins as measured in this assay. t-PA ROTEM was effective in measurement of both high fibrinogen and heparins spiked samples and was sensitive to the expected relevant coagulant changes by these conditions. No clear fibrinolytic effect was observed in different conditions.

Visible‐Light‐Mediated Functionalization of Aryl Diazonium Salts

AbstractAryl diazonium salts are important molecules in organic chemistry. This review discusses advances of their application in light‐mediated reactions summarized in five categories according to the bond formations: (1) C−C formation from alkenes, alkynes, arenes, isocyanide, CO, arylboronic acid, or Grignard reagent. (2–5) C−B, C−N, C−S, and C−P formations. Reactions such as radical addition, elimination, metal‐catalyzed coupling, C−H activation, cyclizations, and rearrangements will be discussed herein.

Printed artificial sweat as replacement for natural fingermarks: Qualitative and quantitative approach considering an amino acid reagent

The study presented in this paper aims at assessing how printed fingermarks can be used to generate realistic latent marks bearing varying quantities of materials to be detected. Considering dilution series of artificial sweat (eccrine secretion) and 1,2-indanedione/zinc as amino acid reagent, we assessed how printed marks behave in comparison to natural fingermarks provided by a set of 30 donors. The results were assessed in terms of relative intensity (contrast, luminescence) and expert grading (ridge details, overall quality). With regards to the set of 30 donors, this study brought a quantitative look to the influence of intra- and inter-variability on the relative intensity values observed when processing natural fingermarks. This provided new data to further understand the concept of “donorship”. With regards to the use of printed marks, it has been illustrated how dilution series of a concentrated solution allows covering a range of cases: unnatural marks (intensity values well above those obtained with donors), rich marks (corresponding to fingermarks left by good donors), and faint marks (associated with the kind of results observed with poor donors). Such a range of detection performance offers the possibility to generate fine-tuned detection exercises of varying difficulty levels. Printed items made of artificial sweat could hence constitute a valuable alternative to natural secretions in the context of education and proficiency testing.

Synthesis and in vitro Antidiabetic Screening of Novel Dihydropyrimidine Derivatives

A series of N-substituted-6-methyl-4-{4-[5-(4-nitrophenyl)-1,3,4-oxadiazol-2-yl]methoxyphenyl}-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamides have been synthesized by the condensation of newly synthesized {4-[5-(4-nitrophenyl)-1,3,4-oxadiazol-2-yl]methoxy}benzaldehyde with variously substituted acetoacetanilides and urea in the presence of ethanol. The synthesized compounds have been characterized by 1H, 13C NMR, IR spectroscopy, and mass spectrometry. All synthesized compounds were evaluated for in vitro antidiabetic activity using the α-amylase inhibition assay with the 3,5-dinitrosalicylic acid (DNSA) reagent.

Boron Isotope Tag-Assisted Ultrahigh-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry for Discovery and Annotation of cis-Diol-Containing Metabolites.

cis-Diol-containing metabolites are widely distributed in living organisms, and they participate in the regulation of various important biological activities. The profiling of cis-diol-containing metabolites could help us in fully understanding their functions. In this work, based on the characteristic isotope pattern of boron, we employed a boronic acid reagent as the isotope tag to establish a sensitive and selective liquid chromatography-high-resolution mass spectrometry method for the screening and annotation of cis-diol-containing metabolites in biological samples. Boronic acid reagent 2-methyl-4-phenylaminomethylphenylboronic acid was used to label the cis-diol-containing metabolites in biological samples to improve the selectivity and MS sensitivity of cis-diol-containing metabolites. Based on the characteristic 0.996 Da mass difference of precursor ions and the peak intensity ratio of 1:4 originating from 10B and 11B natural isotopes, the potential cis-diol-containing metabolites were rapidly screened from biological samples. Potential cis-diol-containing metabolites were annotated by database searching and analysis of fragmentation patterns obtained by multistage MS (MSn) via collision-induced dissociation. Importantly, the cis-diol position could be readily resolved by the MS3 spectrum. With this method, a total of 45 cis-diol-containing metabolites were discovered in rice, including monoglycerides, polyhydroxy fatty acids, fatty alcohols, and so forth. Furthermore, the established method showed superiority in avoiding false-positive results in profiling cis-diol-containing metabolites.

Comparative analysis of detection performance of novel coronavirus nucleic acid detection reagents.

Objective To evaluate the detection performance of novel coronavirus nucleic acid reagents (Maccura Biological Co.,Ltd,fluorescent PCR method),it is validated clinically and used the same kinds of kits for comparsion research.Methods Compared with novel coronavirus nucleic acid reagents (Shanghai Zhijiang Biological Co.,Ltd,fluorescent PCR method),the similar products of Maccura Biological Co.,Ltd was to be estimated.Pharyngeal swab specimens of 14 COVID-19 patients diagnosed by the CDC and 211 general admission patients from February 18 to 24 were taken into our study,and two kits were used for parallel testing novel coronavirus (ORF1ab/N/E gene).Results The positive rate and negative coincidence rate of Maccura detection kit and Zhijiang' were more than 99.5%.Relative deviation of ORF1ab gene and N gene were not more than ±16%.Conclusion Novel coronavirus nucleic acid detection reagents produced by Maccura Biological Co.,Ltd has good consistency with similar reagents approved for marketing,which can meet the needs of clinical testing. (English) [ABSTRACT FROM AUTHOR] 目的 对迈克生物股份有限公司的新型冠状病毒核酸试剂盒(荧光PCR法)进行临床验证,并 用同类试剂盒进行比对研究。方法 以迈克生物股份有限公司的研发生产的新型冠状病毒核酸检测试剂盒 (荧光PCR法)作为待考核试剂,以上海之江生物科技有限公司的同类产品作为比对试剂。分别对14例由疾控 中心确诊的新型冠状病毒肺炎患者和2020年2月18日至2月24日211例普通入院患者的咽拭子标本进行新 型冠状病毒(ORF1ab/N/E基因)检测,比较两种试剂检测检出率的一致性。结果 迈克新型冠状病毒核酸检 测试剂盒与之江新型冠状病毒核酸检测试剂盒的检测结果阳性率和阴性符合率均达99.5%以上,ORF1ab基 因和N 基因测定值相对偏差不超过±16%。结论 迈克新型冠状病毒核酸检测试剂盒与已获批准上市的同类 试剂检测结果一致性良好,可满足临床检测需求。 (Chinese) [ABSTRACT FROM AUTHOR] Copyright of Journal of Modern Medicine & Health is the property of Journal of Modern Medicine & Health and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Differentiation of Market Samples of Chennai Nagakesara and Nagakesara by Chromatographic Techniques

Efficacy of any herbal drugs depends on their chemical profile and their biological activity of ingredients. The anticipated efficacy of any drug could be achieved if authenticated ingredients that are collected as per good collection practices in the appropriate season. The general problem faced in herbal drug industry is correct identification of the source plant. The present study was aimed to develop chromatographic finger print profiles by using high performance thin layer chromatography and high pressure liquid chromatography of Nagakesara and Chennai Nagakesara/Cirunakappu to record the difference between them. Both samples were procured from Chennai market, extracted successively with n-hexane, chloroform, ethyl acetate and ethanol extracts using Soxhlet apparatus and subjected to high performance thin layer chromatography and high pressure liquid chromatography analysis. The thin-layer chromatography of hexane extract of Nagakesara showed more spots than Chennai Nagakesara/Cirunakappu and similarly with chloroform and ethanol extracts also. Maximum number of peaks was observed in all the extracts after derivatization with vanillin sulphuric acid reagent. In the high pressure liquid chromatography results of hexane extract maximum of 22 peaks were separated in Nagakesara whereas in Chennai Nagakesara/ Cirunakappu only 14 peaks were separated; in contrast, in the ethanol extract of Chennai Nagakesara/ Cirunakappu 17 peaks were separated while in Nagakesara it was five peaks only.

Perception of Dental Students of Karnataka on Effectiveness of E-Learning during Covid-19 Pandemic – A Questionnaire Based Survey

Background: Solanum surattense Burm.f. is an important medicinal plant in Indian traditional medicinal systems. Fruits of the plant are used for curing asthma, fever, gonorrhoea, respiratory disease and rheumatism. The aim of the study is to investigate the physicochemical, chromatographic analysis and spectral characterization of fruits of S. surattense Burm.f. Methods: Fruit powder was subjected to loss on drying, total ash, water soluble ash, acid insoluble ash, water soluble extractive, alcohol soluble extractive and pH, High performance thin layer chromatography (HPTLC), High pressure liquid chromatography (HPLC) studies were carried out for identifying the active phyto constituents. Minerals of S. surattense in the form of ash was analysed for exploring the elements through instrumental characterization such as X-ray Fluorescence (XRF), Energy Dispersive X-Ray analysis (EDAX), X-Ray Photoelectron Spectroscopy (XPS), Powder X-Ray Diffractometer (PXRD) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Results: In HPTLC photo documentation under 254 nm, 366 nm and after derivatization with vanillin sulphuric acid reagent observed six, nine and six spots respectively. HPLC chromatogram at 235 nm showed separation of eleven peaks. In the characterization techniques, carbon, oxygen, magnesium, silicon, sulphur, phosphorous, sodium, potassium, chlorine, calcium were the elements identified. Conclusion: The study pay way to quality control parameters as well as mineral value of the plant. Key words: Solanum surattense, Kantakari, Respiratory troubles, Chromatography, Elemental analysis.

Evaluation of the Caries Removal Efficacy of Several Organic Acid Reagents

Purpose: Chemo-mechanical techniques are considered as a minimal intervention in caries removal. The purpose of this study was to evaluate the effectiveness of several organic acid reagents in caries removal.

Sulfated zirconium oxide-decorated magnetite KCC-1 as a durable and recyclable adsorbent for the efficient removal of asphaltene from crude oil.

Sulfated zirconium oxide (ZrO2/SO42−) as a highly durable acidic reagent was immobilized on magnetite KCC-1 nanoparticles (Fe3O4@SiO2/KCC-1@ZrO2/SO42− NPs), and the resulting hybrid was used as a highly efficient recyclable adsorbent for the adsorption and removal of asphaltene from crude oil. The presence of ZrO2/SO42− groups not only promotes the adsorption capacity, but also helps recycle the adsorbents without any significant efficiency loss arising from its high chemical resistance. The results showed an obvious synergistic effect between the magnetic core (Fe3O4 NPs), fibrous silica (KCC-1) and the sulfated zirconium oxide groups with high correlation for asphaltene adsorption. The effective parameters in asphaltene adsorption, including initial asphaltene concentration, catalyst concentration and temperature, were investigated. Maximum adsorption occurred in the presence of 0.7 g L−1 of the adsorbent, at a concentration of 2000 mg L−1 of asphaltene. The asphaltene adsorption by NPs follows a quasi-second order adsorption kinetics. Asphaltene adsorption kinetics were studied by Langmuir, Freundlich, and Temkin isotherms. The prominent advantage of the adsorbent is its ability to be recovered after each adsorption by acid treatment, so that no significant reduction in adsorbent adsorption activity was observed, which can be directly attributed to the presence of ZrO2/SO42− groups in the hybrid.

Anti-diabetic activity of Erythrina subumbrans (Hassk.) Merr.

α-amylase inhibitors present in pancreatic region has an operative strategy by controlling the breakdown of starch and helps to minimize the post-prandial hyperglycemia levels. In this study, vegetative (leaf) part of herbal plant Erythrina subumbrans (Hassk.) was assessed for anti-diabetic activity. Aqueous ethanol (80 %) extract was prepared in the different concentration (10, 20, 40, 80, 160, and 320 µg/ml). Acarbose was used as a standard and treated in similar way as that of sample. Control samples were also prepared without standard and sample solutions. A known volume of α-amylase solution was added (0.1mg/mL) was added to standard, sample, control solutions which were preincubated at 37 °C for 15 minutes. Further, known volume of starch solution was added and incubated for 60 min to initiate the reaction. Hydrochloric acid (HCl) and iodine reagent was added to the test tubes and absorbance was measured at 580 nm in UV-Vis spectrophotometer. A strong pancreatic amylase inhibitory activity (&gt;50 %) was obtained from aqueous ethanolic extract with IC50 (half maximal inhibitory concentration) value of 23 µg/ml against standard acarbose with IC50 value of 27 µg/ml. The values endorse Erythrina subumbrans (Hassk.) for further experiments on their potential for managing Diabetes.

The Antioxidant Content and Activity of Various Plant Organs of Kitolod (Isotoma longiflora)

Antioxidants play a crucial role in human health owing to their ability to neutralize oxidative reactions. Kitolod ( Isotomalongiflora ) is one of the medicinal plants that can be used as a source of antioxidant. The aim of study wasto compare the content of antioxidant compounds (flavonoids, phenolics, chlorophylls, carotenoids, and ascorbic acid) in various organs of the kitolod plant. The plant organs studied includingroots, stems, leaves, flowers, and fruits. The extraction of each plant organ wasconducted by maceration technique using ethanol as a solvent at the room temperature for 48 hours. The analysis of total flavonoids, phenolics, and ascorbic acid was performed by colorimetry method using AlCl 3 , Folin, and sulfosalicyclic acid reagent respectively, while chlorophylls and carotenoids was determined by direct colorimetry method with methanol as a solvent. The antioxidant activity of various plant organs of kitolod was analyzed using the DPPH method. The highest total flavonoid, phenolic, chlorophyll, and carotenoid compounds werefound in leaves, respectively by 10.48, 1.46, 7.25, and 56.98 ppm. The highest ascorbic acid content and antioxidant activity were obtained fromfruits.The research findings provide new and important information aboutthe contents and antioxidant activity of the secondary metabolites (flavonoid, phenolic, chlorophyll, carotenoid, and ascorbic acid) in each organ of kitolod plant. The information from the results of this study can be used to increase the medicinal value ofkitolod plants.

Directing Group-Promoted Inert C-O Bond Activation Using Versatile Boronic Acid as a Coupling Agent.

A simple Ni(cod)2 and carbene mediated strategy facilitates the efficient catalytic cross-coupling of methoxyarenes with a variety of organoboron reagents. Directing groups facilitate the activation of inert C-O bonds in under-utilized aryl methyl ethers enabling their adaptation for C-C cross-coupling reactions as less toxic surrogates to the ubiquitous haloarenes. The method reported enables C-C cross-coupling with readily available and economical arylboronic acid reagents, which is unprecedented, and compares well with other organoboron reagents with similarly high reactivity. Extension to directing group assisted chemo-selective C-O bond cleavage, and further application towards the synthesis of novel bifunctionalized biaryls is reported. Key to the success of this protocol is the use of directing groups proximal to the reaction center to facilitate the activation of the inert C-OMe bond.

PHARMACOGNOSTICAL, PHYSICOCHEMICAL AND PHYTOCEMICAL STUDY OF Glycyrrhiza Glabra Linn.

Introduction - Glycyrrhiza glabra Linn. is a perennial herb of family Leguminoseae, used very extensively in Ayurveda classics. It is having property of aphrodisiac, trichogenous, expectorant, haemostatic, intellect promoting etc. Objective – Objective of this study to examine the Pharmacognastical and Phytochemical properties of Glycyrrhiza glabra Linn. Material and Method – Dry sample of Glycyrrhiza was collected from Market. The qualitative microscopy, phytochemical screening, physicochemical evolution and TLC studies were carried out according to the standard procedure recommended by API and other standards. Result –The sample is having sweetish taste, faint and characteristic odour, externally dark brown in colour and internally golden yellow. Cork, Phellogen and Phelloderm, Secondary phloem, Cambium, Secondary xylem, Medullary rays and Pith are present in microscopic examinations, from outer to inner side. Cork (in surface view), Tangentially cut medullary ray cells, Fragment of vessel, Calcium Oxalate Crystals, Starch, Mucilage were seen in powder microscopy. pH value of test sample was 5.73. Water Soluble Extractive value (25.0064%) was more than Alcohol Soluble Extractive value (12.7398 %). Total ash value of test sample was 6.131 %. Acid insoluble ash value was 0.79 %, Water soluble ash value was 1.819 %. In TLC, Rf values were found 0.23, 0.58, 0.71 after derivatization with vanillin – Sulphuric acid reagent. Car-bohydrate, alkaloid, amino acid, tannin, protein, saponin, glycosides, flavonoids and tannin were present in the sample. Conclusion - test sample of Glycyrhiza complies all standard when matches with the reference standard book. It suggests that test sample is authentic and without any impurities and adulteration.

Anti-Streptococcus mutans and anti-biofilm activities of dextranase and its encapsulation in alginate beads for application in toothpaste.

BackgroundThe accumulation of plaque causes oral diseases. Dental plaque is formed on teeth surfaces by oral bacterial pathogens, particularly Streptococcus mutans, in the oral cavity. Dextranase is one of the enzymes involved in antiplaque accumulation as it can prevent dental caries by the degradation of dextran, which is a component of plaque biofilm. This led to the idea of creating toothpaste containing dextranase for preventing oral diseases. However, the dextranase enzyme must be stable in the product; therefore, encapsulation is an attractive way to increase the stability of this enzyme.MethodsThe activity of food-grade fungal dextranase was measured on the basis of increasing ratio of reducing sugar concentration, determined by the reaction with 3, 5-dinitrosalicylic acid reagent. The efficiency of the dextranase enzyme was investigated based on its minimal inhibitory concentration (MIC) against biofilm formation by S. mutans ATCC 25175. Box-Behnken design (BBD) was used to study the three factors affecting encapsulation: pH, calcium chloride concentration, and sodium alginate concentration. Encapsulation efficiency (% EE) and the activity of dextranase enzyme trapped in alginate beads were determined. Then, the encapsulated dextranase in alginate beads was added to toothpaste base, and the stability of the enzyme was examined. Finally, sensory test and safety evaluation of toothpaste containing encapsulated dextranase were done.ResultsThe highest activity of the dextranase enzyme was 4401.71 unit/g at a pH of 6 and 37 °C. The dextranase at its MIC (4.5 unit/g) showed strong inhibition against the growth of S. mutans. This enzyme at 1/2 MIC also showed a remarkable decrease in biofilm formation by S. mutans. The most effective condition of dextranase encapsulation was at a pH of 7, 20% w/v calcium chloride and 0.85% w/v sodium alginate. Toothpaste containing encapsulated dextranase alginate beads produced under suitable condition was stable after 3 months of storage, while the sensory test of the product was accepted at level 3 (like slightly), and it was safe.ConclusionThis research achieved an alternative health product for oral care by formulating toothpaste with dextranase encapsulated in effective alginate beads to act against cariogenic bacteria, like S. mutants, by preventing dental plaque.

Nucleophilic Dearomatization of N-Heteroaromatics Enabled by Lewis Acids and Copper Catalysis.

Dearomative functionalization of heteroaromatics, a readily available chemical feedstock, is one of the most straightforward approaches for the synthesis of three-dimensional, chiral heterocyclic systems, important synthetic building blocks for both synthetic chemistry and drug discovery. Despite significant efforts, direct nucleophilic additions to heteroaromatics have remained challenging because of the low reactivity of aromatic substrates associated with the loss of aromaticity, as well the regio- and stereoselectivities of the reaction. Here we present a catalytic system that leads to unprecedented, high-yielding dearomative C-4 functionalization of quinolines with organometallics with nearly absolute regio- and stereoselectivities and with a catalyst turnover number (TON) as high as 1000. The synergistic action of the chiral copper catalyst, Lewis acid, and Grignard reagents allows us to overcome the energetic barrier of the dearomatization process and leads to chiral products with selectivities reaching 99% in most cases. Molecular modeling provides important insights into the speciation and the origin of the regio- and enantioselectivity of the catalytic process. The results reveal that the role of the Lewis acid is not only to activate the substrate toward a potential nucleophilic addition but also to subtly control the regiochemistry by preventing the C-2 addition from happening.