Thin-layer Chromatography Bioautography Research Articles

Direct coupling of thin-layer chromatography-bioautography with electrostatic field induced spray ionization-mass spectrometry for separation and identification of lipase inhibitors in lotus leaves

In situ profiling compounds in complex matrices is important technology to develop in analytic chemistry. The aim of this study is to develop a direct coupling method of thin layer chromatography (TLC) to mass spectrometry (MS) via electrostatic field induced spray ionization (EFISI). We proposed a surface treatment method of normal-phase thin layer chromatography (TLC) plates with dimethyl silicone oil coating which successfully allowed TLC to couple to MS via EFISI. Different parameters affecting the ionization efficiency were investigated and optimized, including silicone oil concentrations, air-drying times, applied voltages, and TLC plate types. This optimized TLC-EFISI-MS method was successfully applied to examine lipase inhibitory components present in lotus leaves. Six active alkaloids including three aporphines and three benzylisoquinolines were profiled with their MSn (n = 4) data, or with a comparison with reference substances. This is the first report on the coupling EFISI-MS to TLC or TLC bioautography for in situ identification of active natural products.

Inhibition of α-Glucosidase, Total Phenolic Content and Flavonoid Content on Skin Fruit and Flesh Extracts of Some Varieties of Snake Fruits

This study aimed to determine the antidiabetic activity of the skin fruit and flesh of snack fruit through α-glucosidase inhibition and correlated with total phenolic and flavonoid content as well as thin layer chromatography bio-autography. Seven varieties of varieties of skin and flesh of the fruits each extracted by maceration using ethanol 70%. The results show the highest power of the α-glucosidase inhibition obtained at Manonjaya skin extract with IC50 value of 17.9 µg/mL. The TLC pattern indicates the presence of four active spot on skin extract and two spots on flesh extracts on the use of solvent BuOH:HAc:water (6:2:2). The highest phenolic content obtained at skin fruit extract of Salak Mawar 186.15 ± 1.66 mg of gallic acid equivalents per gram extract. The highest total flavonoid content obtained in Salak Malaka skin fruit extract that is 7:43 ± 0:04 milli gram of quercetin equivalents

Research Advances and Detection Methodologies for Microbe-Derived Acetylcholinesterase Inhibitors: A Systemic Review.

Acetylcholinesterase inhibitors (AChEIs) are an attractive research subject owing to their potential applications in the treatment of neurodegenerative diseases. Fungi and bacteria are major producers of AChEIs. Their active ingredients of fermentation products include alkaloids, terpenoids, phenylpropanoids, and steroids. A variety of in vitro acetylcholinesterase inhibitor assays have been developed and used to measure the activity of acetylcholinesterases, including modified Ellman’s method, thin layer chromatography bioautography, and the combined liquid chromatography-mass spectrometry/modified Ellman’s method. In this review, we provide an overview of the different detection methodologies, the microbe-derived AChEIs, and their producing strains.

Antimicrobial and antioxidant activities of different solvent extracts from fermented and green honeybush (Cyclopia intermedia) plant material

Ethnopharmacological relevanceCyclopia intermedia is indigenous to South Africa and used to prepare honeybush herbal tea. This aromatic herbal tea has been associated with numerous health benefits, mostly based on anecdotal evidence and with very few studies reporting on the antimicrobial activities. AimThe inhibitory effect on the growth of important nosocomial microorganisms and possible association with the antioxidant capacity/content of various solvent extracts of green/unfermented and fermented honeybush plant material were determined in the current study. Materials and methodsThe agar disk diffusion assay was used as a screening assay for the antimicrobial activity of the various honeybush extracts, while the minimal inhibitory concentration (MIC) values, using the broth micro-dilution method, were determined against Streptococcus pyogenes, Staphylococcus aureus and Candida albicans. Active antimicrobial compounds were then shown using thin layer chromatography bioautography. Total antioxidant capacities and -content were also determined for each extract, while the main phenolic compounds were quantified using HPLC. ResultsSix of the eight solvent extracts of honeybush showed antimicrobial activity, with the fermented and green methanol extracts being most effective against S. aureus and C. albicans respectively, whilst the green chloroform extract was most potent against S. pyogenes. Thin layer chromatography-bioautography acknowledged the existence of active antimicrobial fractions within these different solvent honeybush extracts. Regardless of the assay, the green honeybush extracts generally exhibited the highest antioxidant capacity when compared to the fermented honeybush. The total polyphenols were also observed to be highest in green extracts when using water and methanol as solvents. In general the mangiferin and hesperidin contents were higher in the green than the fermented extracts of honeybush plant material. ConclusionsThe inhibitory activity of the various extracts against specific microorganisms was observed to be linearly proportional to the extract concentration. Although the different solvent extracts can only be considered weak antimicrobial agents, three compounds showed specific activity and should be further elucidated in future. It appears the antioxidant capacity of the various solvent herbal extracts did not relate to the antimicrobial activities; however, further work will be required to ascertain this observation. The current data also suggested that the various extracts of honeybush can be considered a good source of a unique blend of natural phytochemical antioxidants and antimicrobial compounds and should be further elucidated.

Three new compounds from the seeds of Trachyspermum copticum

ABSTRACTThe effect of the application of nano-silicon (SiO2; 1.5 and 3 mM) on components of essential oils of Trachyspermum copticum was evaluated. Essential oils extracted by hydrodistillation from Iranian T. copticum was characterized by means of gas chromatography-mass spectrometry and Nuclear Magnetic Resonance. Three new compounds, (1) 2, 5-Dihydroxy-4-methoxy-phenanthrene 2-O-b-Dglucopyranoside; (2) 4-Methoxy-2,5,7,9S tetrahydroxy-9,10-dihydrophenanthrene; and (3) trans-Ethyl cinnamate along with 12 known were isolated from the Eos T. copticum. The essential oil was also subjected to antimicrobial and antioxidant activities. The new compounds were particularly active against Bacillus cereus and Candida albicans, with the lowest minimum inhibitory concentration and minimum bactericidal concentration and minimum fungicidal concentration value. Three new compounds exhibited a higher activity in each antioxidant system with a special attention for β-carotene bleaching test, lipid peroxidation inhibition, and reducing power. The Thin-layer chromatography-bioautography screening and fractionation resulted in the separation of the main antioxidant compound which were identified as trans-Ethyl cinnamate (3). These results indicated that three new compounds might be applicable in natural medicine and healthy food.

Evaluation of in vitro antimicrobial potential and phytochemical analysis of spruce, cajeput and jamrosa essential oil against clinical isolates

Objective: To investigate the phytochemical constituents and thin-layer chromatography (TLC) bioautography of Picea abies (spruce), Melaleuca spp. (cajeput), and Cymbopogon khasans (jamrosa) essential oils. The in vitro antimicrobial potential was also determined against fungal isolates and Gram-positive and Gram-negative bacterial strains isolated from human infections. Materials and Methods: A preliminary phytochemical analysis was performed. The antimicrobial potential of essential oil from spruce, cajeput and jamrosa was evaluated by agar well diffusion method against clinical isolates. The antibacterial effect was investigated using the TLC-bioautographic method. Results: Phytoconstituents analysis demonstrated the presence of few phytochemicals including steroids, reducing sugars and cardiac glycosides in all the tested samples. The essential oils were further investigated for its antimicrobial activity against 11 bacterial clinical isolates and 4 fungi, respectively. The oils showed broad antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal isolates including Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Acinetobacter spp., and Aspergillus niger. The highest in vitro inhibitory activity was observed for S. aureus with a maximum zone of inhibition (27 ± 0.05 mm in diameter) for cajeput essential oil followed by 23 ± 0.07 mm for jamrosa oil against Acinetobacter spp. Among fungal isolates tested, the growth of only A. niger and Aspergillus spp. was inhibited. TLC bioautography assay demonstrated two big spot and one small spot observed at Rf values 0.083 and 0.33 (active spots) and 0.47 (inactive spot) against S. aureus 3 and S. aureus 1. Conclusions: It can be concluded that the essential oils from cajeput and jamrosa possessing antimicrobial potential against clinical isolates can be used in the treatment of various microbial infections.

In Vitro Antimicrobial Bioassays, DPPH Radical Scavenging Activity, and FTIR Spectroscopy Analysis of Heliotropium bacciferum.

The present study deals with the antimicrobial, antioxidant, and functional group analysis of Heliotropium bacciferum extracts. Disc diffusion susceptibility method was followed for antimicrobial assessment. Noteworthy antimicrobial activities were recorded by various plant extracts against antibiotic resistant microorganisms. Plant flower extracts antioxidant activity was investigated against 2, 2-diphenyl-1-picryl hydrazyl radical by ultraviolet spectrophotometer (517 nm). Plant extracts displayed noteworthy radical scavenging activities at all concentrations (25–225 μg/mL). Notable activities were recorded by crude, chloroform and ethyl acetate extracts up to 88.27% at 225 μg/mL concentration. Compounds functional groups were examined by Fourier transform infrared spectroscopic studies. Alkanes, alkenes, alkyl halides, amines, carboxylic acids, amides, esters, alcohols, phenols, nitrocompounds, and aromatic compounds were identified by FTIR analysis. Thin layer chromatography bioautography was carried out for all plant extracts. Different bands were separated by various solvent systems. The results of the current study justify the use of Heliotropium bacciferum in traditional remedial herbal medicines.

Thin Layer Chromatography-Bioautography and Gas Chromatography-Mass Spectrometry of Antimicrobial Leaf Extracts from Philippine Piper betle L. against Multidrug-Resistant Bacteria.

This study isolated and identified the antimicrobial compounds of Philippine Piper betle L. leaf ethanol extracts by thin layer chromatography- (TLC-) bioautography and gas chromatography-mass spectrometry (GC-MS). Initially, TLC separation of the leaf ethanol extracts provided a maximum of eight compounds with R f values of 0.92, 0.86, 0.76, 0.53, 0.40, 0.25, 0.13, and 0.013, best visualized when inspected under UV 366 nm. Agar-overlay bioautography of the isolated compounds demonstrated two spots with R f values of 0.86 and 0.13 showing inhibitory activities against two Gram-positive multidrug-resistant (MDR) bacteria, namely, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The compound with an R f value of 0.86 also possessed inhibitory activity against Gram-negative MDR bacteria, namely, carbapenem-resistant Enterobacteriaceae-Klebsiella pneumoniae and metallo-β-lactamase-producing Acinetobacter baumannii. GC-MS was performed to identify the semivolatile and volatile compounds present in the leaf ethanol extracts. Six compounds were identified, four of which are new compounds that have not been mentioned in the medical literature. The chemical compounds isolated include ethyl diazoacetate, tris(trifluoromethyl)phosphine, heptafluorobutyrate, 3-fluoro-2-propynenitrite, 4-(2-propenyl)phenol, and eugenol. The results of this study could lead to the development of novel therapeutic agents capable of dealing with specific diseases that either have weakened reaction or are currently not responsive to existing drugs.

Characterization of Culturable Actinomycetes Associated with Halophytic Rhizosphere as Potential Source of Antibiotics

The global-scale failure of bacterial drug resistance calls for an urgent need to develop novel antibiotics. Actinomycetes from marshy land or mangrove environment are relatively less explored for novel antibiotics against drug resistant pathogens. In the present work, the authors have characterized a few actinomycete isolates from rhizosphere region of two halophytes, Rhizophora mucronata and Achrostichum aureum which showed potential antagonistic property against Methicillin-resistant Staphylococcus aureus. 16S rDNA phylogenetic analyses revealed four clusters of actinomycetes belonging to the genera Streptomyces, Saccharopolyspora, Rhodococcus and Micromonospora. The bioactive metabolites were produced through agar plate fermentation and extracted with ethyl acetate. Thin layer chromatography bioautography confirmed the presence of anti-MRSA substances by 2,3,5-triphenyl-tetrazolium chloride based detection. The most active five compounds were purified through column chromatography and were found to be diverse molecules based on UV–Vis spectrum and reverse phase high performance liquid chromatography. Time kill experiments of partially purified active principles had proved the antibiotic potential against MRSA. Further activity-guided HPLC fractionation and characterization of these MRSA active actinomycetes are expected to reveal novel antibiotics with feasible potentials against broad spectrum of pathogens.

Rapid identification of α-glucosidase inhibitors from Phlomis tuberosa by Sepbox chromatography and thin-layer chromatography bioautography.

Alpha-glucosidase inhibitors currently form an important basis for developing novel drugs for diabetes treatment. In our preliminary tests, the ethyl acetate fraction of Phlomis tuberosa extracts showed significant α-glucosidase inhibitory activity (IC₅₀ = 100 μg/mL). In the present study, a combined method using Sepbox chromatography and thin-layer chromatography (TLC) bioautography was developed to probe α-glucosidase inhibitors further. The ethyl acetate fraction of P. tuberosa extracts was separated into 150 individual subfractions within 20 h using Sepbox chromatography. Then, under the guidance of TLC bioautography, 20 compounds were successfully isolated from these fractions, including four new diterpenoids [14-hydroxyabieta-8,11,13-triene-11-carbaldehyde-18-oic-12-carboxy-13-(1-hydroxy-1-methylethyl)-lactone (1), 14-hydroxyabieta-8,11,13-triene-17-oic-12-carboxy-13-(1-hydroxy-1-methylethyl)-lactone (2), 14,16-dihydroxyabieta-8,11,13-triene-15,17-dioic acid (3), and phlomisol (15,16-eposy-8,13(16),14-labdatrien-19-ol) (4)], and 16 known compounds. Activity estimation indicated that 15 compounds showed more potent α-glucosidase inhibitory effects (with IC50 values in the range 0.067–1.203 mM) than the positive control, acarbose (IC50 = 3.72 ± 0.113 mM). This is the first report of separation of α-glucosidase inhibitors from P. tuberosa.

Endophytic Fungi Isolated from Coleus amboinicus Lour Exhibited Antimicrobial Activity.

Coleus amboinicus is a medicinal plant traditionally used to treat various diseases such as throat infection, cough and fever, diarrhea, nasal congestion and digestive problems. The plant was explored for endophytic fungi producing antimicrobial agents. Screening for endophytic fungi producing antimicrobial agents was conducted using agar plug method and antimicrobial activity of promising ethyl acetate extracts was determined by disc diffusion assay. Thin layer chromatography (TLC) - bioautography was performed to localize the bioactive components within the extract. TLC visualization detection reagents were used to preliminary analyze phytochemical groups of the bioactive compounds. Three endophytic fungi were obtained, two of them showed promising potential. Agar diffusion method showed that endophytic fungi CAL-2 exhibited antimicrobial activity against P. aeruginosa, B. subtilis, S. aureus and S. thypi, whilst CAS-1 inhibited the growth of B. subtilis. TLC bioautography of ethyl acetate extract of CAL-2 revealed at least three bands exhibited antimicrobial activity and at least two bands showed inhibition of B. subtilis growth. Preliminary analysis of the crude extracts suggests that bioactive compounds within CAL-2 extract are terpenoids, phenolics and phenyl propanoid compounds whilst the antimicrobial agents within CAS-1 extract are terpenoids, propylpropanoids, alkaloids or heterocyclic nitrogen compounds. These data suggest the potential of endophytic fungi of C. amboinicus as source for antimicrobial agents.

Gas Chromatography-Mass Spectrometry Analyses for Detection and Identification of Antioxidant Constituents of Achillea tenuifolia Essential Oil

The present work was designed to study the antioxidant activity and to identify the main active components of the essential oil of Achillea tenuifolia aerial parts. Gas chromatography-mass spectrometry analyses of the essential oil showed the presence of 22 compounds. The main constituents of the oil were thymol (15%), α-pinene (10.11%), Camphene (9.41%), β-pinene (7.54%), α-terpinene (7.21%), p-cymene (4%), 1,8-cineole (2.31%), γ-terpinene (7%), linalool (10%), and carvacrol (20.43%). The antioxidant and free radical scavenging activities of Achillea tenuifolia oil was evaluated by using 2,20-diphenyl-1-picrylhydrazyl assays. The oil exhibited a considerable dose-dependent antioxidant activity. Thymol showed clearly a higher activity (IC50 = 10.04 ± 0.1 μg/ml) followed by Achillea tenuifolia essential oil (15.12 ± 0.4 μg/ml). Antioxidant activity guided fractionation of the oil was carried out by the thin layer chromatography-bioautography screening and fractionation resulted in the separation of the main antioxidant compound which was identified as thymol (80%).

HPTLC-MS as an efficient hyphenated technique for the rapid identification of antimicrobial compounds from propolis

The well-known anti-infective properties of propolis are determined by its chemical composition, which in turn is influenced by geographical factors and reflects the botanical diversity in the vicinity of the beehive. Although there are several reports on the anti-infective properties of crude propolis, few are aimed at identifying specific compound(s) responsible for the observed activities. Using South African propolis as an example, the application of high performance thin layer chromatography-bioautography in tandem with mass spectrometry was investigated for the rapid identification of antimicrobial and anti-quorum sensing (anti-QS) compounds. Pinocembrin was found to be responsible for the observed antifungal activity of the propolis against Candida albicans. Three compounds were found to be active against all of the evaluated Gram-positive and Gram-negative bacteria. The identity of the first was confirmed as pinobanksin, one remains unidentified, while the third corresponds to either pinobanksin 3-O-pentanoate or 2-methylbutyrate. The identification of caffeic acid as the anti-QS component was confirmed quantitatively using the violacein inhibitory assay.

Antimicrobial and cytotoxic activities of endophytic fungi isolated from Piper crocatum Ruiz & Pav

To investigate antimicrobial and cytotoxic activities of endophytic fungi isolated from Piper crocatum Ruiz & Pav (P. crocatum). Ethyl acetate extracts were obtained by liquid-liquid partition of fermentation broth of endophytes followed by evaporation. The antimicrobial activities were determined by diffusion techniques followed by thin layer chromatography-bioautography. Cytotoxicity studies were conducted using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Data generated were used to plot a dose-response curve, of which the concentration of extract required to kill 50% of cell population (IC50) was determined. Two endophytes were isolated from leaves and stem of P. crocatum, designated as DS1 and BS1. Ethyl acetate extracts of BS1 was found to inhibit the growth of Bacillus subtilis, Escherichia coli and Staphylococcus aureus at minimum dose of 31.25, 125 and 250 µg, respectively. thin layer chromatography-bioautography of this extract resulted in at least two inhibition zones. BS1 extract also inhibited the growth of WiDr and T47D cell lines with IC50 of 120.38 µg/mL and 37.43 µg/mL, respectively. BS1 extract produced by endophytic fungi of P. crocatum is potential to be developed as source of novel bioactive compounds.

Quick identification of xanthine oxidase inhibitor and antioxidant from Erycibe obtusifolia by a drug discovery platform composed of multiple mass spectrometric platforms and thin-layer chromatography bioautography.

As a final step of the purine metabolism process, xanthine oxidase catalyzes the oxidation of hypoxanthine and xanthine into uric acid. Our research has demonstrated that Erycibe obtusifolia has xanthine oxidase inhibitory properties. The purpose of this paper is to describe a new strategy based on a combination of multiple mass spectrometric platforms and thin-layer chromatography bioautography for effectively screening the xanthine oxidase inhibitory and antioxidant properties of E. obtusifolia. This strategy was accomplished through the following steps. (i) Separate the extract of E. obtusifolia into fractions by an autopurification system controlled by liquid chromatography with mass spectrometry. (ii) Determine the active fractions of E. obtusifolia by thin-layer chromatography bioautography. (iii) Identify the structure of the main active compounds with the information provided by direct analysis in real time mass spectrometry. (iv) Calculate the IC50 value of each compound against xanthine oxidase using high-performance liquid chromatography. Using the caulis of E. obtusifolia as the experimental material, seven target peaks were screened out as xanthine oxidase inhibitors or antioxidants. Our screening strategy allows for rapid analysis of small molecules with almost no sample preparation and can be completed within a week, making it a useful assay to identify unstable compounds and provide the empirical foundation for E. obtusifolia as a natural remedy for gout and oxidative-stress-related diseases.

English

Ixora coccinea L. (Rubiaceae) has been used traditionally for a variety of ailments and also cultivated for ornamental purposes. The present study investigated antimicrobial activity of methanolic extracts of various parts of I. coccinea and determined the chemical groups of the active constituents. Antimicrobial activity was assessed using agar disc diffusion, microdilution and thin layer chromatography (TLC) bioautography assays. Methanolic extracts of leaf, flower and stem of I. coccinea displayed good antimicrobial activity, with inhibition zone in the range of 6.7 to 11.3 mm. minimum inhibitory concentration (MIC) values for all three extracts ranged from 0.78 to 3.125 mg/ml. Leaf and stem extracts of I. coccinea showed broad-spectrum antimicrobial activity. Of interest, stem extracts had MIC values against Staphylococcus aureus that were only 62.4 times less potent than the vancomycin. Likewise, leaf and stem extracts displayed good antimicrobial activity of 62.4 and 31.2 times, respectively lesser than gentamycin against Shigella flexneri. Minimum bactericidal/ bacteriostatic concentration (MBC) values for active extracts ranged from 0.78 to 6.25 mg/ml. TLC bioautography and phytochemical screening of the leaf and stem extracts showed that the antimicrobial activity of these extracts may be attributed to compounds belonging to terpenoid, flavonoid, coumarin, alkaloid and phenolic groups. Key words: Antimicrobial, Ixora coccinea, minimum inhibitory concentration, minimum bacteriostatic/bacteriocidal concentration, bioautography.

Cyperus rotundus: A potential novel source of therapeutic compound against urinary tract pathogens

Bioactive compounds from medicinal plants offer a potentially beneficial alternative to synthetic antibiotics. The crude extract of Cyperus rotundus was screened for antiuropathogenic activity using the disc diffusion method, which indicated its broad-spectrum antibacterial activity against urinary tract infection (UTI) pathogens. The minimum inhibitory concentrations of the ethanolic extract ranged from 2.5 to 10mg/mL against different uropathogens. Phytochemical analysis of C. rotundus showed the presence of tannins and saponins. Thin layer chromatography (TLC) analysis of the ethanolic extract indicated the presence of two spots. The TLC bioautography confirmed the antibacterial activity of the spot with a resolution front (Rf) of 0.435, which indicated its bioactive property. High performance liquid chromatography (HPLC) was validated using parameters such as linearity, accuracy, precision, limit of detection and limit of quantification. HPLC analysis of the active spot indicated the presence of saponins only, with a retention time of 16.102min. Quantitative studies revealed that 75.6373mg/mL of saponin was present in the ethanolic extract of the rhizome of C. rotundus. Therefore, the study scientifically validated the use of C. rotundus plant for the treatment of UTIs by tribal populations and advocated the potential application of the bioactive compounds from C. rotundus for the treatment of UTIs.

Anti-cholinesterase activity of the standardized extract of Syzygium aromaticum L.

Background:Clove (Syzygium aromaticum) is a well-known culinary spice with strong aroma; contains a high amount of oil known as clove oil. The major phyto-constituent of the clove oil is eugenol. Clove and its oil possess various medicinal uses in indigenous medicine as an antiseptic, anti-oxidant, analgesic and neuroprotective properties. Thus, it draws much attention among researchers from pharmaceutical, food and cosmetic industries.Objective:The aim of the present study was to determine the anti-cholinesterase activity of the methanol extract of clove, its oil and eugenol.Materials and Methods:In vitro anti-cholinesterase activity of S. aromaticum was performed by a thin layer chromatography bio autography, 96 well micro titer plate and kinetic methods. Reverse phase high performance liquid chromatography (RP-HPLC) analysis was carried out to identify the biomarker compound eugenol in clove oil.Results:Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition study revealed that eugenol possess better inhibition of the enzymes than extract and oil. Clove extract, its oil and eugenol showed better inhibition of AChE than BChE. Polyphenolic compound eugenol was detected through RP-HPLC analysis. The content of eugenol in essential oil was found to be 0.5 μg/ml. Kinetic analysis of the cholinesterase inhibition study of the extract; clove oil and eugenol have shown that they possess mixed type of inhibition for AChE and non-competitive type of inhibition for BChE.Conclusion:These results might be useful in explaining the effect of clove as anti-cholinesterase agent for the management of cognitive ailments like Alzheimer's disease.

A Comparative Study on Antioxidant Potentials of Some Leafy Vegetables Consumed Widely in India

The antioxidant activities with respect to the 2,2-diphenyl-1-picrylhydrazyl (DPPH)-radical scavenging activity and reducing activity were assessed and compared for seven edible leafy vegetables (Enhydra fluctuans, Glinus oppositifolius, Amaranthus sp.1, Amaranthus sp.2, Amaranthus spinosus, Ipomoea aquatica and Corchorus sp.) widely consumed in India, especially West Bengal state. Phytochemical analysis of these vegetables revealed the presence of phenolics (gallic acid equivalents 2.87–61.85 mg/g), flavonoids (quercetin equivalents 2.75–406.98 mg/g) and tannins (tannic acid equivalents 7.39–32.52 mg/g). Two of the samples, E. fluctuans and Corchorus sp. exhibited remarkable DPPH radical scavenging activities (>70%) with significant IC50 values of 65.04 and 128.95 μg/mL, respectively. Extracts of these two species were also found to possess significant Fe3+-reducing activities. The constituents of the extracts were separated by thin layer chromatography (TLC) and the positions of the antioxidative active fractions were determined using TLC bioautography followed by spraying with DPPH solution. The study suggested E. fluctuans and Corchorus sp. to be potential sources of antioxidative compounds. Practical Applications Concerns regarding the use of synthetic antioxidants as preservatives in the food industry, because of their toxicity and harmful health hazards, have resulted in the limitation of their usage in the food industry. This has necessitated urgent search for novel antioxidative compounds of natural origin for use as food supplements as well as preservatives in the food industry. Many of the fruits and vegetables consumed daily possess significant antioxidant activities and are good sources of natural antioxidative compounds. The selected seven leafy vegetables, all of which are widely consumed in India, were studied with respect to their relative antioxidative potentials. Accordingly, E. fluctuans followed by Corchorus sp. were found to have the best potential as sources of natural antioxidative compounds for uses in nutraceutical and food industry.

Dereplication strategy for antimicrobial metabolite using thin-layer chromatography-bioautography and LC-PDA-MS analysis

Rapid identification of known compounds, i.e., dereplication, has become a strategically important area for the natural-product chemists involved in bioprospecting of microbes for novel bioactive metabolites. Among microbial biodiversity, endophytic fungi represent an abundant and dependable source of structurally diverse bioactive metabolites. During the course of screening for antimicrobial secondary metabolites from endophytic fungi, an antimicrobial metabolite was identified from the ethyl acetate extract obtained from the culture broth of Xylaria sp., an endophytic fungus from Ficus pumila Linn. (Moraceae) that exhibited a broad spectrum of antimicrobial activity against human and phytopathogenic bacteria and fungi. Chemical investigation of the ethyl acetate fraction using thin-layer chromatography (TLC) bioautography and LC-hyphenated techniques led to the identification of a known benzoic acid derivative. Here, we describe the application of analytical strategies (TLC-bioautography) and hyphenated...