Ultrasensitive and selective colorimetric and smartphone-based detection of arsenic ions in aqueous solution using alliin-chitosan-AgNPs.

In this study, we developed a highly selective and sensitive colorimetric sensor for arsenic [As(iii)] detection using alliin-chitosan-stabilized silver nanoparticles (AC-AgNPs). The AC-AgNPs were synthesized using a complex prepared by mixing aqueous garlic extract containing alliin and chitosan extracted from shrimp. The synthesis of AC-AgNPs was confirmed by UV-vis spectroscopy, which showed a surface plasmon resonance (SPR) band at 403 nm, and TEM analysis revealing spherical nanoparticles with a mean diameter of 7.57 ± 3.52 nm. Upon the addition of As3+ ions, the brownish-coloured solution of AC-AgNPs became colourless. Moreover, the computational study revealed that among all the metal ions, only As3+ was able to form a stable complex with AC-AgNPs, with a binding energy of 8.7 kcal mol-1. The sensor exhibited a linear response to As(iii) concentrations ranging from 0.02 to 1.4 fM, with a detection limit of 0.023 fM. The highest activity was observed at pH 7 and temperature 25 °C. Interference studies demonstrated high selectivity against common metal ions. The study also demonstrated that the concentration of As3+ ions can be estimated by the decrease in red intensity and increase in green intensity in smartphone optical transduction signals. These results indicate the potential of the AC-AgNP-based sensor for reliable and efficient arsenic detection in environmental monitoring.

Anti-diabetic and anti-urease inhibition potential of Amomum dealbatum Roxb. seeds through a bioassay-guided approach.

Using HPLC-PDA and HRMS analysis, five compounds p-coumaric acid, sinapic acid, quercetin, trans-ferulic and gallic acid were identified in seeds of Amomum dealbatum Roxb. The GC-MS analysis identified 1-dodecanol, phenol, 3,5-bis(1,1-dimethylethyl), Oleic Acid and 1-Heptacosanol which possess anti-diabetic properpties. A bioassay-guided technique was used to determine the degree of inhibition that A. dealbatum seeds crude methanol extract and its most active sub-fraction had against the α-glucosidase and Helicobacter pylori urease enzymes. In the Rat L6 myoblast cell line, glucose absorption through the GLUT4 transporter of most active subfraction (EASF80) was examined. According to a molecular docking investigation, these compounds strongly interacted with the GLUT4 transporter, H pylori and α-glucosidase enzyme. Sinapic acid interacted most strongly with the H. pylori urease enzyme while gallic acid interacted with both the α-glucosidase enzyme and the GLUT4 transporter. Additionally, a molecular docking simulation study was carried out to recognise the stability of the complexes.

Anti-diabetic and anti-urease potential of Osbeckia nutans Wall. leaves.

A study was conducted to investigate the anti-diabetic and anti-urease potential of Osbeckia nutans leaves (ONL). Six compounds, i.e. quercetin-3-O-glucoside, myricetin, shikimic acid, catechin, trans-ferulic acid and luteolin were identified from the butanol sub-fraction, BE2 and the ethyl acetate sub-fraction, EA5 of ONL. BE2 inhibited α-glucosidase and Jack bean urease with IC50 values of 0.036 µg/mL (437.46 µg/mL for acarbose) and 0.327 mg/mL (0.039 mg/mL for thiourea), respectively. In the glucose uptake experiment, BE2 (0.05 mg/mL) treatment resulted in a substantial increase in glucose uptake in free fatty acid (FFA)-treated cells at a concentration 10 times lower than that seen in EA5 (0.5 mg/mL) treated cells. The binding energies of quercetin-3-O-glucoside with α-glucosidase, glucose transporter GLUT4 and H. pylori urease were found to be -94.2585, -219.8271 and -254.391 kcal/mol, respectively. This study revealed that ONL has anti-diabetic and anti-urease abilities and further in-depth research may unveil its full potential.

Antidiabetic potential of Amomum dealbatum Roxb. flower and isolation of three bioactive compounds with molecular docking and in vivo study.

Amomum dealbatum Roxb. parts have been traditionally used as remedies for joint pain, diabetes, muscular rheumatism, antiseptic, and abscesses in Arunachal Pradesh, Assam, and Tripura. Ethyl acetate sub-fraction E3 had significantly inhibited the α-glucosidase (IC50 5.385 µg/mL). The molecular docking revealed quercetin-3-O-galactoside to be the most potent α-glucosidase inhibitor (binding energy -43.214 kcal/mol). Using the QSAR model, the pIC50 values of myricetin, gallic acid, quercetin-3-O-galactoside, and acarbose were predicted to be 5.65235, 4.39858, 5.65235, and 6.03058, respectively. For the first time, quercetin-3-O-galactoside, myricetin, and gallic acid have been isolated from the flowers of A. dealbatum (ADF). E3 decreased blood glucose level to a near-normal concentration (100.60 ± 2.94 mg/dL) in comparison to diabetic control rats (575.20 ± 24.80 mg/dL). The results have strongly suggested the potential of ADF in treating diabetes. This lesser-known plant has the potential to uncover its full medicinal properties through further in-depth research.

"AND"-Logic gate-based colorimetric detection of thiocyanate in milk samples using AgNP-EBF as plasmonic nano sensor.

At present, the uses of food additives globally are much of a concern due to their after effects upon consumption in higher proportions. Although different sensing strategies are available for their detection, a need for simple, rapid and cost-effective strategy is much of a concern. Herein, we developed a plasmonic nano sensor i.e., AgNP-EBF which was considered as the transducer component for the AND logic gate-based system with Cu2+ and thiocyanate as inputs. Optimization and detection of thiocyanates were performed through UV-visible colorimetric sensing procedures where the logic gate allowed the detection of thiocyanate in the range of 100 nM-1 µM with LOD of 53.60 nM within 5-10 min. The proposed system showed high selectivity towards the detection of thiocyanate rather than other interferences. To check the credibility of the proposed system, the logic gate was applied for detection of thiocyanates in real milk samples.

Arenga westerhoutii Griff.: bioactive constituents, nutraceuticals, antioxidant and anti-diabetic potential of stem extract and an insight into molecular docking analysis.

Herein, we reported a systematic scientific study of Arenga westerhoutii Griff. by evaluating its bioactive components, nutraceuticals, antioxidant and anti-diabetic properties. Three major bioactive compounds were identified using HPLC and HRMS. Quantification of the components through HPLC yielded the presence of 75.67 ± 0.05, 38.19 ± 0.10 and 13.11 ± 0.02 µg/mL of chlorogenic acid, ferulic acid and epicatechin respectively in 1 mg/ml of the extract. 50% MeOH hydro-alcoholic extract was found to show lowest IC50 value in both in-vitro antioxidant (IC50 = 2.925 ± 0.12 µg/mL, DPPH assay) and anti-diabetic assays (IC50 = 18.03 ± 0.18 µg/mL, α-glucosidase assay). Further analysis by molecular docking study suggested the interaction of components towards α-glucosidase enzyme.

GA-AuNP@Tollens' complex as a highly sensitive plasmonic nanosensor for detection of formaldehyde and benzaldehyde in preserved food products.

Food preservatives nowadays are widely used chemicals throughout the food industries due to their commercial importance in increasing the shelf life of foods. But daily consumption of these preserved food products may be fatal to human health. Among different aldehydic compounds, formaldehyde and benzaldehyde are mainly used for preservation. Therefore, we reported a study on simple, selective and sensitive non-enzymatic detection of formaldehyde and benzaldehyde using GA-AuNP@Tollens'. Plasmonic resonance of GA-AuNP@Tollens' was taken as the basis for sensing formaldehyde and benzaldehyde in the linear range of 10-150 nM and 0.15-0.75 µM respectively. Both optimization and detection were acquired at UV absorbance of 409 nm. Detection limit of formaldehyde and benzaldehyde obtained through the proposed method was 20.08 nM and 0.12 µM respectively. Smartphone based detection method showed good linearity with R-Square value of 0.95 for both analytes. Lastly, GA-AuNP@Tollens' was implemented for the quantification of analytes in real samples.

Phenolic compounds of Zanthoxylum armatum DC as potential inhibitors of urease and SARS-CoV2 using molecular docking approach and with simulation study.

The anti-urease effects of active extract and three isolated phenolic compounds viz., chlorogenic acid, trans-ferulic acid, and gallic acid of leaves of Zanthoxylum armatum DC were evaluated. The compounds were identified based on HPLC-PDA, HR-MS, and NMR analysis. Molecular docking analysis revealed that these compounds significantly interacted with Helicobacter pylori urease and SARS-CoV2 vital proteins. Chlorogenic acid was found to show the strongest interaction with the H. pylori urease and coronavirus main protease (Mpro, also called 3CLpro), while gallic acid with five spike proteins (Cathepsin L) of SARS-CoV2. The compounds were checked for their drug-likeliness character and were found to pass the Lipinski filter and abide by Veber's rule and passed through ADMET. Chlorogenic acid was simulated for 50 ns using GROMACS. The study shows that chlorogenic acid isolated from Z. armatum could be a significant antagonist of the H. pylori urease.

Correction: Highly sensitive and selective colorimetric detection of dual metal ions (Hg2+ and Sn2+) in water: an eco-friendly approach.

[This corrects the article DOI: 10.1039/D0RA09926K.].

Bioassay-guided isolation of potent α-glucosidase inhibitory compounds from the fruit of Piper mullesua Buch-Ham ex D Don. and their in silico screening.

Two bioactive compounds caffeic and sinapic acid were isolated from the fruit of the Piper mullesua Buch-Ham ex D Don using bioassay guided approach. These compounds were isolated from water fraction using column chromatography followed by semi preparative HPLC. These compounds showed very potent anti-diabetic and antioxidant activities. The molecular docking was carried out to predict the mode of interaction of the isolated compounds with α-glucosidase. The in vitro α-glucosidase inhibitory activity of caffeic and sinapic acid was determined, and their IC50 values were found 0.67 and 0.82 µg/ml, respectively. A QSAR equation was generated with an R2 value of 84.81%, which is suitable enough for predicting the IC50 values of test molecules. The aforementioned finding confirms the isolated compounds show very significant anti-diabetic potential which is supported by the molecular docking and QSAR study. So, it has ample scope for drug development with further in vivo and clinical study.

Ultrasensitive Pd nano catalyst as peroxidase mimetics for colorimetric sensing and evaluation of antioxidants and total polyphenols in beverages and fruit juices.

Herein, we developed a new Pd NP from the aq extract of Elsholtzia blanda Benth. flower that showed efficient peroxidase mimetic activity. The catalytic mechanism was confirmed through colorimetric analysis. The optimizations of temperature, concentration, PH and time were done to find out the best procedure to implement the intrinsic catalytic activity in practical applications. Michaelis-Menten constants were evaluated for both TMB and H2O2 substrate to investigate the affinity of Pd NP towards them. Km was observed to be 42.35 mM for H2O2 and 0.0076 mM for TMB. Antioxidants were sensed using the peroxidase mimetic property up to nanomolar levels with a LOD = 0.78 nM for Gallic acid 0.85 nM for Tannic acid. The method was further implemented in comparing the radical scavenging power of different phenolic compounds. Smart-phone based analysis was done for observing the change in colour which could further be utilized as an analytical tool for study the antioxidant activity. R-Square values of 0.97 and 0.96 for detection of gallic acid and tannic acid respectively suggest good linearity of the plot. Lastly, the system was utilized in the evaluation of total antioxidant capacity (TAC) and total phenolic content (TPC) in commercially available juices and beverages.

Correction: A novel method for the rapid sensing of H2O2 using a colorimetric AuNP probe and its DFT study.

Correction for 'A novel method for the rapid sensing of H2O2 using a colorimetric AuNP probe and its DFT study' by Nirangkush Borah et al., Anal. Methods, 2021, 13, 2055-2065, DOI: 10.1039/D1AY00355K.

A novel method for the rapid sensing of H2O2 using a colorimetric AuNP probe and its DFT study.

Hydrogen peroxide (H2O2) has tremendous applications in industry, medicine and in our day-to-day lives. It is toxic to human health upon exposure at a high concentration. Therefore, a green and cost-effective sensing technique is greatly needed for the sensitive naked eye detection of peroxide. This study is mainly focused on the synthesis of Au nanoparticles (AuNPs) using an aqueous extract of Elsholtzia blanda, a flower that is widely available in the North Eastern part of India, the characterization of which was carried out using different analytical techniques. The bioactive molecule (epigallocatechin gallate) present in the aqueous extract was identified, isolated and confirmed through high-performance liquid chromatography-photodiode array, high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy analysis which could be responsible for the reduction of Au3+ ions. By approaching this greener route, the synthesized nanomaterial was further used as a colorimetric probe for the detection of H2O2 and the degradation of AuNPs was observed. The limit of detection was found to be 0.7435 µM in the present work. The degradation of the AuNPs was found to be linearly dependent on peroxide concentration. Along with these results, kinetic studies were carried out by considering different effects to monitor the sensing speed of the AuNPs. The plausible mechanism of the work was supported by density functional theory study.

Dual colorimetric sensing of ascorbic acid and thyroxine using Ag-EGCG-CTAB via a DFT approach.

In this work, a colorimetric approach for the detection of ascorbic acid (AA) and thyroxine (TH) was developed by synthesizing cost-effective silver nanoparticles (AgNPs) decorated with epigallocatechin gallate (EGCG) and CTAB. EGCG is the major bioactive chemical constituent that played a significant role in this study. The environment around the nanoparticle (NP) was controlled by adding CTAB surfactants. The synthesized NPs were characterized by different advanced techniques including XRD, XPS, SEM, and TEM. UV-visible spectra were thoroughly analyzed for sensing of AA and TH and the colour change of the solution can be visually monitored. The change in the localized surface plasmon resonance (LSPR) properties was used as an asset for the detection of AA and TH. A good linear relationship was obtained in both the sensing schemes with a limit of detection (LoD) of 0.67 µM and 0.33 µM for AA and TH respectively. Furthermore, the nanoparticles (NP) were implemented for real-sample analysis (pharmaceutical tablets). A cost-effective filter paper strip-based method coupled with smartphone scanning sensing was developed for the detection of AA. The interaction of AA and TH with the probe was depicted by a density functional theory (DFT) analysis. The synthesized NPs show tremendous selectivity towards AA and TH and excellent potential for practical applications.

Highly sensitive and selective colorimetric detection of dual metal ions (Hg2+ and Sn2+) in water: an eco-friendly approach.

Application of an alliin-based precursor for the synthesis of silver nanoparticles (Ag NPs) which is an emerging, reliable and rapid sensor of heavy metal ion contaminants in water is reported here. The Ag NPs were characterized by using UV-visible spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy analysis techniques. The Ag NPs simultaneously and selectively detect Hg2+ and Sn2+ ions from aqueous solution. The sensitivity and selectivity of the prepared Ag NPs towards other representative transition-metal ions, alkali metal ions and alkaline earth metal ions were also studied. For more precise evidence, a density functional theory study was carried out to understand the possible mechanism and interaction in the detection of Hg2+ and Sn2+ by Ag NPs. The limits of detection for Hg2+ and Sn2+ ions were found as 15.7 nM and 11.25 nM, respectively. This assay indicates the possible use of garlic extract-synthesized Ag NPs for sensing Hg2+ and Sn2+ in aqueous solution very significantly. So, the simple, green, eco-friendly and easy method to detect the dual metal ions may further lead to a potential sensor of heavy metal ion contaminants in water of industrial importance.

Biosynthesis of Ag nanoparticles using pedicellamide and its photocatalytic activity: an eco-friendly approach.

The synthesis of silver (Ag) nanoparticles using by pedicellamide (A), isolated from Piper pedicellatum C.DC leaf is demonstrated here. TEM analysis revealed that the Ag nanoparticles predominantly form spherical in shape. The compound 'A' act as a reducing, stabilizing and capping agent. The reaction mechanism was established by using density functional theory (DFT). Photocatalytic property of the Ag nanoparticles is investigated by degradation of Methyl Red (MR) dye under UV light. The kinetic, reaction mechanism and rate constant of photocatalytic degradation of MR was evaluated. The results show that Ag nanoparticles have suitable photocatalytic activity for the degradation of MR dye.

Antifungal and antioxidant pyrrole derivative from Piper pedicellatum.

In continuation of our search for efficient pest control natural products from the flora of the South Eastern Sub-Himalayan biodiversity region, we have investigated wild edible Piper pedicellatum C. DC (Piperaceae) from Arunachal Pradesh, India against five important plant pathogenic fungi through an activity guided method, and a new compound, pedicellamide, was isolated. The structure was determined on the basis of extensive spectroscopic studies and confirmed by X-ray crystallography. The compound exhibited antifungal activities against the phytopathogenic fungal organisms Rhizoctonia solani (MIC 38.4 +/- 1.6 microg/mL), Fusarium oxysporum (MIC 29.7 +/- 0.8 microg/mL), Aspergillus niger (MIC 48.6 +/- 0.7 microg/mL), Puccinia gramini (MIC 46.8 +/- 1.4 microg/mL) and Curvularia lunata (MIC 49.1 +/- 0.1 microg/mL). Additionally, the antioxidant potential of the compound was estimated by DPPH, ABTS and FRAP assay and found to be 2.87 +/- 0.20, 2.19 +/- 0.13 and 3.96 +/- 0.17 VCEAC (microM/g), respectively.

In situ biosynthesis of Ag, Au and bimetallic nanoparticles using Piper pedicellatum C.DC: green chemistry approach.

The synthesis of Ag, Au and Ag-Au bimetallic nanoparticles using Piper pedicellatum C.DC leaf extract is demonstrated here. The rapid formation of stable Ag and Au nanoparticles has been found using P. pedicellatum C.DC leaf extract in aqueous medium at normal atmospheric condition. Competitive reduction of Ag(+) and Au(3+) ions present simultaneously in solution during exposure to P. pedicellatum C.DC leaf extract leads to the synthesis of bimetallic Ag-Au nanoparticles in solution. Transmission electron microscopy (TEM) analysis revealed that the Ag nanoparticles predominantly form spherical in shape with the size range of 2.0±0.5-30.0±1.2 nm. In case of Au nanoparticles, the particles are spherical in shape along with few triangular, hexagonal and pentagonal shaped nanoparticles also observed. X-ray diffraction (XRD) studies revealed that the nanoparticles were face centered cubic (fcc) in shape. Fourier transform infrared spectroscopy (FTIR) showed nanoparticles were capped with plant compounds. The chemical constituents, viz. catechin, gallic acid, courmaric acid and protocatechuic acid of the leaf extract were identified which may act as a reducing, stabilizing and capping agent. The expected reaction mechanism in the formation of Ag and Au nanoparticles is also reported.

4-[Bis(4-hydroxy-3,5-dimethylphenyl)methyl]pyridinium chloride and bromide.

The isostructural title salts, 4-[bis(4-hydroxy-3,5-dimethylphenyl)methyl]pyridinium chloride and bromide, C22H24NO2+.Cl- and C22H24NO2+.Br-, exhibit extended hydrogen-bonded ribbons in the solid state. The halide ions form hydrogen bonds to the pyridinium NH+ group and to the phenol OH groups of the cation. These bonds are coplanar to within 0.1 A and form a T configuration at the anion.