Characterization of the chemical composition of different parts of Dolichos lablab L. and revelation of its anti-ulcerative colitis effects by modulating the gut microbiota and host metabolism.

ETHNOPHARMACOLOGICAL RELEVANCE: Ulcerative colitis (UC) is a non-specific inflammatory disease characterized by long duration and easy relapse. Dolichos lablab L. (DLL) belongs to the family Fabaceae, was listed in a famous Chinese medical classic, Compendium of Materia Medic, and described as possessing features that invigorate the spleen, alleviate dampness, provide diarrhea relief, and other effects. The DLL-dried white mature seeds (DS) and dried flower (DF), which hold significant medicinal value in China, were used in clinical prescriptions to prevent and treat UC. DS and DF have appeared in different editions of the Pharmacopoeia of the People's Republic of China from 1977 to 2020. However, their chemical composition, pharmacological effects, and mechanism of treating UC are unclear. AIM OF THE STUDY: This study aimed to characterize the chemical composition of different parts of DLL (seeds and flowers), further explore their pharmacological effects, and elaborate its underlying mechanism of treating UC. METHODS: The chemical composition of DS and DF crude polysaccharides (DSP and DFP) and ethanolic extracts (DSE and DFE) were characterized by high-performance anion-exchange chromatography (HPAEC), ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS), and gas chromatography-mass spectrometry (GC-MS). Then, based on the acute UC mice model, the pharmacodynamic effects were investigated by Western blotting, ELISA, and other methods. Finally, the 16S rRNA gene sequencing and metabonomic analysis were used to explore the regulatory effects of DS and DF on intestinal microbiota and host metabolism. RESULTS: DSE and DFE inhibited the oxidative stress response, reducing proinflammatory factor production and maintaining intestinal barrier integrity in UC mice. The 16S rRNA gene sequencing and metabonomic analysis revealed that DS and DF treated UC by regulating the intestinal microbiota structure and reversing the abnormal metabolism of the host. CONCLUSION: This study suggested that different parts of DLL (flowers and seeds) may be potential medicines for treating UC, which exert their therapeutic effects through various active ingredients and might contribute significantly to reducing the economic pressures and challenges of UC treatment worldwide.

Aromatic compounds from the seeds of Dolichos lablab L. with anti-inflammatory activity.

Twenty-four aromatic compounds including five novel ones, dolilabphenosides A (1), B1 (2), B2 (3), C1 (4), and C2 (5) were obtained from the seeds of Dolichos lablab L. Their structures were established based on spectroscopic analyses and chemical reactions. Among the known compounds, 9, 10, 14, 17, 19, and 22-24 were gained from the family Leguminosae for the first time, and 6, 8, 11-13, 15, 16, 18, 20, as well as 21 were firstly identified from Dolichos genus. Moreover, the inhibitory effect evaluation of all the isolates against LPS-induced nitric oxide (NO) production in RAW264.7 macrophages suggested that compounds 1-3, 6, 7, 11-15, 17, 20, 21, 23, 24 exhibited anti-inflammatory activity in a concentration-dependent manner. Moreover, the novel compounds, dolilabphenosides A (1), B1 (2), B2 (3) were found to inhibit the secretion of inflammatory cytokine IL-1ß.

Study on the interaction and functional properties of Dolichos lablab L. protein-tea polyphenols complexes.

Tea polyphenols (TP) and plant proteins are significant materials in the food industry, the interactions between them are beneficial for their stability, functional properties, and biological activity. In this study, the mechanism and interaction between Dolichos lablab L. protein (DLP) obtained from nine treatments and three tea polyphenol monomers (EGCG, ECG, and EGC) were investigated. The results showed that the fluorescence of DLP was noticeably quenched and exhibited static quenching after the addition of polyphenols. DLP exhibited 1-2 binding sites for EGCG and ECG, but weakly binding to EGC (<1). The binding sites of DLP-TP were found to be in close proximity to the tyrosine residues, primarily interacting through hydrophobic interactions, van der Waals forces, and hydrogen bonds. The antioxidant capacity of DLP-TP compound was significantly improved after digestion. ECG showed a strong resistance to intestinal digestion. Compared with ECG (653.456 µg/mL), the content of free tea polyphenols of 20/40 kHz-ECG after digestion was 732.42 µg/mL. DLP-TP complexes significantly improved the storage stability, thermal stability, and bioaccessibility of tea polyphenols. The interaction between TP and DLP, as a protein-polyphenol complex, has great potential for application in preparing emulsion delivery systems due to their antioxidant activity and improved stability.

The effects of Cynodon dactylon (Poaceae family) and Dolichos biflorus (Fabaceae family) extracts on decreasing size and excretion of kidney and urinary tract stones: a randomized, double-blind controlled trial.

OBJECTIVES: Given high and growing prevalence rate of urolithiasis in most societies as well as the problems caused by this issue, it is necessary to apply more cost-effective and safer therapeutic methods, which are accessible for all the individuals worldwide. Therefore, this study aimed to investigate efficacy of herbal medicines named Cynodon dactylon and Dolichos biflorus on solving and excretion of renal and urinary tract stones in patients with urolithiasis. METHODS: This study included 96 patients with urolithiasis who were randomly allocated into three groups. The first group received the extract of D. biflorus seeds (1,600 mg), the second group received extract of C. dactylon rhizome (1,600 mg) and the third group received placebo for 21 days. In this study, we used an hydroalcoholic extract of D. biflorus and C. dactylon prepared by Soxhlet method. For each patient, the size of the stones, the amount of calcium in the urine, the number of stones excreted and their chemical substance type were measured. RESULTS: In this study, changes were observed at the significance level in the interventions groups of 1 and 2, and the placebo group in the left kidney, so that changes in size of the stone in left kidney as intergroup were significantly different in these three groups (p=0.02). The mean of changes in stone size in left kidney in the group C. dactylon was 3.78 ± 7.1 and in the group D. biflorus, it was 0.27 ± 0.6. CONCLUSIONS: A significant difference in the results of this study show that C. dactylon rhizome and D. biflorus seed extracts are able to decrease the size of the stone and can be effective on kidney stones excretion.

In-vitro anti-inflammatory activity of serine protease inhibitor from Cassia siamea and Dolichos biflorus: A comparative study.

Cassia siamea is a nonedible legume belonging to Fabaceae. The seed of C. siamea contains ~16% of protein. The study reports the biochemical characterization of purified novel serine protease inhibitor from seeds of C. siamea, aimed with assessing the anti-inflammatory activity. The seed extract was subjected to ammonium sulfate precipitation followed by fast protein liquid chromatography (FPLC)-anion exchange chromatography and affinity-chromatography to obtain a relative pure protease inhibitor. Thirty-fivefold purification with the specific activity of 250 U/mg of trypsin inhibitory unit was obtained. The characterization of protease inhibitor for optimum temperature, pH, and metal ions were measured using N-α-benzoyl-DL-arginine-p-nitroanilide (BAPNA) assay and casein zymogram. The C. siamea trypsin inhibitor (CsTI) has a relative molecular mass of 25.540 kDa. Purified CsTI and Dolichos biflorus were tested for anti-inflammatory efficacy against A549 and RAW264.7 cell lines. The inhibitory activity of both purified inhibitors are comparable and are potent toward anti-inflammatory activity. The purified inhibitor shows to be a promising candidate as anti-inflammatory agent by targeting the serine proteases.

Structural characteristic of pectin-glucuronoxylan complex from Dolichos lablab L. hull.

Polysaccharides are important constituents in Dolichos lablab hull. Herein, pectin-glucuronoxylan complex from D. lablab hull designated as DLHP-3 (D. lablab hull polysaccharide,) was prepared by ion exchange and gel permeation chromatography, and further characterized by acid degradation and enzymatic hydrolysis, methylation combined with GC-MS, NMR and MALDI-TOF-MS analysis. Both of pectin and glucuronoxylan regions were found in DLHP-3. The glucuronoxylan region consisted of a →4)-ß-Xylp-(1→ backbone with branches of α-GlcpA-(1→ substituted at O-2 site, and the ratio of xylose to glucuronic acid was about 5:1. Acetyl groups were mainly attached to O-3 site of →2,4)-ß-Xylp-(1→ residues. The main chain of pectin region could be represented by →4)-α-GalpA-(1→4)-α-GalpA-(1→ and →2)-α-Rhap-(1→4)-α-GalpA-(1→ with partial methyl-esterification. The side chains were deduced to embrace arabinan and arabinogalactan linked to rhamnogalacturonan-I region. Pectin was probably covalently bound to glucuronoxylan. Our findings uncovered the molecular structure of pectin-glucuronoxylan complex from D. lablab hull.

Assessment of natural DNA methylation variation and its association with economically important traits in dolichos bean (Lablab purpureus L. Var. Lignosus) using AMP-PCR assay.

As a prelude to exploit DNA methylation-induced variation, we hypothesized the existence of substantial natural DNA methylation variation and its association with economically important traits in dolichos bean, and tested it using amplified methylation polymorphism-polymerase chain reaction (AMP-PCR) assay. DNA methylation patterns such as internal, external, full and non-methylation were amplified in a set of 64 genotypes using 26 customized randomly amplified polymorphic DNA (RAPD) primers containing 5'CCGG3' sequence. The 64 genotypes included 60 germplasm accessions (GA), two advanced breeding lines (ABLs) and two released varieties. The ABLs and released varieties are referred to as improved germplasm accessions (IGA) in this study. The association of DNA methylation patterns with economically important traits such as days to 50% flowering, raceme length, fresh pods plant-1, fresh pod yield plant-1 and 100-fresh seed weight was explored. At least 50 genotypes were polymorphic for DNA methylation patterns at 10 loci generated by seven of the 26 RAPD primers. The GA and IGA differed significantly for total, full and external methylation and the frequency of methylation was higher in GA compared to that in IGA. The genotypes with external methylation produced longer racemes than those with full, internal and non-methylation in that order at polymorphic RAPD-11-242 locus. High pod yielding genotypes had significantly lower frequency of full methylation than low yielding ones. On the contrary, the genotypes that produced heavier fresh seeds harboured higher frequencies of total and externally methylated loci than those that produced lighter fresh seeds.

Isolation and structure characterization of glucuronoxylans from Dolichos lablab L. hull.

Polysaccharides were extracted by hot water and alkali in sequence from Dolichos lablab L. hull, and further purified by ion-exchange and gel columns. Hot water extracted D. lablab hull polysaccharide (DLHP) was rich in glucuronoxylan and pectin, and alkali extracted polysaccharide (DLHAP) mostly embraced glucuronoxylan. The structures of purified glucuronoxylans from DLHP and DLHAP were mainly analyzed by HPAEC-PAD, methylation combined with GC-MS, NMR and SEC-MALLS. DLHP-1 was identified as acetylated glucuronoxylan containing →4)-ß-Xylp-(1→ backbone with substitution at O-2 site by α-GlcpA/4-O-methyl-α-GlcpA. The molar ratio of ß-Xylp to α-GlcpA was 6.9:1, and acetylation was mainly at O-3 site of ß-Xylp with acetylation degree of 21.5%. DLHP-1 and DLHP-2 had similar physicochemical properties, except for molecular weight (Mw). DLHAP-1 was the non-methylated glucuronoxylan almost without acetylation, and it had the molar ratio of ß-Xylp to α-GlcpA of 5.6:1. Besides, DLHP-1 (Mw of 20.0 × 103 g mol-1) adopted semi-flexible chain, while DLHAP-1 (Mw of 15.4 × 103 g mol-1) showed flexible chain. These results provided a structural basis for study on polysaccharides from D. lablab hull, which was benefit for understanding biological activities and developing functional food or pharmaceuticals of D. lablab.

Noroleanane-type triterpenoids from Dolichos trilobus L. and their anti-α-glucosidase activities.

Falcatane A (1) and B (2), 4-oxo-3,24-dinor-2,4-secooleanane- and 3-oxo-24- noroleanane-type triterpenoids, together with seven known triterpenoids involving 2-hydroxy-3-oxo-24-noroleana-1,4,12-trien-28-oic acid (3) and oleanolic acid (4), were separated from the ethyl acetate roots extract of Dolichos trilobus using the column chromatography of silica gel, MCI gel, and Sephadex LH-20. The compounds were determined by analysis of IR, NMR spectroscopic data and mass spectrometry. In the bioassay, all isolates showed varying degree of the α-glucosidase inhibitory activity except compound 2.

Dolichos Lablab-an underutilized crop with future potentials for food and nutrition security: a review.

Achieving the Sustainable Development Goals (SDGs) particularly goal number two in developing countries by 2030 is challenging. The State of Food Security and Nutrition (2019) in the World show prevalence of undernourishment which has practically remained unchanged for the last three years. This calls for sustainable synergies between food and nutrition in addressing the challenge. Exploring the potential of underutilized legumes such as Dolichos Lablab (Lablab purpureus) in improving food and nutrition security is of importance. Lablab is known among nutritious underutilized diversified legumes, which is drought tolerant relative to other legumes. However, it is less popular as human food. This review focuses on providing details on the nutritional potential of underutilized Lablab varieties for food availability, accessibility and satisfactorily utilization for improved livelihood. So far research attention has been focusing on good agronomic performance with less information on their nutritional quality and its contribution to the wellbeing of people. Both wild and cultivated Lablab accessions do differ morphologically and across diverse habitat environments. This may make them less known, untapped and underutilized despite its promising potential as a food resource in developing countries where malnutrition still exists. Efforts are needed to popularize high-quality nutritional accessions, enhancing their consumption and commercialization for feeding the ever-increasing population in the future.

Phytochemical Fingerprinting and Activity of Extracts from the Leaves of Dolichos kilimandscharicus (Fabaceae) on Jurkat-T Cells.

Plants are a source of over a quarter of the prescription drugs currently in use worldwide. Zimbabwe has a rich plant biodiversity with only a limited number reported for the treatment of cancer. The leaf extracts of Dolichos kilimandscharicus were selected for the screening of their antiproliferative efficacy and cytotoxicity effects. This plant has increasingly been used by local folk as a treatment for cancer or cancer-related symptoms though its bioactivity has not been scientifically determined. This investigation also sought to identify constituent compounds in the crude extract preparations responsible for their antiproliferative efficacy. The antiproliferative effects of six-leaf extracts on Jurkat-T in vitro were investigated using the Trypan blue exclusion assay. The extracts were tested with increasing concentration, using chlorambucil as a standard anticancer drug. Cytotoxicity of extracts was determined against RAW 264.7 cells using a colorimetric tetrazolium-based assay. In additionthe ability of the extracts to induce apoptosis was determined for the most potent leaf extracts. The order of potency of the leaf extracts of D. kilimandscharicus against Jurkat-T cell line was found to be MeOH < Ethyl Acetate < DCM: MeOH < EtOH with IC50s of 33.56, 30.44, 22.93, and 21.59 µg/mL, respectively. Furthermore, the most potent extracts exhibited very low cytotoxicity against all the tested cells. D. kilimandscharicus leaf extracts induced apoptosis in the Jurkat-T cells as was shown by DNA fragmentation. UPLC-MS analysis of crude extracts led to the identification of 23 compounds from the ethanol extract and these may be responsible for the observed antiproliferative effects. Rutin, quercetin, luteolin, apigenin, hispidulin, kaempferol derivatives, as well as caffeoylquinic acid are some of the compounds identified in the extracts. The results of this study showed that the ethanol and ethyl acetate leaf extracts of D. kilimandscharicus have antiproliferative activity against Jurkat-T cells and may act by inducing apoptosis.. The current findings offer supporting evidence for the use of these plant species in the treatment of cancer in ethnomedicinal practices.

High resolution structural and functional analysis of a hemopexin motif protein from Dolichos.

It is increasingly evident that seed proteins exhibit specific functions in plant physiology. However, many proteins remain yet to be functionally characterized. We have screened the seed proteome of Dolichos which lead to identification and purification of a protein, DC25. The protein was monomeric and highly thermostable in extreme conditions of pH and salt. It was crystallized and structure determined at 1.28 Å resolution using x-ray crystallography. The high-resolution structure of the protein revealed a four-bladed ß-propeller hemopexin-type fold containing pseudo four-fold molecular symmetry at the central channel. While the structure exhibited homology with 2S albumins, variations in the loops connecting the outermost strands and the differences in surface-charge distribution may be relevant for distinct functions. Comparative study of the protein with other seed hemopexins revealed the presence of four conserved water molecules in between the blades which cross-link them and maintain the tertiary structure. The protein exhibited intrinsic peroxidase activity, which could be inhibited by binding of a heme analog. The identification of redox-sensitive cysteine and inhibition of peroxidase activity by iodoacetamide facilitated characterization of the possible active site. The determined peroxidase activity of DC25 may be responsible for rescuing germinating seeds from oxidative stress.

Triterpene Glycosides from the Seeds of Dolichos lablab.

Two new triterpene glycosides (1 and 2), together with nine known triterpene glycosides (3-11), were isolated from the seeds of Dolichos lablab (Leguminosae). The structures of the new compounds were determined by spectroscopic analysis, including two-dimensional NMR spectroscopy, and chromatographic analysis of the hydrolyzed products. The isolated compounds did not show cytotoxicity against HL-60 human leukemia cells and HepG2 human hepatoma cells at sample concentrations of 20 µM.

Utilization of extracts of Musa paradisica (banana) peels and Dolichos lablab (Indian bean) seeds as low-cost natural coagulants for turbidity removal from water.

In this study, aqueous extracts of Musa paradisica (banana) peels and Dolichos lablab (Indian beans) seeds were prepared and tested as natural coagulants for turbidity removal from simulated turbid water. Effects of extraction time (15, 30, and 45 min), dosage (0.2 to 1.0 mL/L), and water pH on turbidity removals by the natural coagulants were evaluated. In both cases, the extraction time of 45 min for the preparation of aqueous extract and dosage of 0.6 mL/L gave the best results in terms of turbidity removal. Natural coagulants from M. paradisica peels powder could efficiently remove turbidity (> 83%) at all tested pH values (3.0 to 12.0) with maximum turbidity removal of 98.14% at pH 11. In the case of D. lablab seeds, low turbidity removal (71-74%) was observed at pH between 5.0 and 9.0. The maximum turbidity removal (98.84%) was obtained at pH 11. The scanning electron microscopy (SEM) analysis of the settled flocs revealed that more compact flocs formed using M. paradisica peels extract than those developed using D. lablab seeds extract. The chemical analysis and Fourier transform infrared (FTIR) spectroscopy of the extracts revealed that polymeric substances (carbohydrate and proteins) having functional groups -OH, C-N, C-C, -COOH, and N-H might be responsible for the coagulation activity. The zeta potential measurements of natural coagulants revealed that the possible coagulation mechanism would be adsorption and bridging between particles. This study demonstrated the potential use of aqueous extracts of M. paradisica peels and D. lablab seeds as low-cost natural coagulants for turbidity removal.

α-Glucosidase Inhibitory and Anti-Inflammatory Coumestans from the Roots of Dolichos trilobus.

Four new coumestans dolichosins A - D (1: -4: ) were isolated from the roots of Dolichos trilobus, together with four known compounds: isosojagol (5: ), phaseol (6: ), psoralidin (7: ), and 4″,5″-dehydroisopsoralidin (8: ). Their structures were elucidated on the basis of spectroscopic data interpretation, mass spectrometric analyses, and the comparison with literature data of related compounds. The anti-inflammatory activity of these compounds (1: -8: ) was evaluated through the inhibition of nitric oxide production in lipopolysaccharide-activated murine macrophage RAW 264.7 cells, in which compounds 1: and 6: displayed moderate inhibitory activity and no cytotoxic effects. In a α-glucosidase inhibitory assay, compounds 1: and 5: -8: exhibited appreciable inhibition on α-glucosidase. Especially compounds 1, 7: , and 8: showed IC50 values lower than 20.0 µM.

Alleviation of Irritable Bowel Syndrome-Like Symptoms and Control of Gut and Brain Responses with Oral Administration of Dolichos lablab L. in a Mouse Model.

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder manifesting as unexplained abdominal pain and bowel habit changes. The pathogenesis of post-infectious IBS is associated with gut⁻brain axis dysfunction, including low-grade colonic inflammation and anxiety-related long-term brain changes. This study analyzed the efficacy of a standardized extract of Dolichos lablab L. extract (DL), a bean species, in an IBS mouse model resembling post-infectious, diarrhea-dominant IBS. Using a zymosan-induced animal IBS model, we found that oral administration of DL significantly attenuated zymosan-induced increases in colonic macroscopic scores and minimized weight loss without affecting food intake. In the DL-treated mice, the mast cell count and tumor necrosis factor-α level in the colon markedly decreased, similar to results in sulfasalazine-treated mice and in mice with lipopolysaccharide-stimulated bone marrow-derived mast cells. The number of visceral pain-related behaviors was much lower in the DL-treated mice. Anxiety-like behaviors significantly improved, comparable to that after treatment with amitriptyline. The c-Fos expression level in the prefrontal cortex was significantly reduced. Our data suggest that DL could be beneficial for treating IBS by acting on the gut and brain.

Anti-Obesity Activities of Chikusetsusaponin IVa and Dolichos lablab L. Seeds.

Obesity, a condition where excess body fat accumulates to the extent, causes a negative effect on health. Previously, we reported the extract of Dolichos lablab L. (DLL-Ex) inhibited high-fat diet (HFD)-induced increases in body weight and body fat mass and ameliorated increases in body weight. In the present work, we studyed the molecular mechanism for the inhibitory effect of DLL-Ex or Chikusetsusaponin IVa (CS-IVa), as isolated from Dolichos lablab L. (DLL) seeds extract, on adipocyte differentiation. We evaluated the effect of DLL-Ex, an anti-obesity agent, and CS-IVa, an active component of DLL-Ex, on 3T3-L1 cell differentiation via Oil red O assay and Q-PCR, along with their effects on CCAAT element binding protein alpha (C/EBPα), peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid synthase (FAS), and fatty acid-binding protein 4 (FABP4) mRNA transcriptions. FAS and FABP4 protein expression levels after exposure to CS-IVa were also tested. The results showed that DLL-Ex and CS-IVa have potent inhibitory activity on adipocyte differentiation. Therefore, DLL and CS-IVa may be developed as a functional food material to treat obesity.

Structural basis of noncanonical polyphenol oxidase activity in DLL-II: A lectin from Dolichos lablab.

Lectins known to possess an additional enzymatic function are called leczymes. Previous studies reported a unique polyphenol oxidase (PPO) activity in DLL-II-a leczyme from Dolichos lablab. DLL-II shares a high sequence and structural homology with DBL-another leczyme from Dolichos biflorus. Incidentally, DBL possesses lipoxygenase activity, but not the PPO activity. Legume lectins usually possess two metal-binding sites A and B. Although these sites are conserved in both DBL and DLL-II, site A in DLL-II is occupied by Mn2+ and site B by Ca2+ . In contrast, DLL-II binds Cu2+ and Ca2+ at sites A and B, respectively. Here, investigating the structural basis of PPO activity in DLL-II, we find that the PPO activity is only dependent on Cu2+ , but not Ca2+ ; and the lectin activity requires only Ca2+ . Further, our analysis suggests that an alternative mechanism of PPO reaction may be operative in DLL-II, which involves a mononuclear Cu2+ metal center; this is in contrast to the bi-nuclear Cu2+ metal center commonly observed in all PPOs. Importantly, structural and computational approaches employed here, we hypothesize possible PPO binding sites and the corresponding migration channels for accessing the active site.

Expression profiling of the Dolichos lablab lectin during germination and development of the seed.

The temporal expression of the field bean (Dolichos lablab) galactose specific lectin, DLL-II, during germination, post-germination and seed development was evaluated using Native-PAGE followed by activity staining, immunodetection and quantitative Real Time PCR (qPCR). A rapid and steep decline in the polyphenol oxidase (PPO) and hemagglutinating activity during the initial stages of germination, which did not correlate with the slow decline in total protein was observed. During post germination period, PPO and hemagglutination activities were negligible, whereas a rapid resorption of the protein was evident. These results suggest that DLL-II is not a storage protein. The presence of mRNA in the quiescent seed and initial stages of germination are indicative of a very stable mRNA. DLL-II was expressed in high copies during seed development and increased dramatically between 10 and 20 days after flowering (DAF), suggesting a switch over stage in DLL-II expression. Transcript levels reached a maximum at the mature stage of seed development. Among the non-seed tissues examined, root showed the highest level. The high affinity binding to kinetin and indole acetic acid, the key hormones that regulate root development and its vascular differentiation add a new dimension to the physiological role of DLL-II in the seed. This finding, coupled with the PPO and hemagglutinating activity makes DLL-II, truly a multifunctional protein.

A novel inhibition based biosensor using urease nanoconjugate entrapped biocomposite membrane for potentiometric glyphosate detection.

A potentiometric biosensor based on agarose-guar gum (A-G) entrapped bio-nanoconjugate of urease with gold nanoparticles (AUNps), has been reported for the first time for glyphosate detection. The biosensor is based on inhibition of urease activity by glyphosate, which was measured by direct potentiometry using ammonium ion selective electrode covered with A-G-urease nanoconjugate membrane. TEM and FTIR analysis revealed nanoconjugate formation and its immobilization in A-G matrix respectively. The composite biopolymer employed for immobilization yields thin, transparent, flexible membrane having superior mechanical strength and stability. It retains the maximum activity (92%) of urease with negligible leaching. The conjugation of urease with AUNps allows improvement in response characteristics for potentiometric measurement. The biosensor shows a linear response in the glyphosate concentration range from 0.5ppm-50ppm, with limit of detection at 0.5ppm, which covers maximum residual limit set by WHO for drinking water. The inhibition of catalytic activity of urease nanoconjugate by gyphosate was confirmed by FTIR analysis. The response of fabricated biosensor is selective towards glyphosate as against various other pesticides. The biosensor exhibits good performance in terms of reproducibility and prolonged storage stability of 180days. Thus, the present biosensor provides an alternative method for simple, selective and cost effective detection of glyphosate based on urease inhibition.